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Minor elements in pyrites from the smithers map area, b.c. and exploration applications of minor element… Price, Barry James 1972

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MINOR ELEMENTS IN PYRITES FROM THE SMITHERS MAP AREA, AND-EXPLORATION APPLICATIONS OF MINOR ELEMENT STUDIES by BARRY JAMES PRICE B.Sc. (1965) U.B.C. A t h e s i s submitted i n p a r t i a l f u l f i l l m e n t o f the requirements, f o r the degree of Master o f Science i n the DEPARTMENT OF GEOLOGY We accept t h i s t h e s i s as conforming to the r e q u i r e d standard TEE UNIVERSITY OF BRITISH. COLUMBIA A p r i l 1972 In present ing th i s thes is in pa r t i a l fu l f i lment o f the requirements for an advanced degree at the Un ive rs i t y of B r i t i s h Columbia, 1 agree that the L ib ra ry sha l l make it f r ee l y ava i l ab le for reference and study. I fu r ther agree that permission for extensive copying of th i s thes i s fo r s cho l a r l y purposes may be granted by the Head of my Department or by h i s representat ives . It is understood that copying or pub l i c a t i on o f th i s thes is fo r f i nanc ia l gain sha l l not be allowed without my wr i t ten permiss ion. Department of The Un ive rs i t y o f B r i t i s h Columbia Vancouver 8, Canada i MINOR ELEMENTS IN PYRITES FROM THE SMITHERS MAP AREA, B.C.  AND EXPLORATION APPLICATIONS OF  MINOR ELEMENT STUDIES • ABSTRACT This study was undertaken to determine minor element geo-chemistry of p y r i t e and the a p p l i c a b i l i t y of p y r i t e minor-element rese a r c h to e x p l o r a t i o n f o r m i n e r a l d e p o s i t s . Previous s t u d i e s show tha t Co, N i , and Cu are the most pre v a l e n t c a t i o n s s u b s t i t u t i n g f o r Fe i n the p y r i t e l a t t i c e ; s i g n i f i c a n t amounts of As and Se can s u b s t i t u t e f o r S. Other elements s u b s t i t u t e l e s s commonly and i n s m a l l e r amounts w i t h i n the l a t t i c e , i n i n t e r s t i t i a l s i t e s , o r w i t h i n d i s c r e t e mechanically-admixed phases. Mode of s u b s t i t u t i o n i s determined most e f f e c t i v e l y w i t h the e l e c t r o n microprobe. 2+ C a t i o n s u b s t i t u t i o n f o r Fe i s favored by t r a n s i t i o n elements w i t h non-bonding "d" e l e c t r o n s .in low-spin c o n f i g u r a t i o n s , an o c t a -h e d r a l covalent r a d i u s s i m i l a r to that o f Fe (1 .23 and h i g h e l e c t r o n e g a t i v i t y . Anion s u b s t i t u t i o n f o r S i s favored by chalcogeri and pnigogen elements w i t h a t e t r a h e d r a l c o o r d i n a t i o n r a d i u s c l o s e to 1.04 and h i g h e l e c t r o n e g a t i v i t y . S t a t i s t i c a l t e s t s performed on s e v e r a l hundred p y r i t e analyses compiled from the l i t e r a t u r e and s t o r e d on computer cards support: ( l ) log-normal frequency d i s t r i b u t i o n s of minor elements i n hydrothermal p y r i t e ; (2) r e d i s t r i b u t i o n of minor elements i n pyrite by metamorphism; (3) s t a t i s t i c a l d i f f e r e n t i a t i o n of hydro-thermal, volcanic-exhalative, and syngenetic pyrites on the basis of Co and Ni concentrations and r a t i o s ; (4) relationship of minor element "spectra" and concentrations i n disseminated p y r i t e to those i n adjacent rocks; and (5) relationship of minor-element concentra-tions i n hydrothermal pyrites to major ore-forming elements present. Forty pyrite samples from several d i s t i n c t types of mineral deposits i n the Smithers area, B.C. were analyzed f o r Co, Ni, Mn, Cu, Pb, and Zn using atomic-absorption spectrophotometry. Co concentrations are highest i n pyrites from volcanic rocks, massive sulphide deposits and a breccia pipe. Ni and Mn concentrations are uniformly lo*r. High contents of Cu, Fb, and Zn are caused by inclusions of common sulphides. Calculation of corre l a t i o n c o e f f i -cients f o r minor elements revealed that contamination does not s i g n i f i c a n t l y affect Co or Ni concentrations. Minor element data from the Smithers pyrites provides evidence f o r genetic relationships between several d i f f e r e n t mineral deposits, the presence of "metallogenetic" sub-provinces, and minor-element zonation i n mineral deposits. Research into minor-element geochemistry of pyrite can be useful i n exploration for mineral deposits; most ef f e c t i v e use i s during secondary stages of exploration. Most useful elements for exploration applications are Co, N i , Cu, Au, Ag, Hg, T l , Sn, As, and Se. ACKNOWLEDGMENTS I would l i k e to thank Dr. A.J. S i n c l a i r , who suggested the f i e l d of study, provided f i n a n c i a l a s s i s t a n c e f o r the •c o m p u t e r - b a s e d . s t a t i s t i c a l s t u d i e s , and who o f f e r e d much c o n s t r u c t i v e c r i t i c i s m and many h e l p f u l suggestions d u r i n g p r e p a r a t i o n o f the t h e s i s . F i e l d work was c a r r i e d out wh i l e the w r i t e r was employed by Manex -Mining L t d . , who provided t r a n s p o r t a t i o n and f i n a n c i a l a s s i s t a n c e f o r the p r o j e c t . Dr. W.K. F l e t c h e r provided f a c i l i t i e s f o r a n a l y t i c a l work, developed techniques f o r sample s o l u t i o n and e l i m i n a t i o n of a n a l y t i c a l i n t e r f e r e n c e s . Much t e c h n i c a l a s s i s t a n c e was provided d u r i n g sample p r e p a r a t i o n and a n a l y s i s by Mr. A. Bentzen and Mr. A. D h i l l o n . F a c i l i t i e s f o r r o c k - c r u s h i n g were provided by the M i n e r a l Engineering Department and Bondar-Clegg L t d . ( A s s a y e r s ) . F i n a l l y I would l i k e to thank A l e x i s Clague f o r t y p i n g the t h e s i s . i v TABLE OP CONTENTS Page. , ABSTRACT i ACKNOWLEDGMENTS i i i .TABLE OF CONTENTS i v LIST OF TABLES v i i i LIST OF FIGURES x i i INTRODUCTION 1 CHAPTER I PYRITE CRYSTAL CHEMISTRY 3. A. The P y r i t e Group and Related Groups 3 1. The P y r i t e Group 3 2. Marcasite and Other S t r u c t u r a l Groups 5 B. The R e l a t i o n s h i p o f C r y s t a l - F i e l d Theory 9 to P y r i t e Group M i n e r a l s C. The Co-Ni-Fe-S 2 System 22 1. N a t u r a l and S y n t h e t i c Phases 22 2. V a r i a t i o n of P r o p e r t i e s w i t h Composition 25 a. U n i t - c e l l Dimensions 26 b. Color, R e f l e c t i v i t y and Hardness 26 c. A n i s o t r o p i s m 33 d. Thermoelectric E f f e c t 35 CHAPTER I I MINOR ELEMENTS' CONTAINED IN PYRITE 37 A. General D i s c u s s i o n 37 TABLE OF CONTENTS (Continued) Page B. Anion S u b s t i t u t i o n i n P y r i t e - 40 C. C a t i o n S u b s t i t u t i o n i n P y r i t e 42 D. The I n c o r p o r a t i o n of Minor Elements i n P y r i t e 45 E. D i s t r i b u t i o n of Minor Elements w i t h i n a S i n g l e C r y s t a l 49 F. S p e c i f i c Minor Elements Contained i n P y r i t e 53 1. The Copper Content of P y r i t e 53 2. The Gold Content of P y r i t e 57 3 . The S i l v e r Content of P y r i t e 62 4. Platinum Group Elements i n P y r i t e 63 5c The Uranium Content of P y r i t e 64 6. T h a l l i u m Content of P y r i t e 67 7. The Mercury Content of P y r i t e 69 8. Manganese Content of P y r i t e 71 9. T i n Content of P y r i t e 71 10. The Selenium Content of P y r i t e 72 CHAPTER I I I THE GEOCHEMISTRY OF COBALT AND NICKEL IN ROCKS 77 A. Igneous Rocks 77 B. Sedimentary Rocks 83 C. Metamorphic Rocks 90 v i TABLE OF CONTENTS (Continued) Page CHAPTER IV STATISTICAL STUDIES OF MINOR ELEMENTS IN PYRITE . 95 A. I n t r o d u c t i o n 95 B. Frequency D i s t r i b u t i o n s of Minor Elements 97 C. Sedimentary P y r i t e 101 D. Massive-Sulphide - V o l c a n i c - E x h a l a t i v e P y r i t e 110 E. E f f e c t s o f Metamorphism on P y r i t e 112 F. Hydrothermal P y r i t e 124 1. Porphyry-Cu-Mo Deposits 124 2. Normal Vein and Replacement Deposits 129 G. Minor Elements i n P y r i t e and S i l i c a Content of A s s o c i a t e d Igneous Rocks 137 CHAPTER V MINOR ELEMENTS IN PYRITE FROM THE SMITHERS AREA, B.C. • 141 A. I n t r o d u c t i o n 141 B. General Geology of the Thesis Area 143 1. S t r a t i g r a p h y ' 143 2. S t r u c t u r e 143 3. Igneous Rocks 144 4. M i n e r a l Deposits 144 C. A n a l y t i c a l Method and R e s u l t s 146 D. D i s c u s s i o n of R e s u l t s 149 1. Dome Mountain Area 151 TABLE OF CONTENTS (Continued) Page 2. Grouse Mountain Area 152 a. Molymine Deposits 152 b. Other Deposits .162 3. E x p l o r a t i o n A p p l i c a t i o n s i n the S n i t h e r s Area 164 CHAPTER VI SUMMARY AND CONCLUSIONS - 166 APPENDICES I . PROPERTY DESCRIPTIONS 191 I I . • SAMPLE PREPARATION,. ANALYSIS, AND PRECISION CALCULATIONS . 211 I I I . EXPLANATION OF DATA FILING SYSTEM . " 221: IV. APPLICATION OF MINOR ELEMENT STUDIES -.• • TO EXPLORATION FOR MINERAL DEPOSITS 223 LIST OF TABLES Table Page 1. Pyrite Group - Minerals and properties 6 2. Electronic configurations of the elements of the f i r s t transition series 11 3. Electronic configurations and crys t a l - f i e l d stabilization energies of transition metal ions i n octahedral coordination 12 4. The number of non-bonding d-electrons i n -\": dianionic compounds - 16 5. Minerals with 6, 7, or 8 non-bonding "d"-electrons 16 6. Chalcogenides and pnictides of transition „ elements 17 7. Reflectivity and hardness values for the zoned bravoite crystal i n relation to composition 30 8. Reflectivities, effective number of free electrons and electronic configuration of cations in the pyrite type disulphides 32 9. Results of the quantitative determination of trace elements by the electron microprobe on the two types of pyrite 34 10. Physicochemical parameters of anions 40 11. Physical parameters of cations 43-44 12. Ionization potentials, electronegativities, and ionic r a d i i for divalent and trivalent cations 47 "13. Comparison of minor element content of pyrite crystal cores and margins, Belukhinskoye and Bukhinskoye deposits, U.S.S.R. 52 14. Uranium content of pyrite samples from uranium deposits 66 LIST OF TABLES (Continued) Table Page 15. Selenium content of pyrites from some 76 Canadian ore deposits • 16. Variation of cobalt and n i c k e l with rock types 78 17. Average Co and K i contents and Co/Ni. r a t i o s of sediments 83 18. Average Co, Ni contents and Co/Ni r a t i o s of syngenetic copper deposit sediments 84 19. Zero order correlations f o r Mn-Fe-Co-Ni i n sediments from various environments 89 20. Comparison of minor element content of medium and high-grade metamorphic rocks, Adirondack Mountains, New York 91 21. Comparison of minor element content of low, medium and high-grade metamorphic rocks, New Hampshire 91 22. Comparison of means, standard deviations and t-test values f o r "syngenetic',' "hydrothermal" and "massive sulphide" pyrites 107 23. Comparison of means, standard deviations, and t-test values for minor elements i n medium-grade and high-grade metamorphic pyrites 116 24. Comparison of means, standard deviations, and t-test values for minor elements i n pyrites from the Berg and Endako "porphyry" deposits 126-127 25. Minor element data - "porphyry" pyrites 130 26. Minor element data - hydrothermal vein and replacement pyrite 131 27. Comparison of means, standard deviations, and t-test values for minor elements i n pyrites from mineral deposits of di f f e r e n t major metals 133-134 28. Relationship of maximum Ni content and Ni/Co r a t i o of sulphides to composition of adjacent igneous rocks 138 LIST OF TABLES (Continued) Table Page 29. M i n e r a l d e p o s i t s of the Done Mountain-Grouse Mountain a r e a , Smithers, B.C. 145 30. P y r i t e analyses from Smithers. map a r e a , B.C. 147 31. Comparison of Dome Mountain and Dome Babine p y r i t e s 154 32. Comparison of means, standard d e v i a t i o n s and., t - t e s t v a l u e s f o r p y r i t e s from Dome Mountain and Grouse Mountain m i n e r a l d e p o s i t s 155 33. Comparison of Molymine p y r i t e s - minor element means 157 34. Comparison of Molymine p y r i t e - t - t e s t data 158-159 35. R e p l i c a t e analyses - Smithers and Tchentlo Lake p y r i t e s 217 36. P a i r e d p r e c i s i o n t e s t data f o r combined Smithers and Tchentlo Lake p y r i t e s 218 37. R e p l i c a t e analyses and p a i r e d p r e c i s i o n t e s t date f o r Smithers p y r i t e s 219 38. Minor element d a t a , Slocan and Slocan C i t y p y r i t e s 229 39. . New Brunswick v e i n and e x h a l a t i v e p y r i t e 231 40. Amount of ore i n each range of Co content a t the Kabu mine 245 41. Standard d e v i a t i o n s and c o e f f i c i e n t s o f determina-t i o n f o r the three c a l c u l a t e d t r e n d - s u r f a c e s i l l u s t r a t e d i n Figure 90 above 247 42. Selenium content of Noranda p y r i t e a n d - p y r r h o t i t e . w i t h depth 251 43. Selenium i n Campbell-Chibougamau p y r r h o t i t e w i t h depth 251 44. Selenium i n Geco s u l p h i d e s w i t h depth 251 LIST OF TA3LBS (Continued) Comparison of Co and Ni contents and Co/Ni r a t i o s i n p y r r h o t i t e s from economic and : "barren" m i n e r a l d e p o s i t s of the F l i n F l o n area D i s t r i b u t i o n of t r a c e elements among s p h a l e r i t e galena, and p y r i t e i n t i n , tungsten, and molybdenum-polymetallic ore d e p o s i t s of T r a n s b a i k a l i y a LIST OF FIGURES The s t r u c t u r e of p y r i t e Three dimensional view of the p y r i t e s t r u c t u r e The orthorhombic marcasite s t r u c t u r e The s t r u c t u r e of marcasite showing the S 2 group between the two i r o n t r i a d s Boundary su r f a c e s of atomic o r b i t a l s Molecular o r b i t a l e n e r g y - l e v e l diagram f o r p y r i t e Combination of octahedra i n (A) p y r i t e , (B) marcasite, ( c ) l o e l l i n g i t e , \D) a r s e n o p y r i t e Diagrammatic r e p r e s e n t a t i o n o f the i n t e r a c t i o n of the t£g o r b i t a l lobes i n s e c t i o n s p a r a l l e l to the c - a x i s : (A) marcasite, (B) l o e l l i n g i t e , ( c ) a r s e n o p y r i t e S o l i d - s o l u t i o n f i e l d s , shown i n shaded a r e a s , " i n v a r i o u s p o l y a n i o n i c compounds of Fe, Co, and N i : (A) d i s u l p h i d e s , (3) sulpha r s e n i d e s , ( c ) d i a r s e n i d e s , (D) t r i a r s e n i d e s S o l i d - s o l u t i o n f i e l d s f o r s y n t h e t i c phases i n the system Co-Ni-Fe~S2 at v a r i o u s temperatures N a t u r a l l y o c c u r r i n g s o l i d s o l u t i o n s i n the system Co-Ni-Fe-S2 V a r i a t i o n s of c e l l - e d g e w i t h composition i n the CoS2~CoSe2 system V a r i a t i o n of c e l l edge v/ith composition i n the NiS2-NiSe2 system Weight percentage c o b a l t p l o t t e d a g a i n s t the d(51l) spacing f o r members of the FeS2~CoS2 system C e l l edge versus composition f o r members of the FeS2~CuS2 system X l l l Figure LIST OF FIGURES (Continued) Page 16. L a t t i c e parameter "a" o f n a t u r a l and s y n t h e t i c p y r i t e s versus temperature 28 17. L a t t i c e parameter "a" of C0S2 versus temperature 28 18. L a t t i c e parameter "a" versus composition of mixed (Co,Fe)S 2 s u l p h i d e s a t 25°C 28 19. Change i n l e n g t h of c e l l - e d g e (Angstroms) w i t h i n c r e a s i n g atomic number of anion 29 20. Change i n l e n g t h of c e l l - e d g e (Angstroms) w i t h i n c r e a s i n g . a t o m i c number of c a t i o n 29 21. Zoned b r a v o i t e c r y s t a l s e l e c t e d f o r r e f l e c t i v i t y s t u d i e s 30 22. V a r i a t i o n i n r e f l e c t i v i t y (at 589 nm. i n a i r ) over the b r a v o i t e c r y s t a l 30 23. P l o t o f percent r e f l e c t i v i t y (R) a g a i n s t e f f e c t i v e number of f r e e e l e c t r o n s per u n i t volume ( H e f f ) f o r p y r i t e type compounds. Data f o r gold and s i l v e r are a l s o shown. 32 24. E l e c t r o n microprobe scan across p y r i t e c r y s t a l (a) V a r i a t i o n i n i n t e n s i t y o f CoK<* r a d i a t i o n : along scan p r o f i l e normal to growth steps of (100) (b) V a r i a t i o n i n i n t e n s i t y of CoK-* r a d i a t i o n normal to growth steps ( i l l ) 51 25. Copper zon a l p a t t e r n s i n i n t e r g r o w t h of p y r i t e c r y s t a l s as i n t e r p r e t e d from 15 e l e c t r o n micro-probe t r a v e r s e s 55 26. E l e c t r o n microprobe t r a c e of CuK«>< r a d i a t i o n along t r a v e r s e A-B 55 27. D i s t r i b u t i o n of gold and s i l v e r i n the p r i n c i p a l ore m i n e r a l s of the Almalyk d e p o s i t , U.S.S.R. 60 28. D i s t r i b u t i o n of selenium and t e l l u r i u m i n p r i n c i p a l ore minerals of the Almalyk ore d e p o s i t , U.S.S.R. 60 29. i ) Gold i n p y r i t e from i r o n skarns I i ) Gold i n p y r i t e from gold-quartz v e i n s 61 LIST OF FIGURES (Continued) V a r i a t i o n of Co, N i , Cu, and S i n rocks and r e s i d u a l melts of the Skaergaard igneous complex V a r i a t i o n of c o b a l t - n i c k e l r a t i o w i t h s i l i c a content o f igneous rocks S t a b i l i t y - f i e l d s f o r c o b a l t compounds as f u n c t i o n s of Eh and pH at 25° C and 1 atm, t o t a l pressure, c h l o r i n i t y 19 ppt. S t a b i l i t y c o n d i t i o n s of n i c k e l compounds under s i m i l a r c o n d i t i o n s as i n F i g u r e 32 S t a b i l i t y f i e l d s f o r manganese compounds as f u n c t i o n s of Eh and pH at 25° C and 1 atm. t o t a l pressure, c h l o r i n i t y = 19 ppt. D e p l e t i o n o f Co and Fe i n b i o t i t e adjacent to . qu a r t z - s c h e e l i t e - m o l y b d e n i t e v e i n s , K i c h i p i c o t e n area, Ontario Histogram of Ni i n p y r i t e from "porphyry" d e p o s i t s . A r i t h m e t i c data Histogram of Ni i n p y r i t e from "porphyry" d e p o s i t s . Logarithmic data Histogram of Co i n hydrothermal p y r i t e . A r i t h m e t i c data Histogram of Co i n hydrothermal p y r i t e . Logarithmic data Histogram of N i i n hydrothermal p y r i t e . A r i t h m e t i c data Histogram of N i i n hydrothermal p y r i t e . L ogarithmic data S c a t t e r diagram - Cobalt vs. N i c k e l i n syngenetic p y r i t e S c a t t e r diagram - Comparison of c o b a l t and n i c k e l content of marine sediments from the Red Sea and a s s o c i a t e d a u t h i g e n i c p y r i t e XV LIST OF FIGURES (Continued) F i g u r e Page 44. : Comparison of Co/Ni r a t i o s i n sediments and a s s o c i a t e d s u l p h i d e s of Red Sea d e p o s i t s 105 45. S c a t t e r diagram - Comparison of c o b a l t and n i c k e l content of syngenetic and v o l c a n i c exhala-t i v e (massive s u l p h i d e ) p y r i t e 108 46. Histogram of Co i n p y r i t e from sedimentary r o c k s . A r i t h m e t i c data 109 47. Histogram of Co i n p y r i t e from sedimentary r o c k s . Logarithmic data 109 48. Histogram of Ni i n p y r i t e from sedimentary r o c k s . A r i t h m e t i c data 109 49• Histogram of N i i n p y r i t e from sedimentary r o c k s . Logarithmic data 109 50. Cobalt and n i c k e l contents of p y r i t e s from main.types of ore d e p o s i t s i n the L i t t l e Carpathian mountains 113 51. Cobalt and n i c k e l contents o f p y r i t e s from 1 h i g h l y metamorphosed ores from Lower Carpathian d e p o s i t s 113 52. Histogram o f Co i n p y r i t e from medium-grade metamorphic r o c k s . A r i t h m e t i c data , . 117 53. Histogram of Co i n p y r i t e from medium-grade metamorphic r o c k s . Logarithmic data 117 54. Histogram of Ni i n p y r i t e from medium-grade metamorphic r o c k s . A r i t h m e t i c data 117 55. Histogram of Ni i n p y r i t e from medium-grade metamorphic r o c k s . Logarithmic data 117 56. Histogram of Co content of p y r i t e from h i g h -grade metamorphic r o c k s . A r i t h m i t i c data 118 57. Histogram of Co content of p y r i t e from h i g h -grade metamorphic r o c k s . Logarithmic data 118 LIST OF FIGURES (Continued) Histogram of Ni i n p y r i t e from high-grade metamorphic rocks. A r i t h m e t i c data Histogram of Ni i n p y r i t e from high-grade metamorphic rocks. Logarithmic data Comparison of c o b a l t and n i c k e l contents of p y r i t e s from medium and high-grade meta-morphic rocks i n the Carpathian mountains Comparison o f c o b a l t and n i c k e l contents of p y r i t e from Steeprock Lake and Cyprus d e p o s i t s V a r i a t i o n of Co contents and Co/Ni r a t i o s i n p y r i t e s w i t h depth. Data from Darneley (1962) Diagrammatic r e p r e s e n t a t i o n of general ranges, and means f o r c o b a l t and n i c k e l i n p y r i t e from s e v e r a l types of hydrothermal d e p o s i t s S c a t t e r diagram. Comparison of Co and Ni contents of igneous rocks and p y r i t e s disseminated i n igneous rocks G e o l o g i c a l map of the Smithers area, B.C. showing boundaries of t h e s i s area and l o c a t i o n of p r o p e r t i e s s t u d i e d S c a t t e r diagram - Co and Ni i n p y r i t e from Dome Mountain-Grouse Mountain area Comparison of Co/Ni r a t i o means f o r p y r i t e s from Dome Mountain and Grouse Mountain m i n e r a l d e p o s i t s Sketch map of Molymine b r e c c i a pipe Diagrammatic r e p r e s e n t a t i o n of m i n e r a l o g i c a l and minor element zonation i n Molymine b r e c c i a pipe Map of Dome Mountain area, near Smithers, B.C. showing gold-bearing quartz v e i n s and l o c a t i o n of samples BDM 1-7 LIST OF FIGURES (Continued) F i g u r e Page 71. Hap of Dome Babine gold prospect, east s i d e of Dome Mountain, showing l o c a t i o n of samples BD 1-6 196 72. Geologic map of Molymine prospect, showing sample l o c a t i o n s 201 73. Map of Copper Ridge Cu-Zn prospect on Grouse .Mountain, near Houston, B.C. showing l o c a t i o n of samples BCR 1,2 and 5 207 74. Map of La s t Chance Ag-Cu prospect on the n o r t h end of Grouse Mountain near Houston, B.C. 210 75. Flow sheet, p r e p a r a t i o n o f p y r i t e concentrates 214 76. Stocks ,• mines and tr a c e element groupings of c h a l c o p y r i t e and s p h a l e r i t e , C e n t r a l mining d i s t r i c t , New Mexico 225 77. D i s t i n c t i o n of c h a l c o p y r i t e o f the C e n t r a l d i s t r i c t based on Sn and In content 225 78. S c a t t e r diagram - Co vs. N i i n Tasmanian p y r i t e 227 79. Map of West of England showing g r a n i t e p l u t o n s ,( and l o c a t i o n of m i n e r a l d e p o s i t s 235 80.. R e l a t i o n s h i p of minor element content o f galena and s p h a l e r i t e to d i s t a n c e from g r a n i t e plutons 235 81. V a r i a t i o n i n minor element content of s p h a l e r i t e - from m i n e r a l d e p o s i t s of h i g h and low d e p o s i t i o n temperature 236 82. S c a t t e r diagram of bismuth and antimony contents of galena from d e p o s i t s i n carbonate rocks 237 83. Gallium-indium r a t i o s i n s p h a l e r i t e s of d i f f e r e n t o r i g i n s 238 84. L a t e r a l zoning of Co, Mn, and FeS i n s p h a l e r i t e of the C e n t r a l d i s t r i c t 239 85. Cobalt content of ores of the Frolovskoe (1 and 2) and N i k i t i n s k o e (3) skarn-massive s u l p h i d e d e p o s i t s , U.S.S.R. 240 LIST OF FIGURES (Continued) F i g u r e ' Page 86. V a r i a t i o n s i n the contents o f Co and N i i n p y r i t e a l o n g - s t r i k e o f the Vostochnaya d e p o s i t of the P e r v y i Severnyi n i n e , U.S.S.R. 240 87. G e o l o g i c a l cross s e c t i o n o f the Kabu orebody 242 88. C o r r e l a t i o n between Co/Fe and Se/S i n p y r i t e from the Yanahara ore d e p o s i t s 243 89. D i s t r i b u t i o n o f Co i n the Kabu orebody (a) p l a n o f l e v e l 21, (b) pl a n of l e v e l 24 244 90. D i s t r i b u t i o n of Co i n the Kabu orebody (a) p l a n o f l e v e l 27, (b) cr o s s s e c t i o n 244 9 1 . V a r i a t i o n s i n Co/Fe, Se/S, 34g^ and S/Fe i n the p y r i t e v e i n s from the Hi d a s h i r o d e p o s i t 245 92. Quadratic trend and r e s i d u a l maps f o r minor elements i n su l p h i d e s from Slocan d i s t r i c t , B.C. (A) Ag i n galena, ppm/100, (B) AS i n p y r i t e , ppm, (c) Sn i n s p h a l e r i t e , ppm 247 93. V a r i a t i o n s of minor elements w i t h depth a t Noranda, Quebec: (A) p y r r h o t i t e (B) c h a l c o -p y r i t e 249 94. V a r i a t i o n s of elements i n p y r i t e w i t h depth at (A) H o l l i n g e r , Quebec; (B) Noranda, Quebec 250 95. Co and N i content of p y r r h o t i t e s from "economic" d e p o s i t s of the F l i n F l o n area 255 96. Co and N i i n p y r r h o t i t e s from "barren" m i n e r a l d e p o s i t s of the F l i n F l o n area 256 97. Frequency d i s t r i b u t i o n histograms f o r Co and N i i n p y r r h o t i t e s from economic and barren m i n e r a l d e p o s i t s , F l i n F l o n area 257 98. Example of "Roozeboom" diagram showing d i s t r i -b u t i o n of Co and Ni between p y r i t e and p y r r h o t i t e from s e v e r a l m i n e r a l d e p o s i t s 260 LIST OF FIGURES (Continued) Figure Page 99. Example of "concentration" diagrams showing dependence of partition coefficients on element concentrations in one or more phases 260 100. Example of "interaction" diagrams showing relationship of Co/Ni ratio i n pyrite to distribution coefficients for Co and Ni between pyrite and pyrrhotite 261 101.. Plots of mole-fraction ratios PbSe/PbS vs. ZnSe/ZnS calculated from experimental data for six temperatures 261 102. Summary of variation of distribution coefficients with temperature. Values are derived from study of synthetic sulphide systems by Bethke and Barton (1971) 263 103. Variation of crystal habit with changes i n temperature and concentration of solutions: (A) magnetite, (B) brookite, (c) cassiterite 269 104. Comparison of cobalt and nickel content of cubic and pyritohedral pyrite from Cyprus deposits 270 MINOR ELEMENTS IN PYRITE FROM THE SMITHERS MAP AREA, B.C. AND EXPLORATION APPLICATIONS OF MINOR ELEMENT STUDIES INTRODUCTION P y r i t e , FeS2, the most abundant of a l l s u l p hide m i n e r a l s , i s commonly found i n m i n e r a l d e p o s i t s , i n igneous and sedimentary rocks and t h e i r metamorphic e q u i v a l e n t s . The " s p e c t r a " and c o n c e n t r a t i o n s of minor elements present i n p y r i t e depend on a v a r i e t y o f f a c t o r s i n c l u d i n g the supply of elements present at the s i t e of d e p o s i t i o n , p r e s s u r e , temperature, and composition of f l u i d s r e s p o n s i b l e f o r d e p o s i t i o n . In a d d i t i o n , p y r i t e present i n any given environment may have formed by more than one process at one or more separate times, and p o s t - d e p o s i t i o n a l e f f e c t s may a l t e r composition of the p y r i t e . Thus, we cannot expect t h a t simple chemical c h a r a c t e r i s t i c s of one p y r i t e sample w i l l enable us to decipher i t s genetic h i s t o r y . However, minor element data from a l a r g e number of samples i n a given area, s t u d i e d w i t h r e f e r e n c e to g e o l o g i c a l i n f o r m a t i o n can help support or d i s c r e d i t g e n e t i c hypotheses. This study of minor elements i n p y r i t e i s presented u s i n g s e v e r a l d i f f e r e n t approaches. In the f i r s t chapter, p y r i t e c r y s t a l chemistry i s examined i n order to acquaint o u r s e l v e s w i t h f a c t o r s c o n t r o l l i n g r e l a t i o n s h i p s between anions and c a t i o n s i n p y r i t e - t y p e s t r u c t u r e s . Evidence f o r a c c e p t a b i l i t y of i o n s f o r s u b s t i t u t i o n i s derived from the study of: (l) natural and synthetic minerals belonging to or related to the pyrite group, (l) l i g a n d - f i e l d (molecular-orbital) theory, (3) parameters such as electronegativity and covalent-radius. In the second chapter, mode and extent of minor element substitution i n pyrite are examined through investigation of previous research and a n a l y t i c a l data. Chapter I I I describes numerous s t a t i s t i c a l tests performed on groups of pyrite analyses compiled from the l i t e r a t u r e and stored i n a computer card d a t a - f i l e . The tests enable us to examine c r i t i c a l l y several hypotheses formulated by e a r l i e r workers from more l i m i t e d data. In the f i n a l chapter, the writer presents his own d a t a — pyrite analyses from several types of mineral deposits i n an area where geological relationships are reasonably well known. Minor element data are interpreted with reference to theoretical material presented i n e a r l i e r chapters. Technical information concerning a n a l y t i c a l methods, sample preparation, and a n a l y t i c a l precision are contained i n the appendices i n addition to a detailed summary of previous applica-tions of minor element studies to exploration for mineral deposits. I. PYRITE CRYSTAL CHEMISTRY THE PYRITE GROUP AND RELATED GROUPS Sulphide minerals of the type AX^ (where A i s gener a l l y a transition-element cation and X i s a chalcogen or pnigogen anion) are divided i n t o several d i s t i n c t groups on the basis of molecular str u c t u r e . Four c l o s e l y r e l a t e d groups are: P y r i t e group Marcasite group Arsenopyrite group L o e l l i n g i t e group A l l are polyanionic ( H u l l i g e r , 1958) containing anion p a i r s represented by X 2 or XY, and are characterized by octahedral coordination of the cat i o n to the s i x neighboring anions, best i l l u s t r a t e d by the p y r i t e structure (Figures 1 and 2). The most common cations involved i n minerals of the above-mentioned groups are Mn, Fe, Co, Ni, and Cu. Less common cations are T i , V, Cr, Zn, Au, Ag, and the platinum group elements Ru, Rh, Pd, Os, I r , and Pt. Common anions are the chalcogen elements .S, Se, Te, and the pnigogen elements As, Sb, B i , and i n rare cases P ( H u l l i g e r , 1968;. The P y r i t e Group Minerals of the p y r i t e group belong to the isometric d i p l o i d a l symmetry group 2/m3, and space group Th^ - Pa3, with FIGURE 2. Three dimensional view of the p y r i t e s t r u c t u r e . (From H u l l i g e r . F . , 1968) the unit c e l l 4(AX2J(i«e., Z = A). The structure of pyrite i s i l l u s t r a t e d i n Figure 2. I f the S 2 atoms are v i s u a l i z e d as one unit the structure i s i d e n t i c a l to that of NaCl. However the S atoms l i e along the tr i g o n a l axis of the space group and account for the lower ( d i p l o i d a l j symmetry. A l l minerals of the group except Hauerite (MnS,,,) have met a l l i c l u s t r e , and most are hard. Minerals'-of the pyrite group and t h e i r properties are l i s t e d i n Table 1. Synthetic and natural "pyrites" and related compounds documented by Hu l l i g e r (1968J are l i s t e d i n Table 6. Marcasite and Other Structural Groups In contrast to the p y r i t e structure, i n which coordination octahedra are joined at the corners (Figure 2) with no metal-metal in t e r a c t i o n , the marcasite, l o e l l i n g i t e , and arsenopyrite structures have octahedra which share edges along one d i r e c t i o n (Figures 3 and 1). In the marcasite group s l i g h t metal-metal i n t e r a c t i o n (repulsion^ occurs, while i n the two remaining groups metal-metal int e r a c t i o n permits maximum spin-pairing of electrons. Minerals belonging to each group are l i s t e d i n Tables 5 and 6. Marcasite group minerals are orthorhombic. Their structure i s somewhat s i m i l a r to that of p y r i t e ; the metal atoms l i e at the corners and center of the orthorhombic c e l l and the i n c l i n e d anion groups are centered midway between iron atoms and l i e on r e f l e c t i o n planes (see Figures 3 and A). Early researchers thought that s l i g h t differences i n the T A B L E 1 PYRITE GROUP - MINERALS AND PROPERTIES NAME COMP. CELL EDGE 8 H. SP.G. Pyrite PeS 2 5.4165 6-6.5 5.018 C a t t i e r i t e CoS 2 5.523 4.80 Vaesite N i S 2 5.679 4.45 Bravoite CPe,Co,NiJS2 var. Villamaninite (Fe,Co,Ni,Cu;S2 5.69 Pukuchilite C u 3 F e S 8 var. Hauerite MnS2 6.097 4.0 3.463 Trogtalite CoSe 2 5.88 Penroseite (,Fe,Ni,CujSe2 6.017 2.5-3 6.69? Cobaltite CoAsS 5.65 6.28 Gersdorffite NiAsS 5.68 5.964 Ullmanite NiSbS 5.91 Laurite RuS 2 5.60 7.5 6.23 Michenerite PdBi 2 6.68 2.5 9.5 Hollingworthite (Rh,Pt,PdHAsSJ 2 I r a r s i t e (Ir,Rh,Ru,Pt;AsS Sperr y l i t e PtAs 2 5.95 6-7 10.58 Aurostibite AuSb 2 6.646 9-91 Erlichmanite 0sS 2 5.6196 9.59 7 FIGURE 4. The s t r u c t u r e of marcasite showing t h e S 2 group between the two i r o n t r i a d s . metal : sulphur r a t i o might e x p l a i n the polymorphism of FeS^, but recent s t u d i e s ( K u l l e r u d and Yoder, 1359) show that d e v i a t i o n s from the t h e o r e t i c a l value of 1 : 2 are probably w i t h i n a n a l y t i c a l e r r o r . P y r i t e and marcasite are commonly found together i n nature and may be intergrown i n c o n c e n t r i c l a y e r s . M a r c a s i t e can be converted to p y r i t e by g r i n d i n g at room temperature or by h e a t i n g at 400-425° C ( K u l l e r u d and Yoder, 1959J, but i t i s not p o s s i b l e to change p y r i t e to marcasite a t any temperature. Marcasite can be p r e c i p i t a t e d o n l y by a c i d i c s o l u t i o n s and i s l e s s s t a b l e than p y r i t e , o x i d i z i n g r a p i d l y i n a i r . M a rcasite nodules of a u t h i g e n i c o r i g i n are common i n shales and mudstones. Few marcasite analyses are a v a i l a b l e and t r a c e element contents are not w e l l known. 9 B. THE RELATIONSHIP OF CRYSTAL FIELD THEORY TO PYRITE GROUP MINERALS For a complete and s o p h i s t i c a t e d study of minor element i n c o r p o r a t i o n i n t o the p y r i t e l a t t i c e , the relevance of c r y s t a l -f i e l d theory must be considered. A b r i e f review o f c r y s t a l f i e l d theory i s i n c l u d e d , w i t h much o f the m a t e r i a l taken d i r e c t l y from H u l l i g e r (1968); Burns (1970); N i c k e l (1967, 1970); B i t h e r , e t a l . (1968); and Larsen (1965). C r y s t a l f i e l d theory d e s c r i b e s the o r i g i n s and r e s u l t s of i n t e r a c t i o n s o f surroundings on the o r b i t a l e n e r g y - l e v e l s of a t r a n s i t i o n - m e t a l i o n . T r a n s i t i o n - e l e m e n t s are those elements, the atoms or i o n s of which c o n t a i n p a r t l y - f i l l e d "d" o r b i t a l s , which p a r t i c i p a t e i n chemical bond formation. The elements most commonly reported as t r a c e s i n p y r i t e are T i , V, Cr, Mn, Co, N i , and Cu, which belong to the f i r s t s e r i e s of the t r a n s i t i o n elements; Ag and Au from Group IB; chalcogen elements Se, and Te; and pnigogen elements As, Sb, and B i . The " i n t e r a c t i o n s , " mentioned above, are e l e c t r o s t a t i c  f i e l d s t h a t o r i g i n a t e from n e g a t i v e l y charged anions or d i p o l a r anion groups ( l i g a n d s ) . These l i g a n d s , v a r y i n g i n type, p o s i t i o n , and symmetry, induce changes i n the symmetry and i n t e n s i t y of the e l e c t r o s t a t i c f i e l d surrounding the metal i o n . Each t r a n s i t i o n metal atom c o n s i s t s o f a nucleus w i t h e l e c t r o n s present i n a s e r i e s o f o r b i t a l s . The inner-most o r b i t a l s , the argon "core" e l e c t r o n s , 2 2 6 2 6 (1s) (2s) (2p) (3s) (3p) , do not take p a r t i n chemical bonding, but the 3d and 4s o r b i t a l s are f i l l e d p r o g r e s s i v e l y i n the s e r i e s Sc-Cu and take p a r t i n bonding. The 3d o r b i t a l s are i l l u s t r a t e d 10 i n F i g u r e 5 and c o n f i g u r a t i o n s are l i s t e d i n Tables 2 and 3. I n i s o l a t e d gaseous atoms or i o n s of a given element, the f i v e "d" o r b i t a l s are a l l of the same energy. I n s o l i d s t a t e or i n s o l u t i o n , the e l e c t r i c a l charge f i e l d s of adjacent d i p o l e s or " l i g a n d s " a c t upon the "d" o r b i t a l s , r a i s e them i n energy, and s p l i t them i n t o d i f f e r e n t energy l e v e l s . E l e c t r o n s that l i e a long the same a x i s as the l i g a n d s w i l l be r a i s e d i n energy; those d i r e c t e d away from the l i g a n d s w i l l be reduced i n energy (see F i g u r e 6). A p p l i c a t i o n s to P y r i t e Group M i n e r a l s I n p y r i t e group compounds w i t h o c t a h e d r a l l y - c o o r d i n a t e d metal i o n s , the o r b i t a l - e n e r g i e s are s p l i t i n t o two groups - three o r b i t a l s of lower energy and two o r b i t a l s of higher energy (see Figure 6). The s t r e n g t h of the l i g a n d f i e l d determines how the "d" e l e c t r o n s are d i s t r i b u t e d i n the o r b i t a l s . E l e c t r o n s i n the s u l p h i d e s , a r s e n i d e s , s e l e n i d e s , and t e l l u r i d e s o f the t r a n s i t i o n - m e t a l s are g e n e r a l l y i n the low-spin s t a t e , and c r y s t a l s t r u c t u r e s adopted by these compounds are those which permit maximum s p i n - p a i r i n g of the non-bonding ( t ^ g ) e l e c t r o n s . T r a n s i t i o n - m e t a l c a t i o n s w i t h s i x or more non-bonding e l e c t r o n s form s t r u c t u r e s i n which s p i n - p a i r i n g i s achieved without a p p r e c i a b l e i n t e r a c t i o n between c a t i o n s , e.g., p y r i t e , m a r c a s i t e , and s k u t t e r u d i t e s t r u c t u r e s (see Figure 7 ) . The c a t i o n s w i t h fewer than s i x non-bonding e l e c t r o n s can only achieve s p i n - p a i r i n g by adopting s t r u c t u r e s i n which there i s metal-metal i n t e r a c t i o n , e.g., arseno-p y r i t e and l o e l l i n g i t e s t r u c t u r e s (Figure 7 ) . Compounds w i t h s i x FIGURE 5. Boundary surfaces of atomic o r b i t a l s . (From Burns, Roger G., 1970) • E l e c t r o n i c configuration A t o m i c e -n u m b e r E l e m e n t A t o m M ( I I ) M (III) M ( I V ) 19 K ( A r ) 4 s 1 — — . — • 20 C a (Ar).p= ( A r ) — — 1 21 Sc ( A r ) 3 r f ' 4 j 2 ( A r ) 3 r f 1 ( A r ) — _o 22 T i ( A r ) 3 r f V ( A r) 3rf- (Ar) 3 <f' ( A r ) tJ V, 23 V (Ar)3<f34S2 ( A r ) 3 r f 3 (Ar) 3 </ 2 ( A r ^ 1 C O 24 C r ( A r ) " 3 r f V (Ar ) 3 rf 4 ( A r ) 3 r f 3 (Ar) 3 </ 2 25 M n (Ar) 3rf 5 4j"- (Ar) 3rf> (Ar) 3rf* ( A r ) 3 r f3 c i * 26 F e ( A r) 3rf« 45 ! (Ar)3rf* ( A r) 3rf 5 — 91 27 C o ( A r ) 3 r f ' 4 * s ( A r ) 3 r f ' (Ar) 3rf« — I* E 28 N i ( A r ) 3 r f V (Ar ) 3 rf ' ( A r ) 3 ^ ( A r ) 3 r f ' 29 C u ( A r ) 3 r f 1 ° 4 j 1 ( A r) 3rf s ( A r ) 3 J 3 — 30 Z n (Ar)3rf'»4j= ( A r f c r f " ( A r ) 3 J » - — 31 G a ( A r ) 3 r f 1 » 4 i = 4 / . 1 (Ar)3rf'<4/>» ( A r f c r f 1 0 — 32 G e (Ar) 3 rf"> 4 j=4^ (Ar)3rf>«^ s — (Ar ) 3rf ' ° ( A r ) = A r g o n core, i$-2s-2p r'$$ 3/>6. TABLE 2. E l e c t r o n i c c o n f i g u r a t i o n s of the elements of the f i r s t t r a n s i t i o n s e r i e s . ( F r o m Burns, Roger G., 1970) High-spin state * Low-spin state Number of Electronic configuration Unpaired Electronic con figuration Unpaired . s 3'/ electrons Ion M« -et • electrons CFSfi electrons CFSE o Ca8*, Sc2*, Ti«+ o o o o I T i3* t I •°A0 t .. I , 'A0 2 T i2 +, V3* t t 2 ' *A0 t t 2 iA 0 3 V21", Cr3*, Mn1* t f t 3 •S-A. t f t 3 4. • Cr1*, Mn3* t t . t t 4 vA„ t l t t 2 »A„ 5 •. Mn2* Fe2* . t t f t t 5 o t l t l t I i'A0 6 Fe21-, Co3*, Ni** t i t t t t 4 •»A„ t l t l t l O 7 Co2'-, Ni3* t l t l t t t 3 • vA0 t l t l t l t X vA0 8 Ni2* t i t i t i t t 2 vA0 t l t l t l t t 2 "A„ 9 Cu2* n t i t i t i t i vA„ t l t l t l N ' t • I ;-A0 1 0 Zn2*, Ga3*, Gc4* t i t; t i t i t i o o t l t l t l t l t l O 0 TABLE 3. Electronic configurations and c r y s t a l f i e l d s t a b i l i z a t i o n energies of t r a n s i t i o n metal ions i n octahedral co-ordination. (From Burns, Roger G.,1970) 13 O l BONDING ORBITALS *2g r.-4p"-I I I I I • I I .1 1 X l l \> tl = \\ > ll 1 l l t ANTI-BONDING ORBITALS ^ = | = 3<j cov-tr i i cov -TC NON-BONDING ORBITALS ^ g ^ g 3 s . 