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Mineralogy, paragenesis, and mineralogic zonation of the Silver Queen vein system, Owen Lake, central… Hood, Christopher Thomas Saul 1991

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MINERALOGY, PARAGENESIS, AND MINERALOGIC ZONATION OF THE SILVER QUEEN VEIN SYSTEM OWEN LAKE, CENTRAL BRITISH COLUMBIA By C h r i s t o p h e r Thomas Saul Hood B . S c , U n i v e r s i t y of B r i t i s h Columbia Vancouver, B r i t i s h Columbia, 1979 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES ( G e o l o g i c a l Sciences) We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA SEPTEMBER, 1991 @ • H • • „ C h r i s t o p h e r Thomas Saul Hood, 1991 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying; of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. The University of British Columbia Vancouver, Canada Department of Cr?e~o[e>ai\ (2/88) i i ABSTRACT The S i l v e r Queen mine, southeast of Houston, B.C., consists of a series of epithermal base- and precious-metal bearing veins hosted by Late Cretaceous volcanic rocks of the Tip Top H i l l formation. Mineralogically, the veins are complex, di s p l a y i n g several discrete mineralizing stages characterized by the presence of c e r t a i n s u l f i d e and gangue species. The complexity of the vein mineralogy has presented a problem i n assessing the systemic evolution of the hydrothermal system. This study describes i n d e t a i l the nature of the mineralogy, d i v i d i n g the assemblages present into four d i s t i n c t paragenetic stages. P a r t i c u l a r attention was paid to the occurrence of p o t e n t i a l l y economic phases (e.g. electrum). S u l f i d e phases which were compositionally s e n s i t i v e to trace element variations were examined by electron microprobe to determine variati o n s on single grain and deposit scales. Microbeam analysis also assisted i n the i d e n t i f i c a t i o n of several s u l f o s a l t species. Evaluation of the mineralogy and paragenesis allowed for the assessment of the evolution of the deposit. Paragenetically, the mineralization i s divided into four d i s t i n c t stages. The f i r s t stage i s characterized by f i n e grained p y r i t e and quartz mineralization, with hematite abundant i n the assemblage i n the c e n t r a l segment of the most extensive (Number Three) vein. Barite, svanbergite, and h i n s d a l i t e become abundant towards the south end of the Number Three vein, with marcasite more abundant towards the north. Stage II i s dominated by the presence of massive sphalerite and layered carbonate ( c a l c i t e i n the south, manganoan carbonates i n the north). Stage I I I , however, i s more complex. Mine r a l i z a t i o n consists of chalcopyrite, galena, fahlores (tetrahedrite-tennantite), electrum, quartz, and s u l f o s a l t s . Included i n the s u l f o s a l t assemblage are the unusual Pb-Bi-Cu-Ag species b e r r y i t e , m a t i l d i t e , gustavite, and a i k i n i t e . The f i n a l stage of mineralization i s volumetrically minor and i s dominated by fine-grained quartz, pyrobitumen, and c a l c i t e . Minor element trends i n tetrahedrites and sphalerites reveal a mineralizing f l u i d with a high degree of compositional v a r i a b i l i t y . Tetrahedrite grains show well developed o s c i l l a t o r y compositional zoning i n Sb, As, B i , Ag, and Cu, while sphalerites are commonly v i s u a l l y well layered. The l a t t e r was found to be the main repository for the unusual metals Ga, Ge, and In, which are found i n anomalous l e v e l s i n S i l v e r Queen ore. The S i l v e r Queen veins are proposed to have evolved from f l u i d s o r i g i n a t i n g at depth to the south of the Number Three vein. Pulses of metal-bearing f l u i d s interacted with cooler groundwaters, producing the observed d i s t r i b u t i o n of assemblages. The presence of Ga, Ge, and In may have been sourced i n an organic-rich layer exposed i n several locales i n the S i l v e r Queen mine area. i v TABLE OF CONTENTS Page ABSTRACT i i TABLE OF CONTENTS i v LIST OF TABLES v i i i LIST OF FIGURES X LIST OF PLATES x i i i ACKNOWLEDGEMENTS x v i i i CHAPTER 1.0 INTRODUCTION 1 1.1 General Statement 1 1.2 Location and Access 1 1.3 History of Deposits and Previous Work 3 1.4 Purpose and Scope 6 CHAPTER 2.0 GEOLOGIC SETTING OF THE SILVER QUEEN MINE 8 2.1 Introduction and Tectonic Setting 8 2.2 Regional Geology 9 2.2.1 Geologic Setting 9 2.2.2 Geology of the Owen Lake Area 14 2.3 Geology of the Mine Area 15 2.3.1 Introduction 15 2.3.2 Geology and Petrography 18 (1) Unit 1 18 (2) Unit 2 19 (3) Unit 3 20 (4) Unit 4 22 (5) Unit 4a 23 (6) Unit 5 23 (7) Unit 5a 24 (8) Unit 5b 25 (9) Unit 6 26 (10) Unit 7 28 (11) Unit 8 29 V TABLE OF CONTENTS cont'd page 2.3.3 Geochronology 30 2.3.4 Structure 35 2.4 Character of Veins 36 CHAPTER 3.0 MINERALOGY AND PARAGENESIS 42 3.1 Introduction and Scope 42 3.2 Character of Veining 43 3.3 Sampling and Analysis 45 3.4 Number Three vein and associated veining 48 3.4.1 Introduction 48 3.4.2 Vein Mineralogy 49 (1) P y r i t e 49 (2) Sphalerite 52 (3) Chalcopyrite 54 (4) Galena 54 (5) Tetrahedrite 55 (6) A i k i n i t e 60 (7) Berryite 60 (8) M a t i l d i t e 64 (9) Seligmannite-Bournonite 64 (10) Polybasite, Freibergite, and Pyrargyr i t e 66 (11) Bismuthinite and associated sulfosalts.66 (12) Proustite and Geocronite 66 (13) Arsenopyrite 71 (14) Marcasite 71 (15) Electrum 71 (16) Bornite, Chalcocite and C o v e l l i t e 72 (17) Pyrrhotite 72 (18) Hematite and Magnetite 73 (19) Titanium Oxides 73 (20) Quartz 73 (21) Carbonates 75 (22) Barite 76 (23) Svanbergite and Hinsdalite 77 (24) Pyrobitumen 77 v i TABLE OF CONTENTS cont'd page 3.4.3 Paragenesis and Mineralogic V a r i a t i o n 77 3.5 Mineralization i n Other Veins 85 3.5.1 Camp Vein System 85 3.5.2 Chisholm Veins. 98 3.5.3 Portal Veins 101 3.5.4 Cole Lake Veins 109 3.5.5 George Lake Veins 117 CHAPTER 4 . 0 COMPOSITIONAL V A R I A T I O N IN S U L F I D E S 120 4.1 Introduction and Objectives 120 4.2 Sampling Techniques 122 4.3 A n a l y t i c a l Methodology 122 4.4 Tetrahedrite Zonation 124 4.4.1 Introduction 124 4.4.2 Single Grain Zonation i n Tetrahedrites 125 4.4.3 Deposit-scale variations i n Tetrahedrite Composition.... 139 4.4.4 Tetrahedrites from other veins 141 4.4.5 Bismuthian Tetrahedrites-An unusual occurrence 142 4.4.6 Discussion 144 4.5 Sphalerite Zonation ....153 4.5.1 Introduction.. 153 4.5.2 Systematic Trends i n Sphalerite Zonation 153 4.5.3 Discussion 155 4.6 S u l f o s a l t and Electrum Chemistry...160 4.6.1 Introduction 160 4.6.2 S u l f o s a l t Compositions 161 4.6.3 Electrum Compositions 164 CHAPTER 5 . 0 D I S C U S S I O N 172 5.1 Introduction 172 5.2 Conditions of Mineral Deposition...172 5.3 Evolution of the Hydrothermal System 187 v i i TABLE OF CONTENTS cont'd page 5.4 Comparison with other vein deposits 196 CHAPTER 6 . 0 P R A C T I C A L A S P E C T S OF MINERALOGIC S T U D I E S 199 6.1 Introduction 199 6.2 Occurrence and Benefic i a t i o n of Economic Minerals 200 6.3 Recommendations for Future Exploration 206 CHAPTER 7 . 0 SUMMARY AND CONCLUSIONS 215 CHAPTER 8 . 0 R E F E R E N C E S 218 APPENDIX A SAMPLE S I T E LOCATIONS 225 APPENDIX B P A R A G E N E T I C DIAGRAMS FOR M I N E R A L I Z E D STRUCTURES A T S I L V E R QUEEN MINE 233 APPENDIX C MICROPROBE A N A L Y S E S 255 v i i i LIST OF TABLES page TABLE 2.1.1 Stratigraphic Units i n the Buck Creek Area 11 TABLE 2.3.1 Stratigraphic Units of the S i l v e r Queen mine (Owen Lake) Area 17 TABLE 2.3.2 Summary of Whole-rock Potassium-Argon data f o r rocks i n the v i c i n i t y of the S i l v e r Queen mine 31 TABLE 3.3.1 Mineral Species i d e n t i f i e d at the S i l v e r Queen mine 47 TABLE 4.4.1 Zonal Analysis of Tetrahedrite sample 3CHN90-1 128 TABLE 4.4.2 Zonal Analysis of Tetrahedrite sample 3CHN89-46 130 TABLE 4.4.3 Zonal Analysis of Tetrahedrite sample 3CHN89-5 131 TABLE 4.5.1 Zonal Analysis of Sphalerite sample 3CHN89-5 156 TABLE 4.5.2 Zonal Analysis of Sphalerite sample 3CHN89-1 158 TABLE 4.5.3 Zonal Analysis of Sphalerite sample 3CHN90-1 158 TABLE 4.6.1 Microprobe analysis of Su l f o s a l t Compositions 166 TABLE 4.6.2 Electrum Compositions 171 TABLE 5.2.1 Speciation of Ore Metals i n Hydrothermal Solutions 174 TABLE 5.4.1 Comparative Anatomy of Volcanic-Hosted Epithermal Deposits 197 TABLE 6.1.1 Economic Mineralogy of the S i l v e r Queen Property 208 TABLE 6.1.2 Electrum Occurrence, S i l v e r Queen Property 213 i x LIST OF TABLES cont'd page TABLE A - l Underground Sample Sites 226 TABLE A-2 D r i l l Hole Sample Sites 229 TABLE C - l Microprobe Analyses .255 Figure 1.2.1 Figure 2.1.1 Figure 2.3.1 Figure 2.3.2 Figure 3.4.22 Figure 3.4.23 Figure 3.4.24 Figure 3.4.25 Figure 3.4.26 Figure 4.4.6 Figure 4.4.7 Figure 4.4.8 Figure 4.4.9 x LIST OF FIGURES page Location of the S i l v e r Queen Gold-Silver-Copper-Lead-Z inc Mine 1 Geology of the Buck Creek Area, West-central B r i t i s h Columbia 10 Geology of the S i l v e r Queen Mine Area i n pocket Owen Lake Stratigraphy 16 Paragenesis of the Number Three System 82 Longitudinal section of the Number Three vein; Paragenetic stage abundance 86 Longitudinal section of the Number Three vein; Stage I mineral abundance 87 Longitudinal section of the Number Three vein; Stage II mineral abundance 88 Longitudinal section of the Number Three vein; Stage III mineral abundance 89 Contour plo t of Zn/(Zn+Fe) f o r Tetrahedrite grain "cores"; Number Three vein longitudinal section 132 Contour plo t of Zn/(Zn+Fe) f o r Tetrahedrite grain "rims"; Number Three vein longitudinal section 133 Contour plo t of Ag/(Ag+Cu) for Tetrahedrite grain "cores"; Number Three vein longitudinal section 134 Contour plot of Ag/(Ag+Cu) for Tetrahedrite grain "rims"; Number Three vein longitudinal section 135 x i LIST OF FIGURES cont'd Figure 4.4.10 Figure 4.4.11 Figure 4.4.12 Figure 4.4.13 Figure 4.4.14 Figure 4.4.15 Figure 4.4.16 Figure 5.2.1 Figure 5.2.2 Figure 5.2.3 Figure 5.2.4 Figure 5.3.1 page Contour plo t of As/(As+Sb+Bi) for Tetrahedrite grain "cores"; Number Three vein longitudinal section 136 Contour plo t of As/(As+Sb+Bi) for Tetrahedrite grain "rims"; Number Three vein longitudinal section 137 Contour plotof Weight Percent Bismuth i n Tetrahedrites; Number Three vein longitudinal section 138 Ag/(Ag+Cu) vs. As/(As+Sb+Bi) p l o t S i l v e r Queen Tetrahedrites 145 Bi atoms vs. Sb atoms p l o t S i l v e r Queen Tetrahedrites 146 Bi atoms vs. As atoms p l o t S i l v e r Queen Tetrahedrites 147 Schematic diagram of environment of tetrahedrite deposition i n a vein breccia 152 Log ag2~Log aQ2 diagram showing the s t a b i l i t y f i e l d s of common hydrothermal minerals i n the presence of quartz 177 Log aQ2 -P H diagram showing common hydrothermal mineral s t a b i l i t i e s at 250° C and Log t o t a l s u l f u r of -3 178 Log ao2~PH diagram showing s t a b i l i t y f i e l d s of common hydrothermal minerals and arsenic species at a temperature of 250° C and Log t o t a l s u l f u r of -2 179 Log ag2-Temperature diagram for selected s u l f o s a l t s u l f i d a t i o n curves 181 Textural properties i n d i c a t i v e of degree of saturation 188 x i i LIST OF FIGURES cont'd page Figure 5.3.2 S o l u b i l i t y of barite contoured on a Temperature-salinity diagram, showing predicted t r a j e c t o r i e s for b o i l i n g and mixing 189 Figure A - l Surface sample s i t e s , S i l v e r Queen mine area i n pocket Figure A-2 Longitudinal section of Number Three vein showing Sample s i t e pos i t ions. 232 Figure B - l Paragenetic diagrams for mineralized structures at S i l v e r Queen mine (excluding Number Three vein) 233 x i i i Figure 3.2.1 Figure 3.4.1 Figure 3.4.2 Figure 3.4.3 Figure 3.4.4 Figure 3.4.5 Figure 3.4.6 Figure 3.4.7 Figure 3.4.8 Figure 3.4.9 Figure 3.4.10 LIST OF PLATES page Surface exposure of southern part of Number Three vein, at "bend" near Alimak Raise 44 Interlayered Carbonate-Sphalerite vein, northernmost Number Three vein 50 Multiepisodic Quartz mineralization from the southern Number Three vein 51 Brecciated c o l l i f o r m Pyrite (py A), followed by fin e grained intergrown Pyrite (py B) and Quartz (qz) mineralization 51 Colliform low-Fe Sphalerite from the north-central part of the Number Three vein at sample s i t e 3CHN89-87 53 "Chalcopyrite disease" i n Sphalerite from the deep north Number Three vein 53 Intergrown Galena (gn) and Tennantite (tn) on margin of large Sphalerite (si) grain 56 Backscattered electron photomicrograph of Galena (gn) grain from southern Number Three vein 57 Brecciated P y r i t e (py) with l a t e r i n f i l l i n g Tennantite (tn) from south end of Number Three vein 58 Fracture i n f i l l i n g s of Tennantite (tn) i n Chalcopyrite (cpy) from Portal vein Three 59 Backscattered electron photomicrograph of lath-shaped Berryite (ber) grains that have undergone p a r t i a l replacement by Mat i l d i t e (md) 61 xiv LIST OF PLATES cont'd page Figure 3.4.11 Backscattered electron photomicrograph of elongate Berryite (ber) grain replaced along cleavage d i r e c t i o n s by Galena (gn) 62 Figure 3.4.12 Berryite (ber) grain undergoing replacement by Tennantite (tn) along grain margins 63 Figure 3.4.13 Backscattered electron photomicrograph of exsolved Bournonite (bour) i n Galena (gn) from northernmost Number Three vein 65 Figure 3.4.14 Inclusion of Cuprobismutite (cpb) and Cu-Pb-Bi s u l f o s a l t (ss) i n bismuthian Tennantite (tn) 67 Figure 3.4.15 Backscattered electron photomicrograph of unmixing textures i n bismuthian Tennantite (tn) and Bismuthinite (bis) i n Pyrite....68 Figure 3.4.16 Backscattered electron photomicrograph of exsolved Geocronite (gc), Proustite (pr) and an u n i d e n t i f i e d Ag-Sb-Pb s u l f o s a l t (ss) i n massive Galena (gn) .69 Figure 3.4.17 Euhedral Marcasite (mc) from deep north Number Three vein 70 Figure 3.4.18 Electrum (el) i n intergrown Galena (gn) and M a t i l d i t e (md), along the margin of Pyri t e (py) grains 74 Figure 3.4.19 Zoned and brecciated Carbonate (cb A, B, C) from c e n t r a l northern part of Number Three vein 78 Figure 3.4.20 Stage IV C a l c i t e (cc) veining cutt i n g e a r l i e r Quartz (qz) and Sphalerite (si) 79 Figure 3.4.21 Secondary electron image of Svanbergite (sv) grain i n t e r s t i t i a l to P y r i t e (py) 80 XV LIST OF PLATES cont'd page Figure 3.5.1 Backscattered electron photomicrograph of symplectic intergrowths of Pyrargyrite (pyg) and Galena (gn) from northernmost part of Camp veins 91 Figure 3.5.2 Overgrowths of Arsenopyrite (aspy) on bladed phase that has been replaced by Pyrite (py) 92 Figure 3.5.3 Backscattered electron photomicrograph of Pyrrhotite (po) and Pyrite (py) that have replaced bladed mineral 93 Figure 3.5.4 Bladed Barite (ba) i n matrix of manganoan Carbonate (cb) and v u g - i n f i l l i n g Quartz (qz) 96 Figure 3.5.5 Broken Pyrobitumen (pybit) mass i n manganoan Carbonate (cb) and Arsenopyrite (aspy) from sample s i t e 3CHN89-15 (Appendix A) on Camp veins 97 Figure 3.5.6 Cross-sectional slab of Mae Three vein 99 Figure 3.5.7 Argentian Tetrahedrite (tt) pods, with Sphalerite (si) and Galena (gn) i n a Barite (ba) matrix 99 Figure 3.5.8 Backscattered electron photomicrograph of large Electrum (el) grain i n intergrown Galena (gn) and M a t i l d i t e (md) from sample s i t e 2CHN89-4 (Appendix A), Portal vein Three 100 Figure 3 . 5 . 9 Polished section of t y p i c a l Number Five vein material, showing inward growth of Sphalerite ( s i ) , Chalcopyrite (cpy), and Quartz+sulfosalts (qz, ss) episodes 103 Figure 3.5.10 Intergrown Galena (gn) and M a t i l d i t e (md) exsolved from Pb-Bi s o l i d s olution 104 x v i LIST OF PLATES cont'd page Figure 3.5.11 Backscattered electron photomicrograph of Berryite (ber) laths i n Gustavite (gs) matrix, with Galena (gn) replacing both phases along cleavage directions 105 Figure 3.5.12 Backscattered electron photomicrograph of zoning i n Portal vein Three Carbonate 106 Figure 3.5.13 Late stage (Stage IV) pyrobitumen (pybit) from Portal vein Three 107 Figure 3.5.14 Cross-sectional slab of Portal vein Four, showing "breccia" nature of mineralization 110 Figure 3.5.15 Well layered Carbonate (cb), Sphalerite ( s i ) , and Galena (gn) from cenral Cole vein, sample s i t e 1CHN89-12 (Appendix A) I l l Figure 3.5.16 Crustiform growth of Arsenopyrite (aspy) over pre-existing bladed phase that has been replaced by aspy, Pyr i t e (py), and Galena (gn) 112 Figure 3.5.17 Backscattered electron photomicrograph of symplectic intergrowths of Galena (gn) and A i k i n i t e (aik) i n t e r s t i t i a l to Hematite-Magnetite (he-mt) 115 Figure 3.5.18 Inclusion of intergrown Galena (gn) M a t i l d i t e (md), and Electrum (el) i n P y r i t e (py) 116 Figure 3.5.19 Intergrown Galena (gn) and M a t i l d i t e (md) along margin of Pyrite (py) grain, i n matrix of Chalcopyrite (cpy)...116 Figure 3.5.20 Intergrown Pearceite (pc) and Electrum (el) i n Carbonate v e i n l e t c u t t i n g Chalcopyrite (cpy) 119 x v i i LIST OF PLATES cont'd page Figure 4.4.1 O s c i l l a t o r y zoned Tetrahedrite grain from sample s i t e 2CHN89-19 (Appendix A) on the northern Number Three vein at the int e r s e c t i o n of the Bulkley crosscut and the South End d r i f t 127 Figure 4.4.2 Tetrahedrite from sample s i t e 3CHN90-1 (Appendix A) on deep north Number Three vein 128 Figure 4.4.3 Tetrahedrite from sample s i t e 2CHN89-46 (Appendix A) on south central Number Three vein 130 Figure 4.4.4 Tetrahedrite from sample s i t e 3CHN89-5 (Appendix A) on south Number Three vein 131 Figure 4.4.5 Backscattered electron photomicrograph of zonation i n Bismuth contents i n Tetrahedrite from the Number Five vein, sample s i t e 1CHN89-117 (Appendix A) 149 Figure 4.5.1 Layered Sphalerite from sample s i t e 3CHN89-5 (Appendix A), south Number Three vein 156 x v i i i ACKNOWLEDGEMENTS In the course of completing my the s i s , several indivi d u a l s and agencies have provided much appreciated assistance, without which the thesis would have been an im p o s s i b i l i t y . I am e s p e c i a l l y indebted to Dr. A l a s t a i r J. S i n c l a i r for o f f e r i n g me the opportunity to work on the Owen Lake Project, and for his constructive c r i t i c i s m , i nsights, and extraordinary patience that allowed me to complete t h i s work. Dr. Craig L e i t c h and Dr. Margaret (Peggy) Thomson provided much needed assistance i n deciphering the mineralogic story behind the S i l v e r Queen veins and greatly supplemented the evolution of t h i s thesis with t h e i r own work. My thanks also go out to my coworkers X i a o l i n Cheng, Marek Nowak, and Zophia Radlowski for t h e i r suggestions on geology, a l t e r a t i o n , and metal d i s t r i b u t i o n s at S i l v e r Queen. An additional note of thanks for allowing me use of the computing equipment on short notice. P a c i f i c Houston Resources Inc. and New Nadina Explorations Ltd. are thanked for allowing access to the S i l v e r Queen workings and for f i n a n c i a l assistance i n and out of the f i e l d . J . Hutter and W.W. Cummings provided h e l p f u l discussions on the mine area during my stay at S i l v e r Queen mine. Dr. Gerry Carlson i s thanked for his continuing i n t e r e s t and support of the Owen Lake Project, and for h e l p f u l reviews of t h i s report. Dr. Lee Groat i s also thanked f o r he l p f u l last-minute e d i t i n g of t h i s paper. J. Knight and Yvonne Douma provided much-needed technical assistance i n r e l a t i o n to the electron microprobe and scanning electron microscopy work. The mineralogy section of the Owen Lake Project was made possible through a cooperative research grant between the Natural Sciences and Engineering Research Council and New Nadina Explorations Ltd. ( e a r l i e r with P a c i f i c Houston Resources Inc.). 1 1.0 INTRODUCTION 1.1 GENERAL STATEMENT The S i l v e r Queen deposit provides an excellent opportunity to examine a wide v a r i e t y of processes related to the development of an epithermal base- and precious-metal vein system. Despite ongoing exploration and development of the deposit since 1912 (and the occurrence of rare bismuthian s u l f o s a l t species: eg. Harris and Owens, 1973), no previous attempt has been made to systematically i d e n t i f y and categorize the vein mineralogy of the e n t i r e deposit. The aim of t h i s study i s thus to describe i n d e t a i l the vein mineralogy i n order to develop a mine scale paragenetic sequence. An i n t e r n a l l y consistent model of f l u i d composition and mineral deposition i s then presented. 1.2 LOCATION AND ACCESS The S i l v e r Queen (Nadina, Bradina) mine area i s located 35 kilometers southeast of Houston, close to the east shore of Owen Lake i n the Bulkley Valley region of west-central B r i t i s h Columbia (Fig. 1.2.1; l a t i t u d e 54.2 degrees north and longitude 126.4 degrees west). An excellent all-weather forestry road provides access from Houston, and several four-wheel drive accessible roads cross the property. Two gate-controlled d i r t roads also access the northern and eastern sides of the map area (Fig 1.2.1). 2 FIGURE 1.2.1: LOCATION OF THE SILVER QUEEN GOLD-SILVER-LEAD-ZINC-COPPER MINE 3 1.3 HISTORY OF DEPOSITS AND PREVIOUS WORK The his t o r y of development of the S i l v e r Queen mine area i s paraphrased from Marsden (1984), and from subsequent company reports. The property, recently optioned to P a c i f i c Houston Resources Ltd. (at the beginning of t h i s study) and now 100% controlled by New Nadina Explorations Ltd., i s dormant at present. Mineralization at the S i l v e r Queen mine was discovered during a land survey by Jim Holland i n 1912. The area surrounding the well exposed vein mineralization i n the walls of Wrinch canyon subsequently was staked for Dr. H.C. Wrinch and partners of Hazelton, B.C.. The Chisholm Group of claims (to the south) was staked soon a f t e r , with the Diamond Belle Group of claims staked three years l a t e r . The Federal Mining and Smelting group optioned the property i n 1923, completing 500 feet of d r i f t i n g on two adits i n the walls of Wrinch canyon. The property then lay i d l e u n t i l 1928, when F.H. Taylor conceived the Owen Lake Mining and Development Company and combined the three claim groups. Development of the property proceded u n t i l 1930, with the following work completed during that period: 1. ) Construction of roads and camp 2. ) Sinking of the Cole shaft i n order to delineate the continuity of the vein. 3. ) Construction of the 2600' l e v e l E a r l Adit to intersect both the Wrinch (Number Three) and Cole vein systems 4 4.) 1000' of c r o s s - d r i f t i n g to delineate the extent of the Portal veins discovered during creation of the E a r l A d i t . The S i l v e r Queen area was i n a c t i v e u n t i l 1941, when Canadian Exploration Ltd. leased the crown grants from the p r o v i n c i a l government. Limited work was completed i n the period from 1941 to 1963, with Nadina Explorations aquiring the property i n 1963 by staking open ground and an agreement with Canex. A p a r a l l e l program of trenching and surface d r i l l i n g was also c a r r i e d out on the neighbouring claim group near Cole Lake, following i t s a q u i s i t i o n by Frontier Explorations Ltd. i n 1960. The program continued on the series of veins at Cole Lake u n t i l F rontier Explorations Ltd. was succeeded by New Frontier Petroleum Ltd. i n 1977. Nadina r e h a b i l i t a t e d the S i l v e r Queen workings and by 1967 had completed the following work on the property: 1. ) 3500' of trenching 2. ) 1400' of crosscutting and d r i f t i n g on the 2880' l e v e l 3. ) 16 d r i l l holes t o t a l i n g 1600' Kennco optioned the property i n 1967, concentrating on a p o t e n t i a l porphyry copper target associated with the extensive a l t e r a t i o n zone i n the southern portion of the property. Five d r i l l holes penetrated the thick cover of overburden, but f a i l e d to i n t e r s e c t any s i g n i f i c a n t mineralization. Nadina continued work on the property, and by 1971 had completed the following: 5 1. ) 5000' of trenching 2. ) 5060' of underground d r i l l i n g on the Number Three structure. 3. ) 24137' of surface d r i l l i n g on the Number Three and associated systems. 4. ) underground st r i p p i n g and stope preparation. 5. ) 4000' of d r i f t i n g 6. ) s o i l geochemistry, a e r i a l magnetometer, and electromagnetic surveys. In 1971, P a c i f i c Petroleum Resources, Nadina Explorations, and Bralorne Mines formed the Bradina Joint venture. The mine was subsequently hurried into production for 1972, m i l l i n g 192,000 tons of ore at a rate of 350 tons per day. M i l l i n g problems and i n e f f i c i e n t processing methods forced closure of the operation i n 1973. Work was sporadic from 1973 u n t i l 1980, when Nadina reorganized to form New Nadina Explorations Ltd. 8250' of trenching was completed, with d r i l l holes completed on the Number Three and NG3 veins. In 1981, Bulkley S i l v e r Resources continued work on the property, and i n the 1983-84 season, s i x surface holes t o t a l l i n g 3405' were completed. Limited surface d r i l l i n g work on the Number Three and t a i l i n g s pond v i c i n i t i e s continued u n t i l 1986, when Bulkley S i l v e r reorganized to form Houston Metals Corporation. Houston Metals r e h a b i l i t a t e d the workings and ca r r i e d out an extensive surface and underground d r i l l i n g program i n the period from 1987 to 1989. Targets included: 6 1. ) Expansion of confirmed reserves i n the south portion of the Number Three system. 2. ) D r i l l t e s t i n g of the George Lake vein from the newly extended Bulkley crosscut. 3. ) Surface d r i l l i n g on the Cole Lake system. 4. ) Discovery and delineation of the Camp vein system. Extension of the South End d r i f t , construction of a decline to intersect the vein below the 2600' l e v e l , and crosscutting to in t e r s e c t the Number One and Number Two veins, was also completed i n t h i s period. In 1989, Houston Metals (now P a c i f i c Houston Ltd.) continued delineation of reserves i n the high grade portion of the southern Number Three vein. By 1991, f u l l control of the property had reverted to New Nadina Explorations Ltd.. 1.4 PURPOSE AND SCOPE The purpose of t h i s study i s to describe and interpret the mineralogy of the vein systems exposed at the S i l v e r Queen mine and e s t a b l i s h a paragenetic sequence for the major vein systems (Figure 1.4.1). Detailed geologic mapping of the mine area of surface and underground was f i r s t undertaken to characterize the set t i n g of the vein system and provide comparisons with other deposits on a regional scale. Petrographic descriptions further characterized each geologic unit (Leitch et a l . , 1990) and K-Ar is o t o p i c analyses (provided by the University of B r i t i s h Columbia Geochronology Laboratory) produced approximate ages for the l i t h o l o g i e s exposed at S i l v e r Queen. 7 To examine the vein system i n d e t a i l , a t o t a l of 134 surface, 62 underground, and 117 d r i l l hole samples were taken, including 50 vein cross sections of the Number Three/NG3 structure and a number of sections across smaller veins. A t o t a l of about 150 polished t h i n sections and 110 polished sections were examined through r e f l e c t e d and transmitted l i g h t microscopy i n order to characterize the mineralogy and paragenesis of the various vein systems (here defined as veins occurring i n close s p a t i a l association with each other- eg. the Number Three, Footwall, Number One and Number Two veins) present at S i l v e r Queen mine. Scanning electron microscope and electron microprobe analyses of several s u l f i d e phases (tetrahedrite, sphalerite, and s u l f o s a l t s ) was undertaken i n order to i d e n t i f y s u l f i d e phases of uncertain i d e n t i t y and further e s t a b l i s h the paragenesis and environment of ore deposition. The r e s u l t s of the mineralogic studies are part of a broader study concerning geologic setting, mineralogy, a l t e r a t i o n , and deposit evolution of the S i l v e r Queen area. Examples of p a r a l l e l research c a r r i e d out by the Owen Lake Project are included i n Cheng et a l . (1991) and Thomson and S i n c l a i r (1991). 8 2.0 GEOLOGIC SETTING OF THE SILVER QUEEN MINE 2.1 INTRODUCTION AND TECTONIC SETTING S i l v e r Queen mine occurs within a block of Late Cretaceous rocks of the Tip Top H i l l volcanics (Church, 1970; L e i t c h et a l . , 1990)) south of Houston, central B r i t i s h Columbia. The rocks are part of the Buck Creek T e r t i a r y o u t l i e r (Church, 1973), a broad, f a u l t bounded basin containing a number of Late Cretaceous and Eocene volcanic centers (Figure 2.1.1). The ent i r e basin belongs to the S t i k i n e Terrane, which includes : c a l c a l k a l i n e to a l k a l i n e immature volcanic i s l a n d arc rocks of the Late T r i a s s i c Takla Group; subaerial to submarine c a l c a l k a l i n e volcanic, v o l c a n i c l a s t i c and sedimentary rocks of the E a r l y to Middle Jurassic Hazelton Group; Late Jurassic and E a r l y Cretaceous successor basin sedimentary rocks of the Bowser Lake, Skeena and Sustut groups; and l a t e Early Cretaceous to T e r t i a r y c a l c a l k a l i n e continental volcanic-arc rocks of the Kasalka, Ootsa Lake, and Goosly Lake groups (Maclntyre and Desjardins, 1988). Preservation of many of the younger volcanic sequences occurs within grabens, half grabens, and possible cauldron subsidence complexes generated by block f a u l t i n g that was c l o s e l y associated with the eruption of these rocks (Souther, 1977). Well defined i n t r u s i v e b e l t s of Jurassic, Cretaceous, and T e r t i a r y age are also present, with several of the plutons (eg. Glacier Gulch, near Smithers) associated with porphyry copper, stockwork 9 molybdenum, and mesothermal and epithermal base- and precious-metal vein mineralization (Carter, 1981). Armstrong (1988) suggests that the T e r t i a r y plutonic episode spans a temporally narrow period (at most, 45-55 Ma), r e s u l t i n g from a wide subduction-related magmatic arc. 2.2 REGIONAL GEOLOGY 2.2.1 Geologic Setting The S i l v e r Queen mine l i e s on the western margin of the Buck Creek basin, as defined by Church (1973). Church (1973) suggested that the arrangement of known Late Cretaceous and Eocene volcanic centers represented a semi-circular caldera generated structure, with the resurgent center located near the Equity S i l v e r mine (Figure 2.1.1). Church and Barakso (1990) recognized eighteen major geologic units within the basin, ranging i n age from Early Jurassic (Sinemurian) to Miocene. The stratigraphy, including age dates for component units of the Buck Creek basin, i s summarized i n Table 2.2.1 (cf. Church and Barakso, 1990). Oldest rocks i n the Buck Creek basin are a f f i l i a t e d with the Hazelton Group and include an assemblage of gently dipping r e s i s t a n t lavas, pyroclastics and interbedded (and basal) sedimentary rocks. The group i s exposed on the northern, northwestern, and eastern margins of the Buck Creek area and i n several smaller windows eroded into the overlying T e r t i a r y sequences (Church and Barakso, 1990). In the area near Burns Lake, the Hazelton Group i s intruded by the g r a n i t i c Topley Intrusions over an area of about f i f t y square kilometers. FIGURE 2.1.1: GEOLOGY OF THE BUCK CREEK AREA* 11 TABLE 2.1.1: STRATIGRAPHIC UNITS IN THE BUCK CREEK AREA Age/Epoch Formation Lithology MIOCENE 21.4 Ma Poplar Buttes (Tpb) Olivine Basalts EOCENE to 48.2 Ma Buck Creek (KTo) Fine-grained andesitic b a s a l t i c lavas and breccias 48.7 to 54.3 Ma Goosly Lake (KTo) Bladed feldspar porphyritic andesite to trachyandesite lavas 51-52 Ma Goosly Intrusions (KTo) Syenomonzonite-gabbro bodies. Bladed feldspar and amygdular dykes i n S i l v e r Queen area. Burns Lake (KTo) Conglomerates,sandstone and shales 53 Ma Nanika Intrusions (Kg) Gra n i t i c stocks, including Nadina Mtn. UPPER CRETACEOUS 75.5 to Tip Top H i l l 84.6 Ma (KTo) Feldspar-biotite porphyritic andesites and fragmental rocks. Lesser a c i d volcanics 78.7 Ma Bulkley Intrusions (Kg) Mic r o d i o r i t e s i l l s and stocks. Basic to intermediate stocks LOWER CRETACEOUS Skeena Group ( K B ) Conglomerates,sandstone and intermixed f e l s i c fragmental volcanics. L o c a l l y shale or massive r h y o l i t e s JURASSIC Hazelton Group (Jh) Fine-grained andesitic, r h y o l i t i c , and b a s a l t i c lavas and v o l c a n i -c l a s t i c s Telkwa Formation maroon t u f f and t u f f -breccia Topley Intrusions (Jg) Gra n i t i c bodies near Burns Lake •Modified from Church and Barakso (1990) ** " ( ) " correspond to symbols i n Figure 2.1.1. 12 Lower Cretaceous nonmarine and marine sedimentary and volcanic rocks of the Skeena Group unconformably o v e r l i e the Hazelton Group i n the Buck Creek area (Table 2.2.1)(Tipper and Richards, 1976) and are exposed i n a series of small windows i n the Late Cretaceous and T e r t i a r y cover (Church and Barakso, 1990). Exposures of the Skeena Group rocks extend from the v i c i n i t y of Goosly Lake southeast to Francois Lake. The Skeena Group rocks are i n turn unconformably overla i n by Late Cretaceous to Eocene volcanic and sedimentary rocks, informally named the Francois Lake group (Church and Barakso, 1990) (Table 2.2.1). The oldest of the s i x major units and three i n t r u s i v e episodes defined by Church and Barakso (1990) consists of undivided r h y o l i t i c lavas, t u f f s , breccias and related intrusions exposed on the northwest shore of Francois Lake and i n the v i c i n i t y of the S i l v e r Queen mine. The s l i g h t l y younger Tip Top H i l l volcanic rocks o v e r l i e the r h y o l i t e s , with the major exposure occurring on the east side of Owen Lake. Church (1970) considered the body of microdiorite at Mine H i l l to represent the eruptive center of the Tip Top H i l l volcanics, with nearby breccia bodies suggesting proximity to a volcanic vent. The r h y o l i t i c rocks and Tip Top H i l l formation are i n turn intruded by small d i o r i t i c , gabbroic and f e l s i c porphyry intrusions of the Bulkley i n t r u s i v e event (Table 2.2.1). Church and Barakso (1990) also included the Mine H i l l microdiorite with t h i s event and noted the 13 apparent comagmatic r e l a t i o n s h i p between the microdiorite and associated andesitic lavas of the Tip Top'Hill formation. The Nanika Intrusions were emplaced about twenty m i l l i o n years l a t e r (Table 2.2.1) and are represented by two small stocks southeast of the town of Houston, and by the larger Nadina Mountain stock on the west side of Owen Lake. Poorly exposed conglomerates of the Burns Lake formation o v e r l i e the Tip Top H i l l formation, with the p r i n c i p a l exposure occurring north and east of the town of Burns Lake. A series of younger trachyandesitic, trachytic and b a s a l t i c lavas and associated intrusives of the Goosly Lake formation are exposed i n the v i c i n t y of Goosly Lake. Church (1985) suggests that a set of three syenomonzonite stocks with associated dykes, occurring i n westerly alignment between the Equity S i l v e r and the S i l v e r Queen areas, represent an eruptive axis for the Goosly Lake formation. The Buck Creek formation o v e r l i e s the Goosly Lake lavas i n several locations and consists p r i n c i p a l l y of f i n e -grained amygdaloidal lavas and lesser porphyritic lavas and breccias, forming the most widely d i s t r i b u t e d unit i n the Buck Creek area (Table 2.2.1). The unit i s best exposed as t h i n l y layered lava flows on the ridges southeast of town of Houston (Church and Barakso, 1990). Uppermost of the Francois Lake group rocks are r h y o l i t i c and tra c h y t i c rocks of the Fenton Creek formation, exposed i n a small area south of the Morice River and west of the Buck Creek map area. 14 Miocene columnar basalts of the Poplar Buttes formation cap the T e r t i a r y sequence on Poplar Buttes, near the west end of Francois Lake (Church and Barakso, 1990). 2.2.2 Geology of the Owen Lake Area The Owen Lake area i s on the western margin of the Buck Creek basin i n rocks belonging p r i n c i p a l l y to the Late Cretaceous Tip Top H i l l formation. Andesitic lavas, t u f f s , and breccias of the unit form a gently north- to northwesterly-dipping homocline, with the oldest units exposed i n the south. S l i g h t l y older acid intrusives are revealed to the northeast of Owen Lake on Okusyelda H i l l , although Church (1973) considered much of the quartz-s e r i c i t e - p y r i t e altered rocks immediately southeast of the minesite to be of si m i l a r composition. Tip Top H i l l l i t h o l o g i e s also cover much of the southwestern margin of Owen Lake, with a large quartz monzonite stock (dated at 53 Ma by Carter [1981]) and nearby plant f o s s i l - b e a r i n g greywackes and a r g i l l i t e s (Lang, 1929) occurring d i r e c t l y west of the S i l v e r Queen mine at Mount Nadina. Church (1984) also notes large exposures of trachyandesitic Goosly Lake lavas occurring to the south of, and exposed i n the walls of, Riddeck Creek (Figure 2.3.1, i n pocket). The occurrences of Goosly Lake lavas are i n turn over l a i n by amygdular lavas of the Buck Creek formation, which forms a series of prominent c l i f f s bounding the southeastern portion of the Owen Lake v a l l e y . More argillaceous rocks, intruded by 15 r h y o l i t e dykes (possibly related to those on Okusyelda H i l l ) and a small quartz monzonite stock, occur i n the northeastern portion of the Owen Lake area. Ages of units i n the Owen Lake area and associated structure and f a u l t i n g w i l l be discussed i n sections 2.3.2 and 2.3.3. 