3 p • 3 V V V 4s--«- — / /// S-S bond other Fe^4 ions orbitols of free F«2« ion molecular orbilals in FeS2 sulphur orbitols (G atoms) FIGURE 6. Molecular o r b i t a l e n e r g y - l e v e l diagram f o r p y r i t e . (From B i t h e r e t . a l . , 1968) FIGURE 7. Combination of octahedra in (A) pyrite, (B) mar-casite, (C) l o e i l i n g i t e , and (D) arsenopyrite. Metal atoms are solid c i r c l e s ; anions are open. (From Nickel, E.H.,1970) FIGURE 8. Diagrammatic representation of the interaction of the t2g -orbital lobes in sections parallel to the c-axis. (A) marcasite, (B) l o e i l i n g i t e , (C) arseno pyrite. (From Nickel, E.H., 1970) non-bonding "d" e l e c t r o n s have the p y r i t e or marcasite s t r u c t u r e , s i n c e no metal-metal i n t e r a c t i o n i s r e q u i r e d . Those w i t h more than s i x non-bonding "d" e l e c t r o n s a l s o have the p y r i t e or marcasite s t r u c t u r e , except f o r CoTe^ and NiTe2» w k i ° n n a v e ^ e b r u c i t e s t r u c t u r e (somewhat r e l a t e d to the marcasite s t r u c t u r e ) . Tables 5 and 6 l i s t common min e r a l s of the p y r i t e and marcasite groups. Since Se and Te have the same valence as S, they can r e p l a c e the S atoms without u p s e t t i n g the balance of charges. However the •replacement of S^ by one or more As or Sb atoms n e c e s s i t a t e s a change i n the valence of the c a t i o n (both As and Sb have one l e s s valence e l e c t r o n than s u l p h u r ) . Thus, the t o t a l number of non-bonding "d" e l e c t r o n s i s reduced; hence, metal-metal i n t e r -a c t i o n may be necessary to achieve maximum s p i n - p a i r i n g . The c a t i o n - a n i o n r e l a t i o n s h i p d i s c u s s e d here can be r e l a t e d to the nature and extent of s o l i d s u b s t i t u t i o n w i t h i n the p y r i t e group and r e l a t e d groups; and thus, may be r e l a t e d to i n c o r p o r a t i o n of minor elements. I n the system Co-Fe-Ni - S 2 , phase s t u d i e s of s y n t h e t i c compounds has shown that complete s o l i d s o l u t i o n can e x i s t between Fe-Co end members (6 and 7 non-bonding e l e c t r o n s ) and between Co-Ni end members (7 and 8 noh-bonding e l e c t r o n s ) but not between Fe and Hi (6 and 8 ) . * According to N i c k e l (1970) the reason i s that the two e x t r a n i c k e l e l e c t r o n s i n M S 2 i n c r e a s e the m e t a l -anion d i s t a n c e to a p o i n t where the complete range of s o l i d s u b s t i -t u t i o n i s not p o s s i b l e . S i m i l a r r e l a t i o n s h i p s e x i s t i n the *The h i a t u s between Ni and Fe d i s u l p h i d e s i s not supported by data from a n a l y s i s of n a t u r a l b r a v o i t e specimens. S2, Se2 AsS As2 or or or Te 2 SbS Sb2 Fe 6 5 .4 Co 7 6 5 Ni 8 7 6 TABLE A. The number of non-bonding d-electrons i n d i -anionic compounds. (From N i c k e l , E.H., 1970) Minerals with cations having 6 non -bonding d-electrons Composition •Mineral Structural type FeS2 pyrite pyrite CoAsS cobaltite pyrite CoSbS '. - pyrite FeS2 marcasite marcasite ~ -FeSe2 ferroselite marcasite FeTe 2 frohbergite marcasite NiAs 2 rammelsbergite marcasite Minerals conta ining cations with 7 or S non-bonding d-electrons Composition Mineral name No. of d-electrons Structural type CoS2 cattferite 7 pyrite CoSe2 . trogtalite 7. pyrite NiAsS gersdorffite 7 pyrite KiSbS . ullmannite 7 pyrite NiS2 . vaesite 8 pyrite NiSe2 penroseite 8 pyrite CoSe2 hastite 7 marcasite CoTe2 - 7 brucite NiTen melonite 8 brucite TABLE 5. Minerals with 6, 7, or 8 non-bonding d-electrons. (From N i c k e l , E.H., 1970) PYRITE STRUCTURE hi^li-spin il ' : .S' : 5/2. :intifcniiin;i^iii'tii', srmieuiidiicling • MnS... MnSc.,; . M u l e . . . low-spin <1": .S' 0, . s i ' i i i i c i m d i K ' t i n u . metallic*) FeS.,(li), I'VScjfp). l-'i:Ti\,(p)\ KuS... KuSi\,. Ku'lV.,, ().sS., OsSe„ OsTe... Co PS, CoAsS. I'ciAsSc. Klil'S. KhAsS, KhShS, Klii'.iS. Khl'Sc. KliAsSo, UhSbSe, UhliiSc, KhAs'lV, KhSbTe, Khl'.iTo, Irl'S liAsS, liSbS. IrBiS. li'PSe. IrAsSe, liSbSc. lrHiSe, IrAsTe. IrSbTo. Irl'.iTe. Nil\(p)\ NiAs..(p)*, NvsP.l„.5As;. PdAs*, lMSbJ. PtP2. PtAs3. VlSU... PtHi^r)*. KliS-j. RhSe-.,, KhTe~3, IrS~3, IrSc_3, IrTe,3. metallic i l7: 5 — •},•-*• 0, metallic CoS.„ CoSc(li), CoTc.,(p), IvhSc(li), KhTc(r), IrSo(p), XiPS. MAsS. XiSbS. NiAsSe. NiSbSe, XiBiSe. PdAsS. PtlSbS. PdAsSc, PdSbSe, Pdl.iiSc, PdSbTo, PdBiTe, PtAsS. PtSbS, PtSbSc, PtBiSe. PtSbTe, PtBiTe. AnSb... high-spin ds: 5•= 1, semiconducting, 5 < 1, metallic*) XiS2(r). NiSjlp)*, NiSc*..' NiTes(p)*. . metallic d9: 5 = 0, metallic •• - •• CuS,(p). CuSc„(p), CuTc2(p).. ;"; 5 = 0, diamagnctic, semiconducting ZnS2(p), ZnSc2(p), CdS2(p), CdSe.fp). LOELLINGITE STRUCTURE .. high-spin d2: 5 = 1, antifcrromagnctic, semiconducting ' CrSb2. . •• "' d2, d1 5,'= 1, S2 = 0, semiconducting CrFcAs.,. low-spin d': 5 = 0, semiconducting FeP2. FcASo, FcSb2, KuP,, RuAs2, RuSb2, OsP2, OsAs2, OsSb2. MARCASITE STRUCTURE low-spin d°: 5 — 0, semiconducting, metallic ?*) • PcS2(r), FcSc.(r). FcTc2(r), NiAs2(h), NiSb?. metallic d7: S ?t \; metallic CoSc2"(r), CoTe2(r). ' r \ ;- : - \.:. •: metallic d": S = 0, metallic t CuSc2(r). ARSENOPYRITE STRUCTURE . . _ __... ...... .. (d^-d1): 5 = 0, semiconducting CoAsj, CoSb., RhP2, KhAs2. RhSb8. RhBis(r), IrP2, IrAs2, IrSb2, IrBi2" " " " " FcPS, FeAsS, FeSbS. FePSc, FcAsSe, FeSbSo, FcAsTe, FeSbTc, KuPS. RuAsS, KuSbS. RuPSe, KuAsSe, RuSbSc, RuAsTe. RuSbTe, OsPS. OsAsS. OsbbS, OsPSc, OsAsSo, OsSbSc, OsBiSe. OsAsTe, OsSbTe, OsBiTe. TABLE 6. Chalcogenides and pnictides of transition elements. (From Hulliger,F., 1968) (h) High-temperature phase, (r.) Room-temperature phase, (t) Low-temperature phase, (p) Synthesized under pressure. 7 Co 6 Co 650° C 800 C FIGURE 9. Solid-solution fields, shown in shaded areas, in various polyanionic compounds of Fe,Co, and Ni. A) Bisulphides, B) Sulpharsenides, C). Diarsenides, D) T r i -arsenides,. The numbers at the vertices indicate the number of non-bonding "d" electrons. (From Nickel,E.K.,1970). 19 (CoNiFeJAs^ system (see F i g u r e 9 ) . I n the (Co, N i , Fe)AsS system complete s u b s t i t u t i o n of Co and N i end members i s p o s s i b l e (both have the p y r i t e s t r u c t u r e ) but there i s incomplete s o l i d - s u b s t i t u t i o n between FeAsS and the other end members s i n c e a r s e n o p y r i t e i s a 5 - e l e c t r o n compound and has a d i f f e r e n t ( l e s s symmetrical) c r y s t a l s t r u c t u r e . These r e l a t i o n s h i p s h e l p e x p l a i n the l i m i t e d s o l i d s u b s t i t u t i o n of As (and Sb) i n the p y r i t e l a t t i c e . C r y s t a l f i e l d theory i s u s e f u l f o r e x p l a i n i n g the i s o -s t r u c t u r a l (but non-isomorphous) r e l a t i o n s h i p between ~FeS^ and MnS 2 > As documented by H u l l i g e r (1968) and by N i c k e l (1968), MnSg - h a u e r i t e - has the p y r i t e s t r u c t u r e , but the "d" e l e c t r o n s i n the Mn atom are i n the " h i g h - s p i n " s t a t e i n 5 separate o r b i t a l s w i t h p a r a l l e l s p i n s . The corresponding c r y s t a l - f i e l d s t a b i l i z a t i o n energy i s z e r o . * The h i g h - s p i n s t a t e i s a t t r i b u t e d to "the r e l a t i v e l y h i g h p a i r i n g energy and low o r b i t a l s e p a r a t i o n energy r e l a t i v e to other t r a n s i t i o n elements." Thus there i s no pronounced tendency f o r MnS£ to c r y s t a l l i z e i n forms s t a b i l i z e d by a h i g h degree of s p i n - p a i r i n g ( N i c k e l , 1968). Many 4 and 5 e l e c t r o n low-s p i n compounds are known, and s y n t h e t i c mixed c r y s t a l s (MnjCuJS^, (Mn,Cu)Se2 and the corresponding t e l l u r i d e have been prepared ( H u l l i g e r , 1968). Therefore, although the isomorphous s u b s t i t u t i o n of Mn i n the p y r i t e l a t t i c e i s not encouraged by i t s h i g h - s p i n nature, i t s presence by c o u p l e d - s u b s t i t u t i o n i s p o s s i b l e . 3 No " p y r i t e " compounds are known w i t h the low-spin d c o n f i g u r a t i o n . Ions w i t h one, two, or three e l e c t r o n s ( f o r * CFSE f o r o c t a h e d r a l l y coordinated c a t i o n s i s : ( N j . 2 g e l e c t r o n s X 2/5 A Q ) - (Keg e l e c t r o n s X 3/5 & Q) 20 example T i , V , Cr ) can have only one e l e c t r o n i c c o n f i g u r a t i o n -the 3d e l e c t r o n s occupy d i f f e r e n t o r b i t a l s o f the T^g group. Thus T i , V, Cr are not expected to c r y s t a l l i z e i n m o d i f i c a t i o n s of the " p y r i t e " type, although some mixed c r y s t a l s w i t h l o e l l i n g i t e s t r u c t u r e are known (.e.g., CrSb2» CrFeAs^,). Chalcogenides o f T i and V c r y s t a l l i z e i n the Cdlg s t r u c t u r a l system (W e l l s , e t a l . , 1962). The elements Cu, Ag, and Au have been i n c l u d e d w i t h the t r a n s i t i o n elements (Larsen, 1965J but Zn, Cd and Hg are not i n c l u d e d although they have some s i m i l a r i t i e s . E l e c t r o n i c c o n f i g u r a -t i o n s are as f o l l o w s : Cu 3d 4s Zn 3d 4s Au 4d 5s Cd 4d 5s Ag 5d 6s Hg 5d 6s These elements, having 10 non-bonding "d" e l e c t r o n s (complete Tgg f i l l i n g ) , can possess only one e l e c t r o n i c c o n f i g u r a t i o n . The c r y s t a l f i e l d s t a b i l i z a t i o n energies i n o c t a h e d r a l f i e l d s w i t h low-spin s t a t e s are very low: Element C.F.S.E. Cu . 3/5 Zn . • . . . • • . 0 These f a c t o r s , combined w i t h the g r e a t e r i o n i c r a d i i , i n h i b i t acceptance of these elements i n t o p y r i t e s t r u c t u r e s under normal c o n d i t i o n s . However, dic h a l c o g e n i d e s of Cu, Zn and Cd have been synth e s i z e d a t 65 Kbars pressure and 600° C ( B i t h e r , et a l . . 1968,) 21 The gen e r a l e f f e c t o f the r e g u l a r a d d i t i o n of non-bonding e l e c t r o n s i s an energy l o s s w i t h r espect to the t o t a l energy. Thus the cohesive bonding f o r c e s decrease, r e s u l t i n g i n i n c r e a s i n g i n t e r - a t o m i c d i s t a n c e s , l a r g e r u n i t c e l l s and a decrease i n s t a b i l i t y of the compound. T h i s i s i n accord w i t h the p h y s i c a l p r o p e r t i e s of FeS 2 - CoS 2 - N1S 2 - CuS 2 - ZnS 2 > The c r y s t a l - f i e l d r e l a t i o n s h i p between anion and c a t i o n i s a major f a c t o r i n determining whether a s p e c i f i c compound w i l l c r y s t a l l i z e i n the p y r i t e s t r u c t u r e , and i s therefore, a major f a c t o r (but not the only f a c t o r ) i n determining the a c c e p t a b i l i t y o f minor elements i n t o the p y r i t e l a t t i c e . 22 C. THE Co-Ni-Fe-S^ SYSTEM Cobalt and n i c k e l , because of t h e i r s i m i l a r i t y i n i o n i c p r o p e r t i e s to i r o n (e.g., charge, o c t a h e d r a l covalent r a d i u s , e l e c t r o n e g a t i v i t y , e t c . J are g e n e r a l l y the most abundant minor elements i n p y r i t e , and are the o n l y elements w i t h which p y r i t e forms a complete s o l i d - s u b s t i t u t i o n s e r i e s . A review of the Co-Ni-Fe-S2 system i s presented, i n c l u d i n g the extent of s o l i d -s u b s t i t u t i o n i n n a t u r a l and s y n t h e t i c d i s u l p h i d e s , and v a r i a t i o n s i n p r o p e r t i e s w i t h composition. 1. N a t u r a l and S y n t h e t i c Phases The three end members of the system are FeSg ( p y r i t e -m a r c a s i t e j , CcS^ ( c a t t i e r i t e J , and NiS^ ( v a e s i t e J . The end members are d e l i n e a t e d by K e r r (1945.) as those samples i n which the pro-p o r t i o n o f the dominant metal to the t o t a l metal content i s 80$ or g r e a t e r . The r e l a t i o n s are best d i s p l a y e d on a t e r n a r y diagram,* Samples w i t h intermediate composition are termed B r a v o i t e (Co,Ni,Fe I f the system were extended to i n c l u d e copper, a d d i t i o n a l members would be F u k u c h i l i t e (Cu^FeSgJ and V i l l a m a n i n i t e (Cu.NijCo.FeJS^. C a t t i e r i t e and v a e s i t e were o r i g i n a l l y d escribed from the Shinkolobwe and Kasompi d e p o s i t s of the Katangan copper b e l t by K e r r (19451. The minerals are found disseminated i n dolomite, both as cubes and octahedra, and both have cubic cleavage. The c a t t i e r i t e i s p i n k i s h ; the v a e s i t e i s grey. Since K e r r ' s d e s c r i p t i o n , f u r t h e r examples of the two minerals have been found i n the "Rhodesian" * (See Fi g u r e s 10 and 11) copper belt and bravoite i s f a i r l y common. Several.methods of synthesis of Co, Ni , and Fe disulphides have been developed. These include: 1) heating metal powders with S i n an atmosphere; 2) heating metal oxides, S, and NH^Cl i n an evacuated tube; 3) fusion of the elements i n a LiCl-KCl melt (Klemm, 1965); 4) heating of metal sulphates i n solution with B^S and S (Springer, et a l . . 1964); 5) p r e c i p i t a t i o n of Co, Ni , or Fe monosulphides from hot aqueous sulphate or chloride solution by addition of di l u t e d ammonium polysulphide, and heating the dried precipitate with S i n a sealed tube under hydrogen (Straumanis, et a l . . 1964). Early reports by Clark and Kullerud (1959» 1960), and Klemm (1965) showed large areas of the Co-Ni-Fe-^ composition f i e l d i n which s o l i d - s u b s t i t u t i o n does not occur (see Figure 10). Most ternary diagrams at th i s time showed a large gap i n the NiS2~FeS2 j o i n ; the gap was explained by l i g a n d - f i e l d theory (Nickel, 1970). Under certain conditions of synthesis the "gap" may be caused by the i n h i b i t i o n of s o l i d - s o l u t i o n of end-members due to coarseness of the i n d i v i d u a l i n i t i a l phases. Straumanis, et a l . (1964). found that co-precipitation of Co and Fe as monosulphides was necessary to promote s o l i d substitution i n disulphides. Using t h i s method, complete s o l i d - s u b s t i t u t i o n of any proportion of Co : Fe was possible (see Figure 11). Detailed work by Klemm (1965) and FIGURE 11. N a t u r a l l y o c c u r r i n g s o l i d s o l u t i o n s i n the system Co-Ni-Fe-S,.(Modified from Klemm, D.D., 1965) Springer, et a l , (1964), shows that a l l proportions of Co, Ni and Fe are found i n natural and synthetic bravoites (see Figure 11). Most naturally-occurring bravoites are zoned (a t y p i c a l example i s i l l u s t r a t e d i n Figure 24), but unzoned and zoned c r y s t a l s may occur together both i n natural and i n synthetic environments. Kullerud (1962) showed that bravoite, when heated f o r a s u f f i c i e n t length of time, breaks down to pyrite and vaesite. Thus, natu r a l l y occurring bravoites may be metastable. Their zonation probably indicates that temperature of deposition was low, and subsequently was too low to cause decomposition to stable phases (Springer, et a l . , 1964). Zonation may have been caused by l o c a l convection within the ore f l u i d adjacent to growing c r y s t a l s . The study of synthetic phases by Springer and his colleagues sheds l i g h t on the deposition of natural bravoites. 2. Variation of properties with corn-position Properties of pyrite-type minerals which have been noted to change with the addition of s o l i d - s u b s t i t u t i o n impurities are: 1) La t t i c e constants 5) Sp e c i f i c gravity 2) Hardness 6) Anisotropism 3) R e f l e c t i v i t y 7) Thermoelectric e f f e c t 4) Color 8) Crystal form a) U n i t - C e l l Dimensions A r e g u l a r i n c r e a s e i n c e l l edge w i t h a d d i t i o n of i m p u r i t i e s causes the changes i n hardness, r e f l e c t i v i t y and s p e c i f i c g r a v i t y . V a r i a t i o n s i n l a t t i c e constants of p y r i t e - g r o u p minerals are w e l l documented ( E l l i o t t , 1960; R i l e y , 1965; Vaughan, 1969; and others,). F i g u r e s 19'&'20 i l l u s t r a t e , the i n c r e a s e i n c e l l edge w i t h atomic number of major anion or c a t i o n c o n s t i t u e n t s . The i n c r e a s e w i t h atomic number of anion s u b s t i t u e n t s i s e x p l a i n e d r e a d i l y by the r e g u l a r i n c r e a s e of e f f e c t i v e r a d i u s of the anions. I f the i n c r e a s e i n c e l l edge of p y r i t e w i t h a d d i t i o n of c a t i o n s were s o l e l y r e l a t e d to e f f e c t i v e r a d i u s of those c a t i o n s , the c e l l edge would be expected to decrease! Such i s not the case however. Although a s l i g h t i n i t i a l decrease i s noted when Co i s added to the p y r i t e system (Straumanis, et a l . . 1964J, the major e f f e c t i s a r e g u l a r i n c r e a se ( F i g u r e 18;. Thus, the e f f e c t o f the increased number o f . e l e c t r o n s i n "d" (non-bondingj o r b i t a l s must counteract the lower e f f e c t i v e r a d i u s . The e f f e c t s of c o b a l t and copper a d d i t i o n to p y r i t e are i l l u s t r a t e d i n F i g u r e s 14 and 15. S i m i l a r e f f e c t s occur i n the NiS2-Se2 and CoS2~Se2 systems (Klemm, 1962; as i s shown i n F i g u r e s 12 and 13. b j Color. R e f l e c t i v i t y and Hardness Vaughan (1969; had demonstrated that both microhardness and r e f l e c t i v i t y of zones i n b r a v o i t e decrease w i t h i n c r e a s i n g amounts of Co and Ni (Table 7, F i g u r e s 21 and 22;. S i m i l a r c o n c l u s i o n s were reached by Saager and M i h a l i k (1967J a f t e r s t u d i e s of p y r i t e CoS; CcSfj FICURE .13. Variation! of c e l l edge with composition i n the CoSj-CoSe^systeo. (From Klemm, 1966) t so • i-H.Sti.t r «'.h W« J*ng.»I») / -K.5tt . *ynlS(^iU( . lStQ o. NNiS«..iinlr>(!lr1t /,13 ' .Q) s.s tf 58 57 [ - M l . N:Sc2 FIGURE 13. Variation of c e l l edge with composition i n the NiS.-NiSe system. (From Klenm, 1966) V & C H T X C C W - T . FIGURE 14. Weight percentage cobalt plotted against the d(5U) spacing for members of the FeS_-CoS system. (From Riley, John F.,1968). 2 2 1 w. , . . , „ . r,s to IB ». 1. »« FICURE 13. C e l l edge versus composition for members of the FeS. CuS system. (From Shimazaki, H..and Clark, L.A., - 1970). 5 . 4 ! 10 5.4050 • • • '• ' : -1  10 25 35 45 . 55 65 TEMPER AT. IN °C FIGURE 16. Lattice parameter "a" of natural and synthetic pyrites versus temperature. (From Straumanis et. a l . , 196A) FIGURE 17. Lattice parameter "a" of C0S2 versus temp-erature. (From Straumanis et. a l . , 1964) 4 DO X FIGURE 18. Lattice parameter "a" versus composition of mixed (Co,Fe)S2 sulphides at 25°C. (From Straumanis et. a l . , 1964) Mn Fe Co Ni Cu Zn 20 FIGURE 19. Change i n length of cell-edge (Angstroms) with increasing atomic number of anion FIGURE 20. Clinngo i n . l e n c t h of col l-odge (Angntromo) with inc reas ing atonic number of ca t ion t FIGURE 21 . Zoned bravoite crystal selected for r e f l e c t i v i t y studies. (From Vaughan, David J.,1969) FIGURE 22. Variation in r e f l e c t i v i t y (at 589 nm. in air) over the bravoite crystal. (From Vaughan, David J., 1969) Rctleclivity ''.k'( air at 589 nm) Composition (.in Wt. ("c) Zone number F e Co 33.7 1 lO 12.9 14.1 25.5 35.1 ! 12 22.9 3.4 24.2 30.8 j . 2 24.7 2.1 22.8 i 4 3&.4 i 5 .28.5 IS 19.5 ! 6 3S.S ! 8 28.4 0 15.1 39.7 : ' 7 • 31.4 0.3 17.8 -10.1 2S.0 2.0 19.5 40.1 1 31.4 0.4 17.7 41.4 9 28.7 0.2 19.1 4S. 6 U 34.1 1.2 10.9 52.2 13 47.9 0 0.1 Metals1' Total 52.5 50.5 49.6 49.8 43.5 49.5 49.5 49.5: 4S.0 46.2 4S.0 Trend in Vickcrs microhardncss (VHX1W1) "Violet bravoite" VHX„„ = 907±194 "Xickelian p\ rite'' VHXK,I,= 1,332 + 203 " Formula calculated /rum composition; f o r this zone (Fir, Co, Xiji.jSj. '• Calculated values of - metals for the- end members are: FeS2 46.6, CoSj 17.9, XiSi TABLE 7. Reflectivity and hardness values for the zoned bravoite cyrstal in relation to composition. (From Vaughan, David J., 1969) 31 from A u - r i c h " r e e f s " of the Witwatersrand sediments. C o l o r changes i n the Co-Ni-Fe-S^ system are as f o l l o w s : p y r i t e - brass y e l l o w low N i - p y r i t e - y e l l o w ^ p i n k i s h y e l l o w " B r a v o i t e " - p i n k i s h to v i o l e t N i , C o - r i c h p y r i t e - p i n k i s h grey to s t e e l y grey The r e f l e c t i v i t y and c o l o r of p y r i t e c o n t a i n i n g up to 3 mol % copper are not v i s i b l y d i f f e r e n t from pure p y r i t e ( E i n a u d i , 1968J. With i n c r e a s i n g Cu content, however, c o l o r changes from l i g h t grey to p i n k i s h grey, and r e f l e c t i v i t y decreases p r o g r e s s i v e l y .(Shimazaki and C l a r k , 1970). The r e l a t i o n s h i p of r e f l e c t i v i t y o f p y r i t e - t y p e compounds to m o l e c u l a r - o r b i t a l theory i s researched i n d e t a i l by Burns and Vaughan (1970). From a study of the i n t e r a c t i o n of electromagnetic waves w i t h " e x c i t a b l e " or " f r e e " e l e c t r o n s , the authors c a l c u l a t e d " N ( e f f J , " a measure of the e f f e c t i v e number of f r e e e l e c t r o n s per atom or molecule. When electromagnetic energy i s absorbed by the e x c i t a t i o n of f r e e e l e c t r o n s to higher energy p o s i t i o n s , r e f l e c t i v i t y r e s u l t s , as the e l e c t r o n s r e t u r n to t h e i r o r i g i n a l s t a t e and emit energy i n the form of l i g h t . High r e f l e c t i v i t y i s a s s o c i a t e d w i t h a high number of N ( e f f J (see Figure 23, Table 8 ) . More s i g n i f i -c a n t l y , the values of N ( e f f ) are roughly p r o p o r t i o n a l to the number of energy l e v e l s a v a i l a b l e to the t,,g e l e c t r o n s e x c i t e d i n t o the e g o r b i t a l s . The r a t i o s of N ( e f f J f o r FeS 2 : CoS 2 : N i S 2 : CuS 2 are 1.18 : 0.88 : 0.51 : 0.30 = 4 : 3 : 1.7 : 1. The r e l a t i o n s h i p s 32 100 i i i i ' S A g -90 80 - -70 - — ; 60 _ -Ivlty 50 - ® r e s 2 -Reflect AO 30 — X C u T e 2 S A u ® C o S 2 ® N i S 2 C U S e 2 -. 2 0 - -: io -X C u S 2 ' 1 1 1 1 1 1 0 1 2 3 4 ^eff ( P c r unit volume) 5 6 FIGURE 23. Plot of percent r e f l e c t i v i t y (R) against effective number of free electrons per unit volume (N eff) for pyrite type compounds. Data for gold and silver are also shown. (From Burns and Vaughan, 1970) FeS2 C0S2 NiS2 CuS2 Reflectivity at 496 nm (2.5 cV)" >ttti at 496 nm* AW at 496 nmc 51.6 1.18 2.97 34 0.8S 2.08 27 0.51 1.11 17 0.30 0.62 electronic | configurations eA of the metal [ 3d orbitals (K/= Fermi level) / 2 „ | T T T 1 T I T 1 .— EF T . T i T i T 1 T 1 -—EF 1 1 . T 1 • T I -—EF T t i • T i T I TABLE 8.Reflectivities, effective number of free electrons and electronic configurations of cations in the pyrite type disulphides. (From Burns and Vaughan, 1970) 33 are shown dia g r a m m a t i c a l l y i n Table 8. I n the S2-Se2~Te2 systems r e f l e c t i v i t y i n c r e a s e s w i t h anion s i z e , s i n c e the e f f i c i e n c y of covalent bonding i n c r e a s e s w i t h s i z e , as does the p o l a r i z a b i l i t y of the anions (see Figure 23). Thus the d e r e a l i z a t i o n of e x c i t e d " t ^ g " e l e c t r o n s i n c r e a s e s w i t h anion s i z e . T h i s i s the opposite e f f e c t to the FeS2-CoS2-NiS2-CuS2 s e r i e s , . i n which covalent bonding decreases. Since the e l e c t r o n i c c o n f i g u r a -2+ t i o n of Mn has only h a l f - f i l l e d 3d o r b i t a l s , the r e f l e c t i v i t y of „MnS2 i s a p p r e c i a b l y lower than the more covalent Co, N i , and Fe d i s u l p h i d e s . c) A n i s o t r o p i s m A n i s o t r o p i s m of p y r i t e under r e f l e c t e d l i g h t was o r i g i n a l l y considered anomalous, and thought to be caused by n o n - s t o i c h i o m e t r i c p r o p o r t i o n s of Fe and S, or by h i g h a r s e n i c content. I t i s now known th a t the Fe : S r a t i o i n pure p y r i t e i s 1 : 2.00; and d i s -crepancies are w i t h i n l i m i t s of a n a l y t i c a l e r r o r . Stanton (1955. 1957) has found o p t i c a l a n i s o t r o p i s m i n p y r i t e to be the g e n e r a l case; i t i s seen on a l l c r y s t a l faces except the (111) o c t a h e d r a l f a c e s . The a n i s o t r o p i s m i s not a f f e c t e d by temperature up to 570° C, but can be o b l i t e r a t e d by harsh g r i n d i n g . Klemm (1962) observed t h a t p e r f e c t c r y s t a l faces are i s o t r o p i c , and suggests that a n i s o t r o p i s m could r e s u l t from surface p o l i s h i n g . Gibbons (1967) supports t h i s theory - e x p l a i n i n g that p o l i s h i n g may cause a t h i n " s k i n " of d i s t o r t i o n i n the o r d i n a r i l y i s o m e t r i c l a t t i c e . The s k i n could be destroyed by g r i n d i n g . The p o s s i b i l i t y of minor-element contaminants causing o p t i c a l a n i s o t r o p i s m must be considered. Copper-rich p y r i t e from Nukumundu, F i j i , shows marked an i s o t r o p i s m ( F r e n z e l and Ottemann, 1968/. Of two v a r i e t i e s of p y r i t e from the Witwatersrand "basal r e e f " (.see Table 9)* "the a n i s o t r o p i c v a r i e t y contains r e l a t i v e l y great amounts of a r s e n i c , c o b a l t , and n i c k e l (.Saager and M i h a l i k , 1967/. Of these three elements, only a r s e n i c could a f f e c t a n i s o t r o p i s m , s i n c e . -CoS2» NiS^ and intermediate members are a l l i s o t r o p i c . : TABLE 9 -RESULTS OF THE QUANTITATIVE DETERMINATION OF TRACE ELEMENTS BY THE ELECTRON MICROPROBE . ON THE TWO TYPES OF PYRITE Type of p y r i t e A r s e n i c N i c k e l Cobalt I s o t r o p i c v a r i e t y 0.201 0.114 0.049 A n i s o t r o p i c v a r i e t y 0.877 0.460 0.233 Gibbons notes that p y r i t e i s almost i s o t r o p i c under y e l l o w l i g h t . D i f f e r e n c e s i n a n i s o t r o p y reported by d i f f e r e n t authors could r e s u l t from v a r i a t i o n s i n l i g h t sources used. A l s o , because minor elements a f f e c t both r e f l e c t i v i t y and hardness of p y r i t e , these two f a c t o r s , combined w i t h p o l i s h i n g technique may enhance o p t i c a l a n i s o t r o p y . Since minor elements d i s t o r t the normal l a t t i c e c onstants, i t i s l i k e l y t hat c e r t a i n elemental i m p u r i t i e s could cause an i s o t r o p i s m . d) Thermoelectric E f f e c t Smith (1947) i n i t i a t e d t h e r m o e l e c t r i c s t u d i e s of p y r i t e , and found that p o s i t i v e o r negative t h e r m o e l e c t r i c p o t e n t i a l could be found i n v a r i o u s p y r i t e specimens. The e f f e c t i s measured by c l o s e l y - s p a c e d hot and " c o l d " wire probes that touch the sur f a c e of the specimen and convey the s m a l l c u r r e n t generated to a galvano-meter. Smith thought that the more t h e r m o e l e c t r i c a l l y - p o s i t i v e values i n d i c a t e d higher temperatures of d e p o s i t i o n . L a t e r r e s e a r c h by F i s c h e r and H i l l e r (1956,) and Suzuki (1963) r e v e a l s that the c o r r e l a t i o n o f thermal e.m.f. and temperature i s only q u a l i t a t i v e , and i s appa r e n t l y r e l a t e d (again i n a q u a l i t a t i v e way) to minor element content. F i s c h e r and H i l l e r suggest that minor elements Co, N i , and Cu cause p o s i t i v e t h e r m o e l e c t r i c e f f e c t . H i l l and Green (1962) r e l a t e high r e s i s t i v i t y of p y r i t e to "high" contents of copper and molybdenum. However, the Cu and Mo content of t h e i r samples i s by no means high, nor i s the d i f f e r e n c e between t h e i r , "high" and "low" content s t a t i s t i c a l l y s i g n i f i c a n t . A review of Suzuki's d e t a i l e d study of thermal e.m.f. i s presented here, as the theory i s r e l e v a n t to minor-element s t u d i e s . Four types of p y r i t e were s t u d i e d by S u z u k i : (1) syngenetic, (2) metamorphically r e c r y s t a l l i z e d , (3) hydrothermally deposited, and (4) hydrothermal replacement. Four types of i n t e r n a l t e x t u r e s were found; these were revealed by e t c h i n g . R e l a t i o n s h i p s e x i s t between t h e r m o - e l e c t r i c p o t e n t i a l and t e x t u r a l and gen e t i c types of p y r i t e . 36 Both p o s i t i v e and negative thermal e.m.f. are thought by-Suzuki to r e s u l t from i m p u r i t i e s i n the p y r i t e . I n accordance w i t h semi-conductor theory, elements which supply e l e c t r o n s ( c a l l e d donor elements) are Co, N i , and Cu. Donor elements cause negative thermal e.m.f. Acceptor elements, As, Sb, and Mn cause p o s i t i v e thermal e.m.f. Examples used by Suzuki are c r y s t a l s from the Chi c h i b u Mine - almost completely composed of " p o s i t i v e " zones. The c r y s t a l s have a high a r e s n i c content. Although Suzuki's t h e o r i e s sound reasonable, h i s f i n d i n g s are not d e f i n i t i v e , and much research w i t h samples of known minor element content would be necessary to v a l i d a t e h i s c o n c l u s i o n s . I I . MINOR ELEMENTS CONTAINED IN PYRITE GENERAL DISCUSSION .. The f i r s t comprehensive review of minor elements contained i n p y rite was that of Fleischer (1955) who compiled analyses published i n many e a r l i e r studies. Most of these studies include spectrographic analyses with q u a l i t a t i v e or semiquantitative data; few contain quantitative analyses. The most commonly reported minor element "impurities" i n pyrite are cobalt and n i c k e l ; less commonly reported are Cu, Au, Ag, Mn, Zn, Se and As. Some of the more sophisticated early studies were those by Auger (1941)» Hawley (1952), and Eawley and Nichol (1961). I t i s unfortunate that most of t h e i r analyses were reported as "i n t e n s i t y r a t i o s , " and as such, could not be used i n the present s t a t i s t i c a l study. Auger. (1941) found the following elements i n spectrographic l i n e s from pyrites and pyrrhotites analyzed: Mg, A l , S i , S, Ca, Ba (probably contaminants) , Sc, T i , V, Cr, Mn, Co, Ni ( t r a n s i t i o n elements) Cu, Pb, Zn, Mo, Cd, Ag, Au, Pb, B i , Sn, In (base metals, etc.) Sr, Y, Sc (rare earth elements) He concluded that the t r a n s i t i o n elements were those most l i k e l y to be present i n true s o l i d - s o l u t i o n . Hawley (1952*) agreed with Auger's conclusion that Co and Ni could substitute isomorphously for Fe i n p y r i t e , but thought that Pb, Zn, and Mo could be incor-porated as p a r t i c l e s of common sulphides, and Cr, Mn, T i , and V 38 could be incorporated as inclusions of wall rock and accessory magnetite-ilmenite. Hegemann (1943J regarded Mn and Zn as u n l i k e l y elements f o r isomorphous substitution. Hawley and Nichol (1961) proposed that Cr, T i , and V, although having higher valence (+3J than Fe {+2) may to a li m i t e d extent proxy f o r Fe. Irregular d i s t r i b u t i o n of these elements, however, suggested t h e i r presence i n i n c l u s i o n s . As and Pb, according to the authors, have i o n i c r a d i i too large to permit substitution f o r Fe, and the presence of Sn was shown to correlate with admixed c a s s i t e r i t e . A recent study by R.H. M i t c h e l l (1968) revealed the presence of the following elements i n pyrites from various geologic environ-ments: T i , V, Cr, Mn, Co, N i , Cu, Zn, Ga, Ge, As, Se, Y, Zr, Nb, Mo, Sn, Te, Sb, Ba, Ce, La, Pb, and B i . From an evidently lengthy study of metal-sulphur bond lengths i n sulphides, stereo-chemistry of bonds, and experimental phase-equilibria, M i t c h e l l concluded that the following elements can substitute isomorphously i n p y r i t e : For F e 2 + : T i , V, Cr, Mn, Co, N i , Cu, Zn, Mo, Nb, Sn For S 2 2~: As, Se, Te, Sb, B i The incorporation of Zr, Ga, Ge, Au, Hg, Pb, Th, and U occurs at defect s i t e s i n the l a t t i c e ( M i t c h e l l , 1968J. In addition to these elements, the platinum group elements, Pt, Pd, I r , Os, have been reported from pyrite (Hawley, et a l . , 1951; Hawley and Rimsaite, 1953J. Thallium has been reported by Voskre-senskaya (1969J and others; Selenium has been recorded by Coleman and Delevaux (1957J, and Edwards and Carlos (1954J. Germanium, Indium. T e l l u r i u m , Rhenium, and Cadmium contents o f p y r i t e are documented by F l e i s c h e r (.1955}. The chemical r e l a t i o n s h i p s of many of these elements i n p y r i t e w i l l be discussed i n d e t a i l i n subsequent pages of t h i s study. 40 B. ANION SUBSTITUTION IN PYRITE M i t c h e l l (1968J concluded from a study of metal-sulphur bond-lengths i n s u l p h i d e s , stereochemistry of bonds, and s u l p h i d e phase e q u i l i b r i a , that As, Sb, B i , Se, and Te can r e p l a c e sulphur i n the p y r i t e l a t t i c e . This c o n c l u s i o n i s supported by the great number of chalcogenide, p n i c t i d e and mixed compounds c r y s t a l l i z i n g w i t h the p y r i t e s t r u c t u r e , and by physicochemical parameters of the anions given below (Table 10J. TABLE 10 PHYSICOCHEMICAL PARAMETERS OP ANIONS* ;ment Atomic Number E l e c t r o n C o n f i g . Covalent Radius I o n i c Radius a E l e c t r o n e g . eV S 16 3s 3p 1.04 1.84" 2 2.5 Se 34 4 s 2 4 p 4 1.14 1.98 2.3 Te 52 5s 5p 1.32 2.21 2.1 As 33 2 3 4s"4p p 1.18 1.91 2.2 Sb 51 , 2 , 3 5s 5p 1.36 2.08 1.9 B i 83 6 s 2 6 p 3 1.46 2.13 1.9 P 15 * 2, 3 3s 3p - 1.10 1.86~ 5 2.1 Although never considered by other r e s e a r c h e r s as a p o s s i b l e s u b s t i t u t e f o r sulphur, phosphorus has s i m i l a r physicochemical parameters and occurs i n s e v e r a l compounds w i t h the p y r i t e o r r e l a t e d s t r u c t u r e s (see Table 10). From t h e i r t e t r a h e d r a l covalent r a d i i , i t would be expected that As and Se should more r e a d i l y s u b s t i t u t e f o r S •(Yfedepohl, 1969) than should the other anions. Maximum amounts recorded i n p y r i t e by F l e i s c h e r and others are: Se (Coleman and Delevaux, 1957) Te 340 ppm ( F l e i s c h e r , 1955) As jfo (Burkart-Saumann and Ottemann, 1971) Sb 700 ppm ( F l e i s c h e r , 1955) B i 100 ppm " CATION SUBSTITUTION IN PYRITE Evidence f o r the elements s u b s t i t u t i n g f o r i r o n i n the p y r i t e l a t t i c e , and the extent to which they s u b s t i t u t e , can be gained from: 1) Documentation o f n a t u r a l and s y n t h e t i c compounds c r y s t a l l i z i n g w i t h the p y r i t e o r r e l a t e d s t r u c t u r e s . 2) Physicochemical parameters such as c o o r d i n a t i o n r a d i i o f i o n s and atoms, e l e c t r i c a l charges of common i o n s , and e l e c t r o n e g a t i v i t y ; 3) L i g a n d - f i e l d r e l a t i o n s h i p s ; 4) Homogeneity of d i s t r i b u t i o n of minor elements i n n a t u r a l l y o c c u r r i n g phases and l a c k of i n c l u s i o n s c a r r y i n g the admixed element; and 5) Reported amounts of these elements found i n n a t u r a l p y r i t e s . N a t u r a l and s y n t h e t i c compounds and t h e i r c r y s t a l s t r u c t u r e s are l i s t e d i n Tables 5 and 6. L i g a n d - f i e l d r e l a t i o n s h i p s are d i s c ussed under a separate heading, as are reported abundances and d i s t r i b u t i o n . The r e l e v a n t physicochemical parameters o f s u b s t i t u t i n g c a t i o n s are given i n the f o l l o w i n g t a b l e (Table 11) (the i n t e r p r e t a t i o n of o c t a h e d r a l c o v a l e n t - r a d i i i s hindered by the wide range of values p u b l i s h e d by d i f f e r e n t a u t h o r s ) . 43 TABLE 11 PHYSICOCHEMICAL PARAMETERS OP CATIONS Atomic E l e c t r o n Covalent Element Number Co n f i g . E f f e c t i v e R.*(A) Radius (A) Electroneg.(V) Sc 21 3d 4s 0.83 5 1.20 T i 22 2 2 3d^4s 0.76/.69 3 1.32 V 23 3 d 5 4 s 2 0.95 1.43 Cr 24 3d 54s 1 0.64 3 1.56 Mn 25 3 d 5 4 s 2 0.912/-703 1.55 1.4 Fe . 26 3d 4s 0.70 1.23 1.64 Co 27 7 2 3d'4s 0.82 1.32 1.70 N i 28 ^ 8 . 2 3d 4s 0.78 1.39 1.85 Cu 29 3d 4s 0.70 1.35 1.75 Zn 30 3d 4s 0.83 1.31 1-5 Mo 42 4d 55s 1 0.68 4 1.64 Ru 44 4d 75s 1 0.65 4 1.33 2.0 Rh 45 4d 5s 0.68 3 1.323 2.1 Pd 46 4 d 1 0 0.93 1.31 4 2.0 Ag 47 4 d 1 0 5 s 1 1.131/.892 •1 .52 1 1.8 Cd 48 AA^r- 2 4d 5s 1.03 1.48 1.46 In 49 . J 0 C 2 C 2 4d 5s 5p 0.923 1.44 3 1.5 Sn 50 .,10 c 2,. 2 4d 5s 5p 0.93/.71 4 1.42 2 1.72 W 74 5 d 4 6 s 2 0.68 4 1.44 6 1.64 Os 76 5 d 6 6 s 2 0.67 4 1.33 2.0 I r 77 5 d 7 6 s 2 0.66 1.32 2.1 44 TABLE 11 (continued) . PHTSICOCHEKICAL PARAMETERS OF CATIONS Atomic E l e c t r o n Covalent Element Number Co n f i g . E f f e c t i v e R.*(A) Radius Electroneg.(V) Pt 78 5d 9 6 s 1 0.80 1.31* 2.1 Au 79 5d 6s 1.37 1/-85 5 1.40 4 2.3 T l 81 5 d ^ 6 s 2 6 p ^ 1.05 3/1.49 1 1 . 4 7 1 , 3 1.8 Pb 82 5 d ^ 6 s 2 6 p 2 1.32/.84 4 1.46 2 1.6 V 92 5 f 4 6 d 2 1.05 4/.83 6 1.7 •S u p e r s c r i p t numbers r e f e r to valence s t a t e s . Data from Vedepohl (1969) Handbook of Geochemistry V o l . I 45 D. THE INCORPORATION OF -MINOR ELEMENTS IN,PYRITE' . Minor elements can be in c o r p o r a t e d i n t o a growing c r y s t a l by the f o l l o w i n g mechanisms: 1) S u b s t i t u t i o n f o r anions or c a t i o n s a t r e g u l a r l a t t i c e s i t e s - l e a d i n g to isomorphous s o l i d - s o l u t i o n ; -2.) I n t e r s t i t i a l s o l i d - s o l u t i o n , i . e . , i n t e r s t i t i a l to r e g u l a r l a t t i c e s i t e s ; 3) A d s o r p t i o n ; 4) Admixing of s o l i d or f l u i d i n c l u s i o n s as independent phases. Acc o r d i n g to Goldschmidt (.1.937)', " v i c a r i o u s " i o n s i n s o l u t i o n compete f o r l a t t i c e s i t e s on growing c r y s t a l s . Minor.elements s i m i l a r i n s i z e to the major element s u b s t i t u t e e a s i l y because of t h e i r "camouflage" of s i z e . Elements of g r e a t e r r a d i u s are concentrated o n l y i n l a t e r c r y s t a l l i z i n g f r a c t i o n s . Elements w i t h s i m i l a r s i z e but stronger charge are "captured" by the growing c r y s t a l , and those w i t h l e s s s t r o n g charges are "admitted." These three " r u l e s " form the b a s i s of many geochenical s t u d i e s , and i n many cases they agree w e l l w i t h observed major element-minor element r e l a t i o n s h i p s , but many other f a c t o r s have been shown to i n f l u e n c e the s u b s t i t u t i o n of minor elements f o r major elements. Some of these f a c t o r s a r e : 1) The system of c o o r d i n a t i o n o f c a t i o n s and anions. A s p e c i f i c i o n , under d i f f e r e n t nodes of c o o r d i n a t i o n , w i l l have d i f f e r e n t covalent r a d i i . Thus f o r a gi v e n system, f o r example, p y r i t e - w i t h o c t a h e d r a l c o o r d i n a t i o n of anions to c a t i o n s , the o c t a h e d r a l - c o o r d i n a t i o n r a d i u s of c a t i o n s r a t h e r than i o n i c r a d i u s i s a b e t t e r measure o f the p o s s i b i l i t y f o r c a t i o n i c s u b s t i t u t i o n . 2) The r e l a t i v e p r o p o r t i o n of i o n i c v s . covalent bonding. Two f a c t o r s a f f e c t e d by bond types, i o n i z a t i o n p o t e n t i a l and e l e c t r o n a f f i n i t y , are measures of the a b i l i t y of atoms to ^ r e s p e c t i v e l y l o s e o r g a i n e l e c t r o n s . The two p r o p e r t i e s are o f t e n combined i n the term " e l e c t r o n e g a t i v i t y . " The r e l a -t i o n s h i p of i o n i z a t i o n p o t e n t i a l , e l e c t r o n e g a t i v i t y and i o n i c r a d i u s to the c h a l c o p h i l e - l i t h o p h i l e tendencies o f the i o n s i n v o l v e d i s i l l u s t r a t e d i n the accompanying t a b l e (Table 12). 3) The degree of l i g a n d - f i e l d s p l i t t i n g and the e f f e c t o f completeness of f i l l i n g of the non-bonding 3d o r b i t a l s . These t o p i c s are di s c u s s e d i n an e a r l i e r s e c t i o n . 4) The a v a i l a b i l i t y and c o n c e n t r a t i o n of s u b s t i t u t i n g elements a t the s i t e of c r y s t a l l i z a t i o n . 5) The chemical and p h y s i c a l nature of the medium from which the p a r t i c u l a r major m i n e r a l i s c r y s t a l l i z i n g , f o r example, the pH, Eh, temperature, pressure, a c t i v i t y o f vapor phases, e t c . A l l may have some e f f e c t on the spe c i e s of i o n s a v a i l a b l e f o r s u b s t i t u t i o n . DeVore (1955) considers that a d s o r p t i o n of t r a c e elements i s important d u r i n g c r y s t a l l i z a t i o n . A resume of h i s t h e o r i e s i s presented here. Chemisorption r e f e r s to the t r a n s f e r of m a t e r i a l from the d i s p e r s e d phase to the surface of a growing m i n e r a l by any of three processes: MEDIUM-SIZED CATIONS (0.65-0.89 A) j Mg2+ | Mn2* F c = - | Co2* j Zn2* Ni2* | Pi2* .' Pd2* Cu2* Ag2* 22 7 (0-89) /- (V) { 15-03 j 15-64 Electro- ; (1-22 j 1-40 negativity j \l-23 j (1-60)* Radius (A) 0-65 j 0-80 ! i 16-24 ' 17-4 ! 17-94 1-65 (1-7): 1-5 (1-64): (1-7) 1-77 1 0-74 I 0-72 ' 0-69 18-2 i 19-3 j 19-9 1-7 (2-1) j (20) 1-75; (1-44) i (1-35) 1 0-69 (0-80) : (0-80) i i 20-3 20 0-75) (0-89) LARGE DIVALENT CATIONS (0.93-1.35 A) Ba2* Si"* Ca2* Sn2* j V2* Pts* Cd2* ; He2" /(V) Electronegativity Radius (A) 100 fO-85 \0-97 1-34 11-03 10 0- 99 1- 12 119 1-0 1-04 1 -01 14-63 14-65 1-65 — (1-72) (1-45) 0-93 ~0-9 15-05 | 16-9 ; 18-9 1-60 1-50 ' 1-90 (1-55). 1 (1-46) (1-44) 1-20 j 0-97 \ I -10 TRIVALENT CATIONS Scs* Sb3+ Bi5* Vs+ j In3-/3(V) Electronegativity Radius (A) 20-5 fl-2 \1-11 0-92 24-75 1-30 1-20 0-81 24-S3 1-80 0-82) 0-74 25-56 1-80 . n 67) 0-96 26-5 • 2803 1-35 i 1-60 1-45 ! 1-49 i . 