2.3 GEOLOGY OF THE MINE AREA 2.3.1 Introduction Mineralization associated with the S i l v e r Queen mine i s hosted by rocks of the Tip Top H i l l formation and i s roughly delineated by Emil Creek on the north and Riddeck Creek on the south (Figure 2.3.1). The succession displays a gentle northwesterly dip, with the oldest units exposed i n the south and becoming progressively younger to the north. Leitch et a l . (1990) divided the sequence into f i v e major units and three dyke types, and compared the sequence to rocks described as Kasalka Group occurring within the Tahtsa Lake (Maclntyre, 1985) and Mount Cronin (Maclntyre and Desjardins, 1988) map areas. Armstrong (1988) c l a s s i f i e d the Kasalka type section as l a t e Early Cretaceous age, an age which does not agree with the much younger ages obtained for volcanic units i n the S i l v e r Queen mine area. As a r e s u l t , the informal c l a s s i f i c a t i o n of Church (1984) has been used here when considering the proper s t r a t i g r a p h i c nomenclature for the S i l v e r Queen rocks. Figure 2.3.2 and Table 2.3.1 summarize the stratigraphic relationships present i n the succession at FIGURE 2.3.2: OWEN LAKE STRATIGRAPHY " EBV •Refer to Table 2.3.1 for unit i d e n t i f i c a t i o n s 17 TABLE 2.3.1: STRATIGRAPHIC UNITS OF THE SILVER QUEEN (OWEN LAKE) AREA Epoch Age (Ma) Formation Symbol/Unit Lithology Miocene Eocene 21.4 50.4 51.9 51.3 78.7 70.3 78.3 Poplar Buttes Francois Lake MPBv/ EBv/8 EOv/7a /7 Olivine Basalt Basalt,diabase dykes Trachyandes i t e basalt Bladed feldsp. porphyry dykes -MINERALIZATION /6 Amygdule dykes uKqp/5b uKKp/5a uKKud/5 /4a uKKfp/4 uKKb/3 uKKt/2 uKKc/1 Quartz-eye porph. stocks and dykes Intrusive porph. stocks and s i l l s M i crodiorite Feldspar-b i o t i t e porphyry dykes Feldspar porphyritic andesite Medium to coarse t u f f -breccia Ash, c r y s t a l , and l a p i l l i t u f f Polymictic basal conglom-erate, shale and sandstone interbeds 18 S i l v e r Queen mine. A basal reddish purple polymictic conglomerate (Unit 1) i s ove r l a i n by a fragmental unit ranging from c r y s t a l t u f f (Unit 2) to coarse l a p i l l i t u f f and breccia (Unit 3). This i n turn i s succeeded by a thick feldspar porphyritic andesite flow (Unit 4) and intruded by several small microdiorite s i l l s and stocks (Unit 5) (Leitch et a l . , 1990). The succession i s intruded by a series of Eocene age bladed feldspar porphyritic trachyandesite dykes (Unit 6), fine-grained amygdular dykes (Unit 7), and diabase dykes (Unit 8). Lithologies that are p o t e n t i a l l y c o r r e l a t i v e with the Goosly Lake formation of Church (1973) unconformably o v e r l i e the S i l v e r Queen sequence i n the southern portion of the map area. 2.3.2 Geology and Petrography The s t r a t i g r a p h i c succession defined within the S i l v e r Queen area i s included within the Late Cretaceous Tip Top H i l l Formation, as defined by Church (1984). A more complete description of the units recognized at Owen Lake follows. U n i t 1 A poorly sorted polymictic conglomerate unit forms the basal member of the Tip Top H i l l succession, with i d e n t i f i c a t i o n of the unit i n d r i l l hole, underground workings, and i n a roadcut near the southern end of Owen Lake. The unit i s reddish-brown to purple i n colour and h e t e r o l i t h i c , containing predominantly rounded to subangular white quartz and grey-brown to maroon t u f f and porphyry 19 c l a s t s . Clasts are up to one meter i n diameter and display l i t t l e evidence of si z e grading. The matrix i s predominantly fine sand, cemented by quartz, s e r i c i t e , and i r o n oxides. The lower contact of the unit i s not exposed and i s assumed to be i n f a u l t contact with younger Ootsa Lake Group rocks occurring farther to the south. The upper contact has been intersected i n d r i l l hole and i n underground workings near the center of the property. The contact i s t y p i c a l l y occupied by the i n t r u s i v e porphyry unit (Unit 5A) rather than the c r y s t a l - l i t h i c t u f f unit (Unit 2) and appears conformable, although the former unit i s considered to occur as stocks and s i l l s rather than discrete flows (Leitch et a l . , 1990). U n i t 2 A sequence of f i n e c r y s t a l t u f f s with interbedded laminated t u f f s , ash t u f f s , l a p i l l i t u f f s , and tuff-breccias s t r a t i g r a p h i c a l l y o v e r l i e s the conglomerate uni t i n the S i l v e r Queen area. The unit i s present predominantly i n the southern part of the property (Figure 2.3.1) and has been altered hydrothermally to quartz, s e r i c i t e , and p y r i t e . An estimated thickness of up to 100 m has been measured. A massive, grey to white, strongly altered f i n e c r y s t a l t u f f i s the most widespread li t h o l o g y , grading i n t o a porphyry of s i m i l a r appearance and composition (Leitch et a l . , 1990). Broken phenocrysts and interbeds coarsely fragmental or laminated material suggest that the majority of the unit i s tuffaceous. Outcrops on the east side of the George Lake 20 f a u l t also display interbeds of a very f i n e grained, uniform "ash t u f f " ("Unit 2A" on Figure 2.3.1). The f i n e t u f f beds are dark grey and s i l i c e o u s i n appearance, with angular blocks of either mixed (h e t e r o l i t h i c ) material or larger c l a s t s that are barely distinguishable from the matrix. In the Chisholm vein area (Figure 2.3.1), Unit 2 commonly contains t h i n (10 cm. thick) interbeds of laminated t u f f , displaying near v e r t i c a l dips and soft-sediment deformation features. In the coarser grained lenses up to one meter thick, gentle northerly dips are retained. Thin 'sections of Unit 2 material reveal a l i t h o l o g y consisting of broken (1-2 mm. wide), altered plagioclase r e l i c s , with abundant, probably secondary anhedral quartz grains (0.5 mm. wide) i n a matrix of fine-grained secondary s e r i c i t e , carbonate, p y r i t e , and quartz. The o r i g i n a l mafic component i s unknown due to extensive a l t e r a t i o n of the unit . U n i t 3 Unit 3 consists of a d i s t i n c t i v e coarse fragmental unit that overlies or possibly i s interlayered with the upper part of Unit 2. Large bodies of the unit are exposed to the south of the t a i l i n g s pond area and i n the v i c i n i t y of the Cole vein (Figure 2.3.1). In d r i l l core, the uni t displays subvertical contacts with Unit 4 and Unit 5, suggesting a possible i n t r u s i v e r e l a t i o n s h i p with the surrounding units. This concept i s supported by an apparent decrease i n fragment size and density towards the center of the breccia bodies. Since the subvertical contacts occur with the 21 microdiorite (Unit 5) or feldspar porphyritic andesite (Unit 4 ) f there i s also a p o s s i b i l i t y that the orientation of the contacts i s c o n t r o l l e d by the intrusion of Unit 4 and/or Unit 5 into a pre-existing conformable breccia unit. D r i l l hole intersections from the southern end of the Number Three vein system show conformable contacts between Unit 3 and Unit 4, suggesting that the Unit 3 breccia i s older than the feldspar porphyritic andesite unit (Unit 4). L e i t c h et a l . (1990) suggested that Unit 3 may represent a lahar, c i t i n g the unsorted nature of the c l a s t s and l o c a l l y variable c l a s t l i t h o l o g y . Macintyre (1985) also noted a s i m i l a r unit within rocks i n the Kasalka Range near Tahtsa Lake. In outcrop, the unit commonly forms discontinuous lenses with some suggestion of a gentle northerly dip and apparent conformity with the underlying tuffaceous u n i t . Fragments are generally angular to subangular and up to half a meter across (though generally i n the range from 2 to 5 cm.). For the most part, the fragments are composed of material that i s t e x t u r a l l y s i m i l a r to the feldspar porphyritic l i t h o l o g i e s (Units 4 and 5A), with c l a s t s of t u f f or cherty material l o c a l l y present. The matrix i s highly variable, forming anywhere from almost zero to ninety percent of the rock. In t h i n section, the fragments are found to be composed of strongly altered feldspar porphyry, fin e t u f f , and quartz or quartzofeldspathic rocks, enclosed i n a f i n e tuffaceous matrix (Leitch et a l . , 1990). I d e n t i f i c a t i o n of the o r i g i n a l mineralogy i s d i f f i c u l t , due 22 to intense q u a r t z - s e r i c i t e - p y r i t e + carbonate a l t e r a t i o n that i s associated with many of the breccia bodies. In some loca l e s , such as i n the v i c i n i t y of the Cole veins, hydrothermal breccias i n Units 3, 4, and 5 are also present near the major veins. Unit 4 A t h i c k succession of feldspar porphyritic andesite flows forms the most extensive unit i n the S i l v e r Queen mine area, overlying the older fragmental units and forming much of the outcrop i n the northern portion of the map area. Large exposures occur to the north of Wrinch Canyon, with the e n t i r e unit apparently dipping gently to the northwest. L e i t c h et al. (1990) correlated the feldspar porphyry unit with the Tip Top H i l l volcanics of Church (1970), although minor differences i n the siz e and density of the phenocrysts are noted. In outcrop, Unit 4 i s generally well jointed and weathers to a greyish colour, with well defined feldspar phenocrysts v i s i b l e . The phenocrysts normally display t r a c h y t i c textured flow lamination most e a s i l y v i s i b l e on weathered surfaces. Coarser grained exposures may represent s i l l s and stocks, s i m i l a r to those described i n the type sections of Maclntyre (1985) and Maclntyre and Desjardins (1988). Contacts with the microdiorite unit (Unit 5) tended to be gradational over distances of a few meters, although i n some underground exposures contacts were found to be sharp. 23 Chemically/ the feldspar porphyritic u n i t i s between andesite and dacite (Church, 1973), with the composition sim i l a r to that of the microdiorite u n i t (Unit 5). In t h i n section, Unit 4 i s dominated (up to 40 %) by euhedral, two to three millimeter-long andesine c r y s t a l s with lesser amounts of clinopyroxene and hornblende phenocrysts (1-2 mm.) . Unit 4A Narrow (up to two meters thick) b i o t i t e feldspar porphyritic dykes occur i n scattered l o c a l i t i e s around the S i l v e r Queen mine, the most notable c u t t i n g the lower part of the Unit 4 flow section on the north side of Cole Lake (Figure 2.3.1). L e i t c h et al. (1990) considered the dykes to represent feeders to the overlying Unit 4 flows, commenting on the r e l a t i v e t e x t u r a l s i m i l a r i t y between the two units. The dykes are purplish-grey i n outcrop, with scattered books of black b i o t i t e (up to 3 mm. across) and abundant plagioclase phenocrysts (1-2 mm. across) i n an aphanitic groundmass. Unit 5 Unit 5, also termed the "Mine H i l l microdiorite" crops out i n the v i c i n i t y of the Number Three and Cole Lake vein systems (Figure 2.3.1) and i n several smaller l o c a l i t i e s i n the center of the S i l v e r Queen area. The u n i t occurs as subvolcanic stocks, s i l l s , and dykes and i s chemically s i m i l a r to the feldspar porphyry flow u n i t , the difference being elevated potassium contents within the microdiorite 24 (Church, 1970, 1971). Contacts with the feldspar porphyry unit are generally gradational, but dykes cross-cutting older units have been noted. In outcrop, the microdiorite i s equigranular, lacks flow banding, and displays a f i n e r grain s i z e than the feldspar porphyry. Plagioclase phenocrysts (<1 mm.) and r e l i c mafic minerals (<0.5 mm.) occur within a pink feldspathic groundmass, with primary magnetite present within the less a l t e r e d specimens. Leitch et al. (1990) noted the s i m i l a r i t y of the microdiorite-feldspar porphyry assemblage to rocks observed i n the Kasalka Range (Maclntyre, 1985) near Tahtsa Lake, c l a s s i f y i n g them as lati t e - a n d e s i t e s or dacite according to the c l a s s i f i c a t i o n of Streckeisen (1967; c f . Maclntyre, 1985). In t h i n section, Unit 5 i s quite s i m i l a r to the feldspar porphyry u n i t . O s c i l l a t o r y zoned andesine ( ^ 4 5 - 3 0 from petrographic analysis) i s most abundant, with lesser amounts of euhedral clinopyroxene ( p a r t i a l l y a l t e r e d to c h l o r i t e ) and hornblende r e l i c s (altered to c h l o r i t e ) . Scattered quartz phenocrysts (up to 1 mm.), many displaying late-stage overgrowths of quartz, are also present, although not v i s i b l e i n hand sample. The groundmass consists of f i n e -grained quartz, plagioclase, and potassium feldspar (Leitch et a l . , 1990). Unit 5A A coarse feldspar porphyry unit i s exposed near the southern extent of known mineralization, occurring as bodies up to one kilometer across (Figure 2.3.1) i n the v i c i n i t y of 25 Cole Creek. Intersections within d r i l l hole commonly encounter the unit between Units 1 and 3, although the porphyry i s apparently i n t r u s i v e to both. Much of the unit has been intensely altered to q u a r t z - s e r i c i t e - p y r i t e , r e s u l t i n g i n d i f f i c u l t i e s i d e n t i f y i n g the o r i g i n a l mineralogy. In outcrop, the unit i s massive and pale brown i n colour, with altered phenocrysts commonly weathered out to create a "honeycomb" pattern. The rock i s composed of approximately f i f t y percent s e r i c i t i z e d or saussuritized plagioclase phenocrysts up to f i v e millimeters across and often glomeroporphyritic, with lesser amounts of smaller alt e r e d mafic r e l i c s i n a f i n e feldspathic groundmass (Leitch et a l . , 1990). The coarse grained nature and lack of flow banding d i s t i n g u i s h Unit 5A from Units 4 and 5, although a l l three are apparently related to the same magmatic event. Leitch et al. (1990) noted the s i m i l a r i t y to rocks near Tahtsa Lake (Macintyre, 1985) and considered Unit 5A to represent a subvolcanic or int r u s i v e body that was emplaced below or postdates the feldspar porphyry unit . Unit 5B Quartz-feldspar porphyritic rocks c l a s s i f i e d as "Okusyelda" dacite (rhyolite) by Church (1970) occur i n scattered l o c a l i t i e s near the S i l v e r Queen mine. The largest body outcrops on the h i l l s i d e north of Emil Creek (Figure 2.3.1) and i s apparently part of a larger subvolcanic stock. Dyke-like bodies were also found near Cole Creek and i n d r i l l holes located near the southern portions of the Number 26 Three and George Lake veins. Contacts with Units 4 and 5 are uncertain, although i t appears to be i n t r u s i v e into Unit 4. Church (1984) suggested a possible c o r r e l a t i o n between the quartz porphyry unit and acid volcanic rocks i n the eastern part of the Buck Creek area; however, L e i t c h et al. (1990) noted a s i m i l a r i t y to i n t r u s i v e rocks i n the Kasalka Range dated at 76 Ma and thus considered the quartz porphyry unit at Owen Lake to be younger than the encapsulating microdiorite (Unit 5) and feldspar porphyritic andesite (Unit 4). Unit 5B i s believed to be pre-mineralization since i t i s cut by a thick c a l c i t e vein i s the bed of Emil Creek and has undergone q u a r t z - s e r i c i t e - p y r i t e a l t e r a t i o n i n the southern portion of the S i l v e r Queen area. Thin section analysis by L e i t c h et al. (1990) found that the quartz porphyry unit i s distinguishable by the presence of ten to f i f t e e n percent quartz phenocrysts (up to 2 mm. across). Euhedral andesine plagioclase crystals and smaller r e l i c mafic grains are also present, set i n a groundmass consisting of equal amounts of quartz, plagioclase, and potash feldspar. Quartz and lesser plagioclase were also noted as angular fragments and/or shards. Unit 6 Unit 6 consists of series of v a r i a b l y amygdaloidal dykes that are c l o s e l y associated with the major areas of mineralization. Individual dykes are up to 15 meters across and most frequently p a r a l l e l the northwest trending vein 27 systems (eg. Number Three system), although east, northeast, and north-trending dykes were also found. The dykes may also be highly i r r e g u l a r and anastomosing i n form, with dips ranging from subvertical to nearly f l a t l y i n g . The l a t t e r example i s p a r t i c u l a r i l y evident i n dyke exposures on the h i l l s i d e above the S i l v e r Queen camp, where several dykes up to ten meters i n thickness display northeasterly dips i n the 20° to 40° range (Figure 2.3.1). Workers at both the S i l v e r Queen mine and the Equity S i l v e r mine have i n past referred to the amygdular dykes as "pulaskite", although t h i s term i s inaccurate due to i t s compositional implications. Amygdular dykes may be highly weathered i n surface exposure, r e s u l t i n g i n d i f f i c u l t i e s i n i d e n t i f i c a t i o n . Weathered surfaces are generally purplish to greyish-brown in; colour, with the softer, carbonate-bearing amygdales often weathered out on surface. Fresh dyke material from underground exposures i s dark greyish i n colour i n the center of the dykes, paling to l i g h t brown or creamy colour towards the c h i l l e d dyke margins. In some cases, the narrowness (less than two meters) of the dyke re s u l t s i n the entire dyke lacking amygdales and the darker grey colour. Highly a l t e r e d examples were noted where associated with vein mineralization, and sulfide-bearing v e i n l e t s were frequently noted to cut the dykes. Amygdules are most frequently c a l c i t e , with iron oxide mineralogies also noted,; i n d i v i d u a l amygdules may be up to two centimeters across. L e i t c h et al. (1990) noted that the long axes of amygdales 28 commonly p a r a l l e l e d the dyke walls, thus a s s i s t i n g i n determination of the dyke orientation. However, i n the larger dykes, amygdale orientations were found to be random. In t h i n section, Unit 6 consists predominantly of fine grained (0.25 mm. or l e s s ) , trachytic textured feldspar m i c r o l i t e s within an aphanitic matrix that i s commonly altered to s e r i c i t e and carbonate. These dykes appear to be t r a n s i t i o n a l to bladed feldspar trachyandesitic dykes (Unit 7) both t e x t u r a l l y and geochemically. Unit 7 Bladed feldspar trachyandesite dykes of Unit 7 are s p a t i a l l y c l o s e l y associated with amygdular dykes and mineralization. The dykes generally s t r i k e northwesterly and have steep to subvertical dips, with rough orientations commonly maintained f o r distances of one kilometer or more. Thicknesses range from less than one meter to f i v e meters. In outcrop, Unit 7 i s distinguishable by the presence of trachytic textured plagioclase laths up to one centimeter i n length set i n a dark greyish-brown groundmass. Less abundant clinopyroxene phenocrysts up to s i x millimeters across are also present (eg. Bear vein locale-see Figure 2.3.1). Underground exposures of the dykes display pale brownish c h i l l e d margins s i m i l a r to those of the amygdular dykes, but unlike the Unit 6 dykes, appear to post-date mineralization and cut the major mineralized structures. No s i g n i f i c a n t a l t e r a t i o n or cross-cutting v e i n l e t s were noted within the Unit 7 dykes. 