0-76 j 0 81 TABLE 12. Ionization potentials, electronegativities, and ionic r a d i i for divalent and trlvalent cations. (From Ahrens,L.H., 1964) V e r t i c a l d o u b l e l i n e s e p a r a t e s l i t h o p h i l e elements on l e f t from c h a l c o p h i l e elements on r i g h t . 48 1) t r a n s f e r and bonding to the surface of pre-formed a n i o n -c a t i o n groups; 2) t r a n s f e r of ions from a complex to i o n s f i x e d a t the m i n e r a l s u r f a c e (simple base exchange); 3) condensed f i l m s or i o n i c groups may be f i x e d to the m i n e r a l s u r f a c e by van der Waals f o r c e s . I f added m a t e r i a l becomes pa r t of the c r y s t a l s t r u c t u r e , the f i x a t i o n i s r e f e r r e d to as a b s o r p t i o n . I f the added m a t e r i a l cannot become pa r t of the r e g u l a r m i n e r a l s t r u c t u r e , i t must remain o u t s i d e the s t r u c t u r e and occupy s i t e s of i m p e r f e c t i o n s , o r occur as s u r f a c e f i l m s or groups between mosaic and growth-twinning s u r f a c e s . Such unaccommodated m a t e r i a l may even be a cause of such d i s l o c a t i o n s , i m p e r f e c t i o n s , mosaics or twinning s u r f a c e s . The f i x a t i o n of unaccommodated i m p u r i t i e s i s c a l l e d a d s o r p t i o n , even though chemical bonds may form. I f the adsorbed i o n s make a s t r o n g and r e l a t i v e l y s t a b l e bond w i t h the s u r f a c e , a non-displaced i m p e r f e c t i o n may r e s u l t , and f i n a l content of i m p u r i t i e s can be c o n s i d e r a b l e . I f a d s o r p t i o n bonds are weak and unstable the adsorbed m a t e r i a l may be d i s p l a c e d to the outside of the new s u r f a c e . Continuous a d s o r p t i o n of non-displaced m a t e r i a l could e x p l a i n the r e g u l a r d i s t r i b u t i o n o f " e x s o l u t i o n " type i n c l u s i o n s , as the i n c l u s i o n s could be the r e s u l t o f aggregation of adsorbed m a t e r i a l s Into new compounds a t a lower energy l e v e l - a means of reducing i m p e r f e c t i o n and mosaic s t r u c t u r e s . These mechanisms could account f o r the occurrence of exsolved gold i n p y r i t e , the breakdown of f u k u c h i l i t e to p y r i t e w i t h c o v e l l i t e i n c l u s i o n s , and the h i g h T l , As, or Sn contents of i r o n d i s u l p h i d e s which o r i g i n a t e d as monosulphides. DISTRIBUTION OF MINOR ELEMENTS WITHIN A SINGLE CRYSTAL S e v e r a l s t u d i e s have i n v e s t i g a t e d the s p a t i a l . d i s t r i b u t i o n o f minor elements w i t h i n s i n g l e c r y s t a l s . The zonal d i s t r i b u t i o n of c o b a l t and n i c k e l i n b r a v o i t e i s w e l l documented. Copper co n c e n t r a t i o n s i n p y r i t e have s i m i l a r zonal p a t t e r n s (see F i g u r e 25)» I n v e s t i g a t i o n of p y r i t e from ea s t e r n Transbaikaliya.(Muravyeva, et a l . . 1964; showed th a t cores of c r y s t a l s contained more Sn, Zn, and Cd than margins, but Pb and As were concentrated i n c r y s t a l margins. Data from the study i s shown i n Table 13. Because only s i x samples were used, and because many of the minor elements could be present as i n c l u s i o n s , the c o n c l u s i o n s r e g a r d i n g z o n a t i o n are of d o u b t f u l v a l i d i t y . F r o n d e l . et .al.-(1943). i n a study of galena and s p h a l e r i t e c r y s t a l s , a l s o found non-uniform d i s p e r s i o n of minor elements throughout "host" m i n e r a l s . Two types of c o n c e n t r a t i o n p a t t e r n s may be present: \) Pyramidal regions (face l o c i ) i n which c o n c e n t r a t i o n d i f f e r e n c e s a r i s e from unequal a d s o r p t i v e c a p a c i t y of the • d i f f e r e n t forms on the growing c r y s t a l ; 2) Zoning p a r a l l e l to e x t e r n a l growth s u r f a c e s without marked s e l e c t i v i t y as to d i f f e r e n t c r y s t a l s u r f a c e s . The growth zones may be present as a l t e r n a t i n g or p e r i o d i c zones, as i n b r a v o i t e , or as p r o g r e s s i v e z o n a t i o n caused by r e g u l a r v a r i a t i o n of f a c t o r s c o n t r o l l i n g element p a r t i t i o n . Recent s t u d i e s by V e l i k o b o r e t s and Lukyanchenko (1971) have confirmed the r e l a t i o n s h i p between c r y s t a l faces of p y r i t e and a b s o r p t i o n of c o b a l t . I n electron-microprobe s t u d i e s of p y r i t e * S i m i l a r zonation of As i n p y r i t e has r e c e n t l y been noted by Burkart-Baumann and Ottemann (1971). 50 from magnetite skarns, the authors noted h i g h e r c o b a l t c o n c e n t r a t i o n s on (100 J f aces than on (111J faces of the same c r y s t a l . T h e i r e x p l a n a t i o n f o r t h i s phenomenon i s the " l e s s e r , r e t i c u l a r d e n s i t y of the (100; planes composed of r e g u l a r l y a l t e r n a t i n g i r o n and sulphur i o n s , as compared w i t h the monatomic (111J planes." On (10QJ planes, c o b a l t was absorbed r h y t h m i c a l l y along a s l i g h t l y ascending s t r a i g h t l i n e , w h i l e on (111j planes i t was absorbed r h y t h m i c a l l y and u n i f o r m l y (see Figure 24). The authors a l s o noted two d i f f e r e n t types of i n c l u s i o n s present i n the p y r i t e . The f i r s t type contained the same concentra-t i o n s of Co, H i , Cu, Fe, and S as the host p y r i t e . These p a r t i c l e s proved to be i n c l u s i o n s of r e c r y s t a l l i z e d p y r i t e . Other i n c l u s i o n s were shown by electron-microprobe a n a l y s i s to be d i s c r e t e g r a i n s of c o b a l t i t e . I n s t u d i e s of the d i s t r i b u t i o n of minor elements w i t h i n a s i n g l e c r y s t a l , the electron-microprobe has proved to be i n v a l u a b l e as i t enables d i f f e r e n t i a t i o n between isomorphous s u b s t i t u t i o n and "mechanical" admixtures. ( 1 0 0 ) FIGURE 24. Electron-microprobe scan across p y r i t e c r y s t a l : a) v a r i a t i o n i n i n t e n s i t y of CoKa r a d i a t i o n along scan p r o f i l e normal to growth steps of (100) b) v a r i a t i o n i n i n t e n s i t y of CoKa r a d i a t i o n normal to growth steps (111). (From V e l i k o b o r e t s and Lukyanchenko, 1970) .t: Content, % a. & Sp. No. Vein and country rock Part of crystal ni A s Pb Sn Ac Zn Ctl Cu Balance 2004 (,\i:\rry No.. IS Periphery Core Whole crystal 0.0:10 0.030 0.030 Tr. 0.1.10 o.oor. 0.000 0.004 0.004 0.004 — 0.100 0.040 0.100 0.007 0.(XjH 0 . 0 0 H 0.040 0.040 0.040 + Pb o' " ' i c 1 472 Vein No. .'). granodiorite Periphery Core Whole crystal 0.000 0.000 0.045 .0.075 0 . 0 2 0 0.120 0 . 0 0 . 1 0 . 0 0 2 0 . 0 0 . 1 0.010 0.055 0.004 _ 0.100 0.250 0 . 2 0 0 0.007 o.oiw 0.008 0.007 0.040 0.020 -|- As -1-Sn. Zn. Cu <s 2003 Vein No. 53, granodiorite Periphery Core Whole crystal Tr. 0.000 o.oco 0..'I00 0.075 0.120 0 . 0 0 : 1 0 . 0 0 2 0 . 0 0 . 3 Tr. 0.004 0.002 0.0002 0 . 0 0 0 1 0 . 0 0 0 2 0.004 0.015 0.035 0.002 0 . 0 0 1 0.035 0 . 0 0 0 0.001 0.001 -|-Sn, Zn 0 >> 2223 Vein No. 49, quartz diorite Periphery Core Whole crystal 0.000 0.000 0.007 0.080 0.020 0.050 0.007 0.003 0.010 0.004-0.020 0.012 — 0 . 0 0 0 0.150 0.120 0.003 0.020 0.007 0.040 0.020 + As, Pb -j- Sn, Zn, Cd, Cu ; jjukhin.skc 732 Vein Ts, porphyritic quartz diorite • Periphery Core Whole crystal 0.000 0 . 0 0 0 o.oco 0.030 0.040 0.120 0.013 0.C07 0.200 0.009 0.012 0.010 — 0.030 0.040 0.040 0.007 0.012 0.009 0.040 0.007 0.015 4- As, Pb, Qi + Sn, Zn, Cd G 571c Vein Ts, porphyritic quartz diorite Periphery Core Whole crystal 0.000 0.000 o.coo 0.020 0.010 .0.015 0.003 0.002 0.005 0.007 0.030 0.020 0.0002 0 . 0 0 0 1 0.0002 0.040 0.250 0.150 0.003 0.005 0.007 0.040 0.007 0.025 + As, Cu, Cd -j-Sn, Zn TABLE 13;. Comparison of minor element content of pyr i t e c r y s t a l cores and margins, Belukhinskoye and Bukhinskoye deposits, U.S.S.R. (From Muravyeva et, a l . , 1964) ro 53 F. SPECIFIC'MINOR ELEMENTS CPITTAINED IN PYRITE 1. The Copper Content of P y r i t e The p o s s i b i l i t y t h a t copper (,Cu ) could s u b s t i t u t e f o r i r o n i n the p y r i t e l a t t i c e has been c l a r i f i e d by recent s t u d i e s ( F r e n z e l and Ottemannj 1967; E i n a u d i , 1968; K a j i w a r a , 1969). P r e v i o u s l y , F l e i s c h e r (19.55.) reviewed 785 p y r i t e analyses and r e p o r t e d a .maximum content i n p y r i t e of about 6 percent copper, w i t h 75 percent of the samples c o n t a i n i n g over 10 ppm and a f u r t h e r 10 percent c o n t a i n i n g over 1 percent Cu. F l e i s c h e r concluded that most, i f not a l l , of the copper was present as admixed c h a l c o p y r i t e . 2 + 2 + Comparing physicochemical p r o p e r t i e s of Cu and Fe we note that the c o n f i g u r a t i o n s and e l e c t r o n e g a t i v i t i e s are r a t h e r d i s s i m i l a r but covalent r a d i i are s i m i l a r ( F e ^ + - 1.23 &; Cu^ +- 1.35 A*), Previous s t u d i e s suggested that copper, i f present i n minor amounts i n p y r i t e , should occur as i n t e r s t i t i a l s u b s t i t u t i o n s or as d i s c r e t e m i n e r a l i n c l u s i o n s . Evidence to the c o n t r a r y e x i s t s . I n 1967 F r e n z e l and Ottemann discovered t h a t up to 10 percent copper was present i n zoned p y r i t e from the Cu-Zn de p o s i t a t Nukumundu, F i j i . E l e c t r o n -microprobe t r a v e r s e s across the specimen revealed the copper was apparently i n s o l i d s o l u t i o n i n the p y r i t e . E i n a u d i (1968) disco v e r e d up to 1.5 percent copper i n p y r i t e from c a v i t i e s i n c o a r s e l y - b r e c c i a t e d , s i l i c i f i e d v o l c a n i c s from the northern p a r t of the McCune p i t at Cerro de Pasco, Peru. E l e c t r o n -microprobe t r a v e r s e s were made across the c l u s t e r of c r y s t a l s u s i n g copper and c h a l c o p y r i t e as standards; these t r a v e r s e s r e v e a l e d copper r i c h i n t e r m e d i a t e zones f o l l o w i n g c r y s t a l l p g r a p h i c d i r e c t i o n s , w i t h cores and margins of the c r y s t a l s c o n t a i n i n g l e s s than . 2 wt. percent copper. No other s u l p h i d e s were present i n the sample, no i n c l u s i o n s were seen at m a g n i f i c a t i o n s of 1 0 0 0 x , and the zonal v a r i a t i o n s were  not revealed by c o l o r , r e f l e c t i v i t y , a n i s o t r o p i s m . or e t c h i n g changes. The zoning i s i l l u s t r a t e d i n F i g u r e s 25 and 26. Spectrographic a n a l y s i s of the p y r i t e i n d i c a t e s approximately 500 ppm As and 1 0 0 0 ppm Cu, w i t h s i l v e r and l e a d 50 ppm each. The r e p o r t e d c e l l edge i s 5.148 £. S e v e r a l t h e o r i e s have been advanced f o r the method.of s u b s t i t u t i o n o f Cu i n p y r i t e . E i n a u d i (1968) noted that both the Cerro de Pasco and Nukumundu p y r i t e s are a s s o c i a t e d w i t h e n a r g i t e (Luzonite - Cu^AsS^) m i n e r a l i z a t i o n , and suggested that the Cu-Fe-As-S system may l e a d to "coupled s u b s t i t u t i o n . " This mechanism i s e x p l a i n e d by R a d c l i f f e and McSween (1969) u s i n g c r y s t a l f i e l d theory. The 2+ Cu i o n i s g e n e r a l l y s t a b i l i z e d i n t e t r a h e d r a l or d i s t o r t e d o c t a h e d r a l s i t e s , thus does not o r d i n a r i l y e n t er p y r i t e i n s i g n i f i -cant amounts, but c r y s t a l l i z e s i n d i s c r e t e phases i n v o l v i n g t e t r a -h e d r a l c o o r d i n a t i o n . A c c o r d i n g to N i c k e l (1968), i f As i s s u b s t i -tuted f o r Fe i n the p y r i t e s t r u c t u r e , an a d d i t i o n a l "d" e l e c t r o n from the c a t i o n must be used i n bonding. The r e s u l t a n t Cu^ + i o n could be s t a b l e i n the r e g u l a r o c t a h e d r a l f i e l d ; the copper and a r s e n i c forming a coupled s u b s t i t u t i o n . Ypma ( 1 9 6 8 ) s t u d i e d c u p r i a n b r a v o i t e (Co, N i , FeJS^, v i l l a m a n i n i t e (Cu, Co, N i , Fe/S,,, . and c u p r i a n v i l l a m a n i n i t e from the P r o v i d e n c i a Mine i n Spain and found that the c u p r i a n v a r i e t i e s were markedly a n i s o t r o p i c . 1.4 1.0 0.6 0.2 0.0 wt % C u FIGURE 25. Copper zonal patterns i n intergrowth of p y r i t e c r y s t a l s as interpreted from 15 electron microprobe traverses. Traverse shown below i s labeled A-B. (from Einaudi, 1968.) FIGURE 26- Electron microprobe trace of CuKa radiation along traverse A-B. (From Einaudi, 1968) 56 R a d c l i f f e and McSween suggest that the a n i s o t r o p i s m i m p l i e s d i s t o r t i o n 2+ of the o c t a h e d r a l s i t e s of the p y r i t e s t r u c t u r e , and that Cu i o n s could f i t n e a t l y i n t o these d i s t o r t e d s i t e s . C i r c u l a r reasoning i s inherent i n t h i s e x p l a n a t i o n , making i t i n v a l i d . R ecently, Kajiwara (1970) discovered a copper-iron d i s u l p h i d e , P u k u c h i l i t e , i n Kuroko-type sulphide d e p o s i t s i n Japan. Microprobe analyses of 24 samples gave Cu/Fe r a t i o s c l o s e to 3 : 1, and Cu + Fe/S r a t i o s v a r y i n g from 1 : 1.7 to 1 : 2.1. The data suggest the formula Cu^FeSg. Found i n b a r i t e - b e a r i n g gypsum-anhydrite ores w i t h c o v e l l i t e and p y r i t e , F u k u c h i l i t e i s a low-temperature m i n e r a l , as i t decomposes to p y r i t e and c o v e l l i t e at 200° C. A s y n t h e t i c form w i t h i d e n t i c a l o p t i c a l p r o p e r t i e s and x-ray d i f f r a c t i o n p a t t e r n s has been prepared by Shimazaki ( i 9 6 0 ) . The m i n e r a l i s s t a b l e a t 225° C, has the p y r i t e s t r u c t u r e , and a c e l l - e d g e dimension which v a r i e s i n p r o p o r t i o n to the amount of copper i n s o l i d s o l u t i o n ( a Q = 5.59 A* f o r a s o l i d s o l u t i o n w i t h 50 mol percent CuS^). Pure CuS^ has been synt h e s i z e d by B i t h e r , et a l . (1968). The l a r g e number of antibonding e l e c t r o n s present i n CuS^ ( c o n f i g u r a -t i o n 3 d ^ 4 s ^ ) suggests that the compound should be unstable and d i f f i c u l t to prepare. C o n d i t i o n s necessary f o r s y n t h e s i s from a CuS~S mixture ranged from 15 k i l o b a r s pressure at 400° C to 65 k i l o b a r s at 1600° C. Thus the CuS^ compound i s not l i k e l y to be found i n nature. The evidence presented above suggests t h a t more copper may be present i n p y r i t e by isomorphous s u b s t i t u t i o n than i s g e n e r a l l y thought. However, the d i f f i c u l t y i n d e t e c t i n g true isomorphous s u b s t i t u t i o n , i n c o n t r a s t to mechanical admixtures, i n h i b i t s the us e f u l n e s s o f copper i n p y r i t e r e search. f • The Gold Content of P y r i t e Gold i s commonly a s s o c i a t e d w i t h p y r i t e i n hydrothermal base metal d e p o s i t s . There has been much controversy over the form i n which.gold i s present i n the p y r i t e l a t t i c e - as microscopic o r sub-microscopic p a r t i c l e s o f f r e e g o l d , o r isomorphously sub-s t i t u t e d f o r Fe. Evidence e x i s t s f o r both types of occurrence. F l e i s c h e r r e p o r t s 36 p y r i t e analyses i n which gold i s present the mean content of these being l e s s than 10 ppm. More recent, r e s e a r c h on Russian gold d e p o s i t s r e v e a l s that Au content of p y r i t e can be much hig h e r . S y n t h e t i c a u r i f e r o u s p y r i t e has been prepared by M a s l e n i t s k y ( i n Joralemon, 1950) and by K u r a n t i (1941, i n Boyle, 1961J. M a s l e n i t s k y found that the amount of gold contained i n the p y r i t e c ould be c o n t r o l l e d up to a maximum 9.7 oz. per ton (270 ppm). Mic r o s c o p i c i n v e s t i g a t i o n a t 1200x m a g n i f i c a t i o n revealed no d i s c r e t e g o l d p a r t i c l e s ; i t was concluded that the go l d was i n s o l i d s u b s t i -t u t i o n f o r Fe i n the p y r i t e l a t t i c e . K u r a n t i prepared s i m i l a r a u r i f e r o u s p y r i t e i n which no d i s c r e t e gold p a r t i c l e s could be seen at h i g h m a g n i f i c a t i o n . Spectrographic analyses i n d i c a t e d that the gol d was u n i f o r m l y d i s t r i b u t e d and x-ray s t u d i e s showed th a t the p y r i t e l a t t i c e constant decreased w i t h i n c r e a s i n g gold content, r e a c h i n g a constant value at 2000 grams Au per ton. Since the o c t a h e d r a l covalent r a d i u s of gold i s 1.40 & compared to 1.23 X 2+ 2+ f o r Fe , the p y r i t e l a t t i c e should expand i f Au s u b s t i t u t e s isomorphously. Joralemon noted an expansion of the l a t t i c e , ( a 0 = 4.577 of p y r i t e from Amador, C a l i f o r n i a , c o n t a i n i n g about 5 oz. (140 ppmj gold per ton. The a u r i f e r o u s p y r i t e was etched more deeply than normal p y r i t e when t r e a t e d w i t h n i t r i c a c i d . He concluded t h a t the gold was i n s o l i d s o l u t i o n i n the p y r i t e . P y r i t e and a r s e n o p y r i t e from the Dolphin east lode, F i j i c o n t a i n up to 33 oz. (924 ppm) gold per ton ( S t i l l w e l l and Edwards, 1946j although only a few p a r t i c l e s could be seen m i c r o s c o p i c a l l y . Heating to 600° C caused the appearance of coalesced p a r t i c l e s v i s i b l e under the microscope. S t i l l w e l l i n t e r p r e t s these r e s u l t s as an i n d i c a t i o n of the presence of gold i n l i m i t e d s o l i d s o l u t i o n i n the s u l p h i d e s . I t could be argued t h a t h e a t i n g should tend to preserve r a t h e r than terminate the s o l i d s o l u t i o n s t a t e , and i t i s probable t h a t the gold i s present i n independent p a r t i c l e s l a r g e r than the gold u n i t c e l l (Joralemon, 1950). Head (1935) notes t h a t gold f l a k e s coated w i t h a magnetic i r o n m i n e r a l may occur o r i e n t e d p a r a l l e l w i t h c r y s t a l l o g r a p h i c planes, suggesting e x s o l u t i o n o r i g i n . I n the G e t c h e l l Mine, Hevada, Joralemon (1950) concludes that gold i s present i n p a r t i c l e s r a n g i n g i n s i z e from s l i g h t l y l a r g e r than the u n i t c e l l to n e a r l y one m i l l i m e t e r i n diameter, and probably a l s o i n atomic d i s p e r s i o n ( s o l i d s o l u t i o n ) . M i c r o s c o p i c a l l y v i s i b l e gold i s r e s t r i c t e d to the r i c h e r ore shoots, and the submicroscopic gold i s widespread. Joralemon concludes gold may be in solid-solution in pyrite. In the ore-shoots much gold is present in "porous" pyrite, probably due to the great surface area available to adsorption of gold. > The reason for the common association of gold (and also silver,) with pyrite is thought to be the electrochemical nature of the surface of pyrite. In hydrothermal gold deposits many minerals may contain gold, either as microscopic to submicroscopic particles or in solid-solution, but often pyrite is the main "carrier." An example is the Almalyk deposit, U.S.S.R. (Badalov, 1968). Here, the gold is most concentrated in chalcopyrite (up to 22 g/ton), but 72 percent of the total gold is carried in pyrite, at an average of 3 g/ton (see Figure 27). At the same deposit, silver, selenium and tellurium are a l l "carried" in the pyrite, although selenium is "concentrated" in molybdenite and tellurium and silver in galena (see Figures 27 and 28). In an earlier study Badalov and Badalova (1967) found that the gold content of pyrite is highest in gold-quartz (+pyrite) veins. In one such deposit the average Au content was over 650 ppm. Typical abundance range in pyrite from "porphyry" copper and copper molybdenum deposits is 3-4 ppm. Similar results were obtained by Vakhrushev and Tsimbalist (1967J from ore deposits of the Altay-Sayan deposits, where the average content for gold-quartz veins was 35.6 ppm and the average for skarn gold deposits was 3.9 ppm (see Figure 29). This is a most useful study from the point of view of exploration applications, because the gold content of pyrite from auriferous skarns is significantly higher than those from barren magnetite skarns in the same area. Thus the gold Relative m / W g 230 43 JS amounts FIGURE 27. Distribution of gold and silver in the principle ore minerals of the Almalyk deposit, U.S.S.R. Mt-magnetite, Mo-molybdenite, Py-pyrite, Cp-chalcopyrite, Sp-sphalerite, Ga-galena. (From Badalov and Badalova, 1967) FIGURE 28. Distribution of Selenium and Tellurium in principal ore minerals of the Almalyk ore deposit U.S.S.R. (From Badalov and Badalova, 1967) 35 JO 25 20 15 10 5 35 30 25 20 15 10 S *» »» *o" **> "•»****' ** us ^ *-* I I I I I I to ^. l^, «J- <J 55 S3 S5 S$ W —• trV l i l t 1... r- r~ -o *-^> *—> ^ ^ «=> c i «i c-^ c^ , — io" i . - ; ^ V ( t i I t i i t t S i7; X- —* FIGURE 2 9 . I ) Gold i n p y r i t e from i r o n skarns (96 analyses) I I ) Gold i n p y r i t e from gold-quartz v e i n s (37 analyses. (From Vakhrushev and T s i m b a l i s t , 1967) 62 content of p y r i t e s i s u s e f u l as an e x p l o r a t i o n t o o l . 3. S i l v e r Content i n P y r i t e Experimental evidence from the system Ag-Fe-S ( T a y l o r , 1970J a t temperatures up to 700° C show that l e s s than 0.05 percent (.500 ppm; s i l v e r i s s o l u b l e i n FeS^, and that s i l v e r does not measurably a f f e c t the c e l l edge of p y r i t e i n t h i s system. This l i m i t e d s o l u b i l i t y i s expected, s i n c e the s i z e of the Ag +^ i o n i s much l a r g e r (1.52 2+ than the Fe i o n , and charges, i n v o l v e d are d i f f e r e n t . " A r g e n t i f e r o u s p y r i t e " has been a common term i n many g e o l o g i c a l r e p o r t s but most evidence suggests that s i l v e r i s present i n p y r i t e i n m i c r o i n c l u s i o n s (as w i t h gold) and i n f r a c t u r e f i l l i n g s . Such i s the case f o r "a r g e n t i f e r o u s p y r i t e " from the Kidd Creek deposit ( T a y l o r , 1970). Considerable s i l v e r i s present i n many p y r i t e samples from hydrothermal d e p o s i t s . Sudbury p y r i t e s range from 2 to 8 ppm Ag i n ei g h t specimens (Hawley, 1962). P y r i t e s from the Slocan area c o n t a i n over 1 percent s i l v e r i n some cases (W.H. Mathews, unpublished data) but. c o n s i d e r i n g the high contamination l e v e l i n d i c a t e d by Pb, B i , Cu, and Zn analyses, the s i l v e r i s probably present i n admixed s i l v e r - s u l p h o s a l t s , and i n galena. I n the Karamazar r e g i o n (Badalov and Badalova, 1967) s i l v e r occurs i n p r a c t i c a l l y every ore- m i n e r a l , but i s most concentrated i n p y r i t e from p o l y - m e t a l l i c ores (100-2400 ppm) and lowest c o n c e n t r a t i o n s are i n p y r i t e from copper molybdenum "porphyry"-type d e p o s i t s . P y r i t e i s commonly a " c a r r i e r " m i n e r a l f o r s i l v e r , as has 63 been di s c u s s e d p r e v i o u s l y f o r gold (Badalov, 1965, see page 59). I n the Almalyk deposit d i s c u s s e d by Badalov, 83 percent of the t o t a l s i l v e r o f the deposit i s contained i n p y r i t e i n c o n c e n t r a t i o n s of 60 g/ton, w h i l e the remainder i s concentrated i n galena (up to 850 g/ton). 4. Platinum-Group Metals i n P y r i t e Pew p u b l i s h e d analyses are a v a i l a b l e f o r platinum-group metals i n p y r i t e . F l e i s c h e r (1955) r e p o r t s s e v e r a l unpublished •analyses. Those of Schneiderhohn i n d i c a t e 10-100 ppm platinum and palladium and 0.1 to .1 ppm ruthenium, rhodium and i r i d i u m . The remaining analyses showed up to 0.38 ppm Pt and Pd and 0.5 ppm Pd. Spectrographic analyses p u b l i s h e d by Hawley, Lewis and Wark (1951) show one Sudbury p y r i t e w i t h 0.011 oz/ton Pt (0.3 ppm) and 0.009 oz/ton (0.25 ppm) Pd. P y r i t e i s r a r e at Sudbury de p o s i t s and platinum-group metals are more abundant i n c h a l c o p y r i t e and p e n t l a n d i t e . The t o t a l average of Pt group metals i n Sudbury p y r i t e i s r e p o r t e d to be 1 . 90 ppm (Hawley, 1962), d i s t r i b u t e d a s : Pt 56.4$ ) ) Pd 41.4$ ) 100.3$ ) Rh 2.5$ ) P y r i t e from an " o f f s e t " d e p o s i t at Sudbury assayed 4.714 ppm Pt group, w i t h roughly the same r a t i o as above f o r s p e c i f i c metals. T h e o r e t i c a l l y , Pt-group metals are expected to enter the p y r i t e l a t t i c e to a l i m i t e d extent. N a t u r a l l y o c c u r r i n g phases having p y r i t e s t r u c t u r e s a r e : PtAs^ - S p e r r y l i t e RuS^ - L a u r i t e P d B i 2 - Mi c h e n e r i t e •(RhPtPd)(AsS) 2 - H o l l i n g w o r t h i t e ( I r , Rh, Ru, Pt)AsS - I r a r s i t e OsS^ - E h r l i c h m a n i t e I n a d d i t i o n , many s y n t h e t i c phases are known.(see Table 6) i n v o l v i n g Pt metals i n v a r i o u s p o l y a n i o n i c combinations w i t h S, Se, Te, As, Sb, and B i . Octahedral covalent r a d i i f o r Pt metal i o n s are as f o l l o w s : R u 2 + 1.33 X 0 s 2 + 1.33 X R h 5 + 1.32 I I r 5 + 1.32 .2 P d 4 + 1.31 %• P t 4 + 1.31 i 2*4* 0 Comparing these r a d i i w i t h that o f i r o n (Fe 1.23 A ) , isomorphous s u b s t i t u t i o n should be p o s s i b l e , p a r t i c u l a r l y i f As, e t c . are present to e f f e c t coupled s u b s t i t u t i o n s . The s c a r c i t y of platinum and s i m i l a r metals i n p y r i t e i s probably due to l i m i t e d supply o f these metals i n common ore-forming f l u i d s . However, i t i s u n l i k e l y that Pt elements are analyzed f o r i n many s u l p h i d e research p r o j e c t s , and f u r t h e r i n v e s t i g a t i o n s i n t o Pt group geochemistry could prove v a l u a b l e i n d e f i n i n g the r o l e of b a s i c magmas i n r e l a t i o n to ore-forming f l u i d s . The Uranium Content of P y r i t e C o n s i d e r a t i o n of the atomic and i o n i c p r o p e r t i e s o f uranium 65 i n comparison w i t h i r o n i n d i c a t e s l i t t l e p r o b a b i l i t y f o r e x t e n s i v e admittance of uranium i n t o the p y r i t e l a t t i c e : element common valence i o n i c r a d i u s . Fe +2 .82 1 * U +4 1.05 £ •(Wedepohl, 1969) Of the uranium s u l p h i d e s , only US has s t r u c t u r e s i m i l a r to any common su l p h i d e ( i n t h i s case galena); none are s i m i l a r to p y r i t e s t r u c t u r e . The presence of uranium i n sulphi d e s i s r a t h e r easy to detect by means of autoradiographs, and the d i s t r i b u t i o n of uranium i n the sample can be checked a t the same time. This method was used by Wright, Smith and Hutta ( i 9 6 0 ) . According to the authors, the d i s t r i b u t i o n of alpha p a r t i c l e emission t r a c k s should f o l l o w a "Poisson" d i s t r i b u t i o n curve i f the e m i t t e r i s randomly d i s t r i b u t e d i n the sample. Study of autoradiographs showed that the upper l i m i t f o r homogeneously d i s t r i b u t e d uranium i n p y r i t e was 46 ppm; n e a r l y a l l the t r a c k s i n samples w i t h s e v e r a l hundred to s e v e r a l thousand -ppm U are d i s t r i b u t e d along g r a i n boundaries, cleavages, o r i n d i s c r e t e p a r t i c l e s . I t i s assumed by the authors that homogeneous uranium d i s t r i b u t i o n i n d i c a t e s i n c o r p o r a t i o n of uranium d u r i n g c r y s t a l l i z a t i o n , w h i l e non-homogeneous d i s t r i b u t i o n i s more l i k e l y to a r i s e from non-contemporaneous processes. The uranium content of base-metal sulphides i n u r a n i f e r o u s v e i n s would be r e l a t e d to the uranium c o n c e n t r a t i o n of the ore-forming s o l u t i o n s i f : (1) Uranium Not (2) Uranium Homogeneously Distributed Homogeneously Distributed Uranium,* Uranium,* Mine ppm Mine. ppm Calhoun 5700 Democrat 46 Caribou 2300 Sunshine 39 Iron 1700 Sunshine 37 Sunshine 670 De La Fontaine 20 De La Fontaine 530 Democrat 14 Sunshine . 510 Prospector 12 Baby 420 Detroit 12 ' Burlington 390 Democrat 7 Burlington ' 290 Prosperity 7 Klingcr .200 • Democrat 6 Cherokee 170 Merry Wilson 6 Baby 160 Detroit 6 Democrat 130 De La Fontaine 5 Josephine 120 Night Hawk 5 Baby 110 Summit 5 Sunshine 76 Sunshine .4 Democrat 75 German 4 Springdalc 57 Peach Tunnel r> -0 Calhoun 52 Sunshine 3 Calhoun 51 Baby 3 Carroll - 45 Carroll o o Carroll 43 Sunshine O Sunshine 43 Caribou 3 Democrat 42 Democrat 3 Sunshine 39 Calhoun 2 Freedom No. 2 37 Black Hawk 2 Argo 35 Lone Eagle 2 German 32 Democrat 2 • Sunshine 30 Cherokee . 2 : German 25 Bullion 2 Democrat 24 Century 2 Lone Eagle 23 Sunshine 2 Baby 22 Prosperity 1 Baby 17 De La Fontaine . 1 Sunshine 16 Baby 1 Lone Eagle 16 Primrose Detroit 6 Summit 1 Argo 3 Sunshine 1 Democrat 2 Sunshine 1 Summit 2 TABLE 14. Uranium content of p y r i t e samples from uranium d e p o s i t s . (From Wright e t . a l . , 1960) 1) the uranium i s i n c o r p o r a t e d i n the s u l p h i d e l a t t i c e d u r i n g c r y s t a l l i z a t i o n ; 2) the l i m i t of s o l i d s u b s t i t u t i o n i s not c l o s e l y approached; •and 3) the supply of uranium around the c r y s t a l l i z i n g s u l phide i s c o n t i n u o u s l y renewed by i n t r o d u c t i o n of f r e s h s o l u t i o n s and by d i f f u s i o n . I t i s conceivable that the uranium content of p y r i t e and other s u l p h i d e s could be used as an i n d i c a t o r of p r o x i m i t y to economic con c e n t r a t i o n s of uranium, although q u i c k e r and more e f f i c i e n t methods are a v a i l a b l e . Homogeneously and inhomogeneously d i s t r i b u t e d uranium contents of p y r i t e from v a r i o u s mines i n the western United S t a t e s are presented i n Table 14. T h a l l i u m Content of P y r i t e T h a l l i u m d i f f e r s g r e a t l y from i r o n , c o b a l t , and n i c k e l i n chemical p r o p e r t i e s , and t h e o r e t i c a l l y should not be accepted r e a d i l y i n t o the l a t t i c e of i r o n s u l p h i d e s . However, t h a l l i u m content i s s u r p r i s i n g l y h i g h i n both syngenetic and e p i g e n e t i c p y r i t e s . Voskresenskaya, et a l . (1962, 1969) have made an e x t e n s i v e study of t h a l l i u m i n sedimentary s u l p h i d e s . The f o l l o w i n g r e l a t i o n s h i p s have been di s c o v e r e d . 1) T h a l l i u m content i n sedimentary p y r i t e c o r r e l a t e s w e l l w i t h the t h a l l i u m content of adjacent sediments. 2) T h a l l i u m content i n sediments i s d i r e c t l y r e l a t e d to content of organic m a t e r i a l . 3) T h a l l i u m content i s somewhat r e l a t e d to c l a y content. 4) T h a l l i u m i s g e n e r a l l y absent from c l a y s t o n e s and sandstones which are f r e e of s u l p h i d e s . These observations l e a d one to the c o n c l u s i o n that the element i s s u p p l i e d by organic sources, i s p r e f e r e n t i a l l y absorbed on c l a y s and on syngenetic or a u t h i g e n i c p y r i t e s . The authors noted t h a t h i g h e s t T l co n c e n t r a t i o n s appear i n amorphous Fe-sulphides i n c o l l o i d a l or " c o l l o f o r m " masses of s u l p h i d e s , and i n p y r i t e i n . c o a l beds. T h a l l i u m contents i n v a r i o u s sediments a r e : average of sediments .3 ppm c o a l 0.4 - 2.3 ppm Sulphides from c o a l 2 - 360 ppm "Dictyonema" shale p y r i t e 4 - 30 ppm "Fuel Shale" 38 ppm Coal beds, Moscow Basin 0.5 - 30 ppm Coal beds, K i r g i z i a , Uzbekistan 81 ppm Extremely high values have been reported from some types of hydrothermal deposits (Vlasov, 1967). Co l l o f o r m v a r i e t i e s of FeS^ are r i c h e s t i n t h a l l i u m , c o n t a i n i n g up to 0.57 percent (5700 ppm Ads o r p t i o n , once again, i s the most l i k e l y mechanism f o r r e t e n t i o n w i t h the s u l p h i d e s . In some hydrothermal d e p o s i t s t h a l l i u m forms an independent m i n e r a l , h u t c h i n s o n i t e , but i n many d e p o s i t s t h a l l i u m i s contained i n a r s e n i c s u l p h o s a l t s : j o r d a n i t e , g r a f t o n i t e , d u f r e n o y s i t e , and probably r a t h i t e . In a r s e n i c - r i c h d e p o s i t s , t h a l l i u m i n c o l l o f o r m Pe s u l p h i d e s may a c t u a l l y be present i n i n c l u s i o n s of these s u l p h o s a l t s . The maximum and average T l contents appear to f o l l o w a low to high-temperature zoning sequence, w i t h maximum i n As-Sb-Hg d e p o s i t s , l e s s e r amounts i n M i s s i s s i p p i V a l l e y and vein-type Pb d e p o s i t s , and l e a s t i n skarn-type d e p o s i t s . In low to medium grade metamorphosed s t r a t i f o r m s u l p h i d e d e p o s i t s , contents of t h a l l i u m i n p y r i t e range from 0-240 ppm. I n de p o s i t s which have undergone high-grade metamorphism, t h a l l i u m i s r a r e l y detected i n p y r i t e . Vlasov suggests that under these c o n d i -t i o n s , T l may p r e f e r e n t i a l l y enter l a t t i c e s o f other s u l p h i d e s , K-feldspar, o r s e r i c i t e . The h i g h t h a l l i u m content of c o l l o f o r m sulphides i n organic sedimentary environments as w e l l as i n M i s s i s s i p p i V a l l e y - t y p e d e p o s i t s i s "permissive" evidence that hydrocarbons i n subsurface " r e s e r v o i r " f l u i d s may p l a y a p a r t i n the genesis of these d e p o s i t s . •The Mercury Content of P y r i t e Pew analyses of mercury i n p y r i t e are reported i n the l i t e r a t u r e . Because the i o n i c c o o r d i n a t i o n i n Hg minerals i s g e n e r a l l y t e t r a h e d r a l (as w i t h Zn and Cd), and the c o o r d i n a t i o n r a d i u s i s l a r g e , 1.48 2, isomorphous s u b s t i t u t i o n f o r i r o n i n p y r i t e i s not expected. However, Hg may enter t e t r a h e d r a l l y -coordinated m i n e r a l s such as s p h a l e r i t e , c h a l c o p y r i t e , or t e t r a -h e d r i t e i n s o l i d s u b s t i t u t i o n f o r Zn, Cd, or Cu, and thus could be present i n mi n e r a l i n c l u s i o n s i n . p y r i t e . The high vapor-pressure could l e a d to t r a p p i n g of Hg i n f r a c t u r e s o r pores i n p y r i t e (Chan, 1969). From Ag-Pb-Zn d e p o s i t s of the Coeur d'Alene area, Chan r e p o r t s from 1.0-2.5 ppm Hg i n p y r i t e . Other minerals from the same camp concentrate mercury to a g r e a t e r degree. Galena 3.8 - 10.4 ppm C h a l c o p y r i t e 3.5 - 38 ppm T e t r a h e d r i t e 5.1 - 62.6 ppm Dvornikov (1967) d i s c u s s e s mercury content i n syngenetic and hydrothermal p y r i t e from the N i k i t o v k a mercury d e p o s i t , where cinnabar occurs i n f i n e v e i n l e t s i n p y r i t i c c o a l - b e a r i n g sediments. P y r i t e from m i n e r a l i z e d areas contained 2907 ppm i n comparison to 33 ppm contained i n the c o a l i t s e l f . S t r i c t l y syngenetic p y r i t e contained 100 to 1000 times l e s s mercury than the hydrothermal p y r i t e . As and Sb followed much the same p a t t e r n of enrichment i n hydrothermal p y r i t e . The author concluded that a n a l y s i s f o r these minor elements i n p y r i t e could be an e f f e c t i v e e x p l o r a t i o n t o o l w i t h i n the Donetz b a s i n . A s i m i l a r example of the use of supra-ore p y r i t e i n d e t e c t i o n of mercury d e p o s i t s i s discussed i n the appendix. 71 8. Manganese Content of P y r i t e Evidence from l i g a n d - f i e l d theory, m i n e r a l o g i c a l a s s o c i a t i o n s , sedimentation s t u d i e s and i o n i c - c o o r d i n a t i o n theory i n d i c a t e s that only l i m i t e d replacement of i r o n by manganese should occur i n the p y r i t e l a t t i c e . As discussed i n a previous chapter (page 19.) MnS^ 2+ i s i s o s t r u c t u r a l w i t h p y r i t e , but the Mn i o n i s i n h i g h - s p i n s t a t e , l e a d i n g to i o n i c bonding i n h a u e r i t e , compared to predominantly covalent bonding i n p y r i t e . Respective o c t a h e d r a l covalent r a d i i and metal-sulphur bond lengths a r e : F e 2 1.23 8 Fe-S 2.27 2 Mn 2 1.55 1 Mn-S 2.59 A* I n deep-sea sediments manganese i s present i n c o n s i d e r a b l e amounts, 2+ but Eh-pH c o n t r o l of Mn i o n i c species i s such that Mn i s not l i k e l y to c o - p r e c i p i t a t e w i t h i r o n s u l p h i d e s (see page 87). Mohr (1960) r e p o r t s high Mn content i n p y r i t e from Mn-rich shales but contamination of the p y r i t e samples i s probable. The maximum Mn content reported by F l e i s c h e r (1959) i s 1 percent (1 samplej. Since both s p h a l e r i t e and magnetite can c o n t a i n a p p r e c i a b l e Mn i n s o l i d s o l u t i o n , some of the Mn i n p y r i t e may be c o n t r i b u t e d by i n c l u s i o n s of these m i n e r a l s . Limonite or manganese oxide s t a i n s or t a r n i s h on p y r i t e could a l s o account f o r anomalously hi g h c o n c e n t r a t i o n s i n p y r i t e . 9. T i n Content of P y r i t e There i s ample evidence that Sn can s u b s t i t u t e f o r Cu, 72 Zn, or Fe i n t e t r a h e d r a l l y - c o o r d i n a t e d s u l p h i d e m i n e r a l s , such as s p h a l e r i t e and c h a l c o p y r i t e , s i n c e s t a n n i t e (C^FeSnS^) i s i s o s t r u c t u r a l w i t h these m i n e r a l s . N a t u r a l SnS^ has been found, but t h i s compound has hexagonal c r y s t a l s t r u c t u r e . Because of d i s s i m i l a r i o n i c charge and covalent r a d i u s , e xtensive s u b s t i t u t i o n of Sn f o r Fe i n p y r i t e i s not l i k e l y . Most analyses of Sn i n p y r i t e encountered i n the l i t e r a t u r e are l e s s than 300 ppm. Most h i g h contents of Sn i n p y r i t e are reported from massive s u l p h i d e and s t r a t i f o r m v o l c a n i c - e x h a l a t i v e d e p o s i t s (Sutherland, 1967; Roscoe, 1965; Hawley and N i c h o l , 1961), i n which the average Sn content i s approximately 200 ppm. Since c a s s i t e r i t e i s o c c a s i o n a l l y present i n these d e p o s i t s , the p o s s i b i l i t y of m i c r o - i n c l u s i o n s i n p y r i t e should not be ignored. Hawley and N i c h o l (1961) found admixed c a s s i t e r i t e i n p y r i t e and c h a l c o p y r i t e from the Manitowadge (Geco) d e p o s i t ; these minerals assayed up to 7000 ppm and 3500 ppm Sn r e s p e c t i v e l y . 10. The Selenium Content of P y r i t e Many researchers d a t i n g from Goldschmidt (1933J, through to the present, have s t u d i e d the selenium content of p y r i t e . Most of the s t u d i e s have shown that p y r i t e of sedimentary o r i g i n can g e n e r a l l y be d i s t i n g u i s h e d from that of hydrothermal o r i g i n on the b a s i s of selenium content. Goldschmidt and S t r o c k (1935) found that sedimentary p y r i t e had a S : Se r a t i o of 200,000 : 1 or more ( i . e . , low Se content] whereas hydrothermal p y r i t e had r a t i o s of 73 10,000-20,000 : 1. Carstens* found that Norwegian sedimentary p y r i t e had l e s s than 1 ppm Se, but hydrothermal p y r i t e had 20-30 ppm Se. S i m i l a r contents were report e d by Edwards and C a r l o s (.1954); sedimentary and "supergene" p y r i t e and marcasite contained between 1 and 9 ppm Se w i t h S : Se r a t i o s ranging from 38,000 to 500,000 : 1; the m a j o r i t y of hydrothermal p y r i t e s s t u d i e d contained 30 to 50 ppm, w i t h a maximum value of 132 ppm. The corresponding S : Se r a t i o s were 9,000 : 1 to 13,000 : 1. An important f a c t was discovered by Edwards and C a r l o s ; some p y r i t e s o f known hydrothermal o r i g i n c o n t a i n very s m a l l amounts of selenium. Therefore a low selenium content i s not absolute proof of sedimentary  o r i g i n of p y r i t e . Sulphides and s e l e n i d e s form isomorphous m i n e r a l groups, f o r example: Galena (PbS) - C l a u s t h a l i t e (PbSe), and A r g e n t i t e (Ag,>S) - Naumannite (Ag 2Se) FeSe^ ( f e r r o s e l i t e ) c r y s t a l l i z e s w i t h the marcasite s t r u c t u r e (orthorhombic), and the cubic s t r u c t u r e can only be produced a t h i g h pressures ( H u l l i g e r , 1968). Therefore we would expect o n l y l i m i t e d s o l i d s u b s t i t u t i o n between FeS^ and FeSe^ at temperatures and pressures p r e v a i l i n g d u r i n g hydrothermal m i n e r a l d e p o s i t i o n . Coleman and Delevaux (1957), i n a d e t a i l e d study of s e l e n i u m - r i c h sediments adjacent to and c o n t a i n i n g uranium d e p o s i t s , found that p y r i t e can c o n t a i n up to 3 percent Se i n s o l i d s o l u t i o n . Some samples were found to c o n t a i n over 5 percent Se but these were thought to be contaminated. The maximum Se content of marcasite * In F l e i s c h e r (1955) i n the same d e p o s i t s was found to be 0.65$ (6500 ppm,). The selenium content of p y r i t e s from ore and from barren rock were compared f o r f o u r d i f f e r e n t S e - r i c h h o r i z o n s : Se i n p y r i t e Se i n p y r i t e Ore s u l p h i d e s Barren s u l p h i d e s T r i a s s i c ( C h i n l e Fm.j 19 ppm (avg.) 12 ppm J u r a s s i c (Morrison Fm.J 2000 ppm 1400 ppm Cretaceous 50 ppm 60 ppm T e r t i a r y 870 ppm 15 ppm The authors concluded that Se content was not always a r e l i a b l e i n d i c a t o r of hydrothermal o r i g i n of p y r i t e , although there may have been problems w i t h d i s t i n c t i o n between hydrothermal and syngenetic p y r i t e . The major f a c t o r c o n t r o l l i n g Se content i n the d e p o s i t s s t u d i e d seemed to be g e o l o g i c age ( s t r a t i g r a p h i c p o s i t i o n ? ) r a t h e r than geographic l o c a t i o n , suggesting a source f o r the selenium w i t h i n the sediments themselves - perhaps from i n c l u d e d v o l c a n i c d e b r i s . Four a l t e r n a t i v e mechanisms f o r genesis and c o n c e n t r a t i o n of selenium i n Colorado plateau-type d e p o s i t s were proposed by Coleman and Delevaux: a) Primary magmatic o r i g i n and hydrothermal d i s p e r s i o n (not considered l i k e l y ) ; b) A c q u i s i t i o n of Se by hydrothermal f l u i d s p a s s ing through S e - r i c h r o c k s ; c) Diagenetic a d s o r p t i o n by p y r i t e from adjacent S e - r i c h v o l c a n i c m a t e r i a l ; 75 d) Concentration by ground water near the top of the ground-water t a b l e . Hawley and N i c h o l (.1959) s t u d i e d the selenium content of sulphi d e s from s e v e r a l types of m i n e r a l d e p o s i t s . L i m i t s of d e t e c t a b i l i t y were 15 ppm; 173 p y r i t e samples were analyzed. Range and mean f o r each d e p o s i t are given i n Table 15. The h i g h e s t c o n c e n t r a t i o n s were found i n massive Cu-Fe-Zn s u l p h i d e d e p o s i t s , where the averages are 50-590 ppm (.max. 1000 ppm,). S t r a t i f o r m sulphide d e p o s i t s , g o l d - p y r i t e quartz v e i n s , and bedded i r o n and uranium d e p o s i t s contained u n i f o r m l y low amounts of selenium (0-79 ppm). Sutherland (1967) has a l s o found very low amounts of selenium from s t r a t i f o r m Cu-Pb-Zn d e p o s i t s i n New Brunswick. R e l a t i v e l y h i g h amounts (up to 700 ppmj were reported from massive sulphide d e p o s i t s of S k e l l e f t e , Sweden and of the U r a l mountains (Sindeeva, 1964 and B e r g e n f e l d t , 1953 i n Anderson, 1969). "The use of selenium content of p y r i t e as an e x p l o r a t i o n t o o l i s discussed i n the appendix. T y p e of deposit Location No. of samples Range of selenium -content, p p m Mean selenium content, p p m Magnetite (Replacement) Marmora, Ontario 1 <15 Xickeliferous Copper sulfide ores Sudbury, Ontario 4 1 ' 25-60 130 50 130 Massive Cu-Fe-(Zn)-S replace-ment deposits Noranda, Quebec Upper Levels Lower Levels L o v e r Levels (run of mine) 6 20 6 390-1000 38-445 33-88 590 " 175 63 Qucmont, Quebec 4 40-250 120 Normetal, Quebec 7 4 <15 <15-320 <15 155 Aldermac, Quebec 1 56 Campbell-Chibougainau. Quebec 1 51 Geeo Mine, Manitouwadge, Ontario 250' Level 50'-450' Levels 350' Level Average 14 7 5 26 44-88 50-270 97-310 44-310 60 127 163 97 F l i n Flon. Manitoba 2 1 <1S 220 Cu-Fe-Zn-S banded ores Suffield, Quebec 1 <15 Heath Steele. N. B. 1 20 Gold-pyrite quartz vein Mclntyre Mine. Porcupine. Ontario 21 <15-110 33 Miscell.—Renabi. Hardrock. Howey-Hasaga (Red Lake) Cathroy-Larder, Ontario; Granada, Quebec; Cariboo, B. C. 10 <15 <15 Powell Rouyn, Quebec Fondulac, Algold. Sask. 1 2 23-24 34 23 Banded Siderite-Pyrite j Michipicoten, Ontario (Rand Xo. 2) 1 <15 P>Titiferous ( Algoma, Ontario uranium banded or I U-ore in conglom. bedded deposits j Sub-ore conglom. above j and below ore j Polymictic conglom. greywacke j matrix, greywacke, calc. grey-1 wacke (above ore) j Quasi-basal conglom. (below ore) j Argillite (above ore) 1 In Diabase j Pre-Huronian metavolcanics 26 2 11 6 2 1 2 2 16- 46 <15 17- 39 17-63 <15-17 41-43 36-47 28 <15 26 42 <15 79 42 41 TABLE... 15 .Selenium content of p y r i t e s from some Canadian ore d e p o s i t s . (From Hawley and N i c h o l , 1959). I I I . THE GEOCHEMISTRY OF COBALT AND NICKEL IN ROCKS The chemistry of minor elements i n g e o l o g i c a l processes such as magmatic d i f f e r e n t i a t i o n ; hydrothermal d e p o s i t i o n , sedimenta-t i o n and metamorphism w i l l have a d i r e c t e f f e c t on the content of those elements i n minerals formed by each process. I f r e g u l a r i t i e s of minor element contents occur i n minerals formed at d i f f e r e n t times or l o c a t i o n s by the same process, then i n s i g h t i n t o the exact nature of these processes i s gained. Since c o b a l t and n i c k e l are the most important minor elements i n p y r i t e , and the l e a s t l i k e l y to be a f f e c t e d by contamination from other m i n e r a l s , a comprehensive review of c o b a l t - n i c k e l geochemistry i s presented here, IGNEOUS ROCKS In m e t e o r i t e s , c o b a l t and n i c k e l are s t r o n g l y concentrated i n the metal phase i n s o l i d s o l u t i o n w i t h i r o n . Cobalt i s l e s s s i d e r o p h i l e than n i c k e l (Rankama, Sahama, 1950J. The content of Co and N i i n m e t e o r i t i c s u l p h i d e phase i s g e n e r a l l y low, because du r i n g c r y s t a l l i z a t i o n , l a r g e amounts of Co and Ni are s t a b i l i z e d o n l y i n i r o n - n i c k e l a l l o y s or i n s c h r e i b e r s i t e (Fe, N i , CoJ^P. Average contents of Co and N i i n meteorites i s l i s t e d i n Table 16. C o b a l t - n i c k e l r a t i o s range from 0.059 to 0.12. S i g n i f i c a n t l y , Co i s enriched r e l a t i v e to Ni i n the s i l i c a t e phase. In u l t r a b a s i c rocks Co and Ni are abundant; average contents are approximately 200 ppm and 2000 ppm r e s p e c t i v e l y . The elements TABLE 16 VARIATION OF COBALT AND NICKEL WITH ROCK TYPES 78 Rock Type : Co (ppm) Ni (ppm) .: (Co/Ni) M e t e o r i t e s Fe-Ni phase (R+S) Fe-Ni phase (V) T r o i l i t e phase (R+S) S i l i c a t e phase (R+S) U l t r a b a s i c s P e r i d o t i t e U l t r a b a s i c s U l t r a b a s i c s U l t r a b a s i c s U l t r a m a f i c s (G) (S) (T+W) (V) (v; Gabbro (G) Gabbro + D o l e r i t e (S) B a s a l t (T+W) Ba s i c (V) D i o r i t e (G) "Intermediate" (V) Grani t e (G) Gran i t e s (S) C a - r i c h g r a n i t e s (T+W) Ca-poor.granites (T+W) a c i d (V) B r a z i l i a n s h i e l d g r a n i t e s (D) 5700 800 100 400 237 237 150 200 200 79 24 48 45 32 20 0-8 7 1 - 5 3.8 84900 13500 1000 3300 3160 790 2000 1200 2000 158 47 130 160 40 55 . A 2-8 15 4.5 8 8.3 0.07 0.059 0.10 0.12 0.08 0.30 0.075 0.17 0.10 0.50 0.51 0.37 0.28 0.80 0.36 3.3 Max.4.0 0.47 0.22 0.62 0.46 R+S Rankama and Sahama (1950J V Vogt ( i n Davidson, 1962) G Goldschmidt ( i n Davidson, 1962) T+W Turekian and Wedepohl (1§62) D Davidson (1962J are " c a r r i e d " i n ferromagnesian s i l i c a t e s , s u b s t i t u t i n g f o r Fe 2+ and Mg i n o c t a h e d r a l l y coordinated l a t t i c e s i t e s . Cobalt content shows a good c o r r e l a t i o n w i t h Mg + Fe ( C a r r and Turekian, 1961); a s i m i l a r c o r r e l a t i o n would be expected f o r n i c k e l . N i i s concentrated i i i the f o l l o w i n g m i n e rals i n b a s i c and u l t r a b a s i c r o c k s : awaruite, j o s e p h i n i t e (Fe-Ni a l l o y s ) , g a r n i e r i t e (15-33$ N i ) , n i c k e l i a n c h l o r i t e s , t r e v o r i t e (NiFe^O^). Co i s r e l a t i v e l y enriched i n the t i t a n i f e r o u s oxide minerals w i t h the average contents of Co and N i b e i n g 200 ppm and 300 ppm (Co/Ni = 0 . 6 7 ) . I f a b a s i c magma contains a p p r e c i a b l e sulphur, or i f sulphur i s i n t r o d u c e d from an e x t e r n a l source, an e a r l y stage i m m i s c i b l e s u l p h i d e phase may form. Ni and Co p r e f e r e n t i a l l y enter the s u l p h i d e phase and are concentrated i n the r e s u l t i n g s u l phide m i n e r a l s . I f i n i t i a l sulphur content i s low, Co and N i may be taken up by the s i l i c a t e phase before the sulphur i s concentrated enough to p r e c i p i -t a t e s u l p h i d e s . I f t h i s i s the case, l a t e r formed s u l p h i d e s can be r i c h i n Cu r e l a t i v e to Co and Ni (Wager, et a l . . 1957), as i n the Skaergaard i n t r u s i o n (see Figure 30). The average Co : Ni r a t i o o f e a r l y magmatic sulph i d e s i s approximately 0.08.* With i n c r e a s e i n s i l i c a content of d i f f e r e n t i a t i n g magmas, the absolute contents of Co and Ni i n rocks decrease and the Co : N i r a t i o s i n c r e a s e , as i s shown i n F i g u r e s 31 and 64, i n d i c a t i n g that Co i s enriched r e l a t i v e to Ni ( i . e . , N i i s accommodated i n f e r r o -magnesian minerals at a g r e a t e r r a t e ) . * Rankama and Sahama (1950) 3 0 0 2 S O 2 0 0 I ISO IOO S O NICKEL in the rocks ond in the liquids . IOO 8 0 Pr 4 0 20 O COBALT, rocks liquids lOOO 8 0 0 6 0 0 L L 4 0 0 2 0 0 P o lOOOn 8 0 0 6OO 4 0 0 •COPPER in the rocks ond in the liquids 2 0 0 SULPHUR in the rocks , and in the liquids IO 20 30 40 50 6O 70 PH'.CENiACE SOLIDIFIED SO 9 0 IOO FIGURE 30. V a r i a t i o n of Co, N i , Cu, and S i n rocks and r e s i d u a l melts of the Skaergaard igneous complex. (From Wager and M i t c h e l l , 1951) FIGURE 31. Variation of cobalt-nickel ratio with s i l i c a content of igneous rocks. (Data from Davidson, 1962) 82 In some cases Ni (+2) i s concentrated i n r e s i d u a l magmas du r i n g the l a t e r stages o f magmatic c r y s t a l l i z a t i o n (along w i t h + 3 + 3 + 3 V , Cr , and Sc ). An example i s the Skaergaard i n t r u s i o n , where N i , Cr, V, and Sc were l a r g e l y removed from the magma i n f e r r o -magnesian s i l i c a t e s o l i v i n e and pyroxene, but were a l s o enriched i n the l a t e - s t a g e granophyre. Other examples i n c l u d e the g e n e r a l l y l a t e - s t a g e c r y s t a l l i z a t i o n of n i c k e l - b e a r i n g s u l p h i d e s a s s o c i a t e d w i t h b a s i c i n t r u s i v e s (Ringwood, 1955). Ringwood f e e l s t h a t magmas r i c h i n v o l a t i l e s are able to keep the above-mentioned c a t i o n s i n s o l u t i o n as t e t r a h e d r a l complexes w i t h F and (OH) , thus e x p l a i n i n g t h e i r anomalous l a t e - s t a g e enrichment i n granophyres, lamprophyres, and pegmatites. SEDIMENTARY ROCKS Chemical analyses of sediments r e v e a l that i n most normal sediments, the content of n i c k e l exceeds that of c o b a l t , and the corresponding c o b a l t - n i c k e l r a t i o s are low ( < 1 . 0 ) . Analyses of t y p i c a l sedimentary rocks are presented below (Table 1.7) s TABLE 17 : -AVERAGE CO AND NI. CONTENTS AND CO/NI RATIOS OF SEDIMENTS Co ppm. Ni ppm Co/Ni (Turekian and Wedepohl, 1961) Shales 19 68 .28 Sandstones •, • . 0.3 2.0 .15 Carbonates 0.1 20 .005 Deep-sea carbonates 7 30 .233 Deep-sea c l a y s 74 355 .28 .(Rankama and Sahama, 1950) Sandstone 1.0 ppm 2.0 .50 Shale 60 150 .40 Bitum. s c h i s t 30 70 .43 Limestone .3-2.0 3-10 .03-.70 Q u a r t z i t e s 0 2-8 .13-.50 A l - r i c h s c h i s t s 8 24 .33 ( C a r a v a j a l and Landergren, 1969, p. 118) Near shore sediments Off west coast of Sweden Off west coast of A f r i c a (Dakar) Deep-sea sediments Indian Ocean A t l a n t i c Ocean P a c i f i c Ocean ( c e n t r a l e q u a t o r i a l p a r t ) Sediments from i n l a n d se The Mediterranean Sea The Black Sea The Caribbean Sea Sea water Co$ N i $ Co/Ni 0.016 0.086 0.18 0.035 0.19 0.18 as 0.019 0.050 0.38 0.019 0.048 0.40 0.012 0.019 0.71 0.017 0.054 0.31 0.021 0.087 0.24 0.014 0.049 0.28 0.063 0.38 0.17 84 Research i n t o c o b a l t and n i c k e l contents of t y p i c a l sediments by Davidson (1962) revealed over a thousand analyses, none of which showed c o b a l t i n excess of n i c k e l . I n c o n t r a s t , Davidson presented evidence from s e v e r a l "syngenetic" copper sediments i n which c o b a l t exceeds n i c k e l . I n the Rhodesian copperbelt, the average Co : N i r a t i o i s 2.4 : 1 i n a r g i l l i t e s and as h i g h as 25 : 1 i n q u a r t z i t e s . Cobalt m i n e r a l s are common a c c e s s o r i e s to copper, both i n Rhodesian d e p o s i t s and i n s i m i l a r occurrences i n the Katanga province of the Congo, although n i c k e l m i n e r a l i z a t i o n i s l e s s common. Other examples from the U.S.S.R. are discussed by Davidson, f o r example, the Dzhezgkazgan and Udokansk d e p o s i t s . In most of these examples, although c o b a l t m i n e r a l i z a t i o n i s more evident than n i c k e l m i n e r a l i -z a t i o n , the a c t u a l Co/Ni r a t i o s are not documented. Pew analyses are a v a i l a b l e f o r sediments from syngenetic copper d e p o s i t s , but those from the K u p f e r s c h i e f f e r and r e l a t e d sediments r a r e l y show Co>Ni. Analyses are presented below (Table 18): . TABLE 18 AVERAGE CO, NI CONTENTS AND CO/NI RATIOS OP SYNGENETIC COPPER DEPOSIT SEDIMENTS Sedimentary rock Co(ppm) Ni(ppm) Co/Ni Mansfeld, Germany (Davidson) 40 100 .40 Po s i d o n i a L i a s shale (Deans) 0-40 0-250 ? Dictyonema Alum shale (Deans) 20-50 100-240 ? K u p f e r s c h i e f f e r , Germany (Deans) 30-180 40-400 0 Marl S l a t e , Durham (Deans) 30 230 .13 Ze c h s t e i n Pb-Zn shales (Haranczyk) 80 220 .36 85 Thus, although sediments from c e r t a i n syngenetic copper de p o s i t s may c o n t a i n Co i n g r e a t e r amounts than N i , a Co/Ni r a t i o >1.0 cannot be considered r e p r e s e n t a t i v e f o r t h i s type of sediment. I t i s p o s s i b l e , i n the Rhbdesian c o p p e r - r i c h sediments, that high Co contents can be r e l a t e d to the metamorphic grade, or to e n r i c h -ment by thermal f l u i d s o r i g i n a t i n g i n or m i g r a t i n g from the C o - r i c h basement g r a n i t e s (see F i g u r e 61 ).. Other n a t u r a l environments i n which c o b a l t may predominate over n i c k e l are (1) l a t e r i t e s and b a u x i t e s , (2) bog-iron ores, (3) marine Fe or Mn-rich sediments, (4) sediments p r e c i p i t a t e d by Red Sea b r i n e s . The f o l l o w i n g examples are taken from Rankama and Sahama (1950). Sediment Co Ni Co/Ni L a t e r i t e - b a u x i t e 300 ppm 180 ppm 1.67 Bog-iron ores 130 40 3.25 Marine s i l i c e o u s o o l i t i c i r o n ore 200 200 1.00 Marine s i d e r i t e ore 300 50 6.00 Recent analyses of sediments from the P a c i f i c Ocean (Mero, 1965) r e v e a l many examples where Co exceeds N i . The Co/Ni r a t i o s however are gener-a l l y between 1.0 and 2.0. Manganese nodules are o f t e n enriched i n Cu, Co and Ni and i n c e r t a i n areas of the P a c i f i c the Co/Ni r a t i o s of nodules are commonly g r e a t e r than 1.0. The Red Sea b r i n e s and a s s o c i a t e d sediments have been s t u d i e d i n d e t a i l by s e v e r a l i n v e s t i g a t o r s (see Degens and Ross, e d i t o r s , 1969)-In the b r i n e s themselves, Co and N i showed only s l i g h t enrichment over normal seawater. However, the i n t e r s t i t i a l b r i n e s of many cores are more c o n s i s t e n t l y enriched, and Co commonly exceeds N i . The averages f o r each are: Co, 3-4 ppm; N i , 2-3 ppm. In sediments of the A t l a n t i s I I deep, Zn, Cu, Ag, Pb, Cd, As, and Co are enriched i n the s u l p h i d e phase. More d e t a i l s are given i n a subsequent chapter. The i n t e r r e l a t i o n s h i p s of Co, N i , and Mn i n marine sediments have been s t u d i e d by C a r v a j a l and Landergren (1969). Experiments showed that , 1) Mn oxides and to a l e s s e r extent hydrated Fe ( i l l ) oxides are by f a r the g r e a t e s t "chemical scavengers," removing c o b a l t and n i c k e l from sea water. 2) Co and Ni are absorbed and removed i n about the same r a t i o as t h a t of the i n i t i a l s o l u t i o n . Cores from the A t l a n t i c , P a c i f i c , and Indian Oceans and from the Mediterranean Sea were analyzed f o r Co, N i , Fe, Mn. R e s u l t s of f a c t o r a n a l y s i s , shown i n Table 19, i n d i c a t e : 1) I n s h e l f and slope sediments, Co and Ni c o r r e l a t e e q u a l l y w e l l w i t h Fe or Mn. 2) In deep-sea sediments, Co and N i c o r r e l a t e w e l l w i t h Mn only. 3) In reducing environments Co and Ni do not c o r r e l a t e w i t h Fe or Mn. From t h i s , i t i s assumed that hydrated Fe and Mn oxides adsorb Co and Ni i n s h e l f and slope sediments, w h i l e Mn oxides are the main scavengers i n deeper water sediments. In anoxic or reducing 87 environments manganese probably remains i n s o l u t i o n as Mn whereas i r o n i s p r e c i p i t a t e d as FeS, p o s s i b l y scavenging some Co and Ni along w i t h i t (see Table 19). F i r s t order c o r r e l a t i o n c o e f f i c i e n t s f o r Co/Ni-Mn and Co/Ni-Fe are +0.885 and +0.23 r e s p e c t i v e l y i n the study by C a r a v a j a l and Landergren. This i n d i c a t e s that c o b a l t should be removed from sea  water more r e a d i l y than n i c k e l i n manganese-rich deep-sea sediment  r e g i o n s . This theory i s supported by Co/Ni r a t i o s of near shore sediments (avg. 0.18) and i n l a n d sea sediments (.24-.31) compared w i t h deep-sea sediments (.38-.71) reporte d i n Table 17. By examining the s t a b i l i t y f i e l d s f o r Co and N i compounds under d i f f e r i n g pH and Eh c o n d i t i o n s ( F i g u r e s 32 and 33) we see that i n reducing environments the s t a b i l i t y f i e l d s f o r CoS and NiS are almost i d e n t i c a l . Thus the Co/Ni r a t i o i n p r e c i p i t a t e d m a t e r i a l should approach that of sea water. The s t a b i l i t y f i e l d f o r MnS (Fi g u r e 34) i s much more r e s t r i c t e d , s u p p o r t i n g the l a c k o f c o r r e l a t i o n of Co and Ni w i t h Mn i n reducing environments. The e f f e c t of sedimentary c o n d i t i o n s on minor element content o f p y r i t e i s di s c u s s e d i n a subsequent chapter (page 101). 2.4 FIGURE 32. Stability fields for cobalt compounds as functions of Eh and pH at 25 C° and 1 atm. total pressure, chlorinity .» 19 ppt. (From Carvajal and Landergren, 19680 2.0 FIGURE 33. Stability conditions of nickel compounds under similar conditions as in figure 35. (From Carva a l and Landergren, 1968) 1.6 FIGURE 34' Stability fields for manganese compounds as functions of Eh and pH at 25 C a n d 1 atmosphere total pressure, chlorinity-19 ppt.(From Carvajal and Landergren, 1968) Correlated Shelf anj slope Deep-sea Reducint; or anoxic pairs sed imcnts sediments environments r 7 r r r r Mn-Fe + 0.69 + 0.65 + 0.27 + 0.22 -0.86 -0.82 Co-Fc- + 0.78 + 0.75 + 0.27 + 0.22 + 0.34 i Ni-Fe + 0.S7 + 0.S6 + 0.26 + 0.21 + 0.42 i Co-Mn + 0.76 + 0.73 + 0.9S + 0.9S -0.11 i Ni-Mn + 0.SS + 0.S7 + 0.91- + 0.91 -0.1S i Co-Ni + 0.93 + 0.92 + 0.93 + 0.93 + 1.00 +1.00 TABLE 19. Zero order correlations for Mn-Fe-Co-Ni i n sediments from various environments, r = correlation coefficient; r = corrected correlation coefficient. (From Carvajal and Landergren, 1968) 90 C. METAMORPHIC ROCKS Although metamorphic e f f e c t s such as m e l t i n g , m o b i l i z a t i o n , r e c r y s t a l l i z a t i o n and b l a s t e s i s have been w e l l documented from numerous areas, evidence f o r m i g r a t i o n of ore-forming elements and t h e i r asso-c i a t e d minor elements i s scanty. The m i g r a t i o n of ore-forming elements ( i n a f l u i d phase) away from metamorphic centers has been proposed by s e v e r a l people (DeVore, 1955; Sutherland-Brown, 1969) but l i t t l e evidence e x i s t s f o r such mechanisms. S e v e r a l s t u d i e s d i s c u s s e d by Mclntyre show that f r a c t i o n a t i o n of Ba, Sc, T i , V, Cr, Mn, Co, N i , Y, Yb, and Zr between b i o t i t e and garnet may be dependent on metamorphic grade. This i l l u s t r a t e s that d i f f u s i o n , a t l e a s t on a s m a l l s c a l e , does occur d u r i n g metamorphism. DeVore (1955) f e e l s that p r o g r e s s i v e metamorphism could r e l e a s e Cr, Cu, Co, and N i , and that r e t r o g r e s s i v e metamorphism of hornblende could r e l e a s e Pb, Zn, Fe, T i , and Mn. C o n f l i c t i n g evidence i s present f o r the behaviour of Co and Ni d u r i n g r e g i o n a l metamorphism. Shaw (1954) st u d i e d low, medium and high-grade metamorphic p e l i t e s from the Devonian L i t t l e t o n Formation of New Hampshire. Whole-rock analyses i n d i c a t e d most minor elements remained a t remarkably constant c o n c e n t r a t i o n s d u r i n g metamorphism, although there was a weakly-defined tendency f o r decrease of Ni and Cu, and increase of L i and Pb ( c o r r e l a t a b l e w i t h K-metasomatism of the for m a t i o n ) . Average minor-element contents f o r the three metamorphic grades are shown i n Table 2Q0 Engel and Engel (1958) defined two metamorphic processes i n Middle-Grade Metamorphism High-Grade Metamorphism Element Sensi-tivity* Littleton formation (Shaw 1954) Least al-tered gneiss Group 1 Granitic gneiss Group 1 Littleton for-mation (Shaw, 1954) Least al-tered gneiss Group 5 Incipiently granitized gneiss Group 5 1 2 3 4 5 6 Co 2 19 8 4 is 7 5 Cr 5 113 35 4 109 56 18 Cu 1 23 16 19 13 12 18 Ga 5 16 11 12 . 20 14 12 Ni 2 64 15 4 ' 57 21 8 Pb 10 16 12 38 27 15 . - 32 Sc •-' 2 11 .12 6 16 17 8 Sr 2 524 ' 310 270 760 304 225 V 2 125 56 24 120 81 - 30 Y 10 39 46 35 52 • 58 30 ' Zr 2 191 171 150 : 203 176 160 • Number of speci- 20 9 :._ 3 '; - 30 8 4 mens TABLE 20. Comparison of minor element content of medium and high-grade metamorphic r o c k s , Adirondack mountains, New York. (From Engel and Engel, 1958) Element Low-grade Medium-grade High-grade Final average Final S.D. Number of rocks Final average (rounded off) Ga Cr V Li Ni 20.8 116 109 .54.7 80.5 15.9 113 125 108 63.7 19.8 109 120 .127 57.4 18.8 112 119 106 64.2 "" 6.34 33.1 38.5 104 25.5 63 63 63 63 63 19 110 120 110 64 Co 16.8 19.4 18.0 18.2 6.59 63 18 Cu Sc Zr Y" Sr Pb 23.1 11.3 191 38.8 524 16.1 23.8 11.9 213 37.9 731 23.3 12.5 15.6 203 51.7 760 27.3 18.3 13.5 204 44.7 705 23.7 18.0 7.35 72.7 20.0 310 12.3 63 63 63 63 57 63 18 14 200 .. 45 710 24 TABLE 21. Comparison of minor element content of low, medium, and high-grade metamorphic ree k s , New Hampshire. (From Shaw,D.T., 1954) the same general rock types as s t u d i e d by Shaw. " B a s i f i c a t i o n " of tuf f a c e o u s sediments was accompanied by decrease i n K, S i , Fe, H2O, and Ba, w i t h i n c r e a s e i n Mg, Ca, Cr, Ga, N i , and V. G r a n i t i z a t i o n elsewhere w i t h i n the study area caused decrease i n Co, Cr, Mn, N i , Sc, S r , T i , V, and Y. Elements were p a r t l y introduced from unknown sources and p a r t l y "sweated out of a s s o c i a t e d b a s i f i e d g n e i s s . " R e s u l t s o f the study are given i n Table 21 . -A recent study by Makrygina, et a l . (1969) give s some u s e f u l i n f o r m a t i o n r e g a r d i n g the behaviour of Co and Ni d u r i n g metamorphism. Four sedimentary rock u n i t s were i n v e s t i g a t e d i n s e v e r a l metamorphic zones ranging from c h l o r i t e - s e r i c i t e ( g r e e n s c h i s t f a c i e s ) through kyanite-almandine (amphibolite f a c i e s ) . "Concentrator" minerals f o r Co are c h l o r i t e and c h l o r i t o i d i n lower grade metamorphic rocks and b i o t i t e and s t a u r o l i t e i n higher grade r o c k s . ( C o - r i c h s t a u r o l i t e -l u s a k i t e i s p o s s i b l e . ) N i i s concentrated i n c h l o r i t e and b i o t i t e . There i s a c l o s e c o r r e l a t i o n of Ni and Co w i t h Fe^f although no c o r r e l a t i o n e x i s t s w i t h FeO or MgO content of the rock. The accumulation of these minor elements i n concentrator minerals i s supported by marked d i f f e r e n c e s i n p a r t i t i o n c o e f f i c i e n t s between "most and l e a s t - r i c h " m i n eral phases. Changes i n parageneses a t metamorphic f a c i e s boundaries a l s o r e s u l t s i n marked changes i n con c e n t r a t i o n s and p a r t i t i o n - c o e f f i c i e n t s of minor elements. Thus i t i s apparent that Co and N i , as w e l l as many other minor elements are l i k e l y to d i f f u s e from o r i g i n a l m i n e r a l g r a i n s i n t o new minerals formed d u r i n g metamorphism, although d i s t a n c e s of d i f f u s i o n are probably s m a l l . Minor elements appear to accumulate i n c o n c e n t r a t o r minerals as metamorphism progresses. Supporting evidence f o r c o n c e n t r a t i o n of minor elements i n p y r i t e d u r i n g metamorphism i s provided by N i c k e l (1954)• A n a l y s i s o f b i o t i t e s i n w a l l - r o c k s c h i s t s adjacent to q u a r t z -s c h e e l i t e - m o l y b d e n i t e v e i n s shows d e p l e t i o n o f Co and Ni i n p y r i t i c zones (see Figure 35). Cobalt content of the p y r i t e adjacent to the v e i n s i s co r r e s p o n d i n g l y h i g h . 94 FIGURE 35. D e p l e t i o n o f Co and Fe i n b i o t i t e a d j a c e n t to q u a r t z - s c h e e l i t e - m o l y b d e n i t e v e i n s , M i c h i p i c o t e n a r e a . O n t . (From Nickel,E.H., 1 9 5 4 ) . IV.. STATISTICAL STUDIES OF MINOR ELEMENTS IN PYRITE INTRODUCTION In t h i s study, p y r i t e analyses have been compiled from pu b l i s h e d l i t e r a t u r e and from unpublished theses and research, p r o j e c t s undertaken at the U n i v e r s i t y of B r i t i s h Columbia Depart-ment of Geology. Most analyses are from hydrothermal m i n e r a l d e p o s i t s of v a r i o u s types, although a l i m i t e d number are from syngenetic and metamorphosed p y r i t e bodies. Each d e p o s i t was c l a s s i f i e d as to g e n e t i c type, major metals present, igneous a s s o c i a t i o n s and many other f a c t o r s . T h i s i n f o r m a t i o n , along w i t h source of i n f o r m a t i o n and a c t u a l a n a l y t i c a l v a l u e s , was punched on computer cards according to the format o u t l i n e d i n Appendix I I I . The i n f o r m a t i o n was t r e a t e d s t a t i s t i c a l l y u s i n g TRIP ( t r i a n g u l a r r e g r e s s i o n package) r o u t i n e s developed a t the U.B.C. computing centre ( B j e r r i n g and Seagraves, 1970). I t was a n t i c i p a t e d that minor elements i n p y r i t e would have log-normal frequency d i s t r i b u t i o n s ; hence a sub-routine was added to major programmes to transform raw analyses to l o g a r i t h m i c v a l u e s , i n order to c a l c u l a t e geometric means. Using the above-mentioned TRIP computer r o u t i n e s , i t was p o s s i b l e to check s t a t i s t i c a l l y s e v e r a l t h e o r i e s and problems proposed by e a r l i e r minor-element s t u d i e s . Problems which were s e l e c t e d f o r study a r e : 96 1) How are minor elements d i s t r i b u t e d ( s t a t i s t i c a l l y ) i n p y r i t e ? 2) Does syngenetic p y r i t e have s i m i l a r minor-element concentra-t i o n s to surrounding sedimentary rock? 3) Do syngenetic and hydrothermal p y r i t e s d i f f e r s i g n i f i c a n t l y i n minor-element content? 4) Can syngenetic p y r i t e be d i s t i n g u i s h e d from that of "massive-s u l p h i d e " or " s t r a t i f o r m " d e p o s i t s on the b a s i s of minor-element content? 5) Does metamorphism of p y r i t e cause elemental r e d i s t r i b u t i o n ? 6) Does major element content of hydrothermal m i n e r a l d e p o s i t s a f f e c t or c o n t r o l minor-element content of a s s o c i a t e d (contemporaneous) p y r i t e ? 7) Does Co and Ni content of p y r i t e disseminated i n igneous rocks r e f l e c t p a r t i t i o n of elements d u r i n g magmatic d i f f e r -e n t i a t i o n ? 8) Can minor-element c o n c e n t r a t i o n s , r a t i o s or a s s o c i a t i o n s i n p y r i t e be used i n e x p l o r a t i o n f o r mi n e r a l d e p o s i t s ? 97 B. FREQUENCY DTSTBTTOITTONS OF MTNOT? ELEMENTS Most elements i n s p e c i f i c m i n e rals or igneous rock types do not f o l l o w normal d i s t r i b u t i o n laws, although examples of normal d i s t r i b u t i o n of minerals i n rocks are known. Ahrens (1965) has shown th a t SiO^ content i n a c i d i c and b a s i c v o l c a n i c rocks f o l l o w s normal d i s t r i b u t i o n laws, although SIO2 content i n g r a n i t e i s n e g a t i v e l y skewed. Most elements i n minerals have d i s t r i b u t i o n s which are approximately log-normal (Rodionov, 1965). This means l o g a r i t h m i c transforms of a n a l y t i c a l data are normally d i s t r i b u t e d . O e r t e l (1969) b e l i e v e s log-normal frequency d i s t r i b u t i o n s cannot be generated i n a min e r a l body i n which i n i t i a l c o n c e n t r a t i o n s are uniform and which i s c l o s e d to matter. O e r t e l concludes even elements i n one min e r a l s p e c i e s are u n l i k e l y to demonstrate log-normal d i s t r i -b u t i o n , and suggests gamma-distributions are more l i k e l y to s a t i s f y n a t u r a l c o n d i t i o n s . However, f o r most p r a c t i c a l purposes, log-normal  d i s t r i b u t i o n s are considered to s a t i s f y n a t u r a l l y o c c u r r i n g minor- element c o n c e n t r a t i o n s . Since the geometric mean i s more r e p r e -s e n t a t i v e of true mean than i s the a r i t h m e t i c mean, f o r many types of data, the l o g a r i t h m i c transform has been used i n t h i s study f o r s t a t i s t i c a l a n a l y s i s of minor-element data. D e t a i l e d i n v e s t i g a t i o n s i n t o s t a t i s t i c a l d i s t r i b u t i o n s of trace elements i n p y r i t e have been c a r r i e d out by Cambel and Jarkovsky (1967, 1969). Over 500 analyses have revealed log-normal frequency d i s t r i b u t i o n o f Mn, V, T i , Cu, and Zn i n p y r i t e . Co and N i are d i s t r i b u t e d l o g - n o r m a l l y except i n metamorphosed areas i n which r e d i s t r i b u t i o n of these elements has occurred. I n the- present study, p y r i t e analyses from "porphyry" type d e p o s i t s and from hydrothermal base metal d e p o s i t s other than "massive s u l p h i d e " type were processed w i t h a computer program designed by Mr. J . Orr. The program produces ranges, means, standard d e v i a t i o n s , and f r e q u e n c y - d i s t r i b u t i o n histograms f o r both a r i t h m e t i c and l o g a r i t h m i c a l l y - t r a n s f o r m e d data. Analyses were obtained from the l i t e r a t u r e and from c u r r e n t r e s e a r c h p r o j e c t s o f geology graduate students at U.B.C. Prom the r e s u l t a n t histograms i t i s concluded that a l l elements i n p y r i t e from porphyry and other hydrothermal d e p o s i t s have d i s t r i b u t i o n s that are approximately log-normal. D i s t r i b u t i o n s of log-transformed data from "porphyry" d e p o s i t s are d i s t i n c t l y c l o s e r to normal than are those from the hydrothermal data, s i n c e the "hydrothermal" data r e p r e s e n t s s e v e r a l d i s c r e t e types of d e p o s i t , each of which has i t s own c h a r a c t e r i s t i c d i s t r i b u t i o n parameters. Examples from both "porphyry" and "hydrothermal v e i n and replacement" data s e t s are shown on the f o l l o w i n g pages (Figures 36 to 41). True normal d i s t r i b u t i o n curves are p l o t t e d on the f i g u r e s f o r comparison. 99 w o < H W u Pi 40 35 30 25 20 15 10 FIGURE 36. Histogram of Ni i n p y r i t e from "porphyry" d e p o s i t s . A r i t h m e t i c data N = 171 X = 104 ppm S = 145 ppm I = 36 ppm 0 ' ' ' 1 L ' < • ' ' • I—1 LOWER LIMITS - PPM. co o to i n r- cr\ •<t N Ol \D to O T - -si" to O t— r- T- c\i to to i n v o 4o r 35 30 25 o •< H 20 53 w u P i w * 15 10 FIGURE 37. Histogram of N i i n p y r i t e from "porphyry" d e p o s i t s . Logarithmic data N = 171 - X = 1.688 (49 ppm) S = 0.635 ppm I = 0.16 ppm Normal curve drawn from c a l c u l a t e d v a l u e s . o o 00 i n t n o to i n O CM co CM CM LOWER LIMITS PPM (LOG) 4 0 35 30 20 N • 284 X = 717 ppm. S = 1258 ppm. I » 314 ppm. •FIGURE 38. Histogram of Co i n hydrothermal p y r i t e . Arithmetic data -rin> n-i LOWER LIMIT - PPM. CO o oo <r ft lA <T ro csl n» O f> sO C7* lO <N GO H n n 4 0 35 30 25 20 fe 15 10 N = 284 X •» 2.149(141 ppm.) S = 0.997 I " 0.25 FICURE 39. Histogram of Co i n hydrothermal p y r i t e . Logarithmic data. I T ' - . L A L A L A L A L A in m ' -a- LOWER LIMIT -PPM. •"I °. 1 "1 -I ~°. ^ (LOG) o o ~ « — i c s t c s i r - i r o u o < 40 r 35 30 25 20 15 10 -N » 284 X » 507 ppm. S e 790 ppm. I » 197 ppm. FICURE 40.. Histogram of Ni i n hydrothermal p y r i t e . Arithmetic data ha LOWER LIMIT - PPM. CM 40 35 30 25 e w o « u fe 20 15 (121 ppm.) N = 284 £ = 2.084 S = 0.956 I - 0.239 FIGURE 41 . Histogram of Ni i n hydrothermal p y r i t e . Logarithmic data _ • N \ - s • s X s • 1 -1 1 „[7T>» LOWER LIMIT PPM. (LOG) 0 0 . - i » - i r 4 < " ^ rv" > p " v 10T C. SEDIMENTARY PYRITE Conditions o f formation of p y r i t e i n sedimentary e n v i r o n -ments have been o u t l i n e d by Berner (1970). Black, f i n e - g r a i n e d i r o n monosulphides such as FeS ( n o n - c r y s t a l l i n e ) , mackinawite ( t e t r a g o n a l Fe^-xS), and g r e i g i t e ( c u b i c Fe^S^) are formed by the r e a c t i o n of H^S w i t h f e r r o u s i r o n i n s o l u t i o n or w i t h i r o n m i n e r a l s . The monosulphides are converted to d i s u l p h i d e s by o x i d a t i o n with elemental sulphur, which probably o r i g i n a t e s from the oxygenation of R ^ S - r i c h deep water by mixing a t the s u r f a c e . Organic matter i s necessary as an energy source f o r the b a c t e r i a l conversion of d i s s o l v e d sulphate to rL^S, and Berner's research has shown that the extent of p y r i t i z a t i o n of sediments i s p r o p o r t i o n a l to o r g a n i c -carbon content of the sediment. Fac t o r s which a f f e c t the minor-element c o n c e n t r a t i o n s i n sedimentary p y r i t e a r e : (a) minor elements a s s o c i a t e d w i t h d e t r i t a l o r c h e m i c a l l y - p r e c i p i t a t e d i r o n m i n e r a l s ; these minor elements may f o l l o w i r o n i n the formation of monosulphides; (b) the minor element content of organisms which decay i n sediments; (c) the r e l e a s e or acceptance of minor elements by i r o n monosulphides upon conversion to p y r i t e . M i t c h e l l (19)68) proposes that p u r i f i c a t i o n may r e s u l t from t h i s conversion, but i t i s p o s s i b l e that trace i m p u r i t i e s , c o u l d be trapped at g r a i n boundaries or l a t t i c e d e f e c t s d u r i n g the t r a n s -f o r m a t i o n . R e l a t i v e l y few analyses of p y r i t e from normal sedimentary rocks are a v a i l a b l e , and i n t h i s study, "sedimentary e x h a l a t i v e " 102 type p y r i t e such as that from Steeprock Lake was grouped w i t h "syngenetic" p y r i t e , s i n c e c o n d i t i o n s o f formation f o r both types were probably s i m i l a r . Sample l o c a l i t i e s and mean contents of minor elements are l i s t e d i n the appendix. A s c a t t e r diagram o f Co and:Ni content i n sedimentary p y r i t e i s given on the f o l l o w i n g page ( F i g u r e 42). Maximum Co a n d N i contents are 1000 ppm, and valu e s f o r the Co/Ni r a t i o l i e between 1 : 8 and 8 : 1, a narrow range compared to the same r a t i o f o r samples of hydrothermal p y r i t e (see page 131). Average Co and N i contents f o r sedimentary p y r i t e a r e : Geo. Mean S.D. Co 41 ppm .813 N i 65 ppm .672 . Co/Ni 0.63 The average Co/Ni r a t i o (0.63) i s comparable to that from sedimentary r o c k s (approx. 0.50, Rankama and Sahama, 1950). The c o r r e l a t i o n c o e f f i c i e n t f o r Co and N i i n sedimentary p y r i t e i s 0.93; a v e r y s t r o n g c o r r e l a t i o n i s present. F i g u r e s 43 and 44 compare Co and N i contents i n sediments and contained s u l p h i d e s i n Red Sea sediments. I t i s evident that the elements have s i m i l a r ranges of co n c e n t r a t i o n s i n both sediment and s u l p h i d e ; the Co/Ni r a t i o s c o r r e l a t e w e l l , but Co i s s l i g h t l y concentrated r e l a t i v e to N i i n . the s u l p h i d e f r a c t i o n . I n summation, Co and N i c o n c e n t r a t i o n s i n sedimentary p y r i t e are c o n t r o l l e d , at l e a s t i n p a r t , by t h e i r c o n c e n t r a t i o n s i n adjacent sediments. 1000 3 4 5 6 7 8 ° 1 0 5 S * J 6 7 8 9 100 NICKEL ppm 3 4 i 6 7 8»1000 o 105 5 r s M a w 2 / ss — o 0 ' / • •• • / / / / / 0 0 ! 2 Co/Ni RATIO IN SULPHIDE. FIGURE 44. Comparison of Co/Ni ratios in sediments and associated sulphides of Red Sea deposits (From Degens and Ross, ed., 1969). 106 T-test data show geometric means of Co and N i contents i n syngenetic p y r i t e are s i g n i f i c a n t l y lower than those of hydrothermal and v o l c a n i c e x h a l a t i v e ( o r massive s u l p h i d e ) p y r i t e (see Table 22). -Scatter diagrams show the c o n t r a s t between "syngenetic" and "massive •sulphide" p y r i t e more c l e a r l y ( F i g u r e 45). Massive sulphide p y r i t e s are d e s c r i b e d i n d e t a i l under a separate heading (page 110). I t should be noted that numerous hydrothermal p y r i t e s have Co/Ni r a t i o s l e s s than 1.0; thus low Co/Ni r a t i o s are not n e c e s s a r i l y i n d i c a t i v e of syngenetic o r i g i n f o r p y r i t e . A l s o , syngenetic p y r i t e from d e p o s i t s r i c h i n Fe (e.g., Steeprock Lake), Mn (manganese sh a l e s ) and Cu (Rhodesian copper b e l t ) a l l have Co/Ni r a t i o s g r e a t e r than 1.0, i l l u s t r a t i n g the scavenging e f f e c t of Fe and Mn oxides, ..and the enrichment of Co when a s s o c i a t e d w i t h Cu. Frequency d i s t r i b u t i o n s o f Co and Ni i n sedimentary p y r i t e are probably log-normal i n c h a r a c t e r ( F i g u r e s 46 to 49 )» but appear to be bimodal. T h i s probably i s caused by inhomogeneous data (sedimentary p y r i t e s from the Rosebery. area, Tasmania, are abnormally poor i n Co and N i ) . TABLE 22 COMPARISON: OP MEANS, STANDARD DEVIATIONS AND T-TEST VALUES FOR "SYNGENETIC," "HYDROTHERMAL," AND "MASSIVE SULPHIDE" PYRITES Means and Standard D e v i a t i o n s (Logarithmic) Syngenetic Hydrothermal Massive Sulphide 41 ppm (.813) 141 ppm (.996) 486 (.366) N i 65 ppm (.672) 121 ppm (.954) 56 (.600) Co/Ni 0.63 1.17 8.70 T-Test Values Co Syngenetic-Hydrothermal Syngenetic-Massive Sulphide Co 10.33* 22.76* N i 5.67* 9.7* Co/Ni 6.39* 12.36* • s i g n i f i c a n t a t 95$ confidence l e v e l . 35 - N « 74 K • 107 ppm. S • 167 ppm. * I " 42 ppm. FICURE 46. Histogram of Co i n p y r i t e from sedimentary rocks. Arithmetic data n .. LOWER LIMIT - PPM. i * * O "» 00 <H O ON tA <7 ,-t CM m ^ 25 -N = 74 X =172 ppm. S = 236 ppm. 1 - 5 9 ppm. FICURE 48. Histogram of Ni i n p y r i t e from sedimentary rocks. Arithmetic data mn n ;.n LOWER LIMIT - PPM. u 3 35 -30 25 10 N » 74 K » 1.534 ppm. S • 0,807 ppm. I " 0.202 ppn. FICURE 47. Histogram of Co i n pyrite from sedimentary rocks. LoRarithnic data . It*. • * • » LOWER LIMIT PPM. (LOG) O O O r H r t O i r s J r M 40 35 -30 25 20 15 10 N = 74 X" = 1.777 ppm. S •» 0.698 ppa. I • 0.175 ppa. FICURE 49. Histogram of Ni i n p y r i t e from sedimentary rocks. Logarithmic data LOWER LIMIT PPM. (LOO) O O O r t r H f H f N i r s t IN O 110 D. MASSIVE SULPHIDE AND VOLCANIC EXHALATIVE MINERAL DEPOSITS P y r i t e analyses from massive-sulphide replacement d e p o s i t s and s t r a t i f o r m " v o l c a n i c - e x h a l a t i v e " d e p o s i t s were grouped together f o r s t a t i s t i c a l a n a l y s i s because of t h e i r s i m i l a r g e o l o g i c a l e n v i r o n -ment, mineralogy, and minor element content i n p y r i t e . T y p i c a l replacement d e p o s i t s such as Noranda, Matagami, and the Geco de p o s i t at Manitouwadge, occur as lens-shaped ore bodies roughly conformable to e n c l o s i n g s t r a t a which are g e n e r a l l y a c i d i c to intermediate v o l -c a n i c s or p y r o c l a s t i c s . Other replacement de p o s i t s such as P l i n - P l o n or Campbell-Chibougamau are confined to shear zones, which commonly p a r a l l e l e n c l o s i n g s t r a t a . Examples of true s t r a t i f o r m v o l c a n i c e x h a l a t i v e d e p o s i t s are the Pb-Zn-Cu d e p o s i t s of Bathurst-Newcastle area, New Brunswick (Sutherland, 1967), the p y r i t e d e p o s i t s of Cyprus (Johnson, 1970), and p o s s i b l y the Pb-Zn-Cu d e p o s i t s of A n v i l area, Y.T. (although the l a t t e r d e p o s i t s are considered of r e p l a c e -ment o r i g i n by Templeman-Kluit, 1968). A s c a t t e r diagram comparing Co and N i content of sedimentary and v o l c a n i c e x h a l a t i v e massive s u l p h i d e p y r i t e ( F i g u r e 45) has r e v e a l e d that syngenetic p y r i t e g e n e r a l l y has much lower Co/Ni r a t i o s as a r e s u l t of lower Co content and higher Ni content. Massive sulphide p y r i t e i s c h a r a c t e r i z e d by a Co/Ni r a t i o between 5.0 and 50.0, Co u s u a l l y g r e a t e r than 100 ppm, and Ni u s u a l l y l e s s than 100 ppm. The f i e l d occupied by most samples on a Co-Ni s c a t t e r p l o t i s o u t l i n e d on Figure 63. 