29 Thin section analysis reveals a groundmass composed of feathery, i n t e r l o c k i n g plagioclase microlites with i n t e r s t i t i a l quartz, a l k a l i feldspar, opaques, and s k e l e t a l r u t i l e (?) (Leitch et a l . , 1990). Plagioclase phenocrysts are strongly o s c i l l a t o r y zoned i n t h i n section, ranging from andesine (Ansg) cores to o l i g o c l a s e (An^) rims. The clinopyroxene phenocrysts are probably i r o n - r i c h , as indicated by t h e i r strong green colour. Church (1971, 1973) determined trachyandesitic compositions for the Unit 7 dykes at S i l v e r Queen mine and s i m i l a r rocks associated with the Goosly Intrusions near the Equity S i l v e r mine. Both Unit 6 and Unit 7 appear to be r e l a t e d to i n t r u s i o n of the Goosly stocks, a concept that i s supported by age dates from the S i l v e r Queen dykes as described i n Section 2.3.3. Unit 8 A series of diabase dykes forms the youngest unit within the immediate v i c i n i t y of the S i l v e r Queen mine, with perhaps the best example exposed i n the walls of Wrinch canyon (Figure 2.3.1). The dykes are less abundant than Unit 6 or Unit 7, but tend to concentrate i n the v i c i n i t y of major mineralized structures and display northwest or east-west s t r i k e s and subvertical dips. Orientations and thicknesses (up to f i v e meters) tended to display a greater degree of consistancy along s t r i k e than dykes of Units 6 and 7. In outcrop, the dykes are generally topographically 30 rai s e d r e l a t i v e to the surrounding rock, and are dark brown to blackish i n colour. Thin section analysis confirmed the presence of diabasic-textured plagioclase i n a clinopyroxene matrix, with accessory opaque minerals (Leitch et a l . , 1990). The dykes dis p l a y no evidence of a l t e r a t i o n or cross-cutting by mineralization. Although the diabase dykes appear to be much younger and fresher than the amygdular and bladed feldspar dykes, age dates obtained for the three units suggest a close temporal relationship (Section 2.3.3). 2.3.3 Geochronology Several of the units present at the S i l v e r Queen mine were analyzed by whole rock K-Ar i n order to determine p o t e n t i a l c o r r e l a t i o n s with regionally described stratigraphies. Analyses were completed by J. Harakal and D. Runkle of the University of B r i t i s h Columbia; rocks were analyzed for potassium by atomic absorption using a Techtron AA4 spectrophotometer and argon by isotope d i l u t i o n using an AEI MS-10 mass spectrometer and high p u r i t y ^ A r spike. Samples were chosen on the basis of lack of v i s i b l e a l t e r a t i o n (including retention of magnetic character) and representation of the i n d i v i d u a l units. Results are summarized i n Table 2.3.1. 31 TABLE 2.3.2 Summary of whole rock potassium-argon data for rocks i n the v i c i n i t y of the Silver Queen mine, central British Columbia. Sample Site Unit/Lithology Date Obtained 2CHN89-16 Ma Unit 5 microdiorite 78. 7 ± 2.7 1CHN89-47 Ma Unit 4 feldspar-porphyritic andesite (minor b i o t i t e ) 78. 3 + 2.7 1CHN89-15 Ma Unit 4A f e l d s p a r - b i o t i t e porphyritic dyke 70. 3 + 2.5 1CHN89-110 Unit 7 feldspar-porphyritic trachyandesite dyke 51. 9 ± 1.8Ma 2CHN89-14 Unit 6 amygdular trachy-andesite dyke 51. 3 + 1.8Ma 1CHN89-89 Unit 8 diabase dyke 50. 4 + 1.8Ma A sample of Unit 5B was also recovered for U-Pb analysis from an exposure i n Cole Creek (Figure 2. 3.1). A zircon separate was made, with possible contamination induced by the presence of t i t a n i t e ( ? ) i n the heavy mineral f r a c t i o n . Chemical d i s s o l u t i o n and mass spectrometry procedures (see Krogh, 1973) were c a r r i e d out by Janet Gabites of the University of B r i t i s h Columbia, with the isotopic composition of common Pb following Stacy and Kramers (1975). Decay constants used were those recommended 32 by the IUGS Subcommision on Geochronology (Steiger and Jager, 1977). A 206PJ3/238TJ date yielded by the fine zircon f r a c t i o n was 84.6+0.4 Ma, with an upper l i m i t (determined through least squares analysis) of 95+26 Ma. 207/235 and 207/206 dates were found to be more affected by the presence of common Pb, and are thus less precise than the 206/238 date. Ages obtained for the feldspar porphyritic andesite flow (Unit 4) and f o r the microdiorite (Unit 5) agree f a i r l y c l o s e l y with values of 77.1 + 2.7 to 75.5 + 2.0 Ma obtained by Church (1973) fo r the Tip Top H i l l formation between the Equity S i l v e r mine and the Owen Lake area. More importantly, the s i m i l a r i t y i n ages and compositions between the microdiorite and feldspar porphyry support the notion that the former may represent a subvolcanic equivalent to the andesite flows. Church (1984) included strongly altered rocks i n the southern portion of the S i l v e r Queen area within a lower acid volcanic unit s t r a t i g r a p h i c a l l y below the Tip Top H i l l formation, but Leitch et a l . (1990) have suggested that these may, i n part, be altered equivalents of the Tip Top H i l l andesites, with the quartz porphyry in t r u s i o n on Okusyelda H i l l belonging to a l a t e r period of plutonism (see below). Rare b i o t i t e - f e l d s p a r porphyritic dykes (Unit 4A) from the Owen Lake area produced a s l i g h t l y younger whole rock K-Ar age (70.3 + 2.5 Ma) than that for the Tip Top H i l l yolcanics (78 Ma) i n the same area, although the appearence of these dykes i s suggestive of a 33 possible comagmatic re l a t i o n s h i p with the Tip Top H i l l formation. However, the p o s s i b i l i t y that the dykes represent a minor intrusive episode undocumented i n the Buck Creek area can not be ruled out. The U-Pb date of 84.6 + 0.4 Ma obtained for zircons from a dyke of Unit 5B cutt i n g Unit 2 fragmental rocks i n Cole Creek constrains the age of the fragmental rocks at the base of the Tip Top H i l l sequence. Intrusion of the quartz porphyry unit i s probably associated with the same magmatic event that produced the more voluminous feldspar porphyritic andesites and microdiorite. The greater degree of uncertainty associated with the K-Ar dates and the f a c t that K-Ar dates are commonly s l i g h t l y less than the true age, raises the p o s s i b i l i t y of an even greater age f o r Units 4 and 5, with Unit 5B post-dating the volcanic s e r i e s . This p o s s i b i l i t y might explain the apparent i n t r u s i v e r e l a t i o n s h i p between Units 4 and 5A i n the northern part of the S i l v e r Queen map area (Figure 2.3.1). The trachyandesitic dykes of Units 6 and 7 c l o s e l y bracket the period of mineralization i n the S i l v e r Queen mine; altered (near veins) amygdular dykes give a whole rock K-Ar age of 51.3 + 1.8 Ma, while unaltered bladed feldspar dykes produced an age of 51.9 + 1.8 Ma. Consequently, mineralization probably occurred between 51 and 52 Ma and may have been driven by i n t r u s i v e a c t i v i t y associated with e i t h e r the Goosly or the Nanika intrusions. The former c l o s e l y resembles the dyke units at S i l v e r Queen mine, 34 t e x t u r a l l y , chemically and geochronologically. Church (1973) obtained b i o t i t e separate K-Ar ages of 49.7 + 3.0 and 50.3 + 1.5 Ma for s i m i l a r rocks i n the Goosly and Parrott Lakes areas. A date of 50.4 + 1.8 Ma for a diabase dyke i n the S i l v e r Queen area suggests that Unit 8 may also correlate with the Goosly intrusions. Church and Barakso (1990) note the presence of minor amounts of basalts within the Goosly volcanics that may represent extrusive equivalents to the diabase dykes. The Nanika intrusions, represented by the 53 Ma stock at Mount Nadina (Carter, 1981) may also have contributed to providing the "heat engine" for mineralizing solutions at S i l v e r Queen. No equivalents to the Buck Creek formation, dated by whole rock K-Ar at 48.2 + 1.6 Ma (Church, 1973), the Fenton Creek formation, dated by whole rock K-Ar at 48.9 + 1.7 Ma (Church, 1973b), or the Poplar Buttes volcanics, dated by whole rock K-Ar at 21.4 ± 1.1 Ma (Church, 1973), have been recognized at S i l v e r Queen. A p o s s i b i l i t y exists that the diabase dyke unit (Unit 8) may i n fact be c o r r e l a t i v e with the Buck Creek formation, although the age date available more c l o s e l y matches that of the Goosly intrusions. The volcanic succession at the S i l v e r Queen mine has been compared to s i m i l a r rocks occurring within the Tahtsa Lake area (Leitch et al. (1990). However, whole rock K-Ar ages of d a c i t i c l a p i l l i t u f f s of 108 to 107 + 5 Ma, and l a t e r intrusions at 8 7 + 4 to 83.8 + 2.8 Ma (Maclntyre, 1985), are much older than rocks from the Owen Lake area. As 35 a r e s u l t , the l i t h o l o g i e s at S i l v e r Queen w i l l be termed "Tip Top H i l l formation" according to the c l a s s i f i c a t i o n of Church (1984). 2.3.4 Structure The stratigraphy i n the S i l v e r Queen mine area forms a gently northwest-dipping homocline, with l i t t l e evidence of foldin g at the scale mapped. U p l i f t i s apparently the r e s u l t of block f a u l t i n g , l o c a l l i z e d on a series of northwest trending, easterly-dipping f a u l t s that apparently pre-date mineralization. Slickensides i n underground exposures of the f a u l t associated with the Number Three vein indicate that u p l i f t (reverse faulting) of the eastern (hangingwall) sides of the f a u l t s has occurred. Furthermore, the hangingwall l i t h o l o g i e s that are exposed on surface seem to occupy s t r a t i g r a p h i c a l l y lower positions than the footwall rocks. L i t t l e or no horizontal movement along the northwest-trending f a u l t s i s indicated. A second set of f a u l t s , trending i n a northeasterly d i r e c t i o n with possible moderate northerly to subvertical dips, i s also present i n the Owen Lake area. The f a u l t s , represented by the Wrinch Creek and Cole Creek structures . (Figure 2.3.1), display predominantly horizontal movement that post-dates mineralization. M. Thomson (pers. comm., 1991) has suggested that movement along these f a u l t s may have been i n i t i a t e d along a pre-existing structure, possibly a j o i n t plane, since veins interpreted to f i l l j o i n t s i n 36 Wrinch Canyon are subparallel to the i n f e r r e d f a u l t plane. Slickensides and o f f s e t dykes indicate that both r i g h t -l a t e r a l and l e f t - l a t e r a l s t r i k e - s l i p motion has taken place along the Wrinch Creek f a u l t , with no associated v e r t i c a l movement. L e f t - l a t e r a l s l i p , r e s u l t i n g i n o f f s e t of the Number Three vein i n the south, i s i n f e r r e d to have occurred along the Cole Creek f a u l t . Church and Barakso (1990) noted that slickensides along north- and northwesterly s t r i k i n g fractures i n the v i c i n i t y of Mine H i l l displayed evidence of l a t e r a l motion, although the amount of movement i s generally infer r e d to be s l i g h t . 2.4 CHARACTER OF VEINS Mineralization at the S i l v e r Queen mine occurs as f i s s u r e - f i l l , base- and precious-metal veins that dominantly follow northwest-trending f a u l t zones. Less commonly, veins are oriented approximately east-west. The Number Three vein (Figure 2.3.1) i s the largest and most economically important of the known structures at S i l v e r Queen mine, with a s t r i k e length of over 1,500 meters and a probable continuation i n the d r i l l - h o l e - d e l i n e a t e d NG3 vein south of Cole Creek. The vein i s highly variable i n thickness, grade, and textures; i n some s i t e s the vein consists of a single mineralized structure with inward crustiform mineral growth, while i n other s i t e s the vein may anastomose and be associated with both bre c c i a t i o n of the host rock and inte r n a l b r e c c i a t i o n of the vein material. The greatest widths of the structure are present within the cental 37 segment of the vein, around and to the south of the Bulkley crosscut. In t h i s segment, vein margins are often i n d i s t i n c t due to extensive b r e c c i a t i o n of the wallrock accompanied by qu a r t z - s e r i c i t e - p y r i t e a l t e r a t i o n of the fragments. Multiple veining i s present throughout; i n the southern section of the Number Three vein, several mineralized structures have been-defined i n the hangingwall and footwall rocks. The Number Three vein also displays substantial deviations from the northwesterly s t r i k e . Near the Alimak r a i s e on the southern part of the vein, the structure bends abruptly towards the east f o r a distance of several hundred meters before encountering the Cole Creek f a u l t (Figure 2.3.1). The vein i s interpreted to have been l e f t l a t e r a l l y o f f s e t (with an unknown v e r t i c a l component) by the f a u l t , with the continuation represented by the NG3 vein. L e i t c h et al. (1991) considered that the change i n d i r e c t i o n on the vein may be due to o f f s e t by a splay from the Cole Creek f a u l t , but re-examination of surface exposures suggest that the change may simply be due to the mineralization switching from one j o i n t set to another. Leitch et al. (1991) also noted a possible en echelon character for the Number Three system and for other veins, r e s u l t i n g i n variable thicknesses i n d r i l l intersections along s t r i k e and down dip. Thomson and S i n c l a i r (1991) propose an o r i g i n for the Number Three vein as a primary f a u l t plane, with associated smaller veins occurring along conjugate shear and extension planes. Movement along the j o i n t planes i s interpreted to 38 have been governed by i n f l a t i o n and d e f l a t i o n of the rock mass as magmas were i n t r u d e d . The m u l t i - e p i s o d i c nature o f w a l l r o c k and ore b r e c c i a s i n the Number Three v e i n was generated by t h i s movement, and c o n t r i b u t e d t o the r e -openning of f r a c t u r e s d u r i n g m i n e r a l i z a t i o n . A number of s m a l l e r v e i n s and v e i n systems are a s s o c i a t e d w i t h the main Number Three system ( F i g u r e 2.3.1). The George Lake v e i n occupies a prominent northwest t r e n d i n g lineament t o the e a s t of the Number Three v e i n and c o n s i s t s of a s e r i e s of v e i n s hosted by a broad (up t o 30 m. wide) f a u l t zone. No s u r f a c e outcrop o f the v e i n i s a v a i l a b l e , a l t h o u g h the v e i n system has been i n t e r s e c t e d i n s e v e r a l s c a t t e r e d d r i l l h o les f o r a d i s t a n c e o f about 900 meters. As w i t h the Number Three v e i n , m i n e r a l i z a t i o n i s dominated by simple base metal s u l f i d e s i n a g u a r t z - c a r b o n a t e - b a r i t e gajngue. C r u s t i f o r m t e x t u r e s are l e s s abundant i n the George Lake v e i n than i n the Number Three system, and i n one s i t e , p o s t - m i n e r a l i z a t i o n f a u l t movement appears t o have r e m o b i l i z e d the s o f t e r s u l f i d e m i n e r a l s . The C o l e Lake system i n c l u d e s a number of s m a l l , m i n e r a l o g i c a l l y d i s p a r a t e v e i n s (Bear, NG6, B a r i t e , C o l e , Cole shear, Lead and Copper) l o c a t e d e a s t of the George Lake 1 system. The v e i n s are up t o one meter wide and i n the case of the Co l e v e i n system extend f o r lengths o f up t o one k i l o m e t e r . The Cole v e i n i s a l s o n o t a b l e f o r the w e l l -developed l a y e r e d nature o f the m i n e r a l i z a t i o n , which has been t r a c e d t o an i n t e r s e c t i o n i n d r i l l h o l e NGF8 ( F i g u r e 39 2.3.1). Networks of mineralized stringers are associated with a l l of the veins i n the Cole Lake area. Three small, but important vein systems occur i n the western and southwestern portion of the S i l v e r Queen mine area. Each i s distinguished by a r e l a t i v e abundance of carbonate and silve r - b e a r i n g s u l f o s a l t s , and by the discontinuous nature of the veining. The Portal veins are perhaps the most numerous, consisting of ten smaller veins and one large system (the Switchback-Number Five system) located near the entrance to the 2600' l e v e l workings. The veins are highly variable i n mineralogy (e.g. see Chapter 3) and thickness, i n places widening to widths of one meter and then pinching out or o f f s e t by f a u l t s a few tens of meters along s t r i k e . Orientations vary from northwesterly to east-west, with dips varying from subv e r t i c a l to 45°. The veins are well layered and i n places vuggy, with l a t e stage s u l f o s a l t s and pyrobitumen i n f i l l i n g the vugs. The Camp vein system occurs immediately to the west of the Portal veins (Figure 2.3.1) and i s known s o l e l y from d r i l l i n g due to a thick cover of overburden i n the immediate v i c i n i t y of the mine camp. The veins are among the most s i l v e r - r i c h on the property and contain e a s i l y v i s i b l e concentrations of s i l v e r s u l f o s a l t s . The veins have been interpreted to have an en echelon form (Leitch et a l . , 1991), with numerous open-space f i l l i n g textures, including a d e l i c a t e layering. A poorly known group of structures occurs to the south of the Camp veins i n the t a i l i n g s pond 40 area, displaying many of the features of the Camp veins, but sub s t a n t i a l l y less s i l v e r - r i c h . A t h i r d major group of veins, the Chisholm system, occurs i n the southwest extremity of the area. The group consists of four highly i r r e g u l a r veins distinguished by the presence of abundant galena and ba r i t e , with l o c a l l y high concentrations of s u l f o s a l t s . Vein widths are up to forty centimeters, with exposed s t r i k e lengths of less than 150 meters. The system i s oriented roughly northwesterly, with dips varying from less than 50° to sub v e r t i c a l . Several other structures are also present i n the S i l v e r Queen area, e i t h e r associated with larger systems (eg. Number One and Number Two veins) or i n i s o l a t e d structures (eg. Church vein). As with the larger systems, textures are dominated by crustiform ingrowth of s u l f i d e and gangue mineralogies, with de l i c a t e layering common. Large areas of thick overburden may also hide other important systems as well as extensions to the known structures. Wallrock a l t e r a t i o n associated with the veins i s most extensive i n the southern part of the S i l v e r Queen area, where a broad zone of q u a r t z - s e r i c i t e - p y r i t e a l t e r e d t u f f s and porphyry i s exposed. Cheng et al. (1991) characterized a l t e r a t i o n associated with mineralization as weak, moderate, and strong. Weakly altered rock i s abundant throughout the S i l v e r Queen area and i s distinguished by extensive a l t e r a t i o n of mafic phenocrysts to c h l o r i t e and plagioclase margins to clays. Moderately altered rock i s l o c a l l i z e d as broad envelopes around veins, with almost complete conversion of primary minerals to s e r i c i t e , i l l i t e , c h l o r i t e , quartz and carbonate. Strongly al t e r e d material best developed adjacent to the vein, with the primary mineralogy completely al t e r e d to quartz, s e r i c i t e , p y r i t e , and carbonate. Width of the zone of strongly altered rock generally decreases towards the north end of the Number Three v e i n (Cheng e t al., 1991). 42 3.0 MINERALOGY AND PARAGENESIS 3•1 Introduction and Scope Mineralization at the S i l v e r Queen mine occurs mainly i n a series of base- and precious-metal veins oriented along northwest-trending f a u l t s . In addition, several smaller veins that s t r i k e i n an e a s t e r l y d i r e c t i o n are present i n the western part of the property. Surface exposure of t h i s second group of veins i s l i m i t e d , with the Camp vein and Twinkle Zone systems (Figure 2.3.1) defined only from d r i l l hole intersections. The Number Three vein, however, i s exposed underground and by extensive surface trenching and i s the largest known mineralized structure i n the area. I t extends more than 1.5 kilometers along s t r i k e , with the southern extension o f f s e t by a l a t e r northeast-trending f a u l t . The o f f s e t portion has been intercepted i n d r i l l holes and l a b e l l e d the NG3 vein, a f t e r the f i r s t d r i l l hole that intersected the structure. The George Lake vein i s east of the Number Three vein, i n a prominent northwest-trending lineament and associated f a u l t zone. Unlike the Number Three vein, the George Lake vein i s not exposed on surface due to the great depth of overburden with i n the recessed lineament trace. D r i l l hole intersections are few and widely spaced, despite the p o t e n t i a l l y large reserves that may be present within the vein. The Cole Lake veins occur further to the east, c o n s i s t i n g of a series of smaller structures trending i n a northwesterly to northerly d i r e c t i o n . The main Cole Lake vein i s the most l a t e r a l l y 43 extensive and best exposed of the veins i n t h i s area, with a probable continuation i n t e r s e c t i o n i n a d r i l l hole ("NGF8"-see Figure 2.3.1) to the north of the Cole Lake area. The veins at S i l v e r Queen are highly variable mineralogically and display abundant crustiform and other open-space f i l l i n g textures. The mineralogies also show important differences between veins that are close s p a t i a l l y . Hence, the veins must be evaluated systematically both mineralogically and paragenetically i n order to better understand the relationships among d i f f e r e n t vein systems on the property and to define the evolution of the large mineralizing system. An important component of the mineralogical study has been the i d e n t i f i c a t i o n and characterization of minerals with economic p o t e n t i a l , an aspect which may a s s i s t i n defining p o t e n t i a l ore processing problems associated with future development. 3.2 Character of Veining The orientations of veins at S i l v e r Queen c l u s t e r into two general d i r e c t i o n s : veins that trend i n a northwesterly d i r e c t i o n , and veins that trend approximately east-west. Leitch et al.(1991) noted that veins d i d not r e t a i n a simple tabular form, but rather anastomose and form multiple veins, s t r i n g e r s , and shear zones. Individual veins within the major systems also display an en echelon-like character, both along s t r i k e and down dip. The discontinuous nature of the veins r e s u l t s i n uncertainty with c o r r e l a t i o n between d r i l l sections and, thus, problems i n ore reserve estimation 44 F i g u r e 3 . 2 . 1 : Surface exposure of southern par t of Number Three v e i n at "bend" near Alimak Raise. Note smaller splay-f i l l i n g conjugate f r a c t u r e o f f of main s t r u c t u r e . 45 (Leitch et al., 1991; Nowak, 1991). Brecciation of wallrock adjacent to the veins i s also widespread and makes determination of the exact borders of the veins d i f f i c u l t . Furthermore, veins l o c a l l y were sealed during one stage of mineralization and then refractured and mineralized during a subsequent stage, leading to asymmetric mineral d i s t r i b u t i o n patterns with concentrations of s u l f i d e s near the hangingwall or footwall of the veins rather than i n the vein cores. The regional j o i n t i n g pattern has been noted to exhibit a strong control on vein orientation, e s p e c i a l l y i n the Number Three system (Thomson and S i n c l a i r , 1991). In p a r t i c u l a r , the abrupt change i n o r i e n t a t i o n of the main structure i n the v i c i n i t y of the decline i n t e r s e c t i o n i s apparently developed as the r e s u l t of control by a conjugate j o i n t set; vein orientation changes by approximately 60° at t h i s point, and a smaller vein continues past the i n f l e c t i o n point (Figure 3.2.1). 3.3 Sampling and Analysis The goal of the paragenetic study of the veins at the S i l v e r Queen mine was to provide as complete a mineral evolutionary summary as possible for the Number Three and associated structures. For t h i s to be done, a series of v e r t i c a l sections through the Number Three vein, and spaced at approximately equal i n t e r v a l s from north to south, was devised and sampled. Four to s i x samples were taken per v e r t i c a l section. Fifty-seven samples (see Appendix A for 46 site s ) were taken from surface, d r i l l hole, and underground intersections on the vein, with i n d i v i d u a l samples composed of complete vein cross sections from each point. Three samples were also taken from d r i l l hole intersections of the NG3 structure, including material from the o r i g i n a l NG3 d r i l l hole. Approximately 60 samples were taken from other veins intersected at the S i l v e r Queen mine, with i n d i v i d u a l samples comparable to those from the Number Three vein. The Camp, Po r t a l , and Cole Lake systems were sampled extensively to define mineralogical trends occurring within these systems (and with nearby systems) and also to take advantage of the r e l a t i v e l y large amount of material a v a i l a b l e . Smaller vein systems, including the Chisholm, "NG4", George Lake, Twinkle Zone, and Church vein were also sampled. The most representative samples were then made into electron microprobe q u a l i t y 1" polished t h i n sections i n order to define the mineralogical trends from hangingwall to footwall i n each section. A number of samples were also selected to evaluate s u l f i d e populations i n the immediate a l t e r a t i o n halo of the p r i n c i p a l veins. Later analyses of the minor veins or of s p e c i f i c s u l f i d e stages were undertaken on polished chips of vein material, with only a perfunctory evaluation of gangue mineralogy. Samples containing anomalous values of Ag,Au, Ga, Ge, and In were also targeted for polished t h i n section analysis i n order to more c l o s e l y appraise p o t e n t i a l mineral hosts f o r these 47 TABLE 3.3.1: MINERAL SPECIES IDENTIFIED AT SILVER QUEEN MINE (th i s study)  PHASE COMPOSITION Ore Minerals P y r i t e FeS 2 Marcasite FeS 2 Arsenopyrite FeAsS Pyrrhotite FeS!_ x Sphalerite ZnS Galena PbS Tetrahedrite C u 1 2 S b 4 S 1 3 Tennantite Cu 1 2As 4S 13 Freib e r g i t e (Cu /Ag)i 2Sb 4S 13 Bismuthinite Bi2S3 Cuprobismutite CuBiS 2 Proustite Ag 3AsS 3 Pyrargyrite Ag 3SbS 3 C o v e l l i t e CuS Chalcocite Cu 2S Chalcopyrite CuFeS 2 Bornite Cu5FeS 4 A i k i n i t e CuPbBiS3 M a t i l d i t e AgBiS 2 Berryite Pb2(Cu fAg)3Bi5Sn Pearceite ( A g , C u ) 1 6 ( A s , S b f B i ) 2 S 1 1 Polybasite ( A g / C u ) 1 6 ( S b / A s ) 2 S 1 i Arsenpolybasite ( A g / C u ) 1 6 ( S b f A s ) 2 S 1 1 Seligmannite PbCuAsS3 Bournonite PbCuSbS3 Gustavite A g 3 P b 5 B i 1 1 S 2 4 Geocronite P b 5 ( A s / S b ) 2 S 8 Acanthite Ag 2S Electrum Ago.3 A u0.7 Oxides Hematite F e 2 0 3 Magnetite F e 3 0 4 Rutile/Anatase T i 0 2 Gancrue Minerals Barite BaS0 4 Hinsdalite (Pb,Sr)Al 3(P0 4)(S0 4)(OH) 6 Svanbergite ( S r / C a ) A l 3 ( P 0 4 ) ( S 0 4 ) ( O H ) 6 Quartz S i 0 2 C a l c i t e CaC03 Mn-siderite (Fe,Mn)C03 Rhodochrosite MnC03 Dolomite MgC03 Bitumen (C,H,0) 48 elements. Ore m i n e r a l s i d e n t i f i e d a t the S i l v e r Queen mine are summarized i n Table 3 . 3 . 1 . 3.4 Number Three v e i n and A s s o c i a t e d v e i n i n g 3 . 4 . 1 Introduction The Number Three v e i n has been i n t e r c e p t e d i n more than 300 d r i l l h o l e s , an underground d r i f t and s u r f a c e t r e n c h i n g . The v e i n v a r i e s i n width from a few c e ntimeters t o g r e a t e r than two meters and g e n e r a l l y has a s s o c i a t e d s u b s i d i a r y v e i n i n g i n the immediately a d j a c e n t w a l l r o c k . The v e i n d i s p l a y s a wide v a r i e t y of t e x t u r e s , from r e p e t i t i v e monomineralic l a y e r i n g ( F i g u r e 3 . 4 . 1 ) i n the n o r t h segment of the v e i n , t o abundant massive p y r i t i c v e i n i n g i n the south. B r e c c i a t i o n of a d j a c e n t w a l l r o c k s i s p e r v a s i v e , w i t h c r u s t i f o r m overgrowths of m i n e r a l s over the e n t r a i n e d fragments not uncommon. Gangue predominates over s u l f i d e s throughout most of the v e i n , w i t h q u a r t z , b a r i t e , hematite, and carbonate forming the b u l k of the gangue assemblage. P y r i t e , s p h a l e r i t e , galena, c h a l c o p y r i t e , and t e t r a h e d r i t e -t e n n a n t i t e are the most abundant s u l f i d e m i n e r a l s , w i t h p y r i t e and s p h a l e r i t e noted i n a l l samples examined. A p o t e n t i a l l i m i t a t i o n of t h i s type of study i s the p o s s i b l e l a c k of r e p r e s e n t i v i t y of samples, r e s u l t i n g from a h i g h degree of m i n e r a l o g i c v a r i a t i o n along the v e i n ; l a r g e -s c a l e m i n e r a l o g i c changes o c c u r over r e l a t i v e l y s h o r t (tens of meters) d i s t a n c e s . As a r e s u l t , p a r a g e n e t i c diagrams w i l l r e f l e c t the average of s e v e r a l c l o s e l y spaced 49 intersections (where available) rather than a single sample s i t e . 3.4 .2 Vein Mineralogy a.) P y r i t e P y r i t e i s the most abundant s u l f i d e phase within the Number Three vein, i n places forming up to 99% of the s u l f i d e assemblage. Several episodes of p y r i t e deposition have been i d e n t i f i e d , the most voluminous of which i s accompanied by quartz. Pyrite-quartz forms the f i r s t episode of mineralization within the vein, i n which p y r i t e occurs p r i n c i p a l l y as f i n e grained anhedral grains (with quartz) that have been brecciated and subsequently surrounded by l a t e r s u l f i d e s (eg. Figure 3 . 4 . 2 ) . In the southern segment of the Number Three vein, p y r i t e commonly exhibits c o l l i f o r m texture that i n places has been brecciated and p a r t i a l l y inverted to marcasite (Figure 3 . 4 . 3 ) . L o c a l l y , as many as three p y r i t e episodes are evident. P y r i t e i s observed most commonly as massive, fine grained material, i n aggregates up to several centimeters across. Towards the north, pyrite i s more common as euhedral grains up to 2 mm across, but i s a smaller proportion of the t o t a l assemblage (less than 5%). P y r i t e grains commonly contain s u b - f i f t y micron inclusions of various minerals. In the southernmost underground exposures of the Number Three vein, fine-grained p y r i t e layers contain replacements (inclusions and rare fracture i n f i l l i n g s ) of chalcopyrite and bornite. Segments of the Figure 3 . 4.1: I n t e r l a y e r e d c a r b o n a t e - s p h a l e r i t e v e i n , northernmost Number Three v e i n . From sample s i t e 2CHN90-2 (Appendix A ) . 51 Figure 3.4.2: M u l t i - e p i s o d i c q u a r t z m i n e r a l i z a t i o n from t h e s o u t h e r n Number Three v e i n . F i n e g r a i n e d "Qz A" has been b r e c c i a t e d , w i t h c o a r s e r "Qz B" e n c r u s t i n g f r a g m e n t s . F o l l o w e d by l a t e r b a r i t e (ba) and g a l e n a (gn) m i n e r a l i z a t i o n . From sample s i t e 3CHN89-24 (Appendix A ) . Figure 3.4.3: B r e c c i a t e d c o l l i f o r m p y r i t e ( p y A ) , f o l l o w e d by f i n e g r a i n e d i n t e r g r o w n p y r i t e (pyB) and q u a r t z (qz) m i n e r a l i z a t i o n . From sample s i t e 3CHN89-3 (Appendix A) on NG3 v e i n . 52 vein that contain hematite include p y r i t e grains that surround specular hematite laths, with p y r i t e or galena commonly replacing a l l or part of the hematite. Inclusions of fine grained p y r i t e have also been observed i n growth zoned quartz grains throughout the vein. In rare cases, p y r i t e has also been observed as minute vermiform inclusions i n tetrahedrite. b.) Sphalerite Sphalerite displays a broad degree of v a r i a t i o n of form i n the Number Three system. I t i s the most abundant s u l f i d e i n the northernmost portions of the vein, where i t forms more than 50% of the s u l f i d e assemblage. Sphalerite from t h i s vein segment i s interlayered with manganoan carbonate (Figure 3.4.1) and generally forms spectacularly coarse grained (up to several cm.), euhedral masses. Farther south, sphalerite i s more abundant as massive to c o l l i f o r m material (Figure 3.4.4) . Sphalerite l o c a l l y i s brecciated and surrounded by carbonates and l a t e r s u l f i d e s i n the central section of the Number Three system. Towards the south, sphalerite i s found most commonly i n pods of massive to layered material up to 10 cm. i n width. Sphalerite i n t h i s portion of the vein occurs i n two forms: as black, resinous grains that contain abundant chalcopyrite and tetrahedrite inclusions, and as paler brown, l o c a l l y growth zoned grains. The l a t t e r v a r i e t y i s more abundant i n the south end and l o c a l l y forms well layered masses up to 3 cm. thick. At the southernmost exposures of the Number Three vein, and i n the 53 Figure 3 . 4 .4 : C o l l i f o r m low-Fe s p h a l e r i t e from the n o r t h -c e n t r a l p a r t o f the Number Three v e i n a t sample s i t e 3CHN89-87 (Appendix A ) . Note l a t e r manganosiderite (cb) v e i n l e t s . Figure 3 . 4 . 5 : "Chalcopyrite disease" i n sphalerite from the deep north Number Three vein. B e r r y i t e (ber) and galena (gn) also present as rounded inclusions i n sphalerite ( s i ) . Note fracture f i l l i n g by chalcopyrite (cpy) i n r i g h t half of photo. From sample s i t e 3CHN89-88 (Appendix A). 54 NG3 vein, sphalerite again becomes the predominant s u l f i d e , forming up to 40-50% of the opaque assemblage. c. ) Chalcopyrite Chalcopyrite i s most abundant i n the segment of vein centered on the Bulkley crosscut, where i t forms up to 30% of the s u l f i d e assemblage. Masses are generally i n t e r s t i t i a l to quartz and/or carbonates and are intergrown with other l a t e r s u l f i d e s . Chalcopyrite i s also present as "chalcopyrite disease", where i t occurs as microscopic inclusions i n sphalerite masses (Figure 3.4.5). The abundance of fracture i n f i l l i n g s of chalcopyrite i n sphalerite, and the l o c a l l i z a t i o n of the inclusions near fractures and along the rims of sphalerite grains suggests a replacement o r i g i n rather than exsolution. Chalcopyrite also occurs along margins between adjacent tetrahedrite and sphalerite grains. Tetrahedrite and chalcopyrite are l i k e l y synchronous, a suggestion supported by the rare occurrence of myrmekitically intergrown chalcopyrite, tetrahedrite, and galena i n the north portion of the vein. Chalcopyrite occurs i n trace amounts i n the southern section of the vein, where i t i s most abundant as inclusions i n p y r i t e , sphalerite, and galena. d. ) Galena Galena i s widely d i s t r i b u t e d i n the Number Three system and i n some intersections forms up to 30% of the s u l f i d e assemblage. The mineral i s most prevalent as a matrix for p y r i t e breccias i n the ce n t r a l and southern sections of the 55 v e i n , and commonly i s c o m p l e x l y i n t e r g r o w n w i t h t e t r a h e d r i t e ( F i g u r e 3 .4 .6 ) . I n t h e n o r t h e r n and s o u t h e r n e x t r e m i t i e s o f t h e Number Three s t r u c t u r e , g a l e n a o c c u r s w i t h s p h a l e r i t e as s u b h e d r a l t o e u h e d r a l g r a i n s up t o 1 mm. a c r o s s . G a l e n a g e n e r a l l y o c c u r s as i r r e g u l a r g r a i n s c o n t a i n i n g s y m p l e c t i c i n t e r g r o w t h s o f Cu-As-Sb m i n e r a l s , most n o t a b l y s e l i g m a n n i t e - b o u r n o n i t e and t e t r a h e d r i t e ( F i g u r e 3 .4 .7 ) . Anomalous Ag and B i c o n t e n t s d e t e r m i n e d t h r o u g h m i c r o p r o b e a n a l y s i s (Appendix C) sug g e s t t h a t i n t e r g r o w t h s o f s i l v e r -b e a r i n g phases may a l s o be p r e s e n t , a l t h o u g h t h e y c o u l d n o t be r e s o l v e d by r e f l e c t e d l i g h t m i c r o s c o p y o r by b a c k s c a t t e r e d e l e c t r o n d e t e c t i o n . I n g e n e r a l , g a l e n a i s a p a r a g e n e t i c a l l y l a t e m i n e r a l and o c c u r s i n a s s o c i a t i o n w i t h 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 . e.) Te trahedr i te The o c c u r r e n c e o f t e t r a h e d r i t e i n t h e Number Three v e i n i s c l o s e l y a s o c i a t e d w i t h t h e p r e s e n c e o f g a l e n a ; t h e two phases a r e commonly i n t e r g r o w n ( F i g u r e 3 .4 .6 ) . T e t r a h e d r i t e i s most abundant i n t h e s o u t h e r n p a r t o f t h e v e i n , where i t o c c u r s w i t h g a l e n a as a m a t r i x f o r b r e c c i a t e d p y r i t e and q u a r t z ( F i g u r e 3 .4 .8 ) . Where a s s o c i a t e d w i t h c h a l c o p y r i t e , t e t r a h e d r i t e commonly o c c u r s i n s e v e r a l forms: as a f r a c t u r e i n f i l l i n g s i n c h a l c o p y r i t e ( F i g u r e 3 .4 .9 ) , as m y r m e k i t i c i n t e r g r o w t h s w i t h g a l e n a and c h a l c o p y r i t e , and as r i m s and re p l a c e m e n t s w i t h f i n e g r a i n e d p y r i t e and m a r c a s i t e . As f r a c t u r e i n f i l l i n g s , t e t r a h e d r i t e commonly d i s p l a y s en e c h e l o n - l i k e forms and i s r a r e l y o b s e r v e d c u t t i n g l a t e 56 Figure 3 . 