111 The c o r r e l a t i o n between Co and Ni i s not pronounced compared to t h a t o f sedimentary p y r i t e (see page 132). A l i s t i n g of mean minor element c o n c e n t r a t i o n s and standard d e v i a t i o n s f o r p y r i t e from "massive s u l p h i d e " d e p o s i t s i s given i n the appendix. Elements which appear to have promise as " i n d i c a t o r s " f o r t h i s type of de p o s i t are t i n (estimated mean 200 ppm), s i l v e r ( estimated mean 35 ppm), and selenium (estimated mean 250 ppm). 112 E. EFFECTS OF METAMORPHISM ON PYRITE The behaviour of minor elements i n p y r i t e d u r i n g metamorphism i s u n c e r t a i n . M i t c h e l l (1968) found t h a t t r a c e elements i n metamorphic p y r i t e (9 samples) were s i m i l a r to those of hydrothermal p y r i t e and concluded that l i t t l e change i n minor element content occurs d u r i n g metamorphism. Since the metamorphosed samples s t u d i e d were from d i f f e r e n t g e o l o g i c a l environments and geographical areas than the hydrothermal p y r i t e s , h i s c o n c l u s i o n can h a r d l y be taken s e r i o u s l y . Cambel and Jarkovsky (1966, 1968) r e p o r t that h i g h l y metamorphosed p y r i t e from the L i t t l e Carpathians c o n t a i n s much more c o b a l t than l e s s h i g h l y metamorphosed ores (see F i g u r e s 50 and 51)• T - t e s t s performed on the analyses support t h e i r c o n c l u s i o n s (Table 23) . In a d d i t i o n they r e p o r t t h a t d u r i n g metamorphic conversion of p y r i t e to p y r r h o t i t e , Co remains concentrated i n the p y r i t e , w h i l e N i becomes concentrated i n the p y r r h o t i t e . In an e a r l i e r study (Cambel and Jarkovsky, 1966) i t was observed that Co and N i are l o g - n o r m a l l y d i s t r i b u t e d i n p y r i t e from unmetamorphosed d e p o s i t s , but d u r i n g metamorphism the minor elements are homogenized, g i v i n g an "arithmetic'-normal d i s t r i b u t i o n . I n a study of the New Calumet d e p o s i t , Sangster (1967) noted t h a t the Co and N i content of p y r r h o t i t e and the Co content o f • s p h a l e r i t e vary i n v e r s e l y w i t h the amount of p y r r h o t i t e i n the ore body. Sangster assumes that p y r i t e was the dominant pre-metamorphism i r o n s u l p h i d e , and proposes that d u r i n g metamorphism n i c k e l and c o b a l t were r e d i s t r i b u t e d to p y r r h o t i t e and s p h a l e r i t e , FIGURE 50. Cobalt and n i c k e l contents of p y r i t e s from main types of ore d e p o s i t s i n the L i t t l e Carpathian H t s . U.S.S.R. (From Cambel and Jarkovsky, 1969) 10°% « • 2 f f 6 4 ! W' 8 e « 2 10J m H i ill I !il!iiH!t? H i ! i ;i ilii ii ! i i Iii! i jjisiiij i !!i iiili iii II i!!{! i liniuilliiiililiiii!! Ii! p i p ! ! IIP ill I! i i i l i ! : J ! i l l H i ! ! i f mM .ilti Si iiiiili ii lil ti tii hi Hi iii ii FIGURE 51, Cobalt and n i c k e l contents of p y r i t e s from h i g h l y metamorphosed ores from Lower Carpathian d e p o s i t s . (From Cambel and Jarkovsky, 1969). 114 w i t h c r y s t a l f i e l d s t a b i l i z a t i o n energy d i f f e r e n c e s i n o c t a h e d r a l and t e t r a h e d r a l f i e l d s accounting f o r the r e l a t i v e c o n c e n t r a t i o n of Co i n s p h a l e r i t e and N i i n p y r r h o t i t e . The energy d i f f e r e n c e s are l i s t e d below. CP.S.E. C.F.S.E. oc t a h e d r a l f i e l d t e t r a h e d r a l f i e l d ( p y r r h o t i t e ) ( s p h a l e r i t e ) Cobalt 8 12 N i c k e l 12 8 Evidence has been presented i n a previous chapter f o r the metamorphic r e d i s t r i b u t i o n of Co from b i o t i t e to p y r i t e d u r i n g metamorphism ( N i c k e l , 1954). I n summary, from trace-element p a r t i t i o n c o e f f i c i e n t theory, from a c t u a l analyses of minerals from metamorphic assemblages, and from observed f i e l d r e l a t i o n s h i p s , i t appears that minor elements ( i n c l u d i n g ore-forming elements) can be r e l e a s e d from s i l i c a t e m i n e r a l assemblages d u r i n g metamorphism and may be accepted by c o - e x i s t i n g or newly-formed p y r i t e . Metamorphosed -pyrite S e v e r a l s e t s of analyses of metamorphosed p y r i t e were t r e a t e d s t a t i s t i c a l l y to check the theory t h a t metamorphism r e d i s t r i b u t e s c o b a l t and n i c k e l i n p y r i t e . 115 The p y r i t i c d e p o s i t s s t u d i e d by Cambel and Jarkovsky occur i n the. L i t t l e Carpathian mountains of Czechoslovakia. A l l d e p o s i t s are s i t u a t e d i n a g e o s y n c l i n a l zone and are i n d i r e c t contact w i t h b a s i c e x t r u s i v e , i n t r u s i v e , or p y r o c l a s t i c rocks i n t e r p r e t e d as " o p h i o l i t e s o " The p y r i t e occurs i n p y r o c l a s t i c and sedimentary rocks both u n d e r l a i n and o v e r l a i n by "magmatogenic" amp h i b o l i t e s which are metamorphosed v o l c a n i c s . The amphibolite-grade r e g i o n a l metamorphism i s complicated i n places by contact metamorphism produced by numerous g r a n i t i c i n t r u s i o n s i n the area. S e v e r a l types of d e p o s i t s have been d i s t i n g u i s h e d based on t e x t u r a l and m i n e r a l o g i c a l d i f f e r e n c e s , but p y r i t e analyses are grouped as "medium" or "high grade metamorphosed" f o r s t a t i s t i c a l a n a l y s i s . Simple p l o t s of analyses, s c a t t e r diagrams and T - t e s t s show th a t d i f f e r e n c e s i n Co and N i c o n c e n t r a t i o n s between the two types of p y r i t e do e x i s t and that these d i f f e r e n c e s are s i g n i f i c a n t . The s t a t i s t i c a l t e s t s are i l l u s t r a t e d on the f o l l o w i n g pages ( F i g u r e s 52 to 60, Table 23). Frequency d i s t r i b u t i o n s of Co and N i i n p y r i t e from the two metamorphic grades were p l o t t e d u s i n g the histogram program. Examination of the medium grade histograms ( F i g u r e s 52 to 55") shows Co has approximate log-normal d i s t r i b u t i o n , but N i f o l l o w s a more normal d i s t r i b u t i o n (which i s not v i s i b l y improved by t r a n s f o r m a t i o n ) . T h i s i n d i c a t e s e i t h e r ( l ) N i was o r i g i n a l l y n o r m a l l y - d i s t r i b u t e d i n the p y r i t e (not considered l i k e l y ) , o r (2) medium-grade metamorphism has "normalized" Ni d i s t r i b u t i o n . D i s t r i b u t i o n of these elements i n h i g h l y metamorphosed p y r i t e i 3 roughly normal ( F i g u r e s 56 and 57). Normality i s not improved by l o g a r i t h m i c transforms ( F i g u r e s 58 and TABLE 23 , COMPARISON OP MINOR ELEMENT MEANS, STANDARD DEVIATIONS "• AND T-TEST DATA FOR METAMORPHOSED PYRITE FROM . .DEPOSITS IN THE CARPATHIAN MOUNTAINS Medium Grade High Grade Element , Mean S.D.(log) Mean S.D.(log) Co 81 ppm 0.415 855 ppm 0.256 N i 1620 0.080 564 0.256 Mn 2 0.519 6 0.690 T i 74 0.506 67 . 0.987 V 6 0.663 5 0.820 Mo 36 0.492 6 0.699 Co/Ni 0.05 0.343 1.5 0.322 T-Value D.F. Co v s . Co -14.097* 65 N i v s . N i 8.631* 29 Mh v s . Mn - 2.633* 42 T i v s . T i 0.222 33 V vs . V. 0.029 45 Mo vs . Mo 5.147* 40 Co/Ni V S o Co/Ni -18.178* 58 • s i g n i f i c a n t value at 95$ confidence l e v e l 35 30 25 20 N < %' S ' I ' 42 114 ppa. 125 ppm. 31 ppm. FIGURE 52. Histogram of Co i n p y r i t e from medium-grade metamorphic rocks Arithmetic data UL LOWER LIMIT - PPM. o m I A r*. o csi <f csi oo *ff o rv n ON rt csl csl o. r l 40 r 35 30 25 20 10 1 N = 42 R = 1.909 (81.0ppm.) S = 0.353 I - 0.09 FIGURE 53. Histogram of Co i n p y r i t e from medium-grade metamorphic rocks. Logarithmic data :£L LOWER LIMIT - PPM. (L00) rt ^ i-i IN 35 -30 25 20 10 N » K » s -' I » 42 1652 ppm. 341 ppm. 85 ppm. n FICURE 54. Histogram of Ni i n pyr i t e from medium-grade metamorphic rocks. Arithmetic data LOWER LIMIT PPM. 40 r 35 30 25 20 15 10 n N = 42 * «• 3.209 (1618 ppn.) S = 0.088 I " , 0.022 . FICURE 55. Histogram of Ni i n p y r i t e from medium-grade metamorphic rocks. Logarithmic data fT>-n O rt rt LOWER 3 LIMIT A PFM. (LOG) 35 30 25 IS 10 -N o 26 K = 976 ppm. S = 470 ppm. I ' » 118 ppm. FIGURE 56. Histogram of Co content of p y r i t e from high-grade metamorphic rocks. Arithmetic data LOWER LIMIT PPM. 35 30 25 20 15 10 N = 26 2 > 2.932 S = .2553 I ° .062 "' FIGURE 57. Histogram of Co content of p y r i t e from high-grade metamorphic rocks. Logarithmic data LOWER LIMIT PPM. (LOC) CN CN CN <N «M n m 35 -30 25 20 15 -10 -N ' S 1 I ' 26 671 ppm. 428 ppm. 107 ppm. FIGURE 58. Histogram of Nl i n p y r i t e from High-grade metamorphic.rocks. Arithmetic data LOWER LIMIT PPM. 40 35 30 25 o < 20 15 10 N = 26 A = 2.751 S.» .2553 I - .065 FICURE 59. Histogram of Ni i n p y r i t e from high-grade metamorphic rocks. Logarithmic data LOWER LIMIT „ „ „ „ „ PPM, (LOG) « « •» * ^ 00 1000 - 0 o / / o o y o o 0 / y ^ 3 o / • • • y ^ ^ * — 1^ 4^  »s» e O 0O0O«» e i i i i i i i i l 1 l t 1 1 » r 1 1 1 1 1 1 11 1 I 1 1 1 , 1 1 FIGURE 60. COMPARISON OF COBALT AND NICKEL CONTESTS OF PYRITES FROM MEDIUM AND HICU GRADE METAMORPHIC ROCKS IN ThE CARPATHIAN MTS. (Data: Cambel and Jarkovsky, 1969) 0 HIGH GRADE DEPOSITS 8 MEDIUM GRADE DEPOSITS B.Price 1971 J V, I [ I I I I I ' • I I I I I I I '  I  T i l l ' 2 3 4 i o 7 8 1 Q 3 3 4 5 6 7 JQQ 2 3 4 5 4 7 , 0 0 0 NICKEL ppm 120 5 9 ) • I t i s concluded that Co and N i i n high-grade metamorphic p y r i t e from the Czechoslovakian d e p o s i t s have been r e d i s t r i b u t e d . Histograms were constructed f o r Co, N i , and Mn i n p y r i t e from Pb-Zn-Cu d e p o s i t s of the A n v i l area ( S t o c k w e l l , 1 9 7 0 ) . The d e p o s i t s have been subjected to medium to high-grade r e g i o n a l metamorphism and frequency d i s t r i b u t i o n histograms i n d i c a t e d p o s s i b l e metamorphic r e d i s t r i b u t i o n of Co and N i . However the number of samples was l i m i t e d and r e l i a b i l i t y of a n a l y s i s was d o u b t f u l , so the histograms , are not i n c l u d e d i n t h i s d i s c u s s i o n . A problem a r i s e s i n i n t e r p r e t a t i o n of Co-Ni r e l a t i o n s h i p s i n p y r i t e from v o l c a n i c e x h a l a t i v e d e p o s i t s which have been subjected t o . r e g i o n a l metamorphism. The o n l y c l u e as to the e f f e c t s of meta-morphism i s the frequency d i s t r i b u t i o n of minor elements (see page 112). but t h i s i n f o r m a t i o n , w i l l not enable one to estimate the o r i g i n a l Co concentrations i n the p y r i t e . Co-Ni r e l a t i o n s h i p s between meta-morphosed and unmetamorphosed v o l c a n i c e x h a l a t i v e p y r i t e s are i l l u s t r a t e d by means of a s c a t t e r diagram i n Figure 6 i . Steeprock Lake p y r i t e , although c l a s s i f i e d i n t h i s study as "sedimentary" e x h a l a -t i v e i n nature, does have v o l c a n i c a f f i l i a t i o n s and might be regarded as an example of an unmetamorphosed "Cyprus" p y r i t i c d e p o s i t . I f so, then low grade metamorphism such as occurs i n the Cyprus d e p o s i t s may be s u f f i c i e n t to i n c r e a s e Co c o n c e n t r a t i o n s i n p y r i t e . The h i g h Co c o n c e n t r a t i o n s and Co/Ni r a t i o s i n sediments and p y r i t e from the Rhodesian copper b e l t may be e x p l a i n e d by h i g h grade metamorphic r e d i s t r i b u t i o n . F i g u r e 62 i l l u s t r a t e s the i n c r e a s e i n 200 300 400 10 5 , ' ve in . , 1' pyrite UPPER SCALE: Co/Ni RATIO IN PYRITE. LOWER SCALE: Co CONTENT IN PYRITE. 1 — r 1— i —r i i i i i : ~ r w o 53 o id o 500 600 700 800 10. 1 I I I M i r 1 0 0 I I I 11 10' 10 J I A.6 o'° A.6 \ Q4S0 A.5 \ \. \ \ A 1.5 \ Q300 A .9 \ \ \ \ QIAO \ N A2 .o N \ 0.1200^ A 9.4 S A 2.8 S i l l A 10.7 I0 4ppm O'osoo *^O.12000 -granite A 58.5 sill FIGURE 62. V a r i a t i o n of Co and Co/Ni i n p y r i t e w i t h depth i n Rhodesian copper d e p o s i t s (from Darneley, 1962; Co c o n c e n t r a t i o n i n p y r i t e w i t h depth i n two separate Cu-Co d e p o s i t s i n Rhodesia ( b a r n l e y , 1966). The hig h c o n c e n t r a t i o n s i n p y r i t e from basement g r a n i t e s suggests that r e m o b i l i z a t i o n of components d u r i n g metamorphism may have l e d to the t r a n s f e r of Co and p o s s i b l y other elements to " c o n c e n t r a t o r " minerals such as -p y r i t e . HYDROTHERMAL PYRITES Seve r a l hundred p y r i t e analyses from hydrothermal mineral d e p o s i t s are recorded i n the l i t e r a t u r e ; most of these have been done by emission spectrographic methods, and r a r e l y are enough analyses a v a i l a b l e from one geographical area to i n v e s t i g a t e thoroughly the gen e t i c i m p l i c a t i o n s o f minor element r e l a t i o n s h i p s . The m a j o r i t y o f p y r i t e s analyzed i n the l i t e r a t u r e are from d e p o s i t s which can be ca t e g o r i z e d as f o l l o w s : 1. Cu-Mo "porphyry" d e p o s i t s 2. W-Sn-Mo v e i n s 3. Cu(Co,Ag) v e i n s 4. Pb-Zn-(Cu,Ag) v e i n s or replacements 5. Au-Quartz v e i n s 6. Massive sulphide replacement or s t r a t i f o r m d e p o s i t s . These c a t e g o r i e s w i l l be examined i n more d e t a i l i n the subsequent pages. Porphyry Cu-Mo Deposits The term "porphyry" i s an a r t i f i c i a l term of c l a s s i f i c a t i o n , used to des c r i b e low-grade copper and/or molybdenum deposits, g e n e r a l l y present as dissemin a t i o n s o r stockwork v e i n s a s s o c i a t e d w i t h a c i d i c to inte r m e d i a t e p o r p h y r i t i c i n t r u s i v e bodies. P y r i t e analyses from f i v e "porphyry" d e p o s i t s from the C o r d i l l e r a n r e g i o n have been completed by graduate students and f a c u l t y of the 125 U n i v e r s i t y of B r i t i s h Columbia Geology Department. Deposits s t u d i e d and sources o f i n f o r m a t i o n are l i s t e d below. Deposit Metals Source Samples A n a l , method Berg, B.C. Mo-Cu Panteleyev, A. 85 Spec. (Ph.D. i n prog.) Endako, B.C. Mo Dawson, K. 67 Spec. (Ph.D. i n prog.) Casino, Y.T. Cu-Mo Godwin, C. 13 A.A. (Ph.D. i n prog.) Tchentlo Lk, B.C. Cu-Mo S i n c l a i r , A.J. .25 A.A. (Pers. r e s . ) -Molymine, B.C. Mo P r i c e , B.J. 6 A.A. (M.Sc. i n prog.) Means and standard d e v i a t i o n s f o r elements analyzed are given i n Table 25. I n ge n e r a l , Co/Ni r a t i o s are gr e a t e r than 1.0; the s m a l l e r d e p o s i t s , Tchentlo Lake and Molymine, have mean Co-Ni r a t i o s o f 31 and 27 r e s p e c t i v e l y , but l a r g e r d e p o s i t s have r a t i o s ranging from 2.7 to 5.7. Most o f the minor elements analyzed are present i n low c o n c e n t r a t i o n s , compared to co n c e n t r a t i o n s i n p y r i t e s from v e i n and replacement d e p o s i t s . oTi-tests showed Co content i n p y r i t e from major d e p o s i t s , Berg, Endako, and Casino to be s t a t i s t i c a l l y i d e n t i c a l , although other elements show cons i d e r a b l e v a r i a t i o n . D i v i s i o n of Berg analyses i n t o two groups, " i n t r u s i v e " and " h o r n f e l s " p y r i t e s , and t e s t i n g of geometric means f o r a l l elements w i t h T - t e s t s , r e v e a l e d no s i g n i f i c a n t d i f f e r e n c e s between the two groups (see Table 24). However, f u r t h e r c l a s s i f i c a t i o n of samples ac c o r d i n g to m i n e r a l o g i c a l a s s o c i a t i o n and v e i n types r e s u l t s i n r e c o g n i z a b l e TABLE 24 COMPARISON OF MINOR ELEMENTS IN PYRITE FROM THE BERG AND ENDAKO "PORPHYRY" DEPOSITS Element Berg H o r n f e l s Berg I n t r u s i o n Endako Mean S.D.do*) Mean S.D.(log) Mean S.D.(lo Co 210 ppm ( .716) 242 ppm ( .448) 164 ppm (.362) N i 77 ( .644) 89 ( .398) 29 (.644) Mn 4 ( .602) 4 ( .653) 25 (.699) T i 368 (1.114) 650 (1.246) 02479 (.519) Mo 58 ( .568) . 48 ( .432) 18 (.634) Cu 1413 ( .898) 1067 ( .839) 164 (.398) Pb 49 ( .519) 45 ( .800) 2.8 (.682) Zn 43 ( .492) 47 ( .813) 21 (.544) Ag 7.5 ( .432) 8.0 ( .580) 1.9 (.301) As 13 (1.452) 6 0.284) n.a. — . B i 5 ( .623) 5.5 ( .692) 7 (.833) Co/Ni 2.72 2.73 5. 55 Berg Deposit: " H o r n f e l s " P y r i t e v s . " I n t r u s i o n " P y r i t e Element T-Value D.F. -Co vs. Co 0.486 83 N i vs. N i 0.544 82 Mn . vs. Mn 0.044 72 T i vs. T i 0.937 72 Mo vs. Mo -0.771 84 TABLE 24 (Continued) COMPARISON OP-MINOR ELEMENTS IN PYRITE FROM THE BERG AND ENDAKO "PORPHYRY" DEPOSITS Berg Deposit: " H o r n f e l s " P y r i t e vs. " I n t r u s i o n " P y r i t e (Continued) Element T-Value D.F. Cu vs. Cu -0.649 78 Pb vs. Pb -0.202 56 Zn vs. Zn 0.262 53 Ag vs. Ag 0.250 62 As vs. As -1.100 80 B i vs. B i 0.399 75 Berg P v r i t e vs. Endako P v r i t e Element T-Value D.F Co vs. Co 1.929 61 N i vs. - N i 4.814* 99 Mn vs. Mn -5.966* 76 T i vs. T i -2.607* 41 Cu vs. Cu 5.5H* 44 Pb vs. Pb 7.682* 62 Zn vs. Zn 2.289* 52 Ag vs. Ag 5.999* 46 B i vs. B i -0.823 85 * S i g n i f i c a n t a t 95$ confidence l e v e l 0 = contaminated 128 minor-element r e l a t i o n s h i p s (Panteleyev, 1971, pers. comm.). C o r r e l a t i o n matrices f o r both groups o f data show r e c o g n i z a b l e d i f f e r e n c e s . P o s i t i v e inter-element c o r r e l a t i o n s i n the p y r i t e from the quartz-monzonite are present between the f o l l o w i n g elements: Mn : Zn, Mo : Ag, Cu : Ag, Pb : Ag, Pb : Zn. I n the h o r n f e l s zone Co : N i , Pb : Zn, Mo : Cu, and B i : Ag have s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t s . The analyses w i l l not be discussed f u r t h e r , as A. Panteleyev w i l l be c o v e r i n g the t o p i c i n g r e a t e r d e t a i l (Ph.D. t h e s i s i n p r o g r e s s ) . F a c t o r a n a l y s i s on p y r i t e analyses from Endako deposit have re v e a l e d s p e c i f i c elemental f a c t o r s c h a r a c t e r i s t i c of the ore zone and the surrounding barren p y r i t i c zone (K. Dawson, Ph.D. t h e s i s , i n p r o g r e s s ) . C o r r e l a t i o n matrices prepared by the w r i t e r from Dawson's data.show mutual c o r r e l a t i o n between N i , Mn, T i , and Sn. The l a t t e r , three elements thus a f f e c t Co/Ni r a t i o s . The c o r r e l a t i o n s may r e s u l t from contamination of the p y r i t e by one or more m i n e r a l phases con-t a i n i n g the l i s t e d elements, such as ma g n e t i t e - i l m e n i t e or p o s s i b l y r u t i l e . Some of the p y r i t e may have formed by s u l p h i d i z a t i o n of such f e r r i d e - e l e m e n t r i c h m i n e r a l s . P y r i t e s from the Berg deposit a l s o c o n t a i n h i g h c o n c e n t r a t i o n s of T i . Vague zonation i n minor elements i n p y r i t e from the Tchentlo Lake deposit was noted by S i n c l a i r (1971, personal r e s e a r c h ) . The c e n t r a l p a r t of the i n t r u s i v e i s c h a r a c t e r i z e d by p y r i t e w i t h h i g h Co/Ni values and low Mn, Zn, and Cu contents. Mean values f o r elements i n a l l "porphyry" p y r i t e s are l i s t e d i n Table 25* D i s p e r s i o n of values from t h e i r r e s p e c t i v e means i s s u r p r i s i n g l y low f o r most elements except Cu, Zn, and As, which are probably present as su l p h i d e m i c r o i n c l u s i o n s . Normal Vein and Replacement Deposits P y r i t e from the f o l l o w i n g f o u r c a t e g o r i e s o f hydrothermal v e i n and replacement d e p o s i t s were compared s t a t i s t i c a l l y . a. V-Sn-Mo v e i n s 84 analyses b. Cu-(Ag,Co) v e i n s 31 analyses c. Pb-Zn-Ag-(Cu) v e i n s and replacements 109 analyses d. Au-Quartz veins ..57 analyses A t a b u l a t i o n of d e p o s i t s , w i t h means and standard d e v i a t i o n s f o r elements determined i s given i n the appendix. Table 26, which shows o v e r a l l means and standard d e v i a t i o n s appears on page 131. Since the "spectrum" of elements determined v a r i e s c o n s i d e r a b l y between d e p o s i t s , only Co and Ni are discussed i n t h e . f o l l o w i n g s t a t i s t i c a l treatment. L o f t u s - H i l l s and Solomon (1968) proposed that p y r i t e from copper d e p o s i t s a s s o c i a t e d w i t h volcanism may c o n t a i n h i g h e r con-c e n t r a t i o n s of c o b a l t than p y r i t e from l e a d - z i n c d e p o s i t s i n the same g e o l o g i c a l environment and show evidence from Tasmanian d e p o s i t s to support t h e i r c o n c l u s i o n s (see Figure 75). Other authors have suggested that major metals present i n hydrothermal d e p o s i t s TABLE 25 MINOR ELEMENT DATA - PORPHYRY PYRITES Element No. High Low Mean S.D. ( l o g ) Co 171 1605 ppm 2 ppm 204 ppm .4914 N i 171 925 0 49 .6335 Mn 122 240 0 17 .6435 T i contaminated V i n s u f f i c i e n t data Cr i n s u f f i c i e n t data Sn 66 122 2 25 .3979 Ko. 86 2000 13 53 .5185 Cu 159 10000 6 514 .8195 Pb 109 1200 0 41 .6021 Zn 156 10000 0 33 .5911 Ag 147 130 0.5 4.4 • 5185 Au i n s u f f i c i e n t data As 29 15000 300 760 .3617 Sb 2 45 37 41 .0607 B i 100 5000 0 16 .6021 \ MINOR ELEMENT DATA TABLE 26 - HYDROTHERMAL VEIN AND REPLACEMENT PYRITE Element No. High Low Mean S.D. ( l Co 284 10000 ppm 0 ppm 141 ppm .9956 N i 284 6000 0 121 .9542 Mn 134 4000 0 28 .8633 T i 59 3000 15 82 .4771 V 21 100 2 15 .6532 Cr 57 300 0 15 .6990 Mo 18 100 2 28 .5051 Sn 112 16000 0 64 .9031 Cu 198 30000 5 425 .7993 P 95 13000 0 321 .9345 Zn 110 40000 16 1071 .8633 Ag 47 400 0.8 16 .6812 Au i n s u f f i c i e n t data -As 76 .; 85000 10 1268 .7634 Sb 9 200 10 73 .3802 B i 26 3000 10 83 .5911 Se i n s u f f i c i e n t data • I n 19 100 0 10 .5185 T l i n s u f f i c i e n t data -Cd 24. 450 20 69 .3424 132 may c o n t r o l or a f f e c t minor element contents of common sulphide m i n e r a l s . To t e s t these hypotheses, the w r i t e r c a r r i e d out T - t e s t s comparing mean Co and Ni contents i n p y r i t e from the f o u r c a t e g o r i e s above (Table 27),- and p l o t t e d s c a t t e r diagrams of analyses f o r v i s u a l comparison. The s c a t t e r diagrams showed d i s t i n c t f i e l d s f o r W-Sn-Mo vei n s and Au-quartz v e i n s ( o u t l i n e d i n F i g u r e 63). Values from Cu and Pb-Zn-Ag v e i n s are more di s p e r s e d , and no s p e c i f i c f i e l d s c ould be assigned. From the diagrams i t i s apparent that Co/Ni r a t i o s alone cannot p o s s i b l y c h a r a c t e r i z e m i n e r a l d e p o s i t s ; absolute c o n c e n t r a t i o n s and mean con c e n t r a t i o n s are more c h a r a c t e r i s t i c . Boundaries of the p l o t t e d Co-Ni f i e l d s are l i s t e d below. 1. W-Sn-Mo v e i n p y r i t e : Co 100-7000 ppm Ni 100-10,000 ppm Co/Ni 5.0 (avg. 1.03) 2. Au-Quartz v e i n p y r i t e : Co 40-1000 ppm Ni 50-1000 ppm Co/Ni 2.5 (avg. 0.71) I t i s observed from s c a t t e r diagrams and c o r r e l a t i o n m a t r i c e s t h a t these two groups of p y r i t e w i t h the most d i s t i n c t Co/Ni f i e l d s and lowest Co/Ni r a t i o s , a l s o have the h i g h e s t Co/Ni c o r r e l a t i o n c o e f f i c i e n t s . The same r e l a t i o n s h i p i s true of sedimentary p y r i t e (see Figure 42). Thus, i n the d e p o s i t s s t u d i e d there appears to be an i n v e r s e c o r r e l a t i o n between Co/Ni r a t i o and Co-Ni c o r r e l a t i o n c o e f f i c i e n t . Comparisons of the two f a c t o r s are g i v e n below: \ Co/Ni r a t i o Co-Ni c o r r . c o e f f . W-Sn-Mo p y r i t e 1.03 0.7599 Au-Qtz. " 0.71 0.8238 Pb-Zn-Ag " 1.92 0.4809 Cu(Co,Ag) " 1.94 0.3579 Mass sulp h . " 8.70 0.5380 Syng. " 0.63 0.9309 TABLE 27 MINOR ELEMENT DATA - HYDROTHERMAL VEIN AND REPLACEMENT PYRITES EFFECT OF MAJOR ELEMENTS ON COBALT AND NICKEL CONTENTS Major elements Cobalt. Nickel Co/Ni Mean S.D. Mean S.D. Mean w -• Sn - Mo 584 ppm .9031 566 ppm .7482 1.03 Au 318 .6582 164 .4472 1.94 Cu - (Co,Ag) 189 .5315 269 .4624 0.71 Pb - Zn - Ag Name 25 1.1135 13 T-Test Values T-Value .9395 D.F. 1.92 W-Sn-Mo vs. Au Co vs . Co 1.711 74 Ni vs . Ni 5.887* 92 Co/Ni vs . Co/Ni W-Sn--3.002* -Mo vs. Pb-Zn-Ag 50 Co vs . Co '9.404* 190 Ni vs . Ni 13.505* 191 Co/Ni vs . Co/Ni -2.244 N 176 W-Sn-Mo vs. Cu-Co-Ag Co vs. Co 4.050* 136 Ni vs. Ni 3.195* 138 Co/Ni vs. Co/Ni - 2.182* 130 TABLE 27 (Continued) MINOR ELEMENT DATA - HYDROTHERMAL VEIN AND REPLACEMENT PYRITES EFFECT OF MAJOR ELEMENTS ON COBALT AND NICKEL CONTENTS T-Test Values (Continued) Name T-Value D.F. Au vs. Pb-Zn-Ag Co vs. Co 6.946* 84 N i vs. N i 8.241* 110 Co/Ni vs. Co/Ni 0.831 81 Au vs. Cu-Co-Ag Co vs. Co 1.656 51 N i vs. N i -3.407* 65 Co/Ni v s , Co/Ni 4.604* 37 Cu-Co-Ag vs. Pb-Zn-Ag-Cu Co vs. Co -6.872* 163 N i vs. N i -12.076* 163 Co/Ni vs. Co/Ni 3.993* 138 * S i g n i f i c a n t a t 95$ l e v e l of confidence 1 1/ 1 I I I I I I I I I I I I I I I 1 I I I 1 I I 1 I I I , 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 « 100 2 3 4 5 6 7 8°1000 NICKEL ppm 136 I t i s i n t e r e s t i n g to speculate on the cause of the i n v e r s e c o r r e l a -t i o n . Veins c o n t a i n i n g V/, Sn, Mo, and i n some cases Au are t r a d i -t i o n a l l y regarded as being of h i g h temperature o r i g i n , but s e d i -mentary d e p o s i t s s u r e l y must be at the lower-most end of the tempera-t u r e s c a l e . The phenomenon.may not be temperature-dependent, but might r e s u l t from e f f e c t s of composition, or c o n c e n t r a t i o n of ore f l u i d s . Simple o r e - f l u i d composition might lea d to c l o s e r c o r r e l a -t i o n between Co and N i . I f types of d e p o s i t s are ranked a c c o r d i n g to Co or N i con-c e n t r a t i o n s , the sequence i s from W-Sn-Mo through Cu and Au to Pb-Zn-Ag, roughly p a r a l l e l i n g the normal zoning, sequence observed w i t h i n many mineral d i s t r i c t s (Barnes, 1963). A c c o r d i n g l y , the Co and N i contents of hydrothermal p y r i t e can be s a i d to be q u a l i t a t i v e l y r e l a t e d to major metals present i n the accompanying m i n e r a l i z a t i o n . A p o s s i b l e e x p l a n a t i o n f o r h i g h c o n c e n t r a t i o n s o f Co and N i i n W-Sn-Mo de p o s i t s i s the f a c t that r e s i d u a l (or p e g m a t i t i c ) f l u i d s r e s u l t i n g from magmatic d i f f e r e n t i a t i o n may be enriched i n these elements. S i g n i f i c a n t l y , many of the Rooibergarea t i n lodes c o n s i s t \ o f pegmatitic replacement vugs i n sediments. I t i s unfortunate that so few analyses are a v a i l a b l e f o r elements other than Co and N i , bacause i t i s p o s s i b l e t h a t elements such as As, Sb, B i , Se, Te, Sn, e t c . could be u s e f u l i n d i c a t o r elements f o r c e r t a i n types of hydrothermal d e p o s i t s . MINOR ELEMENTS IN PYRITE AND SILICA CONTENT OF ASSOCIATED IGNEOUS ROCKS Wilson (1953) has demonstrated a q u a l i t a t i v e c o r r e l a t i o n between s i l i c a content of igneous rocks and Ni c o n c e n t r a t i o n i n a s s o c i a t e d "magmatic" s u l p h i d e d e p o s i t s (see T a b l e ; 28). I t i s expected that p y r i t e from such d e p o s i t s and p y r i t e disseminated i n igneous rocks should have s i m i l a r q u a l i t a t i v e c o r r e l a t i o n of Co and N i content w i t h s i l i c a content o f a s s o c i a t e d r o c k s . R e l a t i v e l y few analyses o f p y r i t e from igneous rocks are recorded i n the l i t e r a t u r e . Most of the analyses from a c i d i c igneous rocks noted i n t h i s study are from disseminated p y r i t e i n Heemskirk and Mt. B i s c h o f f g r a n i t e s i n Tasmania ( L o f t u s - H i l l s and Solomon, 1968); i n these samples Co and Ni are present i n extremely low c o n c e n t r a t i o n s , and may not be r e p r e s e n t a t i v e of g r a n i t e s I n ge n e r a l . Analyses from b a s i c and u l t r a b a s i c rocks are mainly those from the Sudbury d i s t r i c t . In these samples, e i t h e r Co or N i may be en r i c h e d , and d i s p e r s i o n of values even from a s i n g l e deposit i s u s u a l l y g r eat. Mean values f o r Co and N i i n p y r i t e from a c i d i c and b a s i c igneous rocks are ta b u l a t e d below. A c i d i c rocks B a s i c rocks Mean S.D.(log.) Mean S.D.(log.) Co 6 ppm 0.544 4120 ppm . 0.416 N i 16 ppm 0.590 6575 ppm 0.826 Co/Ni 0.38 0.63 F r e q u e n c y - d i s t r i b u t i o n histograms i n d i c a t i n g mixed pop u l a t i o n s w i t h d i f f e r e n t means are present f o r both elements i n the two c a t e g o r i e s ; MAXIMUM % NICKEL LOCALITY* ROCK IN THE TYPE SULPHIDE Werner Lake, ,10.0 Ontario Peridotite Rankin Inlet, 10.0 N.W.T. Serpentine Shebando- 9.0 wan, Ontario Peridotite Norpax, 8.5 Peridotite Alexo, 8.0 Peridotite Thompson, 7.5 Manitobat.. Peridotite Bruvand, 7.0 Norway Peridotite Mystery Lake, 5.4 Manitobat.. Peridotite Choate, B.C. . Pyroxenite 5.0+ : Espedelen, ' '4.5 : Norway. ...... Pyroxenite Hosander, 6.5 Norite Sudbury, 3.0—6.0 Norite Rice Island, 5.0 Manitoba... Norite Herb Bay, 4.0 Manitoba... Norite Bamle, 3.75—4.0 Norite Romsaas, 3.5—3.75 Norway Norite Yakobi Island, Alaska Norite 3.0 Klefva. 2.6 Norite Erno, Ontario Gabbro 3.1 LakeAtha-baska, Sas-katchewan .. Diorite 1.0 Chibouga-mou, Quebec Anortho-site 0.5 •The data for the Scandinavian deposits are those of Vogt (1923). tThompson and Mystery Lake from a few specimens. DEPOSIT Ni/Co ASSOCIATED ROCK Thompson, Man... 66 Peridotite Rankin Inlet, . N.W.T 52 Werner Lake. Ont.. '• 47' Moak Lake, Man. .40 - a Norpax, Ont 39 Mystery Lake, Man. 36 Hudson Yukon, Y.T.... 28 a Falconbridge, Ont.; 24 Norite Emo, Ont. 19 Gabbro St. Stephen, N.B. . ' 15 Contact Bay, Ont. . 11 ,» Redditt, Ont...... ... 11 Diabase New Manitoba, Man 6 Gabbro TABLE 28. R e l a t i o n s h i p of maximum N i content and Ni/Co r a t i o of sulphides to composition of adjacent igneous r o c k s . (From Wilson and Anderson, 1959).. 139 i n a d d i t i o n , many of the analyses from b a s i c rocks have only one element determined. Thus the f i g u r e s above should be regarded as t e n t a t i v e . When Co and N i analyses from disseminated p y r i t e are p l o t t e d on a s c a t t e r diagram, the extreme d i s p e r s i o n o f values i n p y r i t e s from the Sudbury area i s emphasized. The d i s p e r s i o n r e s u l t s from the mixing of data from magmatic s u l p h i d e p y r i t e , which i s Co r i c h , w i t h data from N i - r i c h p y r i t e disseminated i n the Onaping t u f f (Besborough and Larsen, 1971). I n the s c a t t e r p l o t ( F i g u r e 64) p y r i t e analyses are compared to those o f igneous rocks themselves and to those o f m e t e o r i t e s . I t i s seen that Co and N i co n c e n t r a t i o n s i n p y r i t e s from igneous rocks are c o n t r o l l e d at l e a s t i n part by t h e i r c o n c e n t r a t i o n s i n the rocks themselves. Adams (1963) s t u d i e d p y r i t e from pegmatites and found r e l a t i v e l y h i g h c o n c e n t r a t i o n s of both Co and N i i n h i s samples (h i g h e r than i n hydrothermal v e i n p y r i t e , but lower than i n massive s u l p h i d e ) . This "anomalous" enrichment of l a t e - s t a g e , r e s i d u a l f l u i d s might be comparable to a s i m i l a r e f f e c t noted i n l a t e - s t a g e igneous rocks (see page 82 ). The two pegmatite p y r i t e samples encountered i n t h i s study (Darnley, 1966) both have anomalously h i g h N i content, s u p p o r t i n g Adams's f i n d i n g s . 140 100000 FIGURE 64. S c a t t e r diagram comparison o f Co and Ni contents of igneous rocks and p y r i t e s disseminated i n igneous rocks. Open symbols are p y r i t e s , dark symbols are r o c k s . V. MINOR ELEMENTS IN PYRITE FROM THE SMITHERS AREA, B.C. INTRODUCTION Smithers, i n i t i a l l y a locus f o r base-metal m i n e r a l explora-t i o n i n the e a r l y p a r t of the century, i s p r e s e n t l y a centre f o r i n t e n s i v e e x p l o r a t i o n f o r "porphyry"-type copper and molybdenum d e p o s i t s . The town i s approximately 500 m i l e s n o r t h of Vancouver and i s e q u i d i s t a n t from the c i t i e s of P r i n c e George and P r i n c e Rupert on Highway No. 16. The area was mapped i n reconnaissance by J.E. Armstrong of the G e o l o g i c a l Survey of Canada i n 1944 (Map 44-23). F u r t h e r mapping and c o m p i l a t i o n by N.C. C a r t e r and R.V. Kirkhara was completed i n 1969. (B.C. Dept. of Mines Map 69-1), and the area i s p r e s e n t l y being mapped i n d e t a i l by W.H. Tipper o f the G.S.C. / The area encompassed by the present study i s a range of h i l l s which could be considered the southern c o n t i n u a t i o n of the Babine mountains. The northern boundary i s the Smithers-Babine l a k e road, and Highway 16 from Houston to Telkwa marks the western boundary. Figure 65 ° n the f o l l o w i n g page shows general geology, m i n e r a l d e p o s i t s and o u t l i n e of the t h e s i s area. F o r t y p y r i t e samples were taken from s e v e r a l d i s t i n c t type of m i n e r a l d e p o s i t s ; the p y r i t e s were analyzed f o r Co, N i , Mn, Cu, Pb, and Zn u s i n g atomic a b s o r p t i o n spectrophotometry. From the analyses i n f e r e n c e s were made concerning m e t a l l o g e n e t i c p r o v i n c e s , genetic r e l a t i o n s h i p of d e p o s i t s , and minor element z o n a t i o n w i t h i n d e p o s i t s . 142 Pleistocene T e r t i a r y v o lcanics Eocene sediments 7 V). Jur-L. Cret. sediments HAZELTON CP. M.Jur? volcanics M.Jur,+L.Jur. sediments M.Jur.+L.Jur. volcanics 16 | 2 | U.Cret.-L.Tert. i n t r u s i o n s Mineral deposit (Map modified from Carter and Kirkham, 1969, Map 69-1) miles FIGURE 65. G e o l o g i c a l map of t h e s i s area showing boundaries of t h e s i s area and l o c a t i o n s of p r o p e r t i e s s t u d i e d GENERAL GEOLOGY OF THE THESIS AREA S t r a t i g r a p h y The t h e s i s area i s u n d e r l a i n by v o l c a n i c , p y r o c l a s t i c , and sedimentary rocks of the Hazelton Group, of e a r l y J u r a s s i c to e a r l y Cretaceous age (represented by u n i t s 4 to 8 on the accompanying map). The lowermost u n i t c o n s i s t s of v a r i c o l o r e d a n d e s i t i c to r h y o l i t i c f l o w b r e c c i a s and t u f f s w i t h t h i n i n t e r c a l a t e d sedimentary beds. T h i s u n i t i s c o r r e l a t e d w i t h the Tachek Group to the southeast ( T i p p e r , 1970). U n i t 5, e a r l y and middle J u r a s s i c i n age, i n c l u d e s p y r o c l a s t i c and normal sedimentary rocks c o n t a i n i n g marine f o s s i l s . U n i t 6 c o n s i s t s of predominantly b a s a l t i c and a n d e s i t i c v o l c a n i c f l o w s , b r e c c i a s , and t u f f s . U n i t s 7 and 8 were not observed i n the area of study. S t r u c t u r e Rocks of the Hazelton Group are g e n t l y f o l d e d and block f a u l t e d i n the study area, although complex f o l d i n g and i m b r i c a t e f a u l t i n g have been observed i n the Babine mountains to the north ( T i p p e r , 1970). The v a l l e y of the B u l k l e y R i v e r was generated by normal f a u l t i n g (Armstrong, 1944); major northwest-trending f a u l t s are present on the eas t e r n margin of the v a l l e y , and s i m i l a r f a u l t s bound the eastern margin of the Babine mountains ( T i p p e r , 1970). Prominent northwest-trending lineaments v i s i b l e on a e r i a l photographs are common throughout the area, and i n some areas ( f o r example Dome Mountain) n o r t h e a s t - t r e n d i n g c r o s s - f r a c t u r e s are a l s o common. 144 3. Igneous rocks Hazelton Group rocks i n the t h e s i s area have been in t r u d e d by a wide v a r i e t y of igneous rocks i n c l u d i n g gabbro, quartz d i o r i t e , s y e n o d i o r i t e , t r a c h y t i c g r a n o d i o r i t e , quartz-monzonite, g r a n i t e and a l a s k i t e . S e v e r a l ages o f i n t r u s i o n are probably represented; more complex g r a n o d i o r i t e bodies might be r e l a t e d to "Topley" i n t r u s i o n s o f J u r a s s i c age but simple quartz-monzonite and g r a n i t e stocks are probably of T e r t i a r y (Eocene) age. 4. M i n e r a l de-posits -Most m i n e r a l d e p o s i t s i n the area are r e l a t e d s p a t i a l l y , i f not g e n e t i c a l l y , to a c i d and intermediate i n t r u s i o n s . Deposits are g e n e r a l l y i n the lowermost v o l c a n i c u n i t , c l o s e to i t s upper contact w i t h sediments of u n i t 5. Most m i n e r a l d e p o s i t s i n the t h e s i s area were examined while the w r i t e r was employed w i t h Manex Mining L t d . , engaged i n e x p l o r a t i o n and property development. Where p o s s i b l e , p y r i t e samples and m i n e r a l o g i c a l samples were taken. Table 29 l i s t s d e p o s i t s , c h a r a c t e r i s t i c s and mineralogy o f each, and number of samples taken. Table 30 l i s t s a n a l y t i c a l r e s u l t s . The only other s i g n i f i c a n t d e p o s i t s i n the area are the Bot Brenda showing, c o n s i s t i n g of disseminated copper m i n e r a l s i n v o l c a n i c and sedimentary r o c k s , and the Deep Creek (Tom-Tom) showing of massive p y r r h o t i t e and s p h a l e r i t e . In both d e p o s i t s p y r i t e i s scarce and r e p r e s e n t a t i v e samples could not be c o l l e c t e d . D e t a i l e d g e o l o g i c a l d e s c r i p t i o n s of the p r o p e r t i e s are in c l u d e d i n the appendix; maps of the Dome Mountain and Molymine d e p o s i t s are i n c l u d e d . : •.•}''/¥ "'• v " ' / ; • " "•'--">' TABLE 29 MINERAL DEPOSITS OF THE DOME MOUNTAIN-GROUSE MOUNTAIN AREA, SMITHERS, B.C. Deposit Type Mineralogy* Samples Code Dome Mtn. Quartz v e i n s Qtz-py-sph-gn-(tet,cp) 6 BDM Dome Babine Quartz v e i n s Qtz-py-sph-gn-tet-(cp,Au) 6 BD Fe d e r a l Creek Replacement Sph-cp-py-(gn,asp) 1 BD Ascot S t r a t i f o r m Sph-gn-py 1 BTG Last Chance Quartz v e i n Sph-tet-gn-py 1 BCH Copper Ridge Replacement Sph-cp-py 3 BCR Molymine a; Merkely s h a f t Replacement Cp-py-mag 1 BMH b) D i o r i t e Quartz v e i n Py-sph-gn(tet) 7 BDZ zone c) South zone Quartz v e i n "Porphyry" Py-sph-gn-tet(cp) Py-mo 2 7 BMH BMH d) B r e c c i a B r e c c i a pipe Mo-cp-py(tet,sph) 5 BZ zone • A b b r e v i a t i o n s : qtz = quartz t e t = t e t r a h e d r i t e py = p y r i t e asp = a r s e n o p y r i t e sph = s p h a l e r i t e mo = molybdenite gn = galena mag = magnetite Au = gold ANALYTICAL METHOD AND RESULTS P y r i t e concentrates from the samples were roasted to convert the sulphide to oxide. The oxide m a t e r i a l was d i s s o l v e d i n hydro-c h l o r i c a c i d and r e s u l t i n g s o l u t i o n s were a s p i r a t e d through a Techtron A-4 atomic a b s o r p t i o n spectrophotometer, c a l i b r a t e d pre-v i o u s l y w i t h standard s o l u t i o n s . A complete d e s c r i p t i o n o f concentra-t i o n and a n a l y t i c a l methods i s i n c l u d e d i n the appendix; accuracy and p r e c i s i o n are a l s o d i s c u s s e d . A n a l y t i c a l r e s u l t s are l i s t e d i n Table 30 and repeat analyses i n Table 36. TABLE 30, PYRITE ANALYSES FROM SHITHERS MAP AREA, B.C. (A). DOME MOUNTAIN AREA SAMPLE NUMBER Co ppm. Nl ppm. Mn ppm * Cu ppm. Pb ppm. 1) Doce Babine Au-Pb-Zn-Cu veins BD BD BD BD BD BD 120 3 45 75 55 3 12 5 8 1 1 1 * » contaminated, >10000 ppm 2) Pome Mountain Pb-Zn-Cu-Au veins 4 26 2 8 17 19 1225 2580 336 379 1078 1594 3775 4385 2060 3110 944 1332 1102 5190 3460 1480 1990 BDM 1 90 5 . 2 5780 28 11 EDM 1 R 87 4 5 2675 0 20 BDM 2 45 1 4 17600 745 240 BDM 2 S 63 1 10 2675 345 159 BDM 3 120 10 13 34200 5 197 BDM 3 R 88 10 22 8900 5 294 BDH 4 40 5 4 253 0 35 BDM 5 75 5 4 547 15 88 BDH 5 R 45 6 5 408 14 92 BDM 6 1 1 4 . 