4 . 6 : Intergrown galena (gn) and t e n n a n t i t e (tn) on margin of l a r g e s p h a l e r i t e g r a i n ( s i ) . From northernmost i n t e r s e c t i o n of NG3 v e i n a t sample s i t e 3CHN89-36 (Appendix A) . 57 F i g u r e 3 . 4 .7 : Backscattered electron photomicrograph of galena (gn) grain from southern Number Three vein. Included are complex intergrowths of seligmannite (sel) and tennantite (tn). Grain i s surrounded by sphalerite ( s i ) . From sample s i t e 3CHN89-5 (Appendix A). F i g u r e 3.4 .8: B r e c c i a t e d p y r i t e (py) w i t h l a t e r i n f i l l i n g t e n n a n t i t e (tn) from south end of Number Three v e i n (sample s i t e 2CHN89-35-see Appendix A ) . 59 Figure 3.4 . 9 : Fracture i n f i l l i n g s of tennantite (tn) in chalcopyrite (cpy) from Portal vein Three. Earlier pyrite (PY) grains are also present in photo. From sample site 3CHN89-70 (Appendix A). 60 s u l f o s a l t phases. Tetrahedrite has also been seen as fracture f i l l i n g s i n sphalerite and p y r i t e i n a l l portions of the vein, and i n the deep part of the northern segment (sample s i t e 3CHN90-1; see Appendix A) tetrahedrite fracture f i l l i n g s cut chalcopyrite fracture i n f i l l i n g s i n sphalerite. In general, tetrahedrite represents among the l a t e s t s u l f i d e - s u l f o s a l t phases. f. ) A i k i n i t e C u P b B i S 3 A i k i n i t e , l o c a l l i z e d i n the Number Three vein near the decline i n t e r s e c t i o n , i s c l o s e l y associated with massive galena and tetrahedrite, and commonly displays "spider web" textures with these two phases. Masses are up to 0.1 mm. across and l o c a l l y form up to 5% of the s u l f i d e assemblage. A i k i n i t e has also been noted i n trace quantities with galena i n the deep NG3 vein. g. ) B e r r y i t e Pb2 (Cu,Ag)3 B i s s l l Harris and Owens (1973) described b e r r y i t e from S i l v e r Queen mine as the f i r s t Canadian occurrence of t h i s mineral. D i s t r i b u t i o n of the unusual Ag-Bi-Cu-Pb phase i s r e s t r i c t e d to the ch a l c o p y r i t e - r i c h , northern part of the vein, with the phase found i n seven sample s i t e s . Berryite generally occurs as lath-shaped grains up to 1 mm long, i n a matrix of chalcopyrite, tetrahedrite, or m a t i l d i t e (Figures 3.4.10 and 3.4.11). Galena replaces b e r r y i t e laths along cleavage di r e c t i o n s i n several of the s i t e s , and tetrahedrite has been noted to rim and replace smaller grains (Figure 3.4.12). The phase forms a maximum of 2-3% of 61 Figure 3 . 4 . 1 0 : Backscattered electron photomicrograph of lat h shaped b e r r y i t e (ber) grains that have undergone p a r t i a l replacement by ma t i l d i t e (md). From sample s i t e 3CHN90-2 (Appendix A) i n north-central segment of Number Three vein. 62 Figure 3.4.11: B a c k s c a t t e r e d e l e c t r o n p h o t o m i c r o g r a p h o f e l o n g a t e b e r r y i t e (ber) g r a i n r e p l a c e d a l o n g c l e a v a g e by g a l e n a ( g n ) . From deep n o r t h p a r t o f Number Three v e i n a t sample s i t e 3CHN89-88 (Appendix A ) . 63 F i g u r e 3.4.12: B e r r y i t e (ber) g r a i n undergoing replacement by t e n n a n t i t e (tn) along g r a i n margins. From deep n o r t h p a r t of Number Three v e i n a t sample s i t e 3CHN89-88 (Appendix A ) . ) I 64 the s u l f i d e assemblage and has also been noted as fracture f i l l i n g s i n sp h a l e r i t e . h. ) Matildite AgBiS 2 M a t i l d i t e has been noted coexisting with bladed b e r r y i t e i n one sample on the Number Three vein (Figure 3.4.10). Masses are up to 0.5 mm. across and appear to be pseudomorphs of an e a r l i e r bladed phase (possibly b e r r y i t e ) . M a t i l d i t e may also be present as sub-microscopic intergrowths i n galena, thus explaining the unusually high Ag and B i contents i n much of the galena. i . ) Seligmannite-Bournonite PbCu(As,Sb)S3 Minerals of the seligmannite-bournonite series are an important, i f dispersed, component of paragenetically late s u l f i d e s . In general, the series occurs as sub-0.1 mm. inclusions and intergrowths i n galena and tetrahedrite (Figure 3.4.7). Inclusions i n tetrahedrite are generally vermiform and r e l a t i v e l y rare, whereas inclusions i n galena are widespread and mostly occur as i n c l u s i o n t r a i n s p a r a l l e l to cleavage d i r e c t i o n s (Figure 3.4.13). The occurrence of myrmekitically intergrown seligmannite-bournonite i n the southern part of the vein suggests that seligmannite-bournonite i s probably the r e s u l t of exsolution from galena. For the most part, t h i s series forms less than 1% of t o t a l s u l f i d e s , increasing to 3-5% i n the v i c i n i t y of the decline i n t e r s e c t i o n . 65 Figure 3.4.13: Backscattered electron photomicrograph of exsolved bournonite (bour) i n galena (gn) from northernmost Number Three vein (sample s i t e lCHN89-83-see Appendix A). 66 j . ) Polybasite, Freibergite, and Pyrargyrite These three phases, found only i n sample s i t e 3CHN89-24 (see Appendix A) i n the south segement of the vein, occur as inclusions or as fracture f i l l i n g s i n the sp h a l e r i t e and have r e l a t i v e l y r e c t i l i n e a r boundaries with each other. Galena i s also associated with these three phases. k.) Bismuthinite and associated Sulfosalts Bismuthinite, cuprobismutite, and a number of u n i d e n t i f i e d Cu-Bi-Pb s u l f o s a l t s were found within bismuthian tetrahedrite (Figures 3.4.14 and 3.4.15) from sample s i t e 3CHN89-3 on the NG3 vein (Appendix A). Bismuthinite was the most abundant of the phases, forming approximately 2-3% of the s u l f i d e assemblage. The other Cu-B i phases were seen i n a single grain i n t e t r a h e d r i t e . Complex intergrowths of bismuthinite and bismuthian tetrahedrite are widespread within the NG3 vein surrounding sample 3CHN89-3, where they occur i n t e r s t i t i a l l y to p y r i t e (Figure 3.4.15). 1.) Proustite and Geocronite Proustite and Geocronite form a s i g n i f i c a n t component i n galena-rich vein material from sample s i t e 3CHN89-1 on the NG3 vein (Appendix A). The two phases occur with an u n i d e n t i f i e d Ag-Pb-Sb s u l f o s a l t as rounded inclusions and myrmekitic intergrowths (Figure 3.4.16) i n massive galena with i n d i v i d u a l grains as large as 0.2 mm across. The phases have been observed together and as separate monomineralic c l u s t e r s , apparently the r e s u l t of exsolution. 67 F i g u r e 3 . 4 . 1 4 : I n c l u s i o n o f c u p r o b i s m u t i t e (cpb) and Cu-Pb-B i s u l f o s a l t ( s s ) i n b i s m u t h i a n t e n n a n t i t e ( t n ) . From sample s i t e 3CHN89-3 on c e n t r a l NG3 v e i n . 2 0 . 0 k U 4 4 n Figure 3.4.15: Backscattered electron photomicrograph of unmixing textures i n bismuthian tennantite (tn) and bismuthinite (bis) i n p y r i t e . Uneven surface appearence i s r e s u l t of r e l a t i v e softness of bismuthinite to p y r i t e gangue. From sample s i t e 3CHN89-3 (Appendix A) on cen t r a l NG3 vein. Figure 3 .4.16: Backscattered electron photomicrograph of exsolved geocronite (gc), proustite (pr), and unidentified Ag-Pb-Sb s u l f o s a l t (ss) i n massive galena (gn). From sample s i t e 3CHN89-1 (Appendix A) on deep NG3 vein. 70 F i g u r e 3 . 4.17: Euhedral marcasite (mc) from deep north Number Three vein (sample s i t e 3CHN89-88; see Appendix A). Matrix i s sphalerite (si) and quartz (qz). 71 m.) Arsenopyrite Arsenopyrite occurs scattered i n r e l a t i v e l y deep parts of the Number Three system, generally as intergrowths with fine-grained p y r i t e , or as coarse-grained aggregates that have been replaced by p y r i t e . Arsenopyrite also encrusts and replaces (with pyrite) specular hematite, but r a r e l y displays the c h a r a c t e r i s t i c diamond-shaped cross-section. I t has not been i d e n t i f i e d i n the southern portions of the vein, or within the NG3 vein, n.) Marcasite Marcasite i s almost u n i v e r s a l l y associated with p y r i t e i n the Number Three system, reaching maximum abundance i n the sections of the vein containing abundant chalcopyrite. Marcasite i s prevalent i n t h i s material as subhedral to euhedral grains (up to 0.5 mm. wide) (Figure 3.4.17) and i s generally replaced by low-Sb tetrahedrite. The mineral has also been found i n the c e n t r a l (eg sample s i t e 3CHN89-102) (Appendix A) section of the vein as c o l l i f o r m to massive aggregates that appear to have replaced p y r i t e and form up to 10% of the s u l f i d e assemblage. Marcasite has not been i d e n t i f i e d within the southernmost sections of the vein, or within the NG3 vein, o.)Electrum Electrum i s one of the most important economic phases within the Number Three system, forming an important repository f o r both Au and Ag i n the vein. In general, the phase occurs i n trace amounts, with approximately 90% of the 72 grains contained i n galena. Electrum i n galena commonly i s associated with fine-grained p y r i t e aggregates (eg. Figure 3.4.18, from the Portal veins). This c h a r a c t e r i s t i c occurrence i s of p a r t i c u l a r importance with respect to b e n e f i c i a t i o n , because much of the gold grades have been l o s t to t a i l s during past e x p l o i t a t i o n (refer to Chapter 6). Electrum has also been i d e n t i f i e d within sphalerite, p y r i t e , chalcopyrite, and tetrahedrite, although i n a l l cases, galena i s associated. Grains t y p i c a l l y are less than 30 microns i n diameter and are rounded to i r r e g u l a r i n form. In one s i t e from the southernmost exposures of the Number Three vein (sample s i t e 2CHN89-35; Appendix A), electrum forms i n f i l l i n g s within early tetrahedrite. p.) Bornite, Chalcocite, and C o v e l l i t e Bornite, chalcocite, and c o v e l l i t e occur within several s i t e s i n the southern part of the Number Three vein, where they occur as sub-0.1 mm si z e inclusions within the outermost growth zones of p y r i t e grains. A l l three phases are apparently primary, with the most unusual feature being the Ag-bearing character of chalco c i t e . Chalcocite and c o v e l l i t e were also i d e n t i f i e d as supergene minerals with manganese oxides at the topographically highest sample s i t e (1CHN89-83; Appendix A), q.) P y r r h o t i t e Pyrrhotite was i d e n t i f i e d i n only two samples within the a l t e r a t i o n halo adjacent to the southern portion of the 73 vein. In both cases, the mineral was found as small (<0.1 mm.) rounded inclusions i n p y r i t e . r.) Hematite and Magnetite Hematite i s l o c a l l y abundant as specularite, t o t a l l i n g up to 10-15% of the mineral assemblage. In general, hematite i s confined to the cen t r a l portion of the vein, i n the area between sample s i t e s 2CHN89-27 and 3CHN89-102 (Appendix A). Masses of specular hematite up to several cm. across are found with carbonate, quartz, and p y r i t e within brecciated wallrock adjacent to the vein. Hematite commonly i s replaced by Fe-sulfides, galena, and carbonate, where i t i s a less important component of the vein. Overgrowths of p y r i t e and arsenopyrite on hematite have also been i d e n t i f i e d . Magnetite i s much rarer within the Number Three vein, occurring as intergrowths with hematite i n a few scattered locales. No trend i n magnetite d i s t r i b u t i o n was recognized, s.) Titanium Oxides Euhedral Ti-oxide phases (eg. r u t i l e ) were noted i n scattered l o c a l i t i e s i n the Number Three system and are presumed to represent oxides scavenged from the adjacent wallrock during mineralization. Grains tend to be less than 20 microns i n s i z e and present i n only trace quantities within the vein, t.) Quartz Quartz i s the most ubiquitous gangue phase within the Number Three vein. Fine-grained, anhedral quartz i s intergrown with p y r i t e and was brecciated during the f i r s t 74 Figure 3.4.18: Electrum ( e l ) i n intergrown galena (gn) and m a t i l d i t e (md), along the margin of p y r i t e (py) g r a i n s . From sample s i t e 2CHN90-9 on P o r t a l v e i n Three. 75 stage of mineralization, with coarser c r y s t a l l i n e v a r i e t i e s occurring l a t e r (Figure 3.4.2). Quartz from the southern part of the Number Three vein i s generally subhedral to euhedral and commonly contains minute p y r i t e inclusions within the outer growth zones of c r y s t a l s . Barite blades and quartz-pyrite breccia fragments commonly are encrusted by a layer of fine-grained (<0.2 mm.) quartz. Much quartz from the c e n t r a l and northern parts of the structure displays drusy and cockscomb textures upon which l a t e r s u l f i d e s have been deposited. Quartz from these sections of the vein are l a t e r paragenetically and much coarser grained than quartz of the south end (up to 1 cm. for cockscomb masses). Very l a t e , fine-grained quartz v e i n l e t s which cut l a t e s u l f i d e s are also present within vein material from the c e n t r a l and northern portions of the Number Three vein, u.) C a r b o n a t e s Several v a r i e t i e s of carbonate minerals occur throughout the Number Three vein, with the greatest abundances occurring i n the north. Grains are sparry and well zoned, with layered material most abundant within the northernmost portions of the vein. Carbonates from the north end are generally Mn-rich (manganosiderite to rhodochrosite), with small amounts of l a t e r c a l c i t e . Manganese-bearing carbonates appear to c o r r e l a t e c l o s e l y with c h a l c o p y r i t e - r i c h veins; therefore, as chalcopyrite decreases to the south, c a l c i t e becomes the main carbonate phase. Carbonates i n the south occur i n several mineralizing 76 episodes; e a r l i e r carbonate i s brecciated and surrounded by l a t e r carbonate and s u l f i d e s (Figure 3.4.19). Zoning within carbonates seems to be due to variations i n Fe-content, with the most an k e r i t i c compositions occurring within the c e n t r a l part of the vein. Farther south, unzoned c a l c i t e i s the dominant carbonate mineral, forming up to 5% of the t o t a l assemblage and, i n several l o c a l i t i e s centered around the decline, occurs i n bladed form with b a r i t e . The southernmost sample of the Number Three vein, and material from the NG3 vein, contain a l a t e r stage c a l c i t e that cuts a l l other phases and l o c a l l y f i l l s breccia spaces (Figure 3.4.20). v.) Barite Barite occurs almost e x c l u s i v e l y i n bladed form and i s most abundant i n the southern part of the Number Three system. Blades are very e a r l y paragenetically and can be up to two centimeters i n length, with s u l f i d e s commonly occurring i n t e r s t i t i a l l y . Barite, l o c a l l y , forms up to 10% of the t o t a l assemblage and i s e s p e c i a l l y prominent i n the vein selvage. Towards the north end, however, b a r i t e i s r a r e l y part of the gangue assemblage; trace amounts were noted at high elevations i n two holes. Thomson et al. (1991) note a paragenetically l a t e b a r i t e phase i n minor veins adjacent to the Number Three system; l a t e b a r i t e was not found by the author i n the main structure. 77 w.) Svanbergite (Sr,Ca)Al 3 (PO4)(SO4)(OH)5 H i n s d a l i t e ( P b / S r ) A l 3 (PO4) (SO4)(OH) 6 Two unusual phosphate phases, svanbergite and hi n s d a l i t e , were noted to form up to 1% of the assemblage i n sample s i t e 3CHN89-5 (Appendix A), where they occur with b a r i t e as tabular grains up to two millimeters across. Several grains display basal sections with a c h a r a c t e r i s t i c a n d a l u s i t e - l i k e e x t i n c t i o n . Material within the NG3 vein i s i n t e r s t i t i a l to early p y r i t e grains and i s d i f f i c u l t to i d e n t i f y without S.E.M. analysis (Figure 3 .4.21). Svanbergite and h i n s d a l i t e were also i d e n t i f i e d i n several intersections from the southermost portions of the Number Three vein, with the former phase noted replacing wallrock plagioclase (Thomson, Pers. Comm.). x.) Pyrobitumen Pyrobitumen was found i n both the northern and southern portions of the Number Three system as i r r e g u l a r masses up to three millimeters across. Material from the north end postdates s u l f i d e mineralization and i s generally v i s i b l e i n hand sample. In the south, pyrobitumen i s apparently contemporaneous with b a r i t e , with which i t i s commonly associated. In both areas, vein pyrobitumen i s at best a minor phase, forming less than 1% of the t o t a l assemblage. 3 . 4 . 3 Paragenesis and Mineralogic Variation M i n e r a l i z a t i o n i n the Number Three system can be divided roughly into four major paragenetic stages (Figure 78 Figure 3.4 .19: Zoned and brecciated carbonate (cb A, B, C) from c e n t r a l northern part of Number Three vein. From sample s i t e 3CHN89-87 (Appendix A). F i g u r e 3 . 4 .20: Stage IV c a l c i t e (cc) v e i n i n g c u t t i n g e a r l i e r quartz (qz) and s p h a l e r i t e ( s i ) . From sample s i t e 3CHN89-36 (Appendix A) on NG3 v e i n . Figure 3 .4.21: Secondary e l e c t r o n image of s v a n b e r g i t e ( g r a i n i n t e r s t i t i a l t o p y r i t e (py), sample s i t e 3CHN89-3 (Appendix A), NG3 v e i n . 