2760 210 81 3) Fedral Creek Zn-Pb-Cu-Au replacement BD 7 6 110 28 336 610 2930 4 ) Ascot Pb-Zn syngenetic? (possibly replacement) BIG 1 1 1 11 42 5 187 BIG 1 R 1 1 8 35 0 137 (B) GROUSE MOUNTAIN AREA 1) Molymine Mo "porphyry * deposit BMH 6 115 1 BMH 9 100 1 BMH 10 62 15 BMH 10 A 165 1 BMH 10 A R 165 2 EMU 11 90 15 BMH 12 1605 95 2) Molymine Pb-Zn-Cu-Ag veins BDZ 1 255 1 BDZ 1 R 250 1 BDZ 2 345 12 BDZ 3 780 25 BDZ 4 130 1 BDZ 5 150 1 BDZ 6 345 25 BDZ 6 R 300 12 BMH 7 135 20 BMH 7 A 142 12 3) Molymine breccia pipe Ho-Cu BZ 1 1408 45 BZ 1 R 1508 43 BZ 2. 285 22 BZ 3 1554 50 BZ 4 685 22 BZ 5 895 22 4) Kerkely shoving, Cu replacenen BMH 1 2220 305 5) Copper Ridge Cu-Zn replacement BCR 1 405 18 BCR 2 247 31 BCR 5 202 2 6) Last Chance Pb-Zn-Cu-Ag vein BCH 3 660 440 13 3 14 11 5 15 13 66 12 25 12 11 18 38 7 18 24 36 37 13 48 621 1509 308 208 1810 664 2800 590 457 2342 704 1463 8530 2200 690 1231 267 130 56 580 870 940 2535 957 690 1720 7780 0 63 0 0 0 0 0 6645 5140 0 0 4800 138 860 215 1610 50 10 5 285 1930 33 600 202 420 485 0 0 15. 34 12 25 5 12 223 71 531 465 3900 1670 882 101 43 54 18 134 53 2700 87 1750 2730 120 1025 * » contaminated >10000 ppm. DISCUSSION .OP; RESULTS P y r i t e analyses completed d u r i n g the study provided s u f f i -c i e n t data f o r i n f e r e n c e s concerning m e t a l l o g e n e t i c provinces, genesis of mineral d e p o s i t s , mode of minor-element s u b s t i t u t i o n i n p y r i t e , and a p p l i c a b i l i t y of minor-element s t u d i e s to m i n e r a l explora-t i o n . R e s u l t s conformed to those obtained i n s i m i l a r r e s e a r c h r e p o r t e d i n the l i t e r a t u r e and to t h e o r e t i c a l c o n s i d e r a t i o n s reviewed i n 'previous chapters of t h i s t h e s i s . F a c t o r s which i n h i b i t the a p p l i c a t i o n of p y r i t e minor-element re s e a r c h to mineral e x p l o r a t i o n a r e : 1) Pure p y r i t e concentrates are sometimes d i f f i c u l t to prepare. 2) S e v e r a l u n r e l a t e d generations of p y r i t e may be present i n a s i n g l e m i n e r a l d e p o s i t . 3) Sample p r e p a r a t i o n p r i o r to a n a l y s i s i s time-consuming. Thus, p y r i t e a n a l y s i s i s more u s e f u l d u r i n g secondary stages of m i n e r a l e x p l o r a t i o n , where geology of the deposit i s f a i r l y w e l l known, l a b o r a t o r y f a c i l i t i e s are adequate and a v a i l a b l e , and s u f f i c i e n t time can be spent c o l l e c t i n g a l a r g e number of samples. A l i m i t i n g f a c t o r i n the use of atomic a b s o r p t i o n s p e c t r o -photometry f o r p y r i t e a n a l y s i s at the present time i s the l i m i t e d number of elements that can be analyzed f o r . Emission s p e c t r o -graphic methods have the advantage of simultaneous a n a l y s i s of many elements and simple p r e p a r a t i o n techniques f o r samples, but d e t e c t i o n l i m i t s are hi g h e r , p r e c i s i o n i s not as good, and prepara-t i o n of standards i s more time-consuming. Minor elements i n p y r i t e determined i n samples from the mineral d e p o s i t s i n the t h e s i s area were c o b a l t , n i c k e l , manganese, copper, l e a d , and z i n c . These were the only elements considered p r a c t i c a l f o r atomic a b s o r p t i o n a n a l y s i s c o n s i d e r i n g t e c h n i c a l f a c i l i t i e s a v a i l a b l e and time budgeted f o r the study. Co, N i , and Mn were chosen as elements present i n s o l i d s u b s t i t u t i o n f o r Fe i n the p y r i t e l a t t i c e and Cu, Pb, and Zn were chosen to i n v e s t i g a t e the .e f f e c t s of contamination. Inter-element c o r r e l a t i o n c o e f f i c i e n t s c a l c u l a t e d f o r numerous mi n e r a l d e p o s i t s revealed no s i g n i f i c a n t -c o r r e l a t i o n s of Cu, Pb, or Zn w i t h e i t h e r Co or N i , i n d i c a t i n g contamination o f Co and Ni by m i n e r a l i n c l u s i o n s (such as galena, s p h a l e r i t e , or c h a l c o p y r i t e ) i s not s i g n i f i c a n t . Cobalt shows the most promise as an index of ge n e t i c o r i g i n of p y r i t e f o r the f o l l o w i n g reasons: • 1) Co i s present i n c o n c e n t r a t i o n s w e l l above d e t e c t i o n l i m i t s of the a n a l y t i c a l method used; hence a n a l y t i c a l e r r o r s are s m a l l . 2) D i s p e r s i o n of values of Co contents i n p y r i t e i s low w i t h i n a s i n g l e deposit compared to other elements. 3) S u f f i c i e n t c o n t r a s t i s present i n Co c o n c e n t r a t i o n s between d i f f e r e n t d e p o s i t s . 4) The e f f e c t s of contamination are i n s i g n i f i c a n t . N i c k e l i s probably as u s e f u l as c o b a l t i n c e r t a i n areas, but i n the t h e s i s area, n i c k e l i s present i n low con c e n t r a t i o n s and c o n t r a s t between d e p o s i t s i s s m a l l . Manganese i s present i n very low concentra t i o n s from a l l d e p o s i t s , and i s s u b j e c t to contamination from Mn oxid e s , s p h a l e r i t e , magnetite, and ferromagnesian s i l i c a t e s . Theore-t i c a l c o n s i d e r a t i o n s i n d i c a t e o n l y l i m i t e d s o l i d s o l u t i o n of-Mn i n p y r i t e i s p o s s i b l e . Copper i n p y r i t e i s p o t e n t i a l l y u s e f u l i n minor, element s t u d i e s , as conc e n t r a t i o n s are u s u a l l y h i g h and d i s p e r s i o n o f values i s r e l a t i v e l y low. However the element i s s u b j e c t to contamination by many common s u l p h i d e s , l i m i t i n g i t s u s e f u l n e s s . i. • • • • • Lead and z i n c are present i n w i d e l y v a r y i n g c o n c e n t r a t i o n s i n the p y r i t e s s t u d i e d ( i . e . , standard d e v i a t i o n s are h i g h ) , and c o r r e l a t i o n between these elements i s o f t e n present, i n d i c a t i n g a marked degree of contamination by s p h a l e r i t e and galena. Dome Mountain area Concentrations of Co and N i , and Co/Ni r a t i o s from Dome Mountain p y r i t e s are c o n s i d e r a b l y lower than i n p y r i t e from s i m i l a r environments on Grouse Mountain. Means and standard d e v i a t i o n s f o r the two areas are l i s t e d below: Co N i Co/Ni Dome Mountain mean*" 28 ppm 3 ppm 9.4 (12 samples) s.d.(log) .708 .448 Grouse Mountain mean 229 ppm 6 ppm 38.2 (10 samples) s. d. .230 .634 * geometric 152 T - t e s t s c o n f i r m i n g the s i g n i f i c a n c e of these v a l u e s are shown on the f o l l o w i n g page (Table 31). Contents o f Mn, Cu, Pb, and Zn are not s t a t i s t i c a l l y d i f f e r e n t . P y r i t e s from the v e i n s a t the top o f Dome Mountain d i f f e r from v e i n p y r i t e a t the Dome Babine property o n l y i n Pb and Zn c o n c e n t r a t i o n s . Mineralogy of both areas are i d e n t i c a l except f o r very c l o s e a s s o c i a t i o n of p y r i t e w i t h s p h a l e r i t e and galena i n the Dome Babine v e i n s . The h i g h mean values f o r Cu, Pb, and Zn r e f l e c t contamination by i n c l u s i o n s or f r a c t u r e - f i l l i n g s . S i m i l a r i t y o f p y r i t e s i n m i n e r a l o g i c a l a s s o c i a t i o n s and minor element contents i n the Dome Mountain area suggest that a l l v e i n s sampled had the same or at l e a s t v e r y s i m i l a r g e n e t i c o r i g i n . No zo n a t i o n i s apparent from the data. 2. Grouse Mountain Area a) Molymine d e p o s i t s Three major types o f m i n e r a l i z a t i o n are present at the Molymine property: "porphyry"-type v e i n s and d i s s e m i n a t i o n s , stockwork quartz v e i n s i n a b r e c c i a p i p e , and normal quartz v e i n s . Minor element c o n c e n t r a t i o n s and Co/Ni r a t i o s o f p y r i t e from each type are compared i n Table 33. T-tests comparing these values are shown on page 155. Co/Ni r a t i o s from the three g e n e t i c types of deposit are s t a t i s t i c a l l y the same.* Absolute contents o f Co and N i from "porphyry" and v e i n p y r i t e s are not s t a t i s t i c a l l y d i f f e r e n t , although Mn, Zn, and Pb contents are. P y r i t e from the b r e c c i a p i p e , * See Fi g u r e 67 TABLE 31 COMPARISON OF DOME MOUNTAIN AND DOME BABINE PYRITES Element Dome Mountain Dome Babine Mean S.D.(log) Mean S.D.(log) Co 33 ppm .7559 24 ppm .7160 Ni 3 .4314 3 .5051 Mn 6 .2553 9 .4314 Cu 2600 .7482 939 .3424 Pb 22 1.0170 2260 .2553 Zn 77 .4472 2890 .3617 Co/Ni 9.6 8.6 T-Test Data - Dome Mountain vs. Dome Babine Pyrites  Element T-Value D.F. Co vs. Co -0.304 10 Ni vs. Ni -0.307 10 Mn vs. Mn 0.908 8 Cu vs. Cu -1.308 7 Pb vs. Pb 4.674* 6 Zn vs. Zn 6.706* 10 Co/Ni vs. Co/Ni -0.118 9 * S i g n i f i c a n t at 95^ confidence l e v e l 155 TABLE 32 T-TEST DATA - DOME MOUNTAIN PYRITE VS. GROUSE MOUNTAIN PYRITE Element T-Value D.F. Co v s . . Co -4.215* 14 Ni v s . N i -1.303 18 • Mn v s . Mn -1.281 21 ' Cu v s . Cu 0.491 19 Pb v s . Pb -0.049 20 Zn v s . Zn -0.146 21 Co/Ni v s . Co/Ni -2.411* 21 * S i g n i f i c a n t a t 95$ confidence l e v e l present mainly as f i n e d i s s e m i n a t i o n s i n h o r n f e l s fragments, has s i g n i f i c a n t l y higher Co and Ni contents than p y r i t e from v e i n s . The d i f f e r e n c e may be accounted f o r by genesis of the b r e c c i a p y r i t e by s u l p h i d i z a t i o n of C o - r i c h volcanogenic m a t e r i a l p r i o r to d e p o s i t i o n of q u a r t z , molybdenite and other s u l p h i d e s . Supporting t h i s theory are t e x t u r a l f e a t u r e s i n d i c a t i n g two stages of p y r i t e formation and a n a l y t i c a l evidence; Co content o f sample BZ2 r e p r e s e n t i n g second stage p y r i t e i s s i g n i f i c a n t l y lower than that of the disseminated p y r i t e , and i s comparable to the average Co content of v e i n p y r i t e (see Tables 30 and 33 )• Correspondance of minor element c o n c e n t r a t i o n s and mineralogy support genetic r e l a t i o n o f the porphyry m i n e r a l i z a t i o n and v e i n m i n e r a l i z a t i o n . Zoning i n mineralogy and minor elements i n p y r i t e may be i n d i c a t e d by the r e l a t i o n s h i p s p l o t t e d on the accompanying diagrams ( F i g u r e s 68, 69 ). Although p y r i t e and molybdenite are present throughout the b r e c c i a zone, other s u l p h i d e s such as t e t r a h e d r i t e , c h a l c o p y r i t e , galena, and s p h a l e r i t e appear to be present mainly outside the I f c ^ - r i c h zone (Fi g u r e 6 9 ) . Co i n p y r i t e decreases outward from the M0S2 zone and Cu i n c r e a s e s . Induced p o l a r i z a t i o n surveys show a vague rim of higher c h a r g e a b i l i t y corresponding to the suspected margin of the b r e c c i a . Computer mapping of trend s u r f a c e s generated from Co and Ni analyses from the whole area was attempted, but data are i n s u f f i c i e n t i n q u a n t i t y and d i s t r i -b u t i o n f o r reasonable i n t e r p r e t a t i o n . TABLE 33 COMPARISON OF MOLYMINE PYRITE - MINOR.ELEMENT MEANS Element Veins Breccia Porphyry mean s.d. mean s.d. mean s.d. Co 221 ppm .2553 830 ppm .3010 160 ppm .5051 Ni 6* .6532 30 .1761 5 .8451 Mn 9 .2304 13 .3222 '4 .1461 Cu 1064 .3424 351 .5185 490 .5798 Pb 220 1.4314 154 .9638 2 .7324 Zn 45 .7160 111 .8325 9 .5441 Co/Ni 40.0 28.0 30.0 * Rounded to nearest ppm TABLE 34 T-TEST DATA - COMPARISON OF MOLYMINE PYRITES Name T-Value D.F. Vein pyrite vs. breccia pipe pyrite Co vs. Co -3.718* 7 Ni vs. Ni -3.307* 11 Mn vs. Mn -0.924 6 Cu vs. Cu 1.876 6 Pb vs. Pb 0.247 11 Zn vs. Zn 1.384 7 Co/Ni vs. Co/Ni 0.783 12 Vein pyrite vs. porphyry pyrite Co vs. Co 0.626 6 Ni vs. Ni 0.049 9 Mn vs. Mn 4.642* 14 Cu vs. Cu 1.288 7 Pb vs. Pb 3.761* 14 Zn vs. Zn 5.319* 13 Co/Ni vs. Co/Ni 0.352 9 Breccia pipe pyrite vs. porphyry pyrite Co vs. Co 2.890* 8 Ni vs. Ni 2.128 6 Mn vs. Mn 3.835* 5 TABLE 34 (Continued) T-TEST DATA - COMPARISON OF MOLYMINE PYRITES Name T-Value D.F. B r e c c i a pipe p y r i t e v s . porphyry p y r i t e (continued) Cu vs. Cu -0.440 9 Pb v s . Pb 3.593* 7 Zn vs . Zn 2.500* 7 Co/Ni v s . Co/Ni -0.127 6 * S i g n i f i c a n t v a l u e a t 95$ confidence l e v e l 160 FIGURE 60. SKETCH MAP OF MOLYMINE BRECCIA PIPE l v/iiiA v/im ) LEGEND Overburden d r i l l - h o l e Overburden d r i l l - h o l e , MoS 2 g r e a t e r than 0.12 % Sample l o c a t i o n T r e n c h Induced P o l a r i z a t i o n c o n t o u r ( m i l l i s e c o n d s ) - c h a r g e a b i i i t y . O 3000 in N CO N CD CO N 00 N m O c o g ^ o o -A \ Cu Pb Zn Zone \ — Mo Zone A \ -** \ 100 FIGURE 69. DIAGRAMMATIC REPRESENTATION OF MINERALOGICAL AND MINOR ELEMENT ZONATION IN MOLYMINE BRECCIA PIPE. b) Other Deposits Copper Ridge prospect P y r i t e samples from the massive c h a l c o p y r i t e - s p h a l e r i t e d e p o s i t s a t the Copper Ridge prospect have r e l a t i v e l y h i g h concen-t r a t i o n s o f Cu, Zn, and Mn; the l a t t e r element p o s s i b l y present i n s p h a l e r i t e i n c l u s i o n s . Co/Ni r a t i o s are h i g h , and f a l l i n the range e x h i b i t e d by p y r i t e s from other massive Cu-Zn d e p o s i t s such as Noranda and Mattagami. Examination of p o l i s h e d s e c t i o n s of high-grade m i n e r a l i z a -t i o n r e v e a l s t h a t p y r i t e i s a s s o c i a t e d o n l y w i t h c h a l c o p y r i t e , never w i t h s p h a l e r i t e . S p h a l e r i t e and c h a l c o p y r i t e are i n t i m a t e l y mixed as- a r e s u l t of p o s t - m i n e r a l i z a t i o n s h e a r i n g . The t e x t u r e s suggest t h a t p y r i t e d e p o s i t i o n was e a r l y ; subsequently c h a l c o p y r i t was deposited around the p y r i t e g r a i n s and remained w i t h the p y r i t as the p y r i t e was f r a c t u r e d d u r i n g deformation. Herkely showing < Sample BMH 1, from a massive pod of c h a l c o p y r i t e enclosed i n b a s i c v o l c a n i c r o c k s , c o n t a i n s the h i g h e s t c o n c e n t r a t i o n of Co of a l l samples analyzed i n t h i s study (2220 ppm). N i c k e l content i s a l s o h i g h (305 ppm). The w r i t e r f e e l s that the h i g h c o n c e n t r a t i o n s are a d i r e c t r e s u l t of a s s o c i a t i o n w i t h b a s i c v o l c a n i c m a t e r i a l ; the p y r i t e might have formed by s u l p h i d i z a t i o n of p r e - e x i s t i n g ferromagnesian oxide o r s i l i c a t e m i n e r a l s . (Magnetite i s a s s o c i a t e d w i t h the p y r i t e . ) The c o r r e l a t i o n of h i g h Co/Ni r a t i o s i n p y r i t e w i t h volcanogenic o r i g i n has been noted by L o f t u s - H i l l s and Solomon (1967-)•* L a s t Chance showing Sample BCH 3 c o n t a i n s the highest N i c o n c e n t r a t i o n of any o f the samples (440 ppm) and moderately h i g h Co (660 ppm). The p y r i t e occurs as s m a l l , b r i g h t p y r i t o h e d r a surrounded by quartz a n k e r i t e , and c h l o r i t e , w i t h minor.amounts of s p h a l e r i t e , galena and t e t r a h e d r i t e . Fragments of v o l c a n i c and sedimentary rocks are a l s o present i n the v e i n s and p y r i t e c r y s t a l s are seen w i t h i n the v o l c a n i c fragments. Textures a t the margins of the fragments are i n d i c a t i v e of " l i b e r a t i o n " of p y r i t e c r y s t a l s i n t o the v e i n from the v o l c a n i c r o c k s . Thus, hig h Ni and Co c o n c e n t r a t i o n s i n the p y r i t e might be explained by i t s o r i g i n a l v o l c a n i c a f f i l i a t i o n . Ascot showing Sample BTG 1, provided by Mr. J . F r a s e r , c o n s i s t s of f i n e l y c r y s t a l l i n e p y r i t e i n a matrix of quartz and s e r i c i t e . The p y r i t e c o n t a i n s no Co or N i * and o n l y s m a l l amounts of Mn, Cu, Pb, and Zn. A recent a n a l y s i s by D. Brabec ( o r a l communication) shows 50 ppm Se i n the sample. The content of Se and the absence o f Co and N i i s incompatible w i t h a sedimentary or v o l c a n i c e x h a l a t i v e o r i g i n f o r the p y r i t e . Textures and minor element * Zero values i n Table 30 are noted as 1 ppm f o r purpose of • s t a t i s t i c a l c a l c u l a t i o n s . 164 data suggest a hydrothermal o r i g i n . P y r i t e s from low temperature Pb-Zn d e p o s i t s g e n e r a l l y have low co n c e n t r a t i o n s o f minor elements, and low Co/Ni r a t i o s (see F i g u r e 63 ). 3. E x p l o r a t i o n a p p l i c a t i o n s i n the Smithers area From the analyses completed by the w r i t e r and from data i n v e s t i g a t e d by s t a t i s t i c a l methods i n previous chapters, some g e n e r a l i z a t i o n s can be made which might h e l p i n l o c a t i n g m i n e r a l d e p o s i t s . 1) P y r i t e s from massive sulphide d e p o s i t s and porphyry Cu-Mo d e p o s i t s have h i g h Co content (100-2000 ppm) and h i g h x Co/Ni r a t i o s (5-50). Larger porphyry d e p o s i t s i n the area have p y r i t e s w i t h lower Co/Ni r a t i o s (averaging. 5«0). "Porphyry" p y r i t e s g e n e r a l l y have low Pb and Zn contents. 2) Vein-type Pb-Zn-(Ag.Au) d e p o s i t s have p y r i t e s w i t h low conc e n t r a t i o n s of Co and N i and r e l a t i v e l y low Co/Ni r a t i o s (1.0-10.0). Concentrations o f Cu, Pb, and Zn are u s u a l l y h i g h because of contamination by f r a c t u r e f i l l i n g s and m i n e r a l i n c l u s i o n s , but these i n c l u s i o n s themselves may be i n d i c a t i v e of p r o x i m i t y to higher grade m a t e r i a l . 3) P y r i t e of s t r i c t l y syngenetic o r i g i n commonly has low to moderate Co and Ni co n c e n t r a t i o n s and Co/Ni =1.0. 4) Low conc e n t r a t i o n s of a l l minor elements might be i n d i -c a t i v e of low temperature Pb-Zn replacement d e p o s i t s . 165 5) Zonation of minor elements i n p y r i t e away from thermal centers ( f o r example, a t the Molymine b r e c c i a pipe) might be u s e f u l i n p i n p o i n t i n g target., areas. Even i f the p y r i t e s occur w i t h i n v o l c a n i c rocks by " s u l p h i d i z a t i o n " or by hydrothermal d i s s e m i n a t i o n , c o n c e n t r a t i o n s of minor elements could be i n d i c a t i v e of " b l i n d " ore-bodies underneath. 6) P y r i t e i n unmineralized p o r t i o n s of i n t r u s i o n s can c o n t a i n minor elements i n d i c a t i v e of m i n e r a l i z a t i o n nearby (see page 253, appendix IV )• I t should be kept i n mind that these are only g e n e r a l i z a -t i o n s . Comparisons of minor element data should be made on l y between m i n e r a l d e p o s i t s of one type w i t h i n one m e t a l l o g e n e t i c province or sub-province. V I . SUMMARY AND CONCLUSIONS Prom s t u d i e s of n a t u r a l l y o c c u r r i n g and s y n t h e t i c compounds belonging to the p y r i t e and r e l a t e d m i n e r a l groups, i t i s apparent that the f o l l o w i n g elements are commonly found s u b s t i t u t i n g i n the p y r i t e l a t t i c e : (a) c a t i o n s Co, N i , Cu, Au and platinum group elements; (b) anions As, Sb, B i , Se and Te. Other elements which may be present i n oxide or sulphide m i n e r a l i n c l u s i o n s , f l u i d i n c l u s i o n s , f i l m s on i n t e r g r a n u l a r or twi n n i n g s u r f a c e s , or a t s i t e s of i m p e r f e c t i o n s are T i , V, Cr, Mn, Zn, Cd, Hg, Ga, Ge, I n , T l , Sn, Mo, W, Pb, U, and probably many ot h e r s . Elements such as Cu, Mn, and Cr may be present i n "coupled-s u b s t i t u t i o n " w i t h other elements. Diadochic s u b s t i t u t i o n s are o f t e n accompanied by changes i n p h y s i c a l p r o p e r t i e s such as u n i t c e l l l e n g t h , c o l o r , hardness, r e f l e c t i v i t y and a n i s o t r o p y . Minor elements can be d i s t r i b u t e d homogeneously w i t h i n a s i n g l e c r y s t a l , or can e x h i b i t r e g u l a r , i r r e g u l a r o r rhythmic z o n a t i o n . Zonation i s caused by v a r i a t i o n i n p r o p e r t i e s o f o r i g i n a l d e p o s i t i o n a l f l u i d s or by l a t e r meta-somatism. Study of the d i s t r i b u t i o n of minor elements w i t h i n s i n g l e c r y s t a l s i s most d e f i n i t i v e when done w i t h the e l e c t r o n microprobe. A c c e p t a b i l i t y or n o n - a c c e p t a b i l i t y of minor elements i n l a t t i c e p o s i t i o n s can be p a r t i a l l y e x p l a i n e d u s i n g l i g a n d - f i e l d theory and i t s counterpart f o r covalently-bonded m i n e r a l s , molecular o r b i t a l theory. Ease of s u b s t i t u t i o n by elements o f the f i r s t t r a n s i t i o n - e l e m e n t s e r i e s i s promoted by low-spin c o n f i g u r a t i o n i n the e l e c t r o n s and i s i n h i b i t e d by presence of antibonding "e " e l e c t r o n s . This e x p l a i n s the r e l a t i v e absence of T i , V, Cr, and Mn i n the p y r i t e l a t t i c e because i o n s o f these elements are g e n e r a l l y found w i t h h i g h s p i n c o n f i g u r a t i o n . Elements w i t h reasonably well-known l i m i t s of s u b s t i t u t i o n are Co 100$ Se 3$ K i 100$ As 7-8$ Cu 10$ Sb 700 ppm Because Co and N i are the most common minor elements found i n p y r i t e , the geochemistry of these elements i n rocks i s considered b r i e f l y . I n meteorites and u l t r a b a s i c r o c k s absolute contents of Co and N i are h i g h , w i t h Co/Ni r a t i o s averaging 0.10. With i n c r e a s i n g magmatic d i f f e r e n t i a t i o n ( i . e . , i n c r e a s i n g SiO^ content) absolute c o n c e n t r a t i o n s of both Co and N i decrease, but at d i f f e r e n t r a t e s , r e s u l t i n g i n i n c r e a s i n g Co/Ni r a t i o s . Late stage d i f f e r e n -t i a t e s such as granophyres, pegmatites and lamprophyres might be r e l a t i v e l y enriched i n N i (and other f e r r i d e elements) because o f formation of complex ions w i t h v o l a t i l e c o n s t i t u e n t s . I n most "normal" sedimentary r o c k s , Co and N i concentra-. t i o n s are low and Co/Ni r a t i o s are l e s s than 1.0. However, i n sediments c o n t a i n i n g s i g n i f i c a n t amounts of Fe and/or Mn ox i d e s , f o r example deep water oozes, Red Sea metal-rich sediments, i r o n ores and manganese nodules, Co and Ni are concentrated and Co/Ni r a t i o s generally exceed 1.0. Increased concentrations are due to adsorption of Co and Ni by the oxides during deposition and increased Co/Ni r a t i o s are due to p r e f e r e n t i a l adsorption of Co with respect to Ni. Deep-sea sediments have higher Co/Ni r a t i o s than near shore sediments. Unmetamorphosed cupriferous sediments such as the Kupferschieffer shale have normal Co/Ni r a t i o s ; high Co concentrations and Co/Ni r a t i o s i n Rhodesian copper be l t sediments might be due to Co-metasomatism a f t e r deposition. Although mobilization of minor elements (including ore-forming elements) during metamorphism has been proposed by Shaw (1954) and others, whole rock analyses of metamorphic rocks indicate that mobilization, i f possible, occurs only over short distances, unless effected by f u l i d transport. Makrygina, et a l . (1969), and Nickel (1954) show that Co and Ni can be enriched i n "concentrator minerals" (including pyrite) during metamorphism. A computer-oriented s t a t i s t i c a l study of several hundred pyrite analyses gleaned from the l i t e r a t u r e helps support several hypotheses proposed by e a r l i e r workers. When s u f f i c i e n t analyses from one deposit or one genetic type of deposit are av a i l a b l e , i t is'seen that minor-element frequency d i s t r i b u t i o n s are approximately log-normal. Thus, logarithmic transforms should be performed on analyses before s t a t i s t i c a l t e s t s are c a r r i e d out. Co/Ni r a t i o s of syngenetic p y r i t e are r e l a t e d d i r e c t l y to Co/Ni r a t i o s i n adjacent sediments, although Co i s enriched i n the p y r i t e w i t h respect to N i . Syngenetic p y r i t e s from normal sedimentary rock have Co/Ni r a t i o s averaging l e s s than 1.0, whereas hydrothermal p y r i t e s g e n e r a l l y (but not always) have Co/Ni g r e a t e r than 1.0 and v o l c a n i c e x h a l a t i v e p y r i t e s have Co/Ni r a t i o s r anging from 5 to 50. Th i s c o n c l u s i o n i s supported by T-test data. Mean values f o r the three d i s t i n c t types of p y r i t e are g i v e n below. Type Co(ppm) Ni(ppm) Co/Ni Syngenetic ,. 41 65 0.63 V o l c a n i c e x h a l a t i v e 486 56 8.70 Hydrothermal vein-replacement 141 121 1.17 During medium to h i g h grade metamorphism frequency d i s t r i -b utions o f Co and Ni are changed and become more n e a r l y normal. Evidence i s a v a i l a b l e from s e v e r a l sources i n d i c a t i n g Co i s concen-t r a t e d i n p y r i t e d u r i n g h i g h grade metamorphism, r e s u l t i n g i n anomalously h i g h Co/Ni r a t i o s . Upon conversion of p y r i t e to p y r r h o t i t e , Co can be concentrated i n p y r i t e or other new minerals whereas N i i s concentrated i n the p y r r h o t i t e . Co i s concentrated i n hydrothermal p y r i t e s r e l a t i v e to p y r i t e from barren areas. Such i s the case f o r "porphyry" and 170 " v o l c a n i c e x h a l a t i v e " p y r i t e s as w e l l as many v e i n and replacement p y r i t e s . Other elements such as Se, As, Sn, Ag, e t c . might be u s e f u l ' i n d i c a t o r s " but r e l a t i v e l y l i t t l e data i s a v a i l a b l e f o r these elements a t the present. High co n c e n t r a t i o n s of T i , V, Cr, Mn, Sn, Cu, Pb, Zn, e t c . are g e n e r a l l y i n d i c a t i v e o f contamination by sulphide or oxide m i n e r a l s , but i f contamination i s c o n s i s t e n t l y h i g h w i t h i n or adjacent to ore bodies, then even these i m p u r i t i e s could be u s e f u l " i n d i c a t o r s . " Contaminants can g e n e r a l l y be recognized by c a l c u l a t i n g c o r r e l a t i o n c o e f f i c i e n t s f o r each group of an a l y s e s . Common contaminants such as s p h a l e r i t e , c h a l c o p y r i t e , and galena r a r e l y c o n t a i n enough Co or N i to a f f e c t s i g n i f i c a n t l y Co/Ni r a t i o s o f p y r i t e . A b solute c o n c e n t r a t i o n s of Co and N i are r e l a t e d q u a l i t a t i v e l y to major elements contained i n ore d e p o s i t s . I f types o f d e p o s i t s are ranked a c c o r d i n g to co n c e n t r a t i o n s of Co or N i i n contained p y r i t e , the sequence i s from W-Sn-Mo d e p o s i t s through Au and Cu de p o s i t s to Pb-Zn-Ag d e p o s i t s ; a sequence roughly p a r a l l e l i n g that of normal m i n e r a l o g i c a l z o n a t i o n i n many m i n e r a l d i s t r i c t s . High c o n c e n t r a t i o n s of Co and N i i n peg m a t i t i c p y r i t e s might r e s u l t by formation of i o n i c complexes w i t h v o l a t i l e s i n r e s i d u a l f l u i d s . Although few analyses are a v a i l a b l e f o r p y r i t e s from igneous r o c k s , i t appears that the behaviour o f Co and N i i n p y r i t e s from igneous rocks i s s i m i l a r to t h e i r behaviour i n the rocks themselves. 171 F o r t y p y r i t e samples c o l l e c t e d from s e v e r a l d i s t i n c t types of mineral d e p o s i t s i n the Smithers area, B.C. were concentrated and d i s s o l v e d u s i n g techniques devised by the w r i t e r , Mr. A. Bentzen, and Dr. W.K. F l e t c h e r . Minor element analyses were performed f o r Co, N i , Cu, Mn, Pb, and Zn u s i n g atomic a b s o r p t i o n spectrophotometry. Minor element r e l a t i o n s h i p s i n Smithers p y r i t e s were s i m i l a r to those determined by s t a t i s t i c a l treatment of p r e v i o u s l y r e p o r t e d p y r i t e a n alyses. Co and N i co n c e n t r a t i o n s were hi g h e s t i n p y r i t e s from massive s u l p h i d e d e p o s i t s and a b r e c c i a pipe and lowest i n v e i n p y r i t e s . Mn co n c e n t r a t i o n s were low i n a l l samples; Pb, Zn, and Cu were hi g h e s t i n v e i n p y r i t e s where contamination by other s u l p h i d e s could be seen under the microscope. M e t a l l c g e n e t i c province concepts were i l l u s t r a t e d by p l a t t i n g Co/Ni r a t i o means f o r separate d e p o s i t s on l o g - l o g s c a t t e r diagrams. Mean Co/Ni r a t i o •• f o r Dome Mountain d e p o s i t s i s 10.0; t h a t from Grouse Mountain d e p o s i t s i s 30.0. 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Very l i t t l e i n f o r m a t i o n i s a v a i l a b l e concerning the property, but m i n e r a l i z a t i o n i s thought to be " s t r a t i f o r m " i n nature, w i t h s p h a l e r i t e , galena, and p y r i t e present i n s t r o n g l y - f o l d e d sediments of u n i t 5 of the Hazelton Group. R h y o l i t i c flows o v e r l i e the s e d i -ments a t t h i s l o c a l i t y , as i s the case a t Dome Mountain nearby. The deposit was discov e r e d by geochemical methods; development work has i n c l u d e d d e t a i l e d s o i l sampling, g e o l o g i c a l mapping, and ex p l o r a t o r y diamond d r i l l i n g . A specimen of p y r i t e was-provided by Mr. J . F r a s e r , g e o l o g i s t f o r Texas Gulf Sulphur L t d . d u r i n g the summer of 1969. P y r i t e occurs as t i n y subhedral g r a i n s comprising 80 percent o f the specimen; matrix minerals are quartz and s e r i c i t e . No other s u l p h i d e s are present i n the specimen. P y r i t e g r a i n s appear to have repl a c e d o r i g i n a l bedding laminae, thus the de p o s i t may be of replacement o r i g i n r a t h e r than being s t r i c t l y syngenetic. 192 2. Dome Mountain area (Samples BDM 1-6) Dome Mountain is a glaciated knoll with maximum elevation 5750 feet, situated 20 m i l e 3 due east of Smithers. Dome Mountain and adjacent h i l l s form the southern extension of the Babine Mountains. Access to mineral deposits in the Dome Mountain area i s by four-wheel drive vehicle on gravel road from a point on Highway 16, two miles east of Telkwa to Guess Lake, then eight miles of poor d i r t road which i s generally impassable. An alternate route i s via the newly constructed access road which leaves the Babine Lake road at a point 18 miles from Smithers. This road i s also generally impassable. Transportation to the area during the summer of 1969 was principally by helicopter from Smithers. Sulphide-bearing quartz veins were discovered on the mountain prior to 1914, but exploration has been sporadic since that time. Many short adits and shafts and numerous trenches have explored the veins. Topography and vein locations are shown on Figure 70. Claim names have been changed several times, and resolution of geographic locations of veins from published reports is exceedingly d i f f i c u l t . Sample locations are shown on Figure 70. The top of Dome Mountain has been strongly glaciated and much bare rock i s exposed. The mountain top is underlain by greenish-grey tuffs and andesites and maroon argillaceous tuffs. The rocks are strongly sheared, as evidenced by stretched volcanic fragments. According to Carter (1969) the mountain i s a n t i c l i n a l with fold axes and shearing having a north to northwest strike. Strong northeast trending cross-fractures are enhanced by g l a c i a l " p l u c k i n g " of f r a c t u r e b l o c k s . Quartz v e i n s s t r i k e n o r t h w e s t e r l y , p a r a l l e l to shearing. On the c r e s t of the mountain quartz v e i n s are narrow and di s c o n t i n u o u s ; m i n e r a l i z a t i o n was a t l e a s t i n p a r t predeformation, because deformed v e i n s were noted i n s e v e r a l l o c a l i t i e s . Most m i n e r a l i z a t i o n on the c r e s t of the mountain i s present i n a v e i n system which f o l l o w s a narrow r h y o l i t e dyke ( a l s o deformed); m i n e r a l i z a t i o n c o n s i s t s o f minor amounts of p y r i t e , c h a l c o p y r i t e , and hematite. On the northeast f l a n k o f the mountain v e i n s are wider, more continuous, and c o n t a i n s i g n i f i c a n t amounts of p y r i t e , c h a l c o p y r i t e , s p h a l e r i t e , and galena, w i t h minor amounts of t e t r a h e d r i t e . A r s e n o p y r i t e was recorded by B.C. Department of Mines personnel, but none was observed by the w r i t e r . S i x composite samples were c o l l e c t e d from separate v e i n s , shown on the accompanying map (Figu r e 70). Dome Babine Property (Samples BD 1-6) The Dome Babine showings were discovered i n 1914 by Alex Chisholm, who staked the major showing as Free Gold No. 1 c l a i m . The showings are l o c a t e d on the east slope of Dome Mountain approximately 2 m i l e s due east of the mountain c r e s t (see Figure The camp i s approximately 18 miles east-northeast o f Telkwa, but di s t a n c e by road (see previous property d e s c r i p t i o n ) i s 26 m i l e s . L i t t l e e x p l o r a t o r y work was done on the property u n t i l 1932, when Babine Gold Mines L t d . optioned the property. From 1932 to 1935 s t r i p p i n g and tr e n c h i n g were done; a main a d i t was d r i v e n 350 FIGURE 70, Map of Dome Mountain area, near Smithers B.C., showing gold-bearing quartz veins and location of samples BDM 1 - 7 . (Modified from B.C. Min. Mines Ann.Rept. 1922, p. 101.) 195 f e e t to i n t e r s e c t the major v e i n s , w i t h an a d d i t i o n a l 400 f e e t of cross c u t t i n g to explore the v e i n s . S e v e r a l v e r t i c a l s h a f t s i n t e r -s ect the cr o s s c u t s as shown on the accompanying map (Figu r e 71). S e v e r a l quartz v e i n s and quartzose shear zones are present i n "en echelon" arrangement, s t r i k i n g n orth 35°W and i n most places d i p p i n g s t e e p l y to the nor t h e a s t . The v e i n s , v a r y i n g i n width from s e v e r a l inches to 2-=r f e e t , c o n t a i n p y r i t e , s p h a l e r i t e , and galena, w i t h l e s s e r amounts of t e t r a h e d r i t e and c h a l c o p y r i t e . Free gold i s present i n the quartz as w e l l as i n the sulphide m i n e r a l s . Assays of up to 12 oz. gold and 2-3 oz. s i l v e r per ton have been recorded; bulk samples taken from 1932 to 1938 assayed about 2 oz. gold and 2 oz. s i l v e r per ton w i t h approximately 1.5 percent lead and 5 percent z i n c (B.C.M.H., 1938). Further assays by Dome Babine Mines L t d . and other companies have i n d i c a t e d an o v e r a l l average o f 7 o z . gold per t o n . S e v e r a l e x p l o r a t i o n companies examined the property s i n c e 1935 but l i t t l e e x p l o r a t o r y work was done. The property was acquired by Dome Babine Mines L t d . (N.P.L.) i n 1968, and e x p l o r a t o r y work i n c l u d e d ground magnetometer and electromagnetic surveys, geochemical s o i l sampling, g e o l o g i c a l mapping, f u r t h e r t r e n c h i n g , and seven short diamond d r i l l h o l e s . The magnetometer survey and mapping revealed a s m a l l g r a n i t i c stock roughly 500 f e e t wide by a t l e a s t 1500 f e e t long adjacent to the v e i n system. The major v e i n was found to f o l l o w a narrow " f e l s i t e " dyke of the same composition as the i n t r u s i o n . G r a n i t i c nature of the i n t r u s i o n was i n f e r r e d from quartz "eyes" or phenocrysto, although the f i n e - g r a i n e d nature and s e r i c i t i c 196 • •— \ / GRANITE • Oz.GoldDzSilver:;CoppEr ."iLEad%Zirx 3 t o n d u m p _ 2 . 3 Z II.0 3-Z n i l . 2.8 L E G E N O Andesitic voicanics I Quartz vein Stripping 1 {generally sloughed)) Open-cut Shaft Adit •^•N Oz.Gold Oz.SilvefXCopper%Lead%Zinc \ 3 t o n d u m p _ 8 . 3 0 i ? l 5.0 1.3 I.I 6.3 ft'1". Csbber, grade 1, Oz.GoidOzSilver%Coppergteadg2inc of S'ton dump p - — : — — • — : — • — 1 reet. FIGURE 71 , Map of Dome Babine gold p r o s p e c t , east s i d e of Dome Mtn, showing l o c a t i o n of samples BD 1 - 6. (Modified from B.C. M i n i s t e r of Mines Ann. Rept. 1938, p. B18.) 197 a l t e r a t i o n of the material concealed other textures. Diamond d r i l l i n g revealed fresh granite at depth. The i n t r u s i o n has caused p r o p y l i t i c a l t e r a t i o n of adjacent t u f f s , v/ith the formation of much magnetite. L i t t l e hydrothermal a l t e r a t i o n i s present near veins other than bleached "envelopes" up to a foot wide. The quartz veins are believed by the w r i t e r to be genetically related to the g r a n i t i c stock. At least two generations of pyrite are present at the deposit. The f i r s t type i s f i n e l y c r y s t a l l i n e , contains no gold, and i s present only i n the bleached w a l l rock adjacent to veins. The vein pyrite i s coarser, with subhedral c r y s t a l s up to -5- inch diameter, and contains appreciable gold and inclusions of sphalerite, galena, and minor amounts of chalcopyrite. The pyrite i s strongly shattered and i s veined by other sulphides, esp e c i a l l y sphalerite. Sphalerite and pyrite were probably deposited contemporaneously, as microinclusions of pyrite are abundant i n a l l sphalerite from the deposit, and pyrite contains abundant sphalerite inclusions. The sphalerite also contains t e t r a -hedrite and galena inclusions. The following paragenetic sequence i s reported by the Department of Mines and Resources, Ottawa (B.G.M.M., 1938): pyrite -sphalerite - tetrahedrite - chalcopyrite - galena. In the same study gold was observed to occur as i r r e g u l a r grains i n galena and chalcopyrite. Six samples were taken from four major veins and from ore dumps near the shafts. Locations of samples are shown on Figure 71. Each sample taken was composite i n nature, averaging 5-10 pounds to ensure homogeneity of subsequent pyrite concentrates. 198 Fedral*Creek Property (Sample BD 7) The P e d r a l Creek property, o r i g i n a l l y known as the "Forks" group, was staked by G. Hazelton p r i o r to 1922. L i t t l e development work was done because of deep overburden i n the area. In 1922 about 20 claims i n the immediate v i c i n i t y were optioned by T.E. J e f f e r s o n who employed 10-15 men and an assayer to examine and develop the p r o p e r t y (B.C.M.M., 1923). A major v e i n 20-30 f e e t wide was explored by t u n n e l i n g and c o n s i d e r a b l e ore averaging $20 to $30 per ton i n gold and s i l v e r was o u t l i n e d . The v e i n s t r i k e s N30°E and c u t s r e d d i s h andesite probably belonging to the lowermost v o l c a n i c u n i t (4) of the Hazelton Group, near the upper contact w i t h o v e r l y i n g sediments. The " s c h i s t " o f t e n mentioned i n e a r l y r e p o r t s i s probably s t r o n g l y sheared and a l t e r e d a n d e s i t e . I n i t i a l e x p l o r a t i o n gave encouraging r e s u l t s (average 1-8 oz. gold per ton, a c c o r d i n g to Lang, 1943), and Dome Mountain Gold Mining Company was formed by the F e d e r a l Mining and Smelting Company to develop the p r o p e r t y . A s h a f t was sunk to the 100 f o o t l e v e l on the Forks v e i n and e x t e n s i v e d r i l l i n g c a r r i e d out. D i s c o n t i n u i t y of ore r e s u l t e d i n shutdown of e x p l o r a t i o n , although a l a r g e camp had been b u i l t and much equipment assembled. Up u n t i l 1969 the crown-granted cla i m s were s t i l l h e l d by K.J. S p r i n g e r . P o l i s h e d specimens of ore show th a t the most common sul p h i d e s present are p y r i t e , s p h a l e r i t e , c h a l c o p y r i t e and galena. Extensive shearing of v e i n m a t e r i a l i s r e f l e c t e d i n extreme s h a t t e r i n g and rounding of p y r i t e and i n f i l l i n g of i n t e r g r a n u l a r spaces by more p l a s t i c galena and c h a l c o p y r i t e . C h a l c o p y r i t e i s much more common at t h i s property • O r i g i n a l s p e l l i n g on government maps. 1 than at other properties on Dome Mountain; sphalerite i s more iron-rich, and contains abundant chalcopyrite inclusions. Concentration of sulphide minerals by vein shearing has resulted i n "massive sulphide" appearance of some specimens. One composite sample, BDM 7, was obtained from a small dump near the main shaft. Molymine Property (Samples BMH-1-12, BDZ 1-6, BZ 1-5) The property under option by Molymine Explorations Ltd. (N.P.L.) encompasses several distinct types of mineral occurrence. The property i s on the west facing slope of Grouse Mountain above Helen or "Fishpan" Lake near the Pelissier Ranch. A good road leaves the main highway at the top of "Hungry H i l l " 8 miles north of Houston and reaches the camp at 2900 feet elevation. Branch roads from the main camp extend to the separate mineral showings. The property area, known originally as Mineral H i l l , was explored extensively prior to and during 1926; the Venus group was centered on a significant vein, 3 to 1 4 feet wide containing scattered sphalerite, galena, chalcopyrite, pyrite, and silver-bearing tetra-hedrite. The vein was explored by a shaft 66 feet deep and traced for 275 feet by open cuts. The vein strikes N35°W (mag.) and dips 60° easterly. The present camp is situated directly beside the Venus Shaft. Pyrite samples BMH 7 and 7A were obtained from the vein. Detailed mapping by W.M. Sharp (1966-1968), Cominco geologists 200 (1966), A. Sutherland-Brown (1965), and the w r i t e r (1968-1969) have shown a wide v a r i e t y o f igneous i n t r u s i o n s p e n e t r a t i n g h o r n f e l s e d sediments and t u f f s o f the Hazelton Group. The two most important i n t r u s i o n s are a s m a l l a l a s k i t e ( l e u c o g r a n i t e ) body and a l a r g e r p o r p h y r i t i c g r a n i t e stock approximately 2000 f e e t east of the a l a s k i t e body.* The g r a n i t e body has a p l i t i c margins and both i n t r u s i o n s c o n t a i n disseminated p y r i t e and molybdenite, although m i n e r a l i z a t i o n i s sparse i n the g r a n i t e . Compositions of both bodies are l i s t e d belov; f o r comparison (Sutherland-Brown, 1965): M i n e r a l A l a s k i t e Granite Quartz 35$ . 41$ P e r t h i t e ( M i c r o c l i n e ) 20 29 P l a g i o c l a s e 25 (An 38) 27 (An 33+) Muscovite 4 3 Opaques : 1 - . Both rock types are f a i r l y coarse, have rounded quartz g r a i n s and o n l y s l i g h t s e r i c i t i c a l t e r a t i o n . The molybdenite m i n e r a l i z a t i o n was recognized i n the a l a s k i t e i n 1962 by W.D." Yorke-Hardy; the property has s i n c e been examined by Southwest Potash L t d . (1962), and Cominco L t d . (1966). Extensive geochemical s o i l sampling, magnetometer and I.P. surveys, t r e n c h i n g , overburden and diamond d r i l l i n g have f a i l e d to r e v e a l s u f f i c i e n t ore to warrant development although grade i s reported to be 0.12$ M0S2 (Manex personnel, personal comm.). E x p l o r a t i o n work has been done *See Figure 72. 201 «DZ I *>» * BDZ 3 \ X X I DlORITl » BHH 2 *0- • . . BDZ'S •flOMIE- .... -*"* HO&KFLLS * HAP OF DIORITE ZONE S h O t f l K C G L u l C G Y AND  SAMPLE L O C A I l U S S • c a l l 0 2 0 0 400 6 0 0 8 0 0 ( t . Dot*: Dloricc zone ahtfced 1000 f t . of true loc. FIGURE 7 2 . Geologic map of Molymine prospect showing sample l o c a t i o n s . 202 under the d i r e c t i o n of W.M. Sharp, c o n s u l t i n g g e o l o g i s t , and M.J. Beley,. e x p l o r a t i o n manager f o r Manex Mining L t d . (N.P.L.). Other igneous rock types present on the property which are probably u n r e l a t e d to m i n e r a l i z a t i o n are 1) D i o r i t e : a d i o r i t e stock crops out on the upper slopes of Grouse Mountain from e l e v a t i o n 3900' to the top of the mountain. Minor amounts of p y r i t e and c h a l c o p y r i t e are present i n places as very f i n e g r a i n s disseminated through the i n t r u s i o n . . 2) Dykes of monzonitic composition are found s t r i k i n g northward between the a l a s k i t e and g r a n i t e i n t r u s i v e s . The dykes are " d i a b a s i c " t e x t u r e d , a c c o r d i n g to Sutherland-Brown (1965)* "Diabasic t e x t u r e " i s i n t e r -preted to be s i m i l a r to t h a t present i n t r a c h y t o i d porphyry dykes s t r i k i n g northward at the top of the mountain, which continue to the Copper Ridge property s e v e r a l m i l e s to the south. Magnetite i s an abundant accessory m i n e r a l i n each occurrence. . B o r n f e l s i n g of the sediments i s probably due to c o n t a c t -metamorphic e f f e c t of the a c i d i c p l u t o n s . The metamorphism has camouflaged d i f f e r e n c e s between rock types and new b i o t i t e has been created (Sutherland-Brown, 1965). Much of the h o r n f e l s i s s t r o n g l y f r a c t u r e d and veined w i t h quartz, as i s the a l a s k i t e i n t r u s i o n . The m i n e r a l i z e d area, c o n t a i n i n g p y r i t e and molybdenite, i s shovm i n F i g u r e 72. 203 a) B r e c c i a zone (BZ 1-5) During e x p l o r a t i o n f o r molybdenite m i n e r a l i z a t i o n outside of the " a l a s k i t e zone" a body of m i n e r a l i z e d b r e c c i a was discovered near a s m a l l creek roughly 3000 f e e t n o r t h of the a l a s k i t e i n t r u s i o n . O r i g i n a l l y termed a " c r a c k l e b r e c c i a , " the body i s i n t e r p r e t e d by the w r i t e r as a true b r e c c i a "pipe." Dimensions of the b r e c c i a area are not known as overburden i s very t h i c k over much of the area, but diameter i n d i c a t e d by overburden d r i l l i n g i s at l e a s t 1000 f e e t . A l t e r e d h o r n f e l s fragments i n the b r e c c i a are cemented by c o a r s e l y c r y s t a l l i n e m i l k y quartz w i t h o c c a s i o n a l t a b u l a r K-f e l d s p a r c r y s t a l s . Molybdenum m i n e r a l i z a t i o n i s confined to the eastern p a r t of the b r e c c i a t e d area but c h a l c o p y r i t e i s common i n the westernmost trenches w i t h minor amounts of t e t r a h e d r i t e and,very . r a r e l y , s p h a l e r i t e . B r e c c i a fragments are of v a r y i n g compositions and are p a r t i a l l y a l t e r e d to s e r i c i t e . Many fragments c o n t a i n sub-h e d r a l disseminated p y r i t e g r a i n s o l d e r i n paragenesis than p y r i t e from i n t e r s t i t i a l q u a r t z . There appears to be rough m i n e r a l o g i c a l and a l t e r a t i o n zoning i n the b r e c c i a t e d area although l i m i t e d - outcrop makes t h i s d i f f i c u l t to v e r i f y . Genetic a f f i l i a t i o n of the b r e c c i a zone w i t h "porphyry" and v e i n type m i n e r a l i z a t i o n on the property i s considered p o s s i b l e because:-1) Molybdenite i s present both i n the b r e c c i a pipe and igneous i n t r u s i v e s ; 2') K - f e l d s p a r fragments or c r y s t a l s are present i n the b r e c c i a m a t r i x ; 204 3) S p h a l e r i t e and t e t r a h e d r i t e i d e n t i c a l i n appearance are present both i n v e i n s and i n the b r e c c i a pipe; 4) S p a t i a l l y the d i f f e r e n t m i n e r a l occurrences are c l o s e to each other and f r a c t u r e d e n s i t y and o r i e n t a t i o n suggest consanguinity. F i v e samples, BZ 1-5, were taken from the b r e c c i a zone. b) D i o r i t e zone (BDZ 1-6) Ten p y r i t e samples were obtained from s u l p h i d e - b e a r i n g quartz v e i n s at the "Venus" s h a f t and i n the d i o r i t e zone. The v e i n s have a n o r t h w e s t e r l y s t r i k e , w i t h w i d e l y v a r y i n g d i p s . M i n e r a l i z a t i o n i s r a t h e r sparse i n most v e i n s w i t h s c a t t e r e d c l o t s of s p h a l e r i t e , galena, t e t r a h e d r i t e , c h a l c o p y r i t e and p y r i t e i n quartz gangue w i t h minor amounts of cream-colored carbonate. S i l v e r content ( i n t e t r a h e d r i t e ) g e n e r a l l y ranges between 1 and 10 oz. per ton, although assays from the "Venus" v e i n are c o n s i d e r a b l y higher. The v e i n s i n the d i o r i t e are lens-shaped, f r e q u e n t l y l e s s than 10 f e e t i n l e n g t h . ' P y r i t i z a t i o n i n d i o r i t e adjacent to v e i n s i s common and r a r e l y bleached "envelopes" were seen surrounding v e i n s . S e v e r a l s h a f t s and a d i t s seen on the property are probably those reported from the Mickey group (B.C.M.M., 1926, p. A137). Sample l o c a t i o n s are shown on Figure 72. c) Merkeley showing (BMH 1) The "Merkeley" s h a f t , 40 f e e t deep, and f i l l e d w i t h water s i n c e at l e a s t 1926, i s approximately 4000 f e e t due south of the 205 southernmost " D i o r i t e zone" v e i n s (see F i g u r e 72 ). No road extends to t h i s showing, but s i n c e the t r e e cover i s sparse, i t can be reached overland by four-wheel d r i v e v e h i c l e . The s h a f t i s d r i v e n on a r e l a t i v e l y s m a l l pod of c h a l c o p y r i t e , p y r i t e and magnetite that has r e p l a c e d p r o p y l i t i z e d a n d e s i t e s . O r i e n t a t i o n of the pod i s u n c e r t a i n , but major f r a c t u r e s i n the adjacent a n d e s i t e s s t r i k e northward and d i p s t e e p l y to the west, p o s s i b l y p a r a l l e l to a major a i r - p h o t o l i n e a r thought to be a normal f a u l t . I t i s reported that 20 tons of ore, a s s a y i n g 17 percent copper and 6 oz. s i l v e r per ton, were recovered from the showing. S e v e r a l samples of m i n e r a l i z a t i o n were r e t a i n e d f o r p o l i s h e d s e c t i o n study, and one composite p y r i t e sample was c o l l e c t e d f o r a n a l y s i s (Sample BMH 1 ). . s 6. Copper Ridge. Property (Samples BCR 1, 2, 5) The Copper Ridge property, p r e s e n t l y owned by Copper Ridge Mines L t d . , was discovered i n 1914 by Samuel Bush, Louis Schorn, and p a r t n e r s . C a s s i a r Crown Copper Company was formed to develop the property. From 1914 to 1927 development work i n c l u d e d a s h a f t on the Copper Crown c h a l c o p y r i t e showing, two c r o s s c u t a d i t s on the Copper Crown and Ruby zones w i t h connecting d r i f t s , and shallow a d i t s and trenches on the Lakeview and Schorn zones (see Figure 73 )• Development ceased i n 1927 but resumed again i n 1951 when Copper Ridge S i l v e r Zinc Mines L t d . ( c o n t r o l l e d by T r a n s c o n t i n e n t a l Resources Ltd.) was formed. Over 9000 f e e t of diamond d r i l l i n g was done by the company on the f o u r major zones. The property has remained dormant f o r s e v e r a l years. The area was mapped i n 1915 by J.D. MacKenzie of 206 the G.S.C., and i n 1951 by J.M. Black, of the B.C. Department of Mines. A c c e s 3 to the property i s v i a a steep and rough jeep road "which leaves the main highway near the mid-point of "Hungry" H i l l , 16 m i l e s east of Telkwa. Figure 73 shows the geology of the prospect area and sample l o c a t i o n s . Sedimentary rocks belonging to the Hazelton Group cover most of the area and i n c l u d e thinly-bedded to massive t u f f s , sandstones, a r g i l l i t e s , and v o l c a n i c b r e c c i a s . Some members of the sequence c o n t a i n belemnites (Black, "1951). The s e d i -ments g e n e r a l l y d i p s h a l l o w l y southward. Minor f r a c t u r e s i n t h i n n e r beds s t r i k e northwestward and d i p at moderate angles to the southwest. T h e i r o r i e n t a t i o n i s p a r a l l e l to dykes c u t t i n g the sediments. D i o r i t e dykes occur near no. 2 a d i t and near Coppermine Lake. The widest dyke i s about 200 f e e t i n width, although a wider, i r r e g u l a r d i o r i t e mass occurs east of the l a k e . Feldspar porphyry dykes and masses occur south and west of the a d i t s . These bodies are i n t e r m e d i a t e i n compo-s i t i o n , have t r a c h y t o i d t e x t u r e , w i t h p l a g i o c l a s e phenocrysts up to f o u r inches long, and c o n t a i n much magnetite. S i m i l a r dykes have been noted at the Molymine Prospect to the south and at s i m i l a r topographic e l e v a t i o n . Massive sulphide bodies c o n s i s t i n g of s p h a l e r i t e , c h a l c o p y r i t e , and p y r i t e occur i n sheeted v e i n zones, c o n s i s t i n g of numerous l e n s o i d v e i n s ranging i n t h i c k n e s s from one i n c h to s e v e r a l f e e t . Most v e i n s s t r i k e northeastward to eastward, but a few s t r i k e northwestward. Small amounts of q u a r t z - c a l c i t e gangue are observed, although numerous specimens from dumps near the a d i t s have massive and replacement FIGURE 73. Map of Copper Ridge Cu-Zn prospect, on Grouse Mtn. near Houston, B.C., showing l o c a t i o n of samples BCR 1,2, and 5. (Modified from B.C.Min. Mines Ann. Rept. 1926 ) 208 t e x t u r e s . Disseminations of sulphide i n w a l l r o c k are common ( f r e q u e n t l y i n v o l c a n i c b r e c c i a , a c c o r d i n g to Black, 1951). Exami-n a t i o n of s e v e r a l p o l i s h e d s e c t i o n s of s u l p h i d e s showed extensive p o s t - m i n e r a l i z a t i o n s hearing has occurred. P y r i t e and c h a l c o p y r i t e are c l o s e l y a s s o c i a t e d , p a r t i c u l a r l y where shearing has granulated • the p y r i t e and c h a l c o p y r i t e has deformed p l a s t i c a l l y to surround the p y r i t e g r a i n s . Zonation of.masses of .sphalerite was noted i n some cases; from l i g h t c o l o r e d , c h a l c o p y r i t e - f r e e m a t e r i a l i n the c e n t e r to brown i n c l u s i o n - r i c h m a t e r i a l at margins of the masses. The change from c h a l c o p y r i t e - r i c h m i n e r a l i z a t i o n a t the Copper Crown zone to s p h a l e r i t e - r i c h m a t e r i a l at the Ruby zone may r e f l e c t s i m i l a r z o n a t i o n . Average grade f o r Ruby zone m i n e r a l i z a t i o n i s estimated by B l a c k (1951) to be 5 percent combined copper and z i n c , w i t h -g- oz. s i l v e r per ton. Copper-zinc r a t i o s are between 10 : 1 and 20 : 1. An u n o f f i c i a l estimate of ore tonnage i s 250,000 tons, considered uneconomic at the present time. Sample l o c a t i o n s are shown on the accompanying map.(Figure 73). 7. L a s t Chance Prospect (BCH 3) M i n e r a l i z a t i o n was d i s c o v e r e d on the Last Chance claims i n 1935 by J . Oakes and partners (B.C.M.M., 1937, p. C11). The property was then a c c e s s i b l e by wagon road t r a v e r s i n g the northwest slope of Grouse Mountain from the "Low Ranch" near Walcott. A branch road 209 from the Copper Ridge property access road now makes access by four-wheel d r i v e v e h i c l e p o s s i b l e . The property i s now owned by M. Chapman and pa r t n e r s who have done extensive s t r i p p i n g , t r e n c h i n g , and shallow diamond d r i l l i n g on the v e i n s . Greenish a n d e s i t e s near the p o r t a l s t r i k e N70°E and d i p to the southeast. Narrow disco n t i n u o u s quartz v e i n s i n the s t r i p p e d and trenched area, a l s o exposed i n the a d i t , c o n t a i n t e t r a h e d r i t e , p y r i t e , s p h a l e r i t e , and galena i n q u a r t z -carbonate gangue. Assays and l o c a t i o n s are shown on the accompanying map (F i g u r e 74 ). V e i n widths vary from 6 to 15 inc h e s , average s t r i k e i s N51°E w i t h a 45° d i p to the southeast. I n the c e n t r a l open cut the v e i n i s i n t e r r u p t e d , but not d i s p l a c e d , by a narrow b a s i c dyke c o n t a i n i n g a p a t i t e and magnetite. Three samples were taken from the open cuts and dump near the p o r t a l , but only sample BCH 3 from the dump contained s u f f i c i e n t p y r i t e f o r a n a l y s i s . 210 FIGURE 74, Map o f L a s t Chance Ag-Cu p r o s p e c t on t h e n o r t h end o f Grouse Mtn. near Houston, B.C. Sample BCH 3 i s from a s m a l l dump near t h e n o r t h e r n a d i t . (From B.C. M i n . Mines Ann. Rept. 1937. ) 211 APPENDIX I I SAMPLE PREPARATION, ANALYSIS, AND PRECISION CALCULATIONS A. PREPARATION OF SAMPLES I n p y r i t e a n a l y s i s the most time-consuming o p e r a t i o n , but perhaps the most important, i s the p r e p a r a t i o n of pure p y r i t e concentrates. The optimum method o f c o n c e n t r a t i o n depends on the nature o f the p y r i t e , i t s a s s o c i a t e d m i n e r a l s , and t h e i r r e l a t i v e abundances. Concentration and c l e a n i n g methods most commonly encountered i n the l i t e r a t u r e are: 1 ) panning and super-panning, 2) magnetic s e p a r a t i o n , 3) heavy l i q u i d c o n c e n t r a t i o n . * I n i t i a l samples used i n t h i s study were fragments of rocks and v e i n m a t e r i a l ranging i n s i z e from one i n c h to s e v e r a l inches i n diameter. Some of the samples were sawn to remove most of the sul p h i d e contaminants. The samples were crushed i n a s i x i n c h "chipmunk" jaw crusher a t the l a b o r a t o r y of Bondar-Clegg L t d . i n North Vancouver. The crushed m a t e r i a l was panned to concentrate the su l p h i d e s and to wash o f f " f i n e s " - the f r a c t i o n most l i k e l y to be contaminated. Panning a l s o helps remove much of the molybdenite. The d r i e d con-c e n t r a t e s were sieved to i s o l a t e the 10-40 mesh f r a c t i o n - that which i s most amenable to hand-picking under the b i n o c u l a r microscope. When the sulphides were too f i n e l y intergrown f o r e f f e c t i v e hand-212 p i c k i n g the 40-100 mesh f r a c t i o n was e i t h e r : a) preconcentrated by heavy l i q u i d (Broraoform) i n a sepa r a t o r y f u n n e l , o r b) t r e a t e d d i r e c t l y w i t h the magnetic separator. The magnetic separator i s e f f e c t i v e i n removing Fe-bearing m i n e r a l s , c h a l c o p y r i t e , F e - r i c h s p h a l e r i t e , some t e t r a h e d r i t e , and some l i m o n i t e -s t a i n e d q u a r t z . S e v e r a l passes through the separator are necessary f o r e f f e c t i v e s e p a r a t i o n . T h e o r e t i c a l l y , p y r i t e and quartz can be separated m a g n e t i c a l l y , u s i n g reverse t i l t , low slope angle, and maximum a p p l i e d v o l t a g e to the sepa r a t o r . I n p r a c t i c e the method i s r a r e l y e f f e c t i v e - the electromagnetic c o i l s overheat badly and s e p a r a t i o n time i s long. With lower v o l t a g e and experimentation the method w i l l o c c a s i o n a l l y be u s e f u l . T y p i c a l l y , a f t e r magnetic s e p a r a t i o n , the concentrate c o n t a i n s p y r i t e , q u a rtz, and minor amounts of galena and s p h a l e r i t e . Most of the quartz can be removed by s w i r l i n g the concentrate i n a shallow d i s h f i l l e d w i t h water and t a k i n g the l i g h t e r m a t e r i a l from the center w i t h a p i p e t t e (A. Bentzen, personal comm.). Much of the galena and s p h a l e r i t e can be leached out w i t h hot 6M HC1. The s o l u t i o n of PbS and ZnS i s noted by the e v o l u t i o n of H^S. This method removes much of the l i m o n i t e s t a i n i n g on p y r i t e . T h i s step i s probably important s i n c e Mn02 may accompany the l i m o n i t e . Excess quartz can be leached w i t h warm concentrated h y d r o f l u o r i c a c i d . Remaining contaminants may be hand-picked under a b i n o c u l a r microscope. The f i n a l concentrate i s ground to approximately 200 mesh i n an agate mortar and p e s t l e . The "Spex" b a l l - m i l l was considered f o r the g r i n d i n g o p e r a t i o n but much f i n e l y - d i v i d e d p o r c e l a i n i s mixed i n w i t h the p y r i t e , causing c a r r y - o v e r contamination and weighing e r r o r s A flow sheet i l l u s t r a t i n g the c o n c e n t r a t i o n method i s shown i n F i g u r e 75. PRE-ANALYSIS PREPARATION Before the present system of sample s o l u t i o n was developed, a system u s i n g HNO^ - HCl s o l u t i o n was attempted. The method was simple and s o l u t i o n was e f f e c t i v e but Fe and SO^ ions i n s o l u t i o n caused a n a l y t i c a l i n t e r f e r e n c e s and c o r r o s i o n of the spectrophotomete n e b u l i z e r . A method f o r removal of Fe and S from the system was developed by Dr. W.K. F l e t c h e r w i t h the t e c h n i c a l a s s i s t a n c e of Mr. A. Bentzen. i The f i n e l y - g r o u n d sample (25 mg) i s roasted i n a muffle furnace at 550°C f o r at l e a s t two hours to remove the sulphur (550°C i s the optimum temperature determined by e x p e r i m e n t a t i o n ) . A f t e r the f i r s t hour the oxide i s tamped w i t h a g l a s s rod to break the c r u s t and expose any uno x i d i z e d g r a i n s . A f t e r r o a s t i n g the oxide i s d i s s o l v e d i n a few ml of 6M HCl to convert the oxide to c h l o r i d e . The sample i s d r i e d and then d i s s o l v e d i n 6M H C l , and made up to 25 ml i n a v o l u m e t r i c f l a s k ; the d i l u t i o n f a c t o r i s thus 100. The 25 ml s o l u t i o n i s homogenized thoroughly by shaking, and i s t r a n s -f e r r e d to a separatory f u n n e l where i t i s shaken w i t h an equal FIGURE 75. PREPARATION OF PYRITE CONCENTRATES 214 crush hand p i c k 80 mesh inag <-PO <r-sph,cp <-ferromags _^ SiOo <r 40-80 mesh > magnet > ma j . s e 3 /* s w i r l HC1 Y~*SPH leach I—> gn > S i 0 2 etc heavy l i q sep hand p i c k FINAL CONCENTRATE 215 volume of methyl i s o - b u t y l ketone (MIBK). Upon shaking, the Fe i s p a r t i t i o n e d i n t o the MIBK.. The remaining s o l u t i o n i s drained i n t o c l e a n polythene sample b o t t l e s , and i s ready f o r a n a l y s i s . During the present study i t was found that the presence of copper i n the F e C l ^ s o l u t i o n i n h i b i t s the e x t r a c t i o n o f Fe, and double e x t r a c t i o n s were necessary i n some cases. C. ANALYTICAL METHOD Samples were analyzed w i t h the Techtron AA-4 Spectrophotometer bel o n g i n g to the U.B.C. Geochemistry Laboratory, a c c o r d i n g to procedures o u t l i n e d by Dr. W.K. F l e t c h e r (1970). Secondary standards, prepared f r e s h l y from primary standard s o l u t i o n s , were a s p i r a t e d before and a f t e r each group of twenty sample s o l u t i o n s . No c o r r e c t i o n s were necessary f o r background a b s o r p t i o n f o r Co, N i , or Pb. Hand drawn c a l i b r a t i o n curves were used to convert sample absorbances to concentra-t i o n s . Sample d i l u t i o n s were necessary f o r s e v e r a l samples w i t h h i g h c o n c e n t r a t i o n s o f Cu, Pb, and Zn. D. ANALYTICAL'PRECISION A n a l y t i c a l p r e c i s i o n was c a l c u l a t e d from r e p l i c a t e analyses a c c o r d i n g to the method used by G a r r e t t (1969) f o r geochemical samples. P a i r e d p r e c i s i o n t e s t s were performed u s i n g a computer program w r i t t e n by Mr.. L. Fox. Since minor element frequency d i s t r i b u t i o n s are essen-t i a l l y l o g a r i t h m i c a l l y normal, only l o g a r i t h m i c values were used i n the c a l c u l a t i o n s . 216 P r e c i s i o n c a l c u l a t i o n s are based on the formula P = 1.96 X % ^ X 100$ A r where S.D.<u = a n a l y t i c a l standard d e v i a t i o n and Xr = r e p l i c a t e mean. Because p y r i t e s from Smithers and Tchentlo Lake areas were analyzed c o n c u r r e n t l y , r e p l i c a t e samples from both groups were combined, i n the p a i r e d p r e c i s i o n t e s t . R e p l i c a t e analyses are shown i n Table 35 and p a i r e d p r e c i s i o n t e s t data i n Table 36. Data f o r Smithers p y r i t e s alone are presented i n Table 37. O v e r a l l a n a l y t i c a l p r e c i s i o n i s considered reasonable f o r Co, N i , Cu, and Zn, but i s poor f o r Pb and Mn. Much of the a n a l y t i c a l e r r o r f o r Cu, Pb, Zn, and p o s s i b l y Mn i s caused by the presence of m i n e r a l i n c l u s i o n s i n the p y r i t e ; p r e c i s i o n could be improved by homogenization of the samples by f i n e r g r i n d i n g . In a d d i t i o n , s e v e r a l of the p y r i t e concentrates were hand-picked and leached v/ith HCl p r i o r to r e p e t i t i o n of analyses i n an attempt to reduce the contamination l e v e l s f o r Cu, Pb, and- Zn. Thus, much of the " a n a l y t i c a l " e r r o r i s i n f a c t "sampling e r r o r . " C o r r e l a t i o n c o e f f i c i e n t s c a l c u l a t e d f o r the Smithers samples show that Co and N i are not s i g n i f i c a n t l y a f f e c t e d by the presence of s p h a l e r i t e , galena, or c h a l c o p y r i t e contamination. P r e c i s i o n values f o r Ni and Mn are accentuated by the low c o n c e n t r a t i o n s of these two elements i n the samples s t u d i e d . P a r t of the a n a l y t i c a l e r r o r may be caused by s m a l l changes i n sample weights a f t e r "tamping" (necessary to ensure complete r o a s t i n g ) d u r i n g the r o a s t i n g procedure p r i o r to p r e p a r a t i o n of the sample s o l u t i o n s . Sample Co I i i " ' Mn' Cu Pb Zn BDM L 90. G 5 . 0 2.0 5 780 .0 28 .0 11.0' BDM IR 8 7.0 . 4. 0 5. 0" 2 67 5.0 1.0 . . 20.0 BDM 2 4 5.0 1.3 4.0 17600.0 745.0 2 40.0 BDM 2R 6 3.0 1.0 10.0 2675.0 345.0- 1 59.0 BDM 3 120.0 . - 10. 0 13.0 34 2C0.0 5. 0 197.0 BDM 3R 6 8.0 . 10 .0 22 .0 3 900 .0 5.0 294.0 BDM 5 75.0 5.0 4. 0 547. 0 15.0 88.0 BDM 5R 4 5.0 .. 6 .0 .. .... 5.0. .408.0 14.0 92. 0 BTG 1 1.0 1.0 11.0 42.0 5.0 187.0 BTG IR 1.0 1.0 8. 0 35. 0 1 .0 13 7.0 BMH 10A 16 5.0 . 1.0 2.0 '308.0 1.0 12.0 BMH 10AR 165.0 2.0 3.0 2G8 .0 1.0 25.0 BDZ 1 25 5. 0 1.0 13. C 2800.0 6 645.0 1.0 BDZ IR 250.0 . 1.0 . 3.0 590 .0 5140.0 1.0 BDZ 6 "34 5.0 2 5. 0 13.0 3 5 30.0 860 . 0 3900.0 BDZ 6R 300 .0 12.0 66.0 2200. 0 215. 0 167G.0 BZ 1 14 0 8.0 45 .0 12 .0 267.0 10.0 • 43.0 BZ IR 1 5 0 8 . 0 4 3.0 1 1. 0 130. 0 5 .0 54. 0 P8 1 648.0 10. J 8 .0 214. 0 1.0 . 2.0 P8 2 66 6. 0 ; 17. J . '..__8. 0. ..115.0 -. 1.0 2.0 P8A 1 1250.0 10.0 • 2.0 2 84.0 1. 0 1.0 P8A 2 12 5 0.0 10.0 3.0 154.0 1.0 1.0 P12 1 <?R9,0 21.0 1 . 0 490..0 1 . 0 30.0 P12 2 1012 .0. 23.3 2.0 356. 0 1.0 11.0 P12A1 621 .0 •67 .0 40 .0 287.0 1.0 6.0 P12A2 6 3 6.0.. 62.0 . _:40. 0 .. .193.0 . . 1.0 : 7.0 P15 1 6 14.0 42.0 1.0 1220.0 1.0 6.0 P15 2 625.0 4 6. ) 3.0 S80 .0 1 .0 6.0 P15A1 70 5. 0 44. 0 1.0 84. 0 1.0 1.0 P15A2 716.0 42 .0 1 .0 44 .0 1.0 1.0 P20 1 795.0 17. 0 6. 0 5 86.0 , 1.0 7.0 P20 2 773.0 . 17 .0 6.0 . ,284.0 1.0 . . 4. 0 P20A1 _275.0 3 3.0 3.0 708 .0 1.0 7.0 P20A2 27 3.0 3 3. 0 6. 0 595. 0 1.0 8.0 P25 1 1640.0 4.0 2.0 261 .0 1.0 2. 0 P25 2 16 3 0.0 4. 3 • 3 . 0 191.0 1 .0 2.0 P25A1 289.0 17. 3 3.0 10 7. 0 1 . 0 l.Q P25A2 . 2 6 3.0 17.0 2.0 7 5.0 1.0 1 .0 TABLE 35. R e p l i c a t e analyses - Smithers and Tchentlo Lake p y r i t e s |NAMF 1 ANALYTICAL I ANALYTIC ALTANALYT ICALl R EPL I CAT E I REPLICATE) DATA I DATA | _1_YA£1A mc.E_l_.SIQ ______!.£ £££! S l _ _ l _____ L _£__ 1--M1A----1--I.0-D-- __1 ICO |' " • O.OOl 0.051 4.101 45.951 ; 2.421 ~ ~ 0.571" 6.75| |NI I 0.011' 0.C8I 16. 831 18.651 0.98| 0.351 0.. 59 | | MN | 0.151 0.221 56.311 14.551 0. 77| 0.211 0.461 |CU I 0. 071 0 .26| 19.361 48 .61] 2.56) ' '0.421 C. 64 J ) P R | 0.081 0. 291 97. 53] 11.131 C.59| 1.19| 1.09] |Z___1_ __12l 22_251 21^2Ql 1^121 £__2l________2_l TABLE 36. P a i r e d p r e c i s i o n t e s t data f o r combined Smithers and Tchentlo l a k e p y r i t e s . Sample Co N i ' ' ' 'Mn' Cu Pb Zn BDM 1 90. 0 5.0 2. 0 5 7 8 0.0 2 8.0 . . 11.0 BDM IR 8 7.0 .. .. 4.0 .... 5 .0 2 67 5 .0 . 1.0 20.0 BDM 2 45. 0 1.0 4. 0 17600.0 745.0 2 40.0 BDM 2R* 63.0 1 .0 10.0 2675.0 345. 0 159. 0 BDM 3 120.0 10.0 13.0 34 200 .0 5.0 197.0 BDM 3R* 8 8.0 10. 0 2 2.0 8SC0.0 5.0 294.0 BDM 5 7 5.0 5.0 4.0 547.0 15.0 88. 0 BDM 5R .45.0. 6.0 ... . . 5.0 408.0 3.4 .0 92.0 BTG 1 1.0 1.0 11.0 42.0 5. C 18.7. 0 BTG IR 1 .0 1 .0 • 8 .0 35.0 1.0 137.0 BMH 10A ; 16 5.0 1.0 2.0 2 08 .0 1 . 0 12.0 BMH 10AR 165.0 2.0 . 3.0 2C8. 0 1.0 2 5. 0 BDZ 1 25 5 .0 2 50.0 1 .0 13 .0 2800 .0 6645.0 1.0 BDZ IR* 1.0 . 3.0 590. 0 . 5140.0 1 . C BDZ 6 ' 3 4 5.0 25.0 13.0 8 530.0 86 0.0 3900.0 BDZ 6R* 300.0 12.0 66.0 2200 .0 215.0 1670 .0 BZ 1 140 8.0 45. ) 12.0 267. 0 1 C. 0 4 3. 0 BZ IR 1. 5 G 8 . C 43 .0 11.0 130 .0 5.0 54.0 i n d i c a t e s sample hand-picked or leached p r i o r to r e - a n a l y s i s . I| NAME | ANAL YTIC ll _l_y_ A R I A N I . ;ico :l NI ;| MN )CU ;| PB AL I ANALYTICAL I ANALYTICAL I RE: PL I C AT F: I REPLICATE! DATA | ! DATA |; £ _ i _ S i n . J 0 £ ^ _ l - £ R E C I i l £ N l SUBS i M A N l_^Mlii^££-l-SILL ^ D£M A-l C.C7| 7.30 1 17.61) 1.96| 0.75 1 0.86 1 0.1 11 35. 54 1 5. 39 1 0.601 0.33 I 0.58 1 C.27| 57. 34| 8. 461 0.941 0. 191 0. 43 1 0.34| 23. 73 1 25.501 2.83 | 0.59J 0.77|' 0.42|~ 67.121 31.131 1.24| 1.771 • 1.331 16^.421 i ^ 8 2 l 0 A 8 0 l ; 0*901 01 I Oil 07 | 12 1 18| Q 2 l _ _ C U I S I 1 6 ^ 8 1 TABLE 37. R e p l i c a t e analyses and p a i r e d p r e c i s i o n t e s t data f o r Smithers p y r i t e s . 220 Despite the poor a n a l y t i c a l p r e c i s i o n f o r s e v e r a l elements, the p r e c i s i o n f o r Co and Ni i s considered adequate f o r the use of analyses f o r these elements i n the present study. Analyses f o r a l l samples are l i s t e d i n Table 30. APPENDIX I I I EXPLANATION OF DATA FILING SYSTEM I n f o r m a t i o n f o r each d e p o s i t i s f i l e d on computer c a r d s ; d a t a i s a r r a n g e d as f o l l o w s : CARD 1 : COLUMNS 1 - 2 5 26-30 31-36 37-42 43-48 49-50 51-54 55-58 59-80 CARD 2: INFORMATION Ge o g r a p h i c l o c a t i o n o f samples Type o f d e p o s i t Major m e t a l s i n d e p o s i t Igneous a f f i l i a t i o n s of d e p o s i t Types o f w a l l - r o c k ( t w o t y p e s c a n be e n t e r e d , w i t h t h r e e columns f o r each t y p e Degree o f metamorphism ( p o s t - m i n e r a l ) Age o f d e p o s i t , i f known Number of samples ( p r e f i x e d by " C " where v a l u e s a r e averages o f s e v e r a l samples) Comments, where needed B r i e f d e s c r i p t i o n o f r e f e r e n c e from w h i c h sample a n a l y s e s a r e ta k e n Two c a r d s a r e used f o r s t o r a g e o f a n a l y t i c a l d a t a f o r each sample. On each c a r d t h e f i r s t f i f t e e n columns a r e r e s e r v e d f o r sample name and number. Card number (1 o r 2) i s e n t e r e d i n column s i x t e e n . A n a l y s e s a r e e n t e r e d as p a r t s p e r m i l l i o n (format F5.0) w i t h f i v e spaces f o r each element. Elements a r e a r r a n g e d a s f o l l -ows; 'CARD 1: Co,Ni,Mn,Ti,V,Cr,Mo,Sn,Cu,Pb,Zn,Ag,Au. CARD 2: As,Sb,Bi,Se.Te,In,Ga,Ge,Tl,Cd,Hg,W. A l p h a b e t i c codes used i n t h e f i l i n g system a r e e x p l a i n e d below: TYPES OF DEPOSIT SYNG SEDX VOLCX DISSM PORPH MAG PEG DESCRIPTION Sedimentary p y r i t e o f s t r i c t l y s y n g e n e t i c o r a u t h i g e n i c o r i g i n P y r i t e accompanying m i n e r a l d e p o s i t s i n beds o r l e n s e s o f e x h a l a t i v e o r i g i n . E n c l o s i n g s t r a t a a r e se d i m e n t a r y P y r i t e o f v o l c a n i c e x h a l a t i v e o r i g i n D i s s e m i n a t e d throughout igneous r o c k s D e p o s i t s o f low grade , m i n e r a l i z a t i o n p r e s e n t as d i s s e m i n a t i o n s o r stoc k w o r k s , s p a t i a l l y a s s o c i a t e d w i t h p l u t o n i c i g n e o u s r o c k s D e p o s i t s o f magmatic o r i g i n P e g m a t i t i c d e p o s i t s PYMET Pyrometasomatic d e p o s i t s HYDR Hydrothermal r e p l a c e m e n t d e p o s i t s HYDV Hyd r o t h e r m a l v e i n d e p o s i t s MISSV " M i s s i s s i p p i V a l l e y " type Pb-Zn d e p o s i t s SECND P y r i t e o f s econdary o r i g i n ( a f t e r P y r r -h o t i t e , e . g . N a i r n e p y r i t e d e p o s i t , S o u t h A u s t r a l i a . ) IGNEOUS AFFILIATIONS ACT) A c i d i c c o m p o s i t i o n INT I n t e r m e d i a t e c o m p o s i t i o n BAS B a s i c c o m p o s i t i o n WALL ROCKS GRN G r a n i t e LST L i m e s t o n e GRD G r a n o d i o r i t e DOL D o l o m i t e QMZ Q u a r t z monzonite SST Sandstone ALK A l k a l i n e i n t r u s i v e SHL S h a l e SYT S y e n i t e SLT S i l t s t o n e GBR Gabbro QZT Q u a r t z i t e ANO A n o r t h o s i t e TFF T u f f PRD P e r i d o t i t e SED Sedimentary(Urispec) VLC ^ V o l c a n i c ( u n s p e c i f i e d ) MET Metamorphic ( u n s p e c i f i e d ) SCH S c h i s t PHL P h y l l i t e METAMORPHIC GRADE HI H i g h grade MD Medium grade LO Low grade AGE CAMB, CRET e t c . , r e s t r i c t e d to g e o l o g i c p e r i o d s . The a l p h a b e t i c code c o u l d be e a s i l y c o n v e r t e d to a numeric code f o r more complex computer-based s t u d i e s . F o r t h e computer o p e r a t i o n s used i n the p r e s e n t s t u d y , c a r d s were h a n d - s o r t e d . APPENDIX IV A REVIEW OF APPLICATIONS OF MINOR-ELEMENT STUDIES TO ' GEOLOGY OF MINERAL DEPOSITS One of the main reasons f o r s t u d y i n g the minor-element content of su l p h i d e s i s to determine whether minor element r e l a -t i o n s h i p s can be used to a i d e x p l o r a t i o n f o r m i n e r a l d e p o s i t s . For minor element s t u d i e s to be u s e f u l a) C h a r a c t e r i s t i c minor elements must be present ( i n d i c a t o r elements), ' ' b) C h a r a c t e r i s t i c c o n c e n t r a t i o n s of elements must be present, or o) C h a r a c t e r i s t i c inter-element r e l a t i o n s h i p s o r g r a d i e n t s of element c o n c e n t r a t i o n s must occur (Zo n a t i o n ) . These c r i t e r i a may be a p p l i e d to a s i n g l e m i n e r a l d e p o s i t , a group of d e p o s i t s , o r to d e f i n i t i o n of broad geographical areas -met a l l o g e n i c p r o v i n c e s . I n known m i n e r a l d e p o s i t s , minor element s t u d i e s may be u s e f u l i n d e f i n i n g the d i s t r i b u t i o n o f b e n e f i c i a l i m p u r i t i e s (such as Au, Ag, i n "porphyry" d e p o s i t s ) , or of " a n t a g o n i s t i c " i m p u r i t i e s (such as S and P i n i r o n ore d e p o s i t s , or As i n base metal d e p o s i t s ) . \ 224 I. METALLOGENETIC PROVINCES M e t a l l o g e n e t i c provinces are geographical areas c h a r a c t e r i z e d by anomalous c o n c e n t r a t i o n s of s p e c i f i c metals concentrated i n m i n e r a l d e p o s i t s . The o r i g i n of m e t a l l o g e n e t i c provinces i s u n c e r t a i n ; they c o u l d a r i s e from inhomogeneities i n metal d i s t r i b u t i o n i n c r u s t or mantle, or by c o n c e n t r a t i o n of elements from a homogeneous source by s p e c i f i c combinations of g e o l o g i c a l events w i t h i n a g i v e n area. Burnham (1959) has demonstrated that these provinces can be d e f i n e d by minor element assemblages i n common s u l p h i d e s , h i g h con-c e n t r a t i o n s of minor elements correspond w i t h b e l t s c o n t a i n i n g major m i n e r a l d e p o s i t s . Perhaps the best example of a m e t a l l o g e n e t i c province i n western Canada i s the " t i n b e l t " of n o r t h e r n B r i t i s h Columbia and the Yukon T e r r i t o r y , Anomalous c o n c e n t r a t i o n s o f t i n have been found i n s p h a l e r i t e and gold from t h i s area (Warren and Thompson, 1 9 4 1 ) . . . ' • W i t h i n one mining d i s t r i c t , a s p e c i f i c metal may be concen-t r a t e d i n m i n e r a l d e p o s i t s r e g a r d l e s s of deposit type, age, or a s s o c i a t e d w a l l - r o c k (as i n the area s t u d i e d by Burnham). On the other hand, s e v e r a l m i n e r a l d e p o s i t s w i t h i n a s p e c i f i c mining d i s t r i c t may each have a s p e c i f i c assemblage or c o n c e n t r a t i o n of minor elements. The best example i s the C e n t r a l mining d i s t r i c t (Rose, 1970) i n which c h a l c o p y r i t e s from d i f f e r e n t d e p o s i t s can be d i s t i n g u i s h e d by t h e i r I n and Sn c o n c e n t r a t i o n s (see F i g u r e s 76 and 77 ). Other elements, such as Co and N i are u s e f u l i n c h a r a c t e r i z i n g yMine or pros p e c t , 1 m i l e 3 / v? 2 Y i 1 ' v\ '*/•••* / V L \ 5 I v V / v v /."TV-. y / *-\ 1 / • • / 'XJJ .• FIGURE 76, Stocks, mines and t r a c e element groupings of c h a l c o p y r i t e and s p h a l e r i t e . C e n t r a l mining d i s t r i c t , New Mexico. 1. Santa R i t a stock - porphyry Cu and t a c t i t e 2. Hanover F i e r r o stock - t a c t i t e Cu-Fe and v e i n Cu o r e s . 3. t a c t i t e Cu ore 4. Zn and Pb-Zn ores i n t a c t i t e and v e i n s 5. t a c t i t e Zn ores (modified from Rose, 1970), 100 10 c P. - A A 1 / y ' 3 V , " n D ° o \ so — \ / \ / '\ bo 1 i .i i i o o o i . i A I 11 i n n i p p i I i 11 10 ppm. Sn 100 FIGURE 77. D i s t i n c t i o n of c h a l c o p y r i t e of the C e n t r a l d i s t r i c t based on Sn and In content. Dashed l i n e s i n d i c a t e c o n c e n t r a t i o n ranges w i t h i n which most samples of a group f a l l . (From Rose, 1970) 226 each d e p o s i t . D i f f e r e n c e s i n c o n c e n t r a t i o n of elements a r i s e , i n t h i s example, from d i f f e r e n t i n t r u s i v e bodies w i t h which each d e p o s i t i s a s s o c i a t e d . One of the most e n l i g h t e n i n g s t u d i e s i n the past few years r e l a t i n g minor elements i n p y r i t e to m e t a l l o g e n e t i c provinces has been th a t of L o f t u s - H i l l s and Solomon (1968). The authors s t u d i e d Co and N i co n c e n t r a t i o n s i n p y r i t e from s e v e r a l d i f f e r e n t g e n e t i c types of de p o s i t s i n Tasmania and p l o t t e d the r e s u l t s on s c a t t e r diagrams w i t h a r i t h m e t i c s c a l e . The present w r i t e r has r e p l o t t e d the data on s i m i l a r diagrams, but w i t h l o g a r i t h m i c s c a l e to make minor element r e l a t i o n s h i p s c l e a r e r . An out s t a n d i n g r e l a t i o n s h i p v i s i b l e on the diagrams i s the extremely low and s i m i l a r Co and N i con c e n t r a t i o n s i i i p y r i t e s from Rosebery Pb-Zn r i c h sediments, from d i s s e m i n a t i o n s i n g r a n i t e s , and from Sn and Pb-Zn v e i n d e p o s i t s (see F i g u r e 78 ). The p y r i t e s from v e i n s and g r a n i t e s are probably g e n e t i c a l l y r e l a t e d , both o r i g i n a t i n g from Devonian-Carboniferous magmatic events. The m e t a l l o g e n e t i c province i n t h i s case r e s u l t s from s i m i l a r provenance of a c i d i c i n t r u s i v e s . Deposits i n or asso-c i a t e d w i t h Cambrian Mt. Read v o l c a n i c s have p y r i t e s w i t h much hi g h e r Co and N i content (see Fi g u r e 7 8 ) . S i m i l a r methods have been used to study groups o f p y r i t e analyses from other m e t a l l o g e n e t i c p r o v i n c e s * a) Czechoslovakian p y r i t e d e p o s i t s As demonstrated by Cambel and Jarkovsky (1966), the p y r i t e s 228 from syngenetic d e p o s i t s w i t h i n the same grade of r e g i o n a l meta-morphism have s i m i l a r minor element contents. The e f f e c t s of meta-morphism have a l r e a d y been d i s c u s s e d . b) Smithers area. B.C. Study o f Co and Ni i n p y r i t e s from m i n e r a l d e p o s i t s i n the Smithers area has shown that p y r i t e from "Dome Mountain v e i n d e p o s i t s c o n t a i n s s i g n i f i c a n t l y l e s s c o b a l t , and has lower mean Co/Ni r a t i o than p y r i t e from s i m i l a r v e i n s on Grouse Mountain, 25 m i l e s to the south--.(see F i g u r e 67 )• In the Smithers r e g i o n p y r i t e i s c h a r a c t e r i z e d by low N i content, but d i f f e r e n t i a t i o n of the two s m a l l e r m e t a l l o -g e n e t i c areas i s on the b a s i s of Co co n c e n t r a t i o n s and Co/Ni r a t i o s . c) Slocan area. B.C. P y r i t e analyses from the Slocan and Slocan C i t y mining camps i n the Kootenay d i s t r i c t of B.C. were compared by T - t e s t . The t e s t showed mean contents o f Co, T i , Cr, Cu, Zn, and As are s t a t i s t i c a l l y the same f o r both camps. Only Mn and Sn are s i g n i f i c a n t l y d i f f e r e n t , and c o n s i d e r i n g the low co n c e n t r a t i o n s and hig h standard d e v i a t i o n s o f these elements, the d i f f e r e n c e s could be a r e s u l t o f contamination. T - t e s t data are shown i n ;Table 38. S i m i l a r i t i e s i n mineralogy, s t r u c t u r e , and minor element c o n c e n t r a t i o n s of the d e p o s i t s ( S i n c l a i r , 1967) i n d i c a t e the two mining camps are i n the same m e t a l l o g e n e t i c p r o v i n c e . TABLE 38 MINOR ELEMENT- DATA - SLOCAN AND SLOCAN CITY PYRITES Element Slocan P y r i t e Slocan C i t y P y r i t e Mean S.D.(log.) Mean S.D.