81 3.4.22 and Appendix B). Stage I, i n i t i a t e d by fine-grained pyrite-guartz deposition, i s most prevalent i n the central and southern segments of the vein. A second massive p y r i t e -quartz-barite episode commonly followed b r e c c i a t i o n of the e a r l i e r quartz-pyrite stage, with much quartz occurring as a drusy rim on breccia fragments (Figure 3.4.2). Hematite and carbonate are dominant i n the central part of the vein (from sample s i t e 3CHN89-102 to the Bulkley crosscut), with the former phase often associated with extensive brecciation of the adjacent wallrock. Svanbergite, h i n s d a l i t e , pyrobitumen, arsenopyrite, and marcasite are also present within Stage I material. Stage II i s dominated by sphalerite, c a l c i t e , and the manganoan carbonates, commonly with a d i f f u s e boundary with e a r l i e r Stage I mineralogies. Pyrite i s important l o c a l l y i n Stage I I , and i n several s i t e s a c t u a l l y surrounds brecciated fragments of massive sphalerite. Gallium and germanium, enriched e r r a t i c a l l y i n sphalerite, also appear to be associated paragenetically with sphalerite. Quartz, galena, and arsenopyrite are also part of Stage II mineralization i n the c e n t r a l and northern portions of the vein. Minerals from Stage II commonly seal the vein, with re-opening of the vein occurring between Stage II and Stage I I I . Stage III i s dominated by Cu-bearing phases (eg. chalcopyrite and tetrahedrite) and forms re-brecciated sections or stringers c u t t i n g e a r l i e r minerals. Complex s u l f o s a l t s (eg. b e r r y i t e , a i k i n i t e , and polybasite) are TABLE 3.422: PARAGENESIS OF THE NUMBER THREE SYSTEM STAGE IB IV Type at SUntn J U U l Zn-MnGe Ag-Cv-Pb^l quartz aphBlentB araanopy. btiumnn tjarttB ffflitntsiB ihodoctwoo. hotnsttB magnetite estate skkitu utuL bum AMores peace/to-pymgyr. chutoopf. ocannnB tenyita a/praoam. COVBttiB-tarnto boumorito geoaontB AgSbPb-83 l o c a l l y abundant within Stage I I I , and quartz and manganoan carbonate predominate as gangue phases. Stage III i s also important from an economic standpoint; a l l precious metal bearing phases at S i l v e r Queen mine are associated with Stage III mineralization. Tetrahedrite marks the termination of t h i s stage where i t occurs as fracture i n f i l l i n g s i n chalcopyrite (Figure 3.4.9) . Stage IV, minimally present i n the Number Three system, consists of minor fine-grained s i l i c e o u s veining and vein pyrobitumen i n the north part of the Number Three vein, and c a l c i t e veining i n the south segment and NG3 system (Figure 3.4.20). The mineralogy of the Number Three system appears to disp l a y a rough north to south zoning which may r e f l e c t changes i n wallrock composition, f l u i d conditions, and va r i a b l e degree of vein d i l a t i o n during the four stages of mineralization (see Figures 3.4.23 to 3.4.26). Stage I minerals are most abundant i n the v i c i n i t y of the decline i n t e r s e c t i o n (Figure 3.4.23). For the most part, massive pyrite' and b a r i t e are l o c a l l i z e d within the v i c i n i t y of the decline i n t e r s e c t i o n , with a moderate degree of c o r r e l a t i o n with high precious metal grades (Figure 3.4.24). Stage I hematite and carbonate are l i m i t e d to the region around and immediately to the south of the Bulkley crosscut; to the-north of t h i s region, the o v e r a l l abundance of Stage I drops o f f sharply and Stage II dominates (Figure 3.4.23). Arsenopyrite appears to be concentrated i n the lowest parts 84 of the c e n t r a l and northern segments of the vein (Figure 3.4.24). The habit of quartz and p y r i t e also changes from north to south, with coarser grained, euhedral forms becoming increasingly dominant i n the northernmost segment of the vein. Stage II mineralogies are most abundant i n the southernmost and northern parts of the Number Three system, with s p h a l e r i t e everywhere an important component (Figure 3.4.23). Perhaps the most important v a r i a t i o n observed i n sphal e r i t e i s the change from massive or c o l l i f o r m masses i n the south to coarse grained, euhedral grains i n the north. Manganoan carbonates are important i n vein material associated with chalcopyrite and/or hematite, with peak abundance i n the northernmost extremity of the vein (sample s i t e 2CHN90-2; see Appendix A) (Figure 3.4.25). Conversely, c a l c i t e i s r e s t r i c t e d to the region from sample s i t e 3CHN89-98 (Appendix A) south to the decline v i c i n i t y , and has not been observed i n eithe r shallower or deeper parts of the vein. Both p y r i t e and galena are l o c a l l y abundant as Stage II phases. Prevalence of Stage III mineralization i s highly v a r i a b l e , being most abundant near the Bulkley crosscut and i n scattered s i t e s i n the south end of the vein (Figure 3.4.23). In the north, Stage III material i s dominated by chalcopyrite and s u l f o s a l t s such as b e r r y i t e , with the l a t t e r phase r e s t r i c t e d to deep, chalcopyrite-bearing vein material between sample s i t e s 3CHN90-2 and 2CHN89-27 85 (Appendix A) (Figure 3.4.26). Chalcopyrite i s widely dispersed throughout the Number Three system, occurring i n the south as "chalcopyrite disease" i n sphalerite and i n the north as i r r e g u l a r masses i n t e r s t i t i a l to gangue minerals. Chalcopyrite increases from trace amounts near the Bulkley crosscut, northward to where Stage III becomes unimportant (at the very l i m i t of exposed mineralization) (Figure 3.4.26). In the south, galena and tetrahedrite are the •dominant Stage III phases, with a i k i n i t e an i r r e g u l a r part of the assemblage near the decline i n t e r s e c t i o n (Figure 3.4.26). Seligmannite/bournonite series minerals are sporadic throughout the vein. As mentioned previously, the r e l a t i v e l y i n s i g n i f i c a n t Stage IV mineralization i s l i m i t e d to c a l c i t e i n the southernmost Number Three vein, and fine-grained s i l i c a and pyrobitumen i n the northernmost and shallowest parts of the vein. The NG3 vein, possibly a southern extension of the Number Three zone, does not display p a r t i c u l a r mineralogical trends, perhaps due to the paucity of available samples, although material from sample s i t e 3CHN89-36 (Appendix A) i s more or less s i m i l a r to the southermost extremity of the Number Three vein. 3.5 M i n e r a l i z a t i o n i n Other Veins 3.5.1 Camp Vein System The Camp veins (Figure 2.3.1) occur on the west side of the Owen Lake f a u l t and at present are known only from a 00 \RGURE 3.4.24 LONGITUDINAL SECTION OF NUMBER THREE VEIN STAGE I MINERAL ABUNDANCE 1 2 1 4 5 1 4 • 15 O Y 1 3 8 2 1 w O 4 1 2 °r o ° O i— l l_J-14.10,11,13,14 I o ° 9 2 i ^10,11 ± ± 2 8 41 f-2 4 1 12,13 KEY sample site 1 p/ritia 1 ft... .pyrite 2 tarib to. tvanbsrgte a /nsrcos/ts tf—n/nsofefito 4 quartz 1 12 pymbSumen 5..- ftamatfe 13. Thmda a.._. CGltXXTBtB 14 PJpthdOB OTonqpyrito 15. nmyituBki a.._. quartz 2 0 meters 200 co FIGURE 3.4.25 LONGITUDINAL SECTION OF NUMBER THREE VEIN STAGE II MINERAL ABUNDANCE 173 1 2 O O 3 O O o o o o o o ° 1 2 3 M 1 6 >4 2 1 7,3 KEY sample site 1 sp/jaferite Z quartz a pyrite 4 carbonate a. arsenopyrite & betite 7_„. galena 0 meters 200 co co RGURE 3.4.28 LONGITUDINAL SECTION OF NUMBER THREE VEIN STAGE a M1NERALABUNDANCE E W 6 34 X 5 ' 6 4 8,6 4 8 c 9 . I 4 o " 4 3 -1 >-2,6,10 9 4 3 9 -3 5 | '5,11,12,10,6,14 KEY sumpls sito 1 quartz to bonite 2 cftafcopyrfte 11 paarcete-3 fehtofo 4 gatens 12 mbfsSvem 5 .teSgmannltB- 13. sphaterfe boumonrte 14 fterbargite a efectrum 15—geocronfe 7 carbonate 18 HmUBmlB 8 bsnyte 17 cupiobi&iivUbi 9 aftfnrte 18. AfStyPbauBoul 0 meters 200 co 90 series of d r i l l hole intersections completed i n 1987 and 1988. The veins are singular due to t h e i r unusually high Ag grades (commonly) and associated Ag-bearing mineralogy. Delineation of the i n d i v i d u a l veins i s d i f f i c u l t due the lack of surface exposure, but from mineralogy and s t r u c t u r a l information from d r i l l holes, f i v e veins were defined. The northernmost and perhaps most important economically ("Ruby S i l v e r v e i n " ) i s dominated by the presence of Ag-bearing minerals (tetrahedrite, pearcite, and p y r a r g y r i t e ) , l o c a l l y forming up to 10 volume percent of the vein. Complex symplectic intergrowths of these minerals with galena are common (Figure 3.5.1) i n the larger masses, l o c a l l y with l a t e r rims of acanthite. The vein i s also characterized by the "breccia zone" nature of mineralization, with the vein a c t u a l l y f i l l i n g the i n t e r s t i c e s of brecciated wallrock. Wallrock fragments are surrounded by fine-grained, sparry quartz, followed by l a t e r quartz, p y r i t e , b a r i t e , and manganoan carbonate (or less commonly, c a l c i t e ) . Sphalerite i s also present as i r r e g u l a r masses up to three millimeters across. A smaller, l e s s Ag-rich vein occurs to the southeast of the "Ruby S i l v e r " vein described above, near the Number Five vein p o r t a l . Vein material i s dominated by massive manganoan carbonate, with l e s s e r b a r i t e , fine-grained arsenopyrite^ sphalerite, and quartz. P y r i t e commonly displays bladed forms that r e f l e c t an o r i g i n a l arsenopyrite-dominated mineralization that has been almost completely replaced. F i g u r e 3 . 5 . 1 : B a c k s c a t t e r e d e l e c t r o n p h o t o m i c r o g r a p h o f s y m p l e c t i c i n t e r g r o w t h s o f p y r a r g y r i t e (pyg) and g a l e n a (gn from n o r t h e r n m o s t p a r t o f Camp v e i n s (sample s i t e 3CHN89-13 see Appendix A ) . 92 Figure 3.5.2: Overgrowths of arsenopyrite (aspy) on bladed phase th a t has been rep l a c e d by p y r i t e (py). M a t r i x i s manganoan carbonate (cb) and quartz (qz). Note replacement of F e - r i c h zones i n carbonate by a l a t e r a r s e n o p y r i t e m i n e r a l i z a t i o n (arrow). From sample s i t e 3CHN89-15 (Appendix A) on Camp ve i n s . 93 Figure 3 . 5 . 3 : B a c k s c a t t e r e d e l e c t r o n photomicrograph of p y r r h o t i t e (po) and p y r i t e (py) t h a t have r e p l a c e d bladed m i n e r a l . L a t e r a r s e n o p y r i t e (aspy) a l s o p r e s e n t . From sample s i t e 3CHN89-15 (Appendix A) on Camp v e i n s . 94 Minor galena, chalcopyrite, pyrobitumen, pyrrhotite, and an u n i d e n t i f i e d gangue phase are also present as disseminations. The presence of the pyrrhotite and u n i d e n t i f i e d gangue phase bears a marked s i m i l a r i t y to vein material from the "Portal 11.5" vein, described elsewhere (section 3.5.3); abundances of the two minerals suggest that the two occurrences might i n fact be separate parts of a sin g l e vein. Two other veins were defined i n d r i l l core from the westernmost intersections on the Camp vein systems, with the more southerly of the two consisting of r e p e t i t i v e l y layered mangnaoan carbonate with lesser disseminated quartz, p y r i t e , arsenopyrite, and galena. Sphalerite i s l o c a l l y abundant i n layers up to two mm. thick. The northern vein also contains abundant layered carbonate, but i s characterized by the predominance of arsenopyrite and pyrite among the s u l f i d e phases. Euhedral arsenopyrite forms unusual crustiform overgrowths (with pyrite) on a pre-existing bladed phase (probably hematite), that has been replaced by p y r i t e and pyrrhotite (Figures 3.5.2 and 3.5.3), as well as e a r l i e r carbonate, quartz, and even euhedral sphalerite. Arsenopyrite was followed by deposition of galena, chalcopyrite, pearcite, and f r e i b e r g i t e . The end of mineralization was marked by massive pyrite-arsenopyrite deposition followed by a f i n a l carbonate episode. Pyrobitumen and b a r i t e are also part of the gangue assemblage, but are paragenetically e a r l i e r than the 95 majority of the s u l f i d e mineralization (Figures 3.5.4 and 3.5.5) . The f i f t h and southernmost vein to be defined i n the Camp vein system i s distinguished by the dominance of ear l y b a r i t e and pyrobitumen i n the gangue assemblage. Later carbonate, s u l f i d e s , and quartz occur i n t e r s t i t i a l l y to the ba r i t e blades; late s u l f i d e s (eg. galena, pyrargyrite) are lacking. Both p y r i t e and carbonate grains show well defined zonation, with the former also displaying abundant intergrown pyrrhotite within the outermost zones. The region immediately to the south of the Camp veins i s r e l a t i v e l y unknown due to a thick cover of overburden and li m i t e d d r i l l - h o l e d e f i n i t i o n . Available intersections indicate the presence of several small veins and widespread s t r i n g e r mineralization i n the v i c i n i t y of the t a i l i n g pond and decline p o r t a l . Two veins and the so-called "Twinkle zone" (Figure 2.3.1) were sampled and examined i n r e f l e c t e d l i g h t . Material from the Twinkle zone consists of simple s u l f i d e s (pyrite, galena, sphalerite, and tetrahedrite) with quartz, i n narrow stringers rather than a d i s t i n c t vein. A small (about 20 cm. true thickness), but unusual vein was noted i n a d r i l l i n t e r s e c t i o n from the northeast side of the t a i l i n g s pond; s u l f i d e minerals were almost e n t i r e l y f i n e -grained p y r i t e , with very rare, sub-0.1 mm. inclusions of pyrrho t i t e and sphalerite disseminated throughout. Another smaller vein nearby more c l o s e l y resembled the Camp veins to 96 Figure 3.5.4: Bladed b a r i t e (ba) i n matrix of manganoan carbonate (cb) and v u g - i n f i l l i n g quartz (qz). From sample s i t e 3CHN89-15 (Appendix A) on Camp veins. Figure 3 . 5 . 5 : Broken pyrobitumen ( p y b i t ) mass i n manganoan carbonate (cb) and a r s e n o p y r i t e (aspy) from sample s i t e 3CHN89-15 (Appendix A) on Camp v e i n s . 98 the north, with abundant bladed b a r i t e , carbonate, and arsenopyrite included within the assemblage. 3.5.2 Chisholm Veins The Chisholm vein system consists of four small and highly i r r e g u l a r veins located i n the southwestern part of the study area. The veins are generally less than 30 cm. in... width, l o c a l l y thickening to "podlike" masses. Mineralogy i s si m i l a r to that of the Camp veins, with Ag-bearing minerals, b a r i t e , and arsenopyrite r e l a t i v e l y abundant compared to the Number Three system. Barite commonly occupies a paragenetically intermediate p o s i t i o n i n the veins and has been noted r a d i a t i n g from sphalerite fragments i n the Mae Three and Owl veins (Figure 3.5.6). Unlike other veins i n the area, sphalerite i s among the f i r s t minerals deposited, forming layers of coarse-grained material adjacent to the vein walls. P y r i t e and arsenopyrite are eithe r early or intermediate paragenetically, occurring as fine-grained intergrown masses bordering sphalerite bands. Two stages containing galena were also noted, with the l a t e r stage frequently containing exsolved vermiform inclusions of pyrargyrite, pearcite, f r e i b e r g i t e , and bournonite. Fr e i b e r g i t e i s e s p e c i a l l y important within the Owl vein, where i t occurs as i r r e g u l a r masses i n sphalerite, forming up to 3% of the vein assemblage (Figure 3.5.7). A f i n a l stage of mineralization includes carbonate ( c a l c i t e ? ) , with rare p y r i t e . •I n b I d d ) S S , •» | U I • 0 1 6 8 L 9 . i . l . i , I j . l j J . i i l . i i l ^ J i i . i j . i , i jMJjih.l,i,1,1.1,i.l,i.l.i.l.i.I, F i g u r e 3.5.6: C r o s s - s e c t i o n a l s l a b o f Mae T h r e e v e i n , C h i s h o l m v e i n g r o u p . Note b a r i t e (ba) b l a d e s o v e r g r o w i n g e a r l i e r l a y e r e d s p h a l e r i t e ( s i ) . From sample s i t e 1CHN89-57 ( A p p e n d i x A ) . 14 15 W 171 iljlllt 181 19 2 0 21 23 1 2 4 • ' : n d S S 9 | U i i ; s •lililil.i.;.- ! 6 1,1,' !• 8 xW^^^^^^^tkx I F i g u r e 3.5.7: A r g e n t i a n t e t r a h e d r i t e ( t t ) pods, w i t h s p h a l e r i t e ( s i ) and galena (gn) i n a barite-dominated matrix (sample s i t e 1CHN89-65; see Appendix A ) . F i g u r e 3.5.8: Backscattered e l e c t r o n photomicrograph of l a r g e electrum ( e l ) g r a i n i n intergrown galena (gn) and m a t i l d i t e (md) from sample s i t e 2CHN89-4 (Appendix A), P o r t a l v e i n Three. 101 3.5.3 Portal Veins The P o r t a l veins are between the Owen Lake f a u l t and the Number Three vein (Figure 2.3.1) and form perhaps the most mineralogically complex system on the property. Individual veins are highly i r r e g u l a r , with widths of up to more than f i f t y centimeters and then o f f s e t or tapering to zero over a few tens of meters along s t r i k e . No two of the veins d i s p l a y the same assemblages. In general, the veins can be divided into four categories on.the basis of bulk mineralogy. The f i r s t , and most important economically, includes the ch a l c o p y r i t e - r i c h Number Five and Portal Three veins, both of which contain spectacular concentrations of Ag-sulfosalts i n t e r s t i t i a l to sparry quartz gangue. Electrum (Figures 3.5.8 and 3.4.18) i s also abundant, r a r e l y a t t a i n i n g s u f f i c i e n t s i z e to be seen i n hand specimen. Textures are s i m i l a r to those noted for the northern Number Three system, with massive, coarse grained sphalerite forming the vein margins, followed by euhedral quartz and py r i t e . The quartz and p y r i t e are followed by open-space f i l l i n g chalcopyrite and rare s u l f o s a l t s , which are fractured and cut by tetrahedrite and galena-sulfosalt v e i n l e t s (Figure 3.5.9). Galena and the s u l f o s a l t s (most commonly matil d i t e ) generally occur as symplectic intergrowths (Figure 3.5.10) i n masses up to several millimeters across. Galena also occurs along cleavage directions within e a r l i e r berryite and gustavite masses, an 102 occurrence which may be the r e s u l t of replacement (Figure 3.5.11). Tetrahedrite and rare fine-grained p y r i t e cut the assemblage and replace e a r l i e r p y r i t e masses or form myrmekitic intergrowths with galena and m a t i l d i t e . Well-zoned manganoan carbonate i s l o c a l l y abundant within the l a t e r s u l f i d e assemblage, with i n d i v i d u a l zones recording changes i n Fe-content (Figure 3.5.12). Fine-grained quartz and masses of pyrobitumen up to one centimeter across i n f i l l vugs and mark the termination of mineralization i n these veins (Figure 3.5.13). The second type of vein i n the Portal system i s distinguished by the lack of s u l f o s a l t mineralization and includes the Switchback vein and Portal veins i n the eastern section of the system. In general, mineralization i s dominated by one or more quartz-pyrite+ specular hematite episodes, followed by bladed b a r i t e and layered carbonate deposition. Late minerals are t y p i c a l l y r e s t r i c t e d to galena, chalcopyrite, and sphalerite, with no s u l f o s a l t s recognized within the assemblage. The exception to the unremarkable assemblages observed i n t h i s group of veins i s found i n "Portal 11.5" vein, where two opaque phases (magnetite and hematite?)are disseminated within layered carbonate. Abundant pyrrhotite was also noted within the same vein, occurring as i r r e g u l a r grains that had been rimmed and replaced by l a t e r chalcopyrite. Material from t h i s vein was found to be s i m i l a r to the easternmost of the 103 Figure 3.5.9: Polished section of t y p i c a l Number f i v e vein material, showing inward growth of sphalerite ( s i ) , chalcopyrite (cpy), and quartz-sulfosalt (qz, ss) episodes. From sample s i t e 1CHN89-117 (Appendix A). 