(log.) Co 5 ppm 1.1038 3 ppm .6812 N i 7 1.0086 0 -Mn 17 1.0792 2 .9868 T i 39 .7243 77 .4472 Cr 7 .4150 8 .3802 Sn 48 .9823 9 .2304 Cu 1275 .9191 1272 .6128 Zn 155 1.5977 170 1.9159 As 196 1.8169 63 1.8182 Co/Ni .71 3 T-test Data Element T-Value D.F. Co v s . Co -0.552 35 Mn v s . Mn -2.503* 32 T i v s . T i 1.538 35 Cr v s . Cr 0.518 33 Sn v s . Sn -3.446* 24 Cu v s . Cu 0.211 35 Zn v s . Zn -0.847 26 As v s . As -0.391 30 * s i g n i f i c a n t a t 95$ l e v e l of confidence 230 d) New Brunswick Pb-Zn-Cu d e p o s i t s P y r i t e from v e i n and v o l c a n i c - e x h a l a t i v e Pb-Zn-Cu d e p o s i t s i n New Brunswick have been i n v e s t i g a t e d by Sutherland (1967). F u r t h e r s t a t i s t i c a l t e s t s by the present w r i t e r "-have shown s i g n i f i c a n t d i f f e r e n c e s between the two types of p y r i t e . Means, standard d e v i a -t i o n s and T-test values f o r elements which d i f f e r are shown on the f o l l o w i n g page. Elements which have h i g h e r c o n c e n t r a t i o n s i n v e i n p y r i t e are N i and Sn; t h e i r h i g her c o n c e n t r a t i o n s may be due to g e n e t i c a s s o c i a t i o n of the v e i n s w i t h g r a n i t e s of Devonian age. The v o l c a n i c - e x h a l a t i v e p y r i t e c o n t a i n s h i g h e r c o n c e n t r a t i o n s of Zn, As, B i (because of extremely f i n e - g r a i n e d t e x t u r e of the ores, l e a d i n g to d i f f i c u l t y i n s e p a r a t i o n of p y r i t e s ) and Se, w i t h higher Co/Ni r a t i o s . The two l a t t e r d i f f e r e n c e s may be caused by g e n e t i c a s s o c i a t i o n of d e p o s i t s w i t h v o l c a n i c r o c k s , as i s p o s t u l a t e d by Anderson (1969) and L o f t u s - H i l l s and Solomon (1968). I n d i s c u s s i o n o f m e t a l l o g e n e t i c p r o v i n c e s , i t i s probably wrong to compare p y r i t e s from d i f f e r e n t g e n e t i c types of d e p o s i t , even though the d e p o s i t s are i n the same geographic area. Other geographic areas w i t h c h a r a c t e r i s t i c m i n e r a l d e p o s i t s , such as the Rooiberg area Sn lodes, c o n t a i n p y r i t e w i t h minor element co n c e n t r a t i o n s that v a r y c o n s i d e r a b l y between d i f f e r e n t d e p o s i t s . Thus, f a c t o r s other than m e t a l l o g e n e t i c province a f f e c t minor element r e l a t i o n s h i p s i n p y r i t e . TABLE 39 NEW BRUNSWICK VEIN AND EXHALATIVE PYRITE Element Ve i n P y r i t e V o le. Ex. P y r i t e Mean S.D. Mean S.D. N i 115 ppm 3.0 38 ppm 2.2 Sn 37 1.5 15 2.6 Zn 1158 3.7 3570 3.0 As 292 4.4 1660 5.9 B i 8 6.3 98 1.4 Se 1,0 1.7 4 3.0 Co/Ni 4.6 2.3 17.0 2.7 T-Test Data Element T-Value D.F. T-Prob. P-Prob. Co vs. Co -0.462 12 0.655 0.020 NI v s . Ni 2.617* 16 0.018 0.369 Mn vs . Mn -0.682 12 0.5U 0.096 T i vs. T i -1.214 17 0.240 0.665 V v s . V -0.074 17 0.899 0.871 Cr v s . Cr 0.0 17 1.000 0.857 Mo v s . Mo 1.812 16 0.086 0.615 Sn vs. Sn -4.059* 10 0.002 0.013 Cu v s . Cu -2.144 16 0.046 0.306 Pb vs. Pb -0.498 17 0.630 0.616 Zn v s . Zn -2.231* 17 0.038 0.662 Ag v s . Ag -0.041 17 0.919 0.737 As vs. As -2.311* 16 0.033 0.585 Sb v s . Sb -0.847 12 0.418 0.116 B i vs. B i -4.268* 10 0.002 0.000 Se v s . Se -2.742* 11 0.019 0.032 I n vs. In -0.495 16 0.632 0.665 Ga vs. Ga -0.000 17 0.951 0.821 Cd v s . Cd 0.0 17 1.000 0.429 Co/Ni v s . Co/Ni -3.159* 16 0.006 0.611 • S i g n i f i c a n t value a t 957° l e v e l of confidence ZONATION THEORY M i n e r a l o g i c zoning has been w e l l e s t a b l i s h e d a t Bingham, Utah; B u t t e , Montana; the Cor n i s h t i n l o d e s , England; and many-other l o c a l i t i e s . Zonation o f minor elements i s a l s o w e l l documented; examples are given below. The reasons f o r such zoning have not been completely c l a r i f i e d , but thermal g r a d i e n t s are the most commonly c i t e d cause. Gradients i n ^ S a c t i v i t y a r e thought to a f f e c t zoning a t Butte ( S a l e s , i n Park, 1955). Other f a c t o r s which probably i n f l u e n c e z o n a t i o n o f elements are ( l ) p ressure, (2) c o n c e n t r a t i o n of m i n e r a l i z i n g s o l u t i o n s , (3) r e l a t i v e c o n c e n t r a t i o n s o f elements, (4) r e a c t i o n s w i t h w a l l - r o c k , (5) s o l u b i l i t y o f chemical complexes, (6) r e a c t i o n s w i t h i n the i n i t i a l s o l u t i o n . The f i r s t f o u r f a c t o r s probably a f f e c t minor element p a r t i t i o n c o e f f i c i e n t s ( M c l n t y r e , 1963) , although temperature i s probably the major i n f l u e n c e (Bethke and Barton, 1971; see F i g u r e 99 ). Ovchinnikov (1967) b e l i e v e s that low m o b i l i t y of minor elements (because o f t h e i r low concentra-t i o n s ) causes t h e i r r e g u l a r l o g a r i t h m i c decrease outward from a f l u i d source, i n accordance w i t h laws of d i f f u s i o n . He a l s o p o s t u l a t e s t h i s mechanism f o r the lognormal d i s t r i b u t i o n p a t t e r n s of minor elements i n ore bodies; although the coincidence of lognormal d i s t r i b u t i o n and c o n c e n t r a t i o n g r a d i e n t s does not always occur, and may even be r a r e . Barnes (1962) has shown tha t r e l a t i v e s t a b i l i t y of i o n complexes g e n e r a l l y f o l l o w the order Hg-Cd-Pb-Cu-Zn-Sn-Ni-Fe-Co-Mn ( i n order of de c r e a s i n g s t a b i l i t y ) , which f i t s most m i n e r a l o g i c zoning sequences reasonably 233 v e i l . V a r i a t i o n s from t h i s p a t t e r n could be caused by; 1) V a r i a t i o n s i n abundance i n o r i g i n a l s o l u t i o n s 2) D e v i a t i o n s from normal i o n i c c o o r d i n a t i o n 3) Temperature f l u c t u a t i o n s , e t c . These d e v i a t i o n s w i l l be r e f l e c t e d i n minor element contents as w e l l . Rose (1970) i n h i s d i s c u s s i o n of minor element z o n a t i o n a t the Santa R i t a s t o c k , concludes that major f a c t o r s i n v o l v e d were: 1) Complex i o n formation 2) S o l i d - l i q U i d phase r e l a t i o n s h i p s 3) Subordinate e f f e c t s of temperature The e f f e c t s o f temperature may be more important than i s g e n e r a l l y considered, and the p a r t i t i o n c o e f f i c i e n t between c o e x i s t i n g s u l p h i d e m i n e r a l s ( a l s o temperature dependent) must s u r e l y be a major f a c t o r i n the d i s t r i b u t i o n o f minor elements w i t h i n one m i n e r a l s p e c i e s . A. LATERAL ZONATION OF MINOR1 ELEMENTS Numerous examples of zonation of minor elements have been documented i n recent l i t e r a t u r e . Most zon a l p a t t e r n s are centered on igneous i n t r u s i v e s . 1. Cornwall-Devon area of Great B r i t a i n S p h a l e r i t e deposited w i t h i n o r near g r a n i t e i n t r u s i v e s c o n t a i n s r e l a t i v e l y l a r g e amounts of I n , Mn, and Sn, but s p h a l e r i t e s 234 from t e l e t h e r m a l d e p o s i t s c o n t a i n Ga and Ge; not found i n d e p o s i t s i n or near i n t r u s i v e s ( E l . S h a z l y et a l . . 1957). S i m i l a r l y galenas a s s o c i a t e d w i t h the i n t r u s i v e s c o n t a i n r e l a t i v e l y l a r g e amounts of Sn and B i (see F i g u r e s 79-81 ). The minor element z o n a t i o n i s accompanied by m i n e r a l o g i c z o n a t i o n and i s thought to be temperature-c o n t r o l l e d . T h i s c o n c l u s i o n i s supported by data from high-temperature d e p o s i t s v s . low-temperature d e p o s i t s , and by data from Russian d e p o s i t s (see Figures 82, 83). 2. C e n t r a l mining d i s t r i c t , New Mexico Pronounced l a t e r a l z o n a t i o n i s shown by minor elements i n s p h a l e r i t e from the C e n t r a l mining d i s t r i c t , New Mexico (Rose, 1970). M i n e r a l o g i c zoning i s shown by a decrease i n Pb/Zn r a t i o o f ores outward from the Santa R i t a s tock. T h i s trend i s accompanied by a marked decrease i n Co, Mn, and Fe i n s p h a l e r i t e ( F i g u r e 84). Elements which i n c r e a s e l a t e r a l l y from the i n t r u s i v e c o n t a c t are Ga, and p o s s i b l y Cd, Ag, and Ge. The z o n a t i o n i s thought to r e f l e c t . a combination of changes i n s o l i d - l i q u i d p a r t i t i o n i n g f a c t o r , and complex-ion formation w i t h subordinate e f f e c t s of temperature. 3. Copper-Iron skarns Ovchinnikov (1967) d i s c u s s e s s e v e r a l c o p p e r - i r o n skarn d e p o s i t s i n the U.S.S.R. i n which s e v e r a l d i s t i n c t z o n a t i o n p a t t e r n s of c o b a l t and n i c k e l i n p y r i t e have been observed. Three examples are i l l u s t r a t e d i n F i g u r e s 85 to 86 . Cobalt and n i c k e l g e n e r a l l y 1. K n a p D o w n 2. C o m b e M a r t i n 3. W h e a l E x m o u t h 4. D e v o n a n d C o u r t n e y 5. S o u t h C r e b o r 6. Penhawger 7. L i s k e a r d 8. H e r o d s f o o t 9. P e n a e n n a • 10. S o u t h T e r r a s 11. S o u t h St. G e o r g e 12. T r e s a v e a n 13. W h e a l M a r y FIGURE '79. Map of West of England showing g r a n i t e plutons and l o c a t i o n of m i n e r a l d e p o s i t s . ( E l Shazly e t . a l . 1957) SPHALERITE 6000 4000 2000 n.d. 300, 200 ' 100 n.d. 300 200 100 n.d 100r MANGANESE TIN 100 50 n.d. 1000 500 n.d. GALENA TIN BISMUTH I I I I 0 l'/2 3 3 4 5 6 38 1 Horizontal distance from granite (miles INDIUM — £ o _ 5 c o c „ o t— V f O L. W t- (T J : ? D o ~ C IA V O »J v •_ O O >^ 5 o o. E o u n.d. 50 GALLIUM _1 I I L • f GERMANIUM n.d.I i i i i i c z 3 0 0 1V2 3 .4^ 2 38 38 Horizontal distance from, granite (miles) o * 5 f o a N.B. Wheal Exmouth veins although near to the granite are relatively low-temperature mineralisations as implied by the quartz-barite gangue. All figures in p.p. m. n.d. = not detected ft E o u FIGURE 80. R e l a t i o n s h i p of minor element content of galena and s p h a l e r i t e to d i s t a n c e from g r a n i t e p l u t o n s . (From E l Shazly e t . a l . , 1957). Higher Temperature n r-j__ CALLIUM u> ro a) 1/1 t\j OD \j r\i ^ ^ ^ , ^ 3 , win <z z _j i/> _j «/> *-» Lower Temperature Deposits Higher Temperature Deposits p.p.m. -300 -200 : 100 Ln.d. 500 if: GERMANIUM ANTIMONY i n i < < i | i ! ! ! '"* ! ! m 'A 1-300 -200 -100 .n.d. h300 200 -100 n.d. <\| CO ^ OJ CO rvjCO <I?Tt »/> , 3 , 3 , ^ _ - ttJ • — u c ^ c _ s C «« C JC S'O-i*' « «J -2 c o j - ^ r a o t a. a. X * - *-^ n x > — — 171 1/1 - - J : > * «a «> ^ •» 1- a. ^> „ c u a. cn 3 * FIGURE 81. V a r i a t i o n i n minor element content of s p h a l e r i t e from mi n e r a l d e p o s i t s of high and low d e p o s i t i o n temperature. (From E l Shazly e t . a l . , 1957). ro 237 Bi 10000 1000 2 0L 0_ 100 10 v V o V O ° ° o ° ° o V O Q O o 0 o v o°v^ ° c $ o O v o 0 0 o v ° ' „ ~ ° • V O O O V O o • o u ° ' . V" V V O v v v o o v • • D • • • • • i i i i l . i i I • 1111 i i i I i 11 il 1—i—LJ 1 Sb 10 100 p p|Yj 1000 10000 FIGURE 82. Scatter diagram of bismuth and antimony contents of galena from deposits in carbonate rocks, (Modified from Malakhov.A.A., 1968) • Skarn deposits O Vein deposits a Stratiform deposits 238 FIGURE 83. Gallium-Indium r a t i o s in spha l e r i t e s of d i f f e r e n t o r i g i n s . (Modif ied from Trosh in .Yu.P . ,1962) 239 1 0 0 0 r Co lpl ' I I I I | I I loooor I I I I | I | I 0 2000 4000 6 0 0 0 meters from nearest stock FIGURE 84, L a t e r a l zoning of Co, Mn, and FeS i n s p h a l e r i t e of the C e n t r a l d i s t r i c t p l o t t e d a g a i n s t d i s t a n c e to the nearest stock. Large c i r c l e s are averages of samples over i n t e r v a l s of 610 in., l a s t c i r c l e i s f o r samples over 3060 m, (From Rose, 1970), O.u 0.3 0.2 0.1 0 [3) 3 2 -L i m e s t o n e Garnet s k a r n M a s s i v e p y r i t e - c h a l c o p y r i t e D i s s e m i n a t e d o r e 0 i 2 3 Distance, m FIGURE 85 • C o b a l t c o n t e n t o f p y r i t e from o r e s o f the F r o l o v s k o e (1 and 2) and N i k i t i n s k o e (3) s k a r n - m a s s i v e s u l p h i d e d e p o s i t s , U.S.S.R. . (From O v c h i n n i k o v , 1965). FIGURE 86. V a r i a t i o n i n the c o n t e n t s o f Go and N i i n p y r i t e a l o n g s t r i k e of the Vosto c h n a y a d e p o s i t o f t h e P e r v y i S e v e r n y i mine, U.S.S.R. (From O v c h i n n i k o v , 1965). 241 have s i m i l a r p a t t e r n s , and highest contents of these elements are i n v a r i a b l y i n massive ores, 4. Yanahara p y r i t i c ore d e p o s i t s The Yanahara ore d e p o s i t s are groups of massive and l e n s -shaped ore bodies i n sedimentary rocks near contacts w i t h i n t r u s i v e q u a r t z - d i o r i t e s i l l s o r p h a c o l i t h s . "Ore" minerals are p y r i t e and p y r r h o t i t e ; t h e i r r e l a t i o n s h i p to the i n t r u s i v e bodies i s u n c e r t a i n . Evidence e x i s t s both f o r primary o r i g i n or metamorphic o r i g i n of p y r r h o t i t e . Yamamoto et a l . (1968) have found zonation of c o b a l t and selenium i n the p y r i t e (see F i g u r e s 87 to 91 ) and the r a t i o s Se/S and Co/Fe were found to have l o g a r i t h m i c - l i n e a r c o r r e l a t i o n ( F i g u r e 88). In a d d i t i o n a c l o s e i n v e r s e c o r r e l a t i o n e x i s t s between the amount o f ore and the average Co/Fe r a t i o (shown i n Table 40). Sulphur i s o t o p e r a t i o s measured on the same samples show no c o r r e l a t i o n w i t h Co content. The zonation of selenium, as shown by c o n c e n t r a t i o n p l o t s across the H i d a s h i r o v e i n (Figure 91 ), i s opposite i n nature to t h a t of c o b a l t . Cobalt i s concentrated i n p y r i t e near the p y r i t e -p y r r h o t i t e c o n tact, but selenium i s concentrated i n p y r r h o t i t e . I n the c e n t r a l or p y r i t i c p o r t i o n s of the ore bodies c o b a l t has r e l a t i v e l y low concentrations;- selenium content i s r e l a t i v e l y h i g h (see F i g u r e 91 ). E i t h e r s h o r t range exchange of Co and Se has occurred at margins of ore bodies, or e l s e f o r m a t i o n of 200m FIGURE 87. G e o l o g i c a l c r o s s - s e c t i o n of the Kabu orebody: 1. Orebody, 2. S l a t e , 3. Diabase, 4. Meta-q u a r t z - d i o r i t e , (From Yamamoto e t . a l . , 1968). 50 » Kcbu ore body c . A Hidoshiro era body • • >^ 20 B SfiTioyoriohora ore body o core sample X • 10 X country rock A T / 6 " • n O X to 5 2 a 1 05 0O2 0O5 0.1 02 Q5 1 2 5 10 20 50 Co/Fe x 10* FIGURE 88. C o r r e l a t i o n between Co/Fe and Se/S i n p y r i t e from the Yanahara ore d e p o s i t s . The s o l i d l i n e ( f i t t e d by least-squares method) i s drawn f o r analyses from the Kabu orebody o n l y . (From Yamamoto e t . a l . , 1968). FIGURE 89. D i s t r i b u t i o n of Co i n the Kabu orebody: (a) P l a n o f l e v e l 21, (b) P l a n o f l e v e l 24. (From Yamamoto, e t . a l . , 1968), 244 oPyrtto •Pyrrhotite S. 5 -O Z 3-2 «a>-3 o o oso-i in UL 20-2 (-41)4 7-I-C-I 7-1-1 : .•.;.-"% • . : •.'.'. •*•"« * -•20 ••i9'.-: •'.18'| 17 16 .15 .*.-'•• • 14' .'12*; ; l i " ' . •— • * * • . '•/.'•'.i • : '. .' slate tuft Po Py 0 10 20om FIGURE 91. V a r i a t i o n s i n Co/Fe, Se/S, S, and S/Fe i n the p y r i t e v e i n from the Hidashiro d e p o s i t . (From Yamamoto e t . a l , , 1968). Co content range, ppm Amount of ore xlO3 m3 F Atomic ratio (Co/Fe)'* x 10-« 0- 10 103 1.000 10- 100 1,610 0.967 0.10 100- 200 "747 0.600 1.04 200- 400 670 0.363 1.79 400 - 600 351 0.150 2.87 600 - 800 85 0.039 3.70 800-1,000 36 - 0.012 4.02 > 1,000 2 0.001 4.17 0 0.000 4.19 = ( Co/Fe )\ * Average Co concentration in each range is assumed to be equal to the arithmetic mean of the two boundary figures. In the range higher than 1,000 ppm, the average is assumed to be 2,000 ppm. Weighted average for the ore body. TABLE 40. Amount of ore i n each range of Co content at the Kabu mine. (From Yamamoto e t . a l . , 1968). 246 p y r r h o t i t e i n e q u i l i b r i u m w i t h p y r i t e i s necessary to e x p l a i n the d i s t r i b u t i o n (Yamamoto et a l . . 1968). 5. Slocan D i s t r i c t , B.C. Zonation of minor elements i n p y r i t e and other s u l p h i d e s from Ag-Pb-Zn d e p o s i t s of the Slocan mining area, B.C., has been o u t l i n e d by trend-surface a n a l y s i s ( S i n c l a i r , 1967). Spectrographic analyses f o r s e v e r a l minor elements i n p y r i t e , s p h a l e r i t e and galena were obtained by W.H. Mathews (pe r s o n a l r e s e a r c h ) . The contents of As i n p y r i t e , Sn i n s p h a l e r i t e , and Ag i n galena were f i t t e d to q u a d r a t i c s u r f a c e s by computer (Fig u r e 92 ). Although the f i t of each v a r i a b l e to the q u a d r a t i c surface i s r a t h e r poor i n each case? the f a c t that a l l three p a t t e r n s show s i m i l a r z o n a t i o n w i t h n e a r l y c o i n c i d e n t centers and axes suggests that the trends are v a l i d . A l l three c e n t r a l "highs" l i e c l o s e to the Sandon mining camp - one of the major producers of the Slocan area. Zonation of minor elements outward from a center i s c o n s i s t e n t w i t h hypotheses that temperature g r a d i e n t s are c o i n c i d e n t w i t h minor element content g r a d i e n t s ; the c e n t e r s may i n d i c a t e a source f o r hydrothermal f l u i d s which deposited ores of the Slocan/camp ( S i n c l a i r , 1967). B. VERTICAL ZONATION IH DEPOSITS E a r l y s t u d i e s by Auger (1940),.Hawley (1952), and Hawley and N i c h o l (1961) i n v e s t i g a t e d the p o s s i b i l i t y of v e r t i c a l zonation * see Table 41 247 FIGURE 92, Quadratic trend and r e s i d u a l maps f o r minor elements i n sulphides from Slocan d i s t r i c t , B.C. A) Ag i n galena, ppm./IOO B) As i n p y r i t e , ppm.; C) Sn i n s p h a l e r i t e , ppm. Re s i d u a l maps D,E,and F f o r the r e s p e c t i v e trend maps are contoured i n standard d e v i a t i o n s . C o n t r o l p o i n t s are marked by dots. (From S i n c l a i r , A .J., 1967). Variable No. of specimens Quadratic surface Std. dev. (ppm) Coef. of determ. Ag in Galena As in Pyrite Sn in Sphalerite 61 31 24 102.2 41.2 31.S 0.11 0.13 0.17 TABLE 41 . Standard d e v i a t i o n s and c o e f f i c i e n t s of determination f o r the three c a l c u l a t e d trend s u r f a c e s i l l u s t r a t e d i n f i g u r e above (From S i n c l a i r , A.J., 1967). 248 of minor elements i n p y r i t e from s e v e r a l d e p o s i t s . Data f o r p y r i t e from the Noranda and H o l l i n g e r d e p o s i t s are p l o t t e d as depth vs. speptrographic l i n e - i n t e n s i t y , l o g - i n t e n s i t y , or a c t u a l content i n percent ( F i g u r e 93). Although the data are p o o r l y d i s p l a y e d , marked v e r t i c a l decreases f o r Zn, N i , and Cr are evident a t the H o l l i n g e r mine. At the Noranda mine, Auger's data show i n c r e a s i n g contents of Ag, T i , and V i n p y r i t e toward the base of each of the "upper H" and "lower H" ore bodies (see F i g u r e s 93 and 94 ). Cobalt and z i n c decrease v e r t i c a l l y . The trends of minor element contents i n p y r r h o t i t e and c h a l c o p y r i t e are s i m i l a r except i n the case of c o b a l t , which i n c r e a s e s v e r t i c a l l y (opposite to the trend f o r . p y r i t e ) . Perhaps t h i s anomaly r e f l e c t s m i n e r a l o g i c a l zoning and p y r i t e - p y r r h o t i t e e q u i l i b r i u m , as i n the Yanahara massive sulphide d e p o s i t s (page 241). At the S i s c o e gold mine, Quebec, Auger notes that Ag, N i Mn, T i , I n , and Sr p y r i t e i n c r e a s e w i t h depth. A t the K e r r Addison g o l d mine, Au and Ag i n p y r i t e i n c r e a s e w i t h depth, w i t h l e s s n o t i c e a b l e decrease of Co and N i . At K i r k l a n d Lake, minor element contents are s t r i k i n g l y uniform over the whole d e p o s i t and to a depth of 6000 f e e t . The selenium content of p y r i t e and p y r r h o t i t e a t Noranda orebodies appears to decrease w i t h depth.* I n h i s summary of minor element v a r i a t i o n s , Hawley (1952) concludes "In none of the d e p o s i t s i s there any outstanding change i n composition o f p y r i t e w i t h depth." * see Tables 42-44 249 FIGURE 93. V a r i a t i o n of elements i n p y r i t e w i t h depth at (A) H o l l i n g e r , Quebec, (B) Noranda, Quebec. (From Auger, P.E., 1941). FIGURE 94. V a r i a t i o n of minor elements w i t h depth at Noranda, Quebec: (A) p y r r h o t i t e , (B) c h a l c o p y r i t e . (From Auger, P.E., 1941). Depth Pyrite . Pyrrhotite No. of samples Range Mean No. Range Mean Upper levels 0-200' 6 390-1,000 • 590 9 90-555 375 23A sub-level 14 38-262 132 7 36-143 100 31st level 6 142-330 275 Lower levels 23A. 31st (average) 20 38-445 175 'm -Lower levels (run of mine) 6 33-88 64 TABLE 42 . Selenium content of Noranda p y r i t e and py r rho t i t e with depth. (Se i n ppm.) (From Hawley and N i c h o l , 1959). Depth No. Range Mean Se 250-448' L. 7 32-47 40 • 550-850' L. 9 15-51 22 1.000-1,1501.. 5 49-82 66 TABLE 43. Selenium i n Campbell-Chibougamau p y r r h o t i t e w i th depth. (Se i n ppm.) (From Hawley and N i cho l , 1959). Depth Pyrite Pyrrhotite Chalcopyrite No. of samples Range Se No. Range Se No. Range Se 50' level (1) (70) 70 (2) 50-250 150 (2) 135-210 170 250' level (3) (14) (50-270) (40-80) 190 60 (4) 21-595 180 (2) 230-540 3S5 350'level (5) (130-310) 160 450' level (1) 100 (1) 170 TABLE 44, Selenium i n Geco sulphides with depth. (Se i n ppm.) (From Hawley and N i c h o l , 1959). 252 I I I . INDICATOR ELEMENTS Minor elements i n p y r i t e which show promise as " i n d i c a t o r s " f o r m i n e r a l e x p l o r a t i o n are c o b a l t , a r s e n i c , and selenium. These • elements g e n e r a l l y s u b s t i t u t e f o r Fe and S i n l a t t i c e p o s i t i o n s , and are most u s e f u l s i n c e they show g r e a t e r v a r i a n c e than most minor elements, are i n c o n c e n t r a t i o n s great enough to reduce a n a l y t i c a l e r r o r , and are l e a s t l i k e l y to r e s u l t from contamination. The u s e f u l n e s s of Sn, T i , V, Cr, and Mn i s as yet unproven, p a r t l y due to a n a l y t i c a l and contamination d i f f i c u l t i e s . T i n i s present i n massive sulphide p y r i t e i n c o n c e n t r a t i o n s averaging 200 ppm. Even though the h i g h content may r e s u l t from c a s s i t e r i t e or s t a n n i t e i n c l u s i o n s , i f the contamination i s c o n s i s t e n t (as i t appears to be), i t may prove to be a u s e f u l i n d i c a t o r . Cobalt shows promise as an i n d i c a t o r element f o r massive su l p h i d e ( o r v o l c a n i c - e x h a l a t i v e d e p o s i t s , as w e l l as f o r copper v e i n or replacement d e p o s i t s ; see F i g u r e s 45 and 63 ). T h i s element i s . a l s o enriched i n Rhodesian copper b e l t , "syngenetic" d e p o s i t s , but h i g h c o n c e n t r a t i o n s may r e s u l t from metamorphic r e m o b i l i z a t i o n (Darnely, 1966). Cobalt has been used as an i n d i c a t o r f o r uranium-vanadium d e p o s i t s of the Colorado p l a t e a u area (Coleman and Delevaux, 1957) because Co contents are h i g h i n p y r i t e from ore d e p o s i t s . P y r i t e from the b r e c c i a - p i p e at the Molymine prospect near Smithers, B.C. c o n t a i n s h i g h c o n c e n t r a t i o n s of Co r e l a t i v e to p y r i t e from the adjacent a l a s k i t e and quartz v e i n s . A diagrammatic g e o l o -g i c a l c r oss s e c t i o n w i t h c o b a l t v a l u e s i s presented i n F i g u r e 69. There i s a suggestion of m i n e r a l o g i c z o n a t i o n w i t h i n the b r e c c i a t e d area although outcrop i s poor. I n the same area p y r i t e from a s i l i c i f i e d (but unmineralized) d i o r i t i c i n t r u s i o n adjacent to a l e n t i c u l a r v e i n c o n t a i n i n g coarse galena, s p h a l e r i t e , and a r g e n t i f e r o u s t e t r a h e d r i t e , c o n t a i n s r e l a t i v e l y h i g h c o n c e n t r a t i o n s o f Pb and Zn. Th i s suggests t h a t a n a l y s i s f o r these elements i n p y r i t e could be a u s e f u l e x p l o r a t i o n guide i n t h i s area. S i m i l a r r e l a t i o n s h i p s are present i n the East T i n t i c area, Utah, where v e i n p y r i t e i n v o l c a n i c s above the T i n t i c orebodies, c a r r i e s s i g n i f i c a n t l y h i g h e r c o n c e n t r a t i o n s o f base metals compared t o disseminated p y r i t e i n the v o l c a n i c s (Kennecott Copper Corp. e x p l o r a t i o n s t a f f , personal communication). Selenium, although p r e s e n t i n g a n a l y t i c a l d i f f i c u l t i e s , appears to be a promising i n d i c a t o r . The r e l a t i v e l y h i g h content i n p y r i t e s from S e - r i c h sedimentary sequences i s noted by Coleman and Delevaux ( 1 9 5 7 ) . High Se contents i n s u l p h i d e s from massive Cu-Zn ores have been discussed i n a previous chapter (page 110). The r e l a t i v e l y h i g h content i n p y r i t e - p y r r h o t i t e d e p o s i t s o f the Yanahara r e g i o n i s documented by Yamamoto et a l . (1968). Mercury. Fedorchuk and N i k i f o r o v ( i n Ovchinnikov, 1967) found p y r i t e s i n Carbonaceous shales above mercury-antimony d e p o s i t s to be enriched i n Hg, Sb, As, and Zn. On the a x i a l p o r t i o n of the 254 a n t i c l i n a l s t r u c t u r e c o n t a i n i n g the ore, Sb i s enriched i n p y r i t e to a depth of a few dozen meters, As and Zn to 200 meters, and Hg to many hundreds of meters. Along s t e e p l y d i p p i n g pre-ore f a u l t s minor element contents remain hi g h f o r c o n s i d e r a b l e d i s t a n c e s . The authors s t a t e that minor element s t u d i e s were u s e f u l i n : 1. determining o r e - s t r u c t u r e , 2. o u t l i n i n g t a r g e t areas, 3. e s t i m a t i n g depth to ore. Cobalt i n p y r r h o t i t e . I n the v i c i n i t y of the Coronation mine ( F l i n F l o n area, Manitoba) Faulkner (1970) has shown that Co and N i co n c e n t r a t i o n s i n p y r r h o t i t e are c h a r a c t e r i s t i c f o r economic and barren d e p o s i t s . Economic d e p o s i t s are e s s e n t i a l l y "conformable" massive sulphide ore bodies c o n t a i n i n g p y r i t e , p y r r h o t i t e , c h a l c o -p y r i t e , s p h a l e r i t e and o c c a s i o n a l l y magnetite. W a l l rocks are metamorphosed v o l c a n i c s and p y r o c l a s t i c s . "Barren" d e p o s i t s are v e i n - l i k e replacement bodies c o n t a i n i n g p y r i t e and p y r r h o t i t e , w i t h l e s s than '1$ c h a l c o p y r i t e and s p h a l e r i t e . S c a t t e r diagrams of c o b a l t and n i c k e l contents are shown i n Fi g u r e s 95 and 96 ; ranges and mean contents are given i n Table 45. Histograms of frequency d i s t r i b u t i o n s are a l s o given ( F i g u r e 97). Economic d e p o s i t s have r e l a t i v e l y low n i c k e l contents ( l e s s than 700 ppm) w i t h most Co/Ni r a t i o s g r e a t e r than 1.0. Barren d e p o s i t s have r e l a t i v e l y low c o b a l t contents w i t h most Co/Ni r a t i o s l e s s than 0.5. Faulkner suggests t h a t the economic and barren d e p o s i t s are g e n e t i c a l l y u n r e l a t e d ; barren d e p o s i t s may r e s u l t from s u l p h i d i z a t i o n o f normal rock--I <T cO Q 3 o o o >-> sr oo oo o o o o - 1 —I— /ooo (b) O T H E R ECONOMIC 3SOO- Dmro%rrs ^ j <z CQJooo O <J c" a-a: 8.v<h Lokc M ; „ . #00 l*v«l Q Coo °o boo ltv«l 600 l»y»t.«> C u p r u ( H i n c ^ Had O S*oU LoVt, Mo*, uoo L.a»«l. — I r -P.RM. NICKEL FIGURE 95« Co and N i content of p y r r h o t i t e s from "economic" de p o s i t s of the F l i n F l o n area, (From Faulkner,E,L.,1968). 256 Co ppm Ni ppm Mean Deposits No. Range Mean Range Mean Co/Ni Coronation mine 60 68-4150 890 25-1050 315 2. 82 Other 'economic' deposits 16 85-3450 1550 45- 275 116 13.4 'Barren' deposits 76 10- 525 165 125-2720 925 0. 178 TABLE 42. Comparison o f Co and N i c o n t e n t s and Co/Ni r a t i o s i n p y r r h o t i t e s from economic and " b a r r e n " m i n e r a l d e p o s i t s of t h e F l i n F l o n a r e a . (From F a u l k n e r , E . L . , 1968). FIGURE 96. Co and N i i n p y r r h o t i t e s from " b a r r e n " m i n e r a l d e p o s i t s o f the F l i n F l o n a r e a . (From F a u l k n e r , E , L , , 1968). 10 Barren Pe.fros.~it: IS 1 so 40 E| B fi p f 6r 3o 0-/7S r i o soo t O O O fom. Cobalt- 0-OOI O-Ol o-ID IOO IOO POO Co/Ni Rot.'os. I O O O i r o o . 2 0 0 0 jjoo Pf"*"- Cobalt. flea*, Co 2 IO? Co»"0*lCrf<Orl M.^tT '. *" Ai«o^  W; : SeTf>f>~. / O O I O O O 30 Mean I 2>'30 Heart , C o r o r K i f i^ ^ rli'^ Q * 0-OOI O O l OIO I O O I O O IOO Co/N,' Ratios. . FIGURE 97. Frequency d i s t r i b u t i o n h i s t o g r a m s f o r Co and N i i n p y r r h o t i t e s from economic and b a r r e n m i n e r a l d e p o s i t s , F l i n F l o n a r e a . (From F a u l k n e r , E . L , , 1968). forming s i l i c a t e s , but economic d e p o s i t s probably were deposited by m e t a l - r i c h chlorocomplex hydrothermal f l u i d s a s s o c i a t e d w i t h b a s i c i n t r u s i v e s present i n the area. 259 IV. APPLICATIONS OF MINOR ELEMENT PARTITION COEFFICIENTS Theoretical aspects of minor element p a r t i t i o n c o e f f i c i e n t s are explained h e l l by Mclntyre (1963) and others, and w i l l not be . repeated here. Eethke et a l . (1958, 1959) found that the influence of temperature on p a r t i t i o n c o e f f i c i e n t s i s much greater than that of pressure. P a r t i t i o n relationships i n coexisting sulphides may be displayed by several types of diagrams (Ghosh-Dastidar et a l . . 1970). Simple "Roozeboom" diagrams w i l l show l i n e a r c o r r e l a t i o n of element contents i n two minerals i f equilibrium conditions prevailed during deposition and i f concentrations i n each phase were d i l u t e enough to conform to Henry's Law. Typical Roozeboom diagrams are i l l u s t r a t e d i n Figure 98. Scattered patterns observed on Roozeboom diagrams may be the r e s u l t i f : 1) Henry's Law was obeyed but temperature and/or pressure varied during deposition. 2) Henry's Law was not obeyed. 3) Deposits are i n gross disequilibrium. 4 ) Mineral i n c l u s i o n impurities are present. 5) A n a l y t i c a l errors are present. 6) Complex interactions occur between elements. Scattered patterns do not necessarily mean that minerals were i n gross disequilibrium. I f the data i s replotted on "concentration" or " i n t e r a c t i o n " diagrams (Figures 99 and 100), hitherto unsuspected 260 1. 7 62»/ Letite •1. » 'Jl / so.;58 / 1. 3 I 59./ / •72 • 1.1 >. o. 52V50 . /«49 "SM. •S0. 9 o O X .0. 7 0 . 5 f l i •79 IS •a c o © E <a O •44 /. 1 67 0.3 (a) o -.as -»83 •91 *92.95.97. i i i 0 i I I i i / ^3 * 0 , 1 . . . . 691° 736. 0 , , , , 0 0.1 0. 2 0 0.1 0. 1 0 0.1 072 Wt. % Co in po 0 0.1 0 .3 0.45 0. 35 0. 55 0.15 = • 0 2 0.15 _:0. 05 5 0 0.15 (b) -7t..73 68«* 7 0 Letite •69 • •67 .72 - •77 Cameron & S. Oliv. • 60 52 . . cP D-05 5859<»»»50 0 Oliver 31 34 • c M T — 3 3 s " 0 Gull Pond - 94 « 3 83 1 * 2 2 - . • • .79 _ l -JL. 1 1 1 1 1 1 . 0.5 ....0.7 Wt: % Ni in po FIGURE 9 8 . Example of "Roozeboom" diagram showing d i s t r i b u t i o n of Co and N i between p y r i t e and py r rho t i t e from severa l min mineral depos i t s . (From Ghosh-Dastidar e t , a l . , 1970). 0.35 0.25 o z cc 0.15 0.05 •(c) / 3 t ' 31o» V •43 / 7 0.05 0.15 0.25 Wt. % Ni in py 0.35 ( d ) %Zn in py X102 FIGURE 9 9 . Example of " concen t r a t i on " diagrams showing dependence of p a r t i t i o n c o e f f i c i e n t s on element concentrat ions i n one or more phases. (From Ghosh-Dastidar e t . a l . , 1970). 261 10 o ft 6 M J 13 *, (Oliver) US *33 / / •67 ,69 68.73 '5(Co/Ni) py 25 50 1.4 1.0 2 OC 0.6 0.2 (b) ,68,71 ••73.70 •69 •67 (Oliver) ,5(Co/Ni)py 2 5 (Lento) --' ?7» — N — 50 FIGURE 100, Example of "in t e r a c t i o n diagram" showing relationship of Co/Ni r a t i o i n pyrite to d i s t r i b u t i o n c o e f f i c i e n t s for Co and Ni between pyrite and pyrrhotite, (From Ghosh-Dastidar et. al.,1970).  .12 .04 .08 ZnSe/ZnS FIGURE101. Plots*of mole-fraction r a t i o s PbSe/PbS vs.ZnSe/ZnS calculated from experimental data for s i x temperatures (From Bethke and Barton, 1971). 262 r e l a t i o n s h i p s may appear. Concentration p l o t s show the dependence of p a r t i t i o n c o e f f i c i e n t s on element c o n c e n t r a t i o n s i n one or both c o e x i s t i n g phases. I n t e r a c t i o n p l o t s show the i n f l u e n c e o f other minor elements on d i s t r i b u t i o n c o e f f i c i e n t s . Ghosh-Dastidar et a l . (1970) r e p o r t that i f s u b s t i t u t i o n o f an element i n a s t r u c t u r e n e c e s s i t a t e s s t r u c t u r a l vacancies, p a r t i t i o n c o e f f i c i e n t s f o r th a t element between d i f f e r e n t phases w i l l not f o l l o w the d i s t r i b u t i o n law. The authors present v a r i o u s p a r t i t i o n diagrams and r e l a t i o n s h i p s from s u l p h i d e d e p o s i t s i n Newfoundland and New Brunswick. A c r i t i c i s m o f some of t h e i r work i s the content o f some of the elements i n v o l v e d , Pb, Zn, B i , e t c . , i s so h i g h that contamination as m i n e r a l i n c l u s i o n s must s u r e l y be present. I n a recent study, Bethke and Barton (1971) have shown th a t d i s t r i b u t i o n of c e r t a i n minor elements between s y n t h e t i c s u l p h i d e phases i s independent of composition ( c o n c e n t r a t i o n ) , and p a r t i t i o n r e l a t i o n s h i p s v a r y . s u f f i c i e n t l y w i t h temperature f o r reasonably p r e c i s e temperature estimates. T h i s f i e l d of study seems to h o l d promise f o r d e c i p h e r i n g minor element r e l a t i o n s h i p s i n sulphide d e p o s i t s . Examples of v a r i a t i o n of p a r t i t i o n - c o e f f i c i e n t s i n s y n t h e t i c systems are shown i n Fi g u r e s 101 and 102. FIGURE 102, Summary of v a r i a t i o n of d i s t r i b u t i o n c o e f f i c i e n t s w i t h temperature. Values are d e r i v e d from study of s y n t h e t i c s u l p h i d e systems by Bethke and Barton, (1971). 264 V. OTHER APPLICATIONS A. INDEX OF OXIDATION-REDUCTION REGIME ( T r o s h i n , 1965) T r o s h i n (1965) has attempted to d e f i n e q u a l i t a t i v e l y the o x i d a t i o n - r e d u c t i o n regime of hydrothermal f l u i d s on the b a s i s of d i s t r i b u t i o n o f minor elements i n c o e x i s t i n g s u l p h i d e s . A c c o r d i n g to T r o s h i n , minor elements such as Cd and I n , present i n a s i n g l e valence s t a t e under hydrothermal c o n d i t i o n s are c h a r a c t e r i z e d by a very narrow range o f concentrator m i n e r a l s and "host" elements. Elements which can occur w i t h more than one valence, f o r example Cu and Mn, can isomorphously r e p l a c e a g r e a t e r v a r i e t y of host elements. From a study of i o n i c r a d i i of minor elements i n v a r i o u s s t a t e s of o x i d a t i o n (valence) T r o s h i n s t a t e s that an i n t e n s i f i c a t i o n o f the o x i d i z i n g regime i n a hydrothermal system should s h i f t the e q u i l i b r i u m d i s t r i b u t i o n of minor c a t i o n s towards c r y s t a l l i z a t i o n i n s p h a l e r i t e . Conversely an increased reducing environment should cause increased c o p r e c i p i t a t i o n of minor elements i n p y r i t e and galena. I t i s unfortunate that Troshin's data do not adequately support h i s own c o n c l u s i o n s (Table 46). One must conclude that many other f a c t o r s besides o x i d a t i o n - r e d u c t i o n p o t e n t i a l c o n t r o l the d i s p e r s i o n o f minor elements among .-. c o e x i s t i n g hydrothermal s u l p h i d e s . 8 Accom- Cu Sn A3 Sb Mn panying minerali-zation Zns PbS FeS2 ZnS PbS FeS2 ZnS PbS FeS2 ZnS PbS FeS2 ZnS PbS FeS2 K Tin Srnlrnov 100 40 70 500 1500 70 100 50 1500 200 1800 . 10 200 — _ 0.33 Khapcheranga polymetalllc vein 40 40 100 60 600 100 <50 30 100 — 2000 100 400 600 . 1000 0.14 lead vein 40 40 10 20 300 100 530 — 100 — 2000 — 400 500 200 0.22 Tarbal'dzhey 70 30 400 20 1000 60 300 500 500 — 300 —. 1000 1500 500 0.15 Tungsten Sherlovogorck 40 150 20 — 500 200 — 70 10 — — 300 — 100 (0.42) Buku.Ua 5000 50 60 30 60 100 — — 200 — 200 — 2000 50 30 0.42 Khaltasopskoye 200 50 30 — 5 1 — — — — 50 — 100 — — 0.43 (DzMda) Molybdenum Pe rvo m ay sk oy e 200 —' 5 30 — 2. — — . — 20 - - 1000 - . - (0.54) (Dzhida) BugdaLnskoye 300 200 300 10 — 4 50 50 300 200 400 — 400 — • 50 0.49 Vershlnoshakhtama 300 300 10 20 5 1 50 200 10 300 900 — 250 80 — 0.50 Davenda 300 100 1000 100 4 — 1000 300 3000 200 100 — 250 GO 0.53 TABLE 46. Distribution of trace elements among sphalerite, galena, and pyrite in t i n , tungsten, and molybdenum-polymetallic ore deposits of Transbaikaliya. A l l analyses in J7g. (From Troshin, 1965). * K = distribution coefficient. 266 B. AGES OF MINERALIZATION T u r o v s k i i e t a l , (1967) showed that p o l y m e t a l l i c m i n e r a l d e p o s i t s o f f o u r d i f f e r e n t ages had n o t i c e a b l y d i f f e r e n t minor-. element contents. A l l d e p o s i t s had more or l e s s s i m i l a r m i n e r a l o -g i c a l . composition. Determination of minor elements i n galena,, s p h a l e r i t e , and p y r i t e showed that Permian m i n e r a l d e p o s i t s contained the g r e a t e s t amounts o f Se, Te, B i , T l , and I n , and e l e v a t e d amounts of Ga and Cd were t y p i c a l o f S i l u r i a n - D e v o n i a n ores. S t u d i e s o f t h i s nature may be v a l i d w i t h i n s m a l l geographical areas, but probably r e f l e c t d i f f e r e n t magmatic sources r a t h e r than age of d e p o s i t s . C. METAL RATIOS CHARACTERISTIC OF DEPOSIT TYPES Prokhorov (1965) r e p o r t s t h a t p y r i t e from d e p o s i t s of v a r i o u s types has c h a r a c t e r i s t i c s t y p i c a l of each genetic type o f d e p o s i t . Metal r a t i o s , d e c r e p i t a t i o n temperatures, thermo-EMF, and "d" spacin g o f the p y r i t e l a t t i c e are given f o r each type o f d e p o s i t . Type Cu/Zn Ag/Zn Pb/Zn Co/Ni P y r i t e 4-160 0.01-0.7 0.4-3.0 0.6-9.0 Metamorphic 0.3-0.2 0.006-0.08 0.02-0.14 0.06-0.6 Rare metal 0.9-14 0.24-0.1 1.0-8.0 1.0 Au-bearing 0.7 0.7 0.6 Type T decreg. C Thermo EHF "d" spacing Metamorphic P y r i t e 500-600° 450-550°. -14 to -100 V/°C -76 V/°C 3.8-5.0 X. 4.5-5.0 X Rare metal 300-400 p -72 V/°C 4.8 X Au-bearing 350-450 o +130 to +160 V/°C 4.5-4.9 X Without s u p p o r t i n g s t a t i s t i c a l data, the v a l i d i t y o f Prokhorov's con c l u s i o n s cannot be checked. RELATIONSHIP OF CRYSTAL MORPHOLOGY AND MINOR-ELEMENT CONTENTS . . In a porphyry copper d e p o s i t at Cuajone, Peru, Amstutz (1963) found changes i n morphology of p y r i t e from p y r i t o h e d r a i n normal country rock to cubes i n r e g i o n s of a l t e r a t i o n and h i g h copper content. The author a l s o notes that most sedimentar3 r and metamorphic p y r i t e s are simple cubes, whereas morphology i s much more v a r i a b l e i n igneous and hydrothermal environments. Marked changes i n morphology w i t h temperature and degree of s u p e r s a t u r a t i o n have been disc o v e r e d w i t h b r o o k i t e , c a s s i t e r i t e , and other minerals by Kostov (1966) (see F i g ure 103). N o t i c e a b l e e f f e c t s on c r y s t a l morphology can be seen by adding i m p u r i t i e s to growing s y n t h e t i c c r y s t a l s , t h e r e f o r e , i t i s conceivable that v a r i a t i o n s i n type of c o n c e n t r a t i o n of minor-elements could be manifested i n p y r i t e c r y s t a l s of d i f f e r e n t morphology i n m i n e r a l d e p o s i t s . Observation of e f f e c t would be hindered by complexity of m i n e r a l i z a t i o n or m u l t i - g e n e r a t i o n m i n e r a l i z a t i o n . Johnson (1971) noted that p y r i t o h e d r a l p y r i t e from c u p r i -f e r o u s p y r i t e d e p o s i t s o f Cyprus have v i r t u a l l y no n i c k e l , whereas c u b i c p y r i t e from the same d e p o s i t s c o n t a i n s 100-1000 ppm Co and 10-500 ppm N i ( F i g u r e 104). Although t h i s r e l a t i o n s h i p may h o l d t r u e f o r one d e p o s i t o r one type of d e p o s i t i t cannot be s t a t e d as a g e n e r a l r u l e . Thus, although numerous p r a c t i c a l a p p l i c a t i o n s have been suggested f o r the study o f minor elements i n p y r i t e , the areas of r e s e a r c h which appear to h o l d the most promise a r e : 1. The d e t e r m i n a t i o n of i n d i c a t o r elements f o r c e r t a i n types o f d e p o s i t s , 2. Minor-element zonation w i t h i n and adjacent to ore bodies, 3. P a r t i t i o n - c o e f f i c i e n t s t u d i e s to a i d i n determination of temperatures of d e p o s i t i o n of m i n e r a l d e p o s i t s , 4. D e f i n i t i o n o f m e t a l l o g e n e t i c provinces by minor element r e l a t i o n s h i p s . FIGURE 103. V a r i a t i o n of c r y s t a l h a b i t w i t h changes i n temperature and c o n c e n t r a t i o n of s o l u t i o n s ; (A) magnetite, (B)brookite,(C) c a s s i t e r i t e , (From Rostov, 1966). 

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