104 F i g u r e 3.5.10: Intergrown galena (gn) and m a t i l d i t e (md) exsolved from Pb-Bi s o l i d s o l u t i o n . From sample s i t e 3CHN89-7OB, P o r t a l v e i n s (Appendix A ) . Figure 3.5.11: Backscattered electron photomicrograph of berryite (ber) laths i n gustavite (gs) matrix, with galena (gn) replacing both phases along cleavage d i r e c t i o n s . From sample s i t e 2CHN89-11 (Appendix A) on "Portal 10.5 vein". 106 r 2 0 . 0 0 V l = M 3 2 0 . 0 k U 7 . 7 6 n H Figure 3.5.12: Backscattered electron photomicrograph of zoning in Portal vein Three carbonate. Variations are due to changing Fe content, with brightest zones representing highest Fe content. From sample site 2CHN89-4 (Appendix A). 107 Figure 3.5.13: Late stage (Stage IV) pyrobitumen (pybit) i n f i l l i n g vugs i n P o r t a l v e i n Three. From sample s i t e 2CHN89-4 (Appendix A ) . 108 Camp veins examined, and a possible connection between the two veins i s suggested. The t h i r d s t y l e of mineralization within the Portal system i s exemplified by veins i n the westernmost portions of the system. Mineralization from the Portal One and Portal Two veins i s dominated by the presence of a coarse-grained (grains up to 1 cm. i n diameter) sphalerite layer i n the hangingwall of the vein, followed by massive manganoan carbonate mineralization, and f i n a l l y by volumetrically minor chalcopyrite, p y r i t e , quartz, and s u l f o s a l t s . The arrangement of mineralogies within these two veins suggests that they are rela t e d to the f i r s t s t y l e observed within the Portal system, with the dominant phases being the e a r l i e r sphalerite and carbonate rather than the l a t e r Cu-rich phases observed i n the Portal Three vein. Barite and arsenopyrite also present i n the assemblage, suggesting a possible r e l a t i o n s h i p with the Camp veins. The f i n a l class of Portal veins consists of those that do not f i t into other well-defined categories, s p e c i f i c a l l y the P o rtal Four and Five veins. The Portal Four vein i s a breccia zone with i n f i l l i n g by massive quartz and galena (Figure 3.5.14). Carbonate and chalcopyrite are present i n very minor quantities i n t h i s vein. The Portal Five vein i s dominated by coarse grained sphalerite and quartz, with accessory amounts of p y r i t e , marcasite, and arsenopyrite. In both veins, a minor fracture i n f i l l i n g quartz episode i s present. 109 3.5.4 Cole Lake Veins The Cole Lake system of veins covers a s p a t i a l l y broader region than other l o c a l vein systems discussed here. Mineralogy i s highly variable both between adjacent veins and over the enti r e vein system. The Cole vein-Cole shear vein has the best exposure, and the longest defined s t r i k e length of a l l the Cole Lake veins. Material exposed i n trenches bordering Cole Lake (Figure 2.3.1), i s mainly coarse-grained, euhedral galena and sphalerite i n a matrix of massive to layered manganoan carbonate, quartz, and bladed b a r i t e . Repetitive layering i s well developed i n several locations of the vein, with several episodes of al t e r n a t i v e s u l f i d e and quartz (Figure 3.5.15). Cole vein material recovered from d r i l l hole NGF8 (Map 1) to the north of the main area of trenching displays a mineralogy s i m i l a r to some of the Camp veins, including the presence of arsenopyrite and p y r i t e that has replaced and encrusted a pre-ex i s t i n g bladed phase, possibly hematite (Figure 3.5.16). In t h i s section of the vein, ba r i t e i s less abundant than i n the central section, with galena, f r e i b e r g i t e , and rare chalcopyrite forming the l a t e r s u l f i d e assemblage. The segment of vein known as the Cole shear occurs south of the main area of trenching, and displays a more complex mineral assemblage than elsewhere. The Cole shear vein loses i t s well-defined nature at depth, however, forming a series of mineralized stringers where intersected i n d r i l l hole. Layered carbonate forms less than 30% of the 110 Figure 3.5.14: C r o s s - s e c t i o n a l s l a b of P o r t a l v e i n Four, showing " b r e c c i a " nature of m i n e r a l i z a t i o n . From sample s i t e 2CHN90-8 (Appendix A ) . I l l F i g u r e 3.5.15: Well layered carbonate (cb), sphalerite ( s i ) , and galena (gn) mineralization from the central Cole vein, sample s i t e 1CHN89-12 (Appendix A). 112 Figure 3.5.16: C r u s t i f o r m growth o f a r s e n o p y r i t e (aspy) o v e r a p r e - e x i s t i n g b l a d e d phase t h a t has been r e p l a c e d by aspy, p y r i t e ( p y ) , and g a l e n a ( g n ) . From sample s i t e 3CHN89-66 on n o r t h e r n C o l e v e i n . 113 vein volume, with fine-grained intergrown sphalerite and carbonate comprising up to 20% of the d r i l l intersections studied. As with most veins at Owen Lake, p y r i t e and quartz mark the i n i t i a t i o n of vein mineralization, with a second period of p y r i t e deposition that post-dates sphalerite empalcement. Late minerals are generally dominated by galena and lesser tetrahedrite; seligmannite/bournonite i s also present as minute vermiform inclusions within the galena. The Copper vein (Figure 2.3.1) i s much less important than the Cole vein, both i n extent and from an economic standpoint. The mineralogy, however, i s much more complex than that observed i n the Cole vein system. As with the Cole vein, p y r i t e and/or marcasite with quartz form the i n i t i a l stage of mineralization (the "Stage I" of the Number Three system) i n material from the surface and at depth. Specular hematite intergrown with magnetite i s also present near the footwall of the vein, i n association with euhedral pyrite and fine-grained carbonate. Massive to coarse-grained euhedral sph a l e r i t e , and manganoan carbonate, form the "Stage I I " assemblage within the available d r i l l hole i n t e r s e c t i o n for the Copper vein. The l a t e r s u l f i d e assemblage i s much more complex, dominated by massive chalcopyrite that has been cut by l a t e r tetrahedrite v e i n l e t s . Galena and a i k i n i t e occur as symplectic intergrowths (Figure 3.5.17), with l e s s e r amounts of electrum and m a t i l d i t e (Figure 3.5.18) also present (as ir r e g u l a r grains to f i f t y microns). Individual masses of 114 galena-aikinite are up to 0.5 mm. across, with smaller masses that have rimmed or replaced p y r i t e along cleavage directions (Figure 3.5.19). Galena and a i k i n i t e also occur as myrmekitic intergrowths with tetrahedrite, although these are rare. The mineralogies of the central veins of the Cole Lake system (Barite, NG6, and Lead) are generally quite s i m i l a r , dominated by an intermediate stage ("Stage II") consisting of coarse grained, euhedral sphalerite and l e s s e r galena i n a matrix of bladed b a r i t e , carbonate, and quartz. Fine grained, often euhedral p y r i t e , arsenopyrite, and quartz form the e a r l i e s t mineralization, with galena and tetrahedrite dominating "Stage I I I " . Some tetrahedrite rims galena grains, with pearcite, seligmannite/bournonite, and an u n i d e n t i f i e d s u l f o s a l t as vermiform inclusions i n both tetrahedrite and galena (especially within the Lead vein). The Bear vein i s the westernmost major vein of the Cole Lake system, with specular hematite and rare intergrown magnetite, - forming up to 50% of the vein assemblage. E a r l i e r bladed b a r i t e and anhedral quartz and l a t e r pyrite/marcasite form most of the remaining vein material, with minor amounts of sphalerite and galena as the l a t e s t phases deposited. Tetrahedrite, carbonate, and pearcite a l l occur i n trace amounts with galena. 115 Figure 3.5.17: Backscattered electron photomicrograph of symplectic intergrowths of galena (gn) and a i k i n i t e (aik) i n t e r s t i t i a l to hematite-magnetite (he-mt). From sample s i t e 3CHN89-79 (Appendix A), Copper vein. 116 Figure 3.5.18: I n c l u s i o n of intergrown galena (gn), m a t i l d i t e (md), and electrum ( e l ) i n p y r i t e (py). From sample s i t e 3CHN89-79 (Appendix A ) , Copper v e i n . Figure 3.5.19: Intergrown galena (gn) and m a t i l d i t e (md) along margin of p y r i t e g r a i n (py), i n matrix of c h a l c o p y r i t e (cpy). From sample s i t e 3CHN89-79 (Appendix A ) , Copper v e i n . 117 3.5.5 George Lake Veins D r i l l intersections of veins within the George Lake lineament show that the George Lake "vein" to be a series of smaller en-echelon-like veins i n a shear zone up to 30 meters wide. The several s i t e s studied along the George Lake structure (Figure 2.3.1) have mineralogies s i m i l a r to those i n the Number Three vein. Coarse-grained p y r i t e and quartz are the i n i t i a l stage of mineralization i n the vein, with l o c a l l y abundant specular hematite i n the north and b a r i t e present throughout. Hematite grains commonly are surrounded by massive p y r i t e and subsequently replaced by carbonate, with only l o c a l r e l i c t s of hematite. In the southern segment, the mineralogy i s r e l a t i v e l y simple, c o n s i s t i n g of "Stage I I " sphalerite and up to 10% complexly intergrown tetrahedrite, galena, and chalcopyrite ("Stage III") that have i n f i l l e d fractured and brecciated p y r i t e and quartz. In the ce n t r a l and north parts of the vein, quartz and carbonate are increasingly abundant, with quartz deposition extending over a r e l a t i v e l y long period. Vein material from the Bulkley crosscut i n t e r s e c t i o n of the vein (Figure 2.3.1) displays massive, fine-grained, white quartz that has i n f i l l e d open spaces i n brecciated "Stage I" and "Stage I I " mineralization and apparently spans the entire "Stage I I I " i n f l u x . Carbonate i s l a t e paragenetically, occupying a temporally short period during the l a t t e r half of the aformentioned quartz mineralization. In the north part of the vein, chalcopyrite also becomes increasingly important 118 i n the l a t e s u l f i d e assemblage, forming up to 5% of the ve in mineralogy. Galena, t e t r a h e d r i t e , pearce i te , and an u n i d e n t i f i e d s u l f o s a l t (poss ib ly berry i t e ) occur wi th in larger masses of cha l copyr i t e . Figure 3.5.20: Intergrown p e a r c e i t e (pc) and electrum ( e l ) i n carbonate v e i n l e t c u t t i n g c h a l c o p y r i t e (cpy). From sample s i t e 2CHN89-48, " J a x e l " v e i n . 120 4.0 COMPOSITIONAL V A R I A T I O N IN S U L F I D E S 4.1 Introduction and Objectives Mineral zoning can be i d e n t i f i e d through (1) presence or absence of i n d i v i d u a l species (eg. Susak and Crerar, 1982), (2) systematic variations i n the abundance of a p a r t i c u l a r species, and (3) compositional v a r i a t i o n s i n i n d i v i d u a l mineral species characterized by s o l i d solution (eg. Barton and Skinner, 1979). Textural v a r i a t i o n , e s p e c i a l l y predominant, also contributes to the pattern of mineral zonation. These various aspects of mineral zonation provide important insight into the changing nature of the hydrothermal system. Reflected and transmitted l i g h t microscopy of vein cross-sections from the Number Three and. subsidiary structures reveal the general nature of mineralogical v a r i a t i o n , both l o c a l l y and over the length and breadth of the e n t i r e zone. S.E.M. analysis indicates that three mineral groups (tetrahedrites, sphalerites, and carbonates) display a large degree of chemical v a r i a b i l i t y across grains and from sample s i t e to sample s i t e . Tetrahedrites and sphalerites were chosen for detailed quantitative analysis due to the large number of trace elements that can be incorporated into t h e i r structures (eg. Johnson et al., 1986; Fryklund and Fletcher, 1956) and because they are widely d i s t r i b u t e d throughout the Number Three structure. 121 In addition to providing insights into the behavior of trace elements i n tetrahedrites and sphalerites, the d i s t r i b u t i o n of the component metal species also provides information regarding the evolution of Stage II (sphalerite) and Stage III (tetrahedrite) mineralizations. Studies of tetrahedrites i n other hydrothermal deposits have revealed a c o r r e l a t i o n between distance from f l u i d source and major element (As, Sb, Ag, Cu, Zn, and Fe) contents (Wu and Petersen, 1977; Hackbarth and Petersen, 1984; Petersen et a l . , 1990). Moreover, chemical v a r i a t i o n i n s i n g l e tetrahedrite c r y s t a l s could outline the conditions present during deposition (Johnson and Jeanloz, 1983; Hackbarth and Petersen, 1984). A s i m i l a r s i t u a t i o n exists f o r sphalerite, with i r o n contents providing a potential geothermometer i n the presence of pyrrhotite (Barton and Skinner, 1979). At S i l v e r Queen, however, analyses of sphalerites were undertaken p a r t l y to ascertain the locus of the unusual metals Ga, Ge, and In. Anomalous (up to 2000 ppm) l e v e l s of Ge and In were detected during e a r l i e r geochemical analysis of core and underground samples; sphalerite was considered to be most l i k e l y host for the metals (eg. Bernstein, 1985; Fryklund and Fletcher, 1956). Thus, several sphalerite grains were analyzed to examine possible d i s t r i b u t i o n patterns for Ga, Ge, and In. 122 4 . 2 Sampling Techni qiies The continuity and a v a i l a b i l i t y of intersections on the Number Three vein made the structure the best choice for evaluating changes i n tetrahedrite and sphalerite compositions. Representative tetrahedrite samples were chosen from a series of v e r t i c a l sections, i n order to produce an adequate representation of the entire vein. Twenty-one s i t e s on the Number Three vein and 3 from the NG3 vein were sampled for tetrahedrites, with 10 of these s i t e s also evaluated for sphalerite compositions and several for s u l f o s a l t compositions. Tetrahedrites from the Camp, Po r t a l , Cole, Chisholm, and George Lake systems were also analyzed i n order to provide a more complete regional picture. Electrum from four veins, including the Number Three vein, was also sampled. 4 _ J A n a l y t i c a l MethoHol oqy Samples that were chosen for microbeam analysis were made into polished t h i n sections and immediately coated and analyzed i n order to minimize error due to oxidation of the polished surface. An i n i t i a l S.E.M. study was undertaken of p a r t i c u l a r tetrahedrite, sphalerite, and s u l f o s a l t grains to ascertain those elements for which some v a r i a b i l i t y might be expected. The samples were then transfered to the electron microprobe for quantitative compositional analysis. Tetrahedrite grains were analyzed using the Cu£ a, AgL a, sKa/ Z nKa/ F eKa# s b L a / A sKa/ p bMa/ H9Ma a n d B iMa peaks, at a beam current of 10 nA, an accelerating voltage of 20 kV, 123 and a spot si z e of one micron. Tetrahedrite grain standards were used for c a l i b r a t i n g Cu, As, Zn, S, and Sb, galena f o r Pb, HgTe f o r Hg, t r o i l i t e f or Fe, and pure metal forms f o r Ag and B i . Zonation within the i n d i v i d u a l grains was determined through (1) backscattered electron photomicrographs, and (2) tetrahedrite "stratigraphy", along traverse l i n e s from core to rim. Repeat analyses were done on some of the larger zones i n order to determine r e p r o d u c i b i l i t y . The routine for s u l f o s a l t analyses i s s i m i l a r to that for tetrahedrite, with the A S L Q peak used instead of ASJ^Q, i n order to avoid a Pb-As interference problem. For s u l f o s a l t s only spot analyses were done for i d e n t i f i c a t i o n purposes; no compositional zonation was noted. Sphalerite was not analyzed as extensively as tetr a h e d r i t e , but samples were examined from several s i t e s on the Number Three vein. Peaks for Z n j a , SRa, Fe^a, Mn£ a, C^La, HcJMa/ ^aKai GeRa/ and InL a were evaluated at a beam current of 30 nA, accelerating voltage of 20 kV, and a spot s i z e of f i v e microns. Sphalerite grain standards were used for c a l i b r a t i n g Zn, Fe, and S, GaAs for Ga, HgTe for Hg, and pure metal forms for the remaining elements. Traverses were done from core to rim (where i d e n t i f i a b l e ) or across the grain i n most cases. As with the tetrahedrites, some s i t e s were repeated for r e p r o d u c i b i l i t y , or to obtain a better t o t a l . 124 Electrum grains were evaluated for Cu£ a, AuRa, AgL a / and Hg^a peaks, at a beam current of 10 nA, an accelerating voltage of 20 kV, and a spot size of f i v e microns. Standards used for the c a l i b r a t i o n were pure metals for Au, Ag, and Cu, and HgTe for Hg. 4.4 Tpt.rahpdrit.s Zonat-.irm 4.4.1 Introduction Compositional v a r i a t i o n within single tetrahedrite grains has been documented from several l o c a l i t i e s worldwide (Hackbarth and Petersen, 1984; Johnson et a l . f 1986). Hackbarth and Petersen (1984) have explained the v a r i a t i o n to be the r e s u l t of f r a c t i o n a l c r y s t a l l i z a t i o n , with d i f f e r e n t depositional s i t e s receiving f l u i d s i n d i f f e r e n t stages of compositional evolution. The tetrahedrites from the S i l v e r Queen mine display unusually dramatic examples of growth zoning within i n d i v i d u a l grains (Figure 4.4.1). The tetrahedrites cover a temporally broad portion of Stage III mineralization at S i l v e r Queen (Figure 3.4.22), and thus provide excellent documentation of the evolution of the hydrothermal system at p a r t i c u l a r points. On a whole-vein scale, however, characterization of the hydrothermal c e l l becomes increasingly d i f f i c u l t due to the zoned nature of the i n d i v i d u a l grains. As a r e s u l t , longitudinal sections of the Number Three vein describing v a r i a t i o n s i n composition (Figures 4.4.6 to 4.4.12) are based on average values for 125 the "cores" and "rims" of each grain. In conjunction with the nature of singl e grain zonation, these "element maps" may allow for better appraisal of conditions during Stage III mineralization. The composition of tetrahedrite, given by the generalized formula: (Cu,Ag)6Cu4(Fe,Zn,Cu,Hg,Cd)2(Sb,As,Bi,Te)4(S,Se)!3 (Johnson et a l . , 1986) allows for widespread v a r i a t i o n i n the metal and semimetal contents between s p a t i a l l y disparate samples. Three atomic r a t i o s , however, are thermodynamically important (Sack et a l . , 1987): X1 = Zn/(Zn+Fe) X 2 = As/(As+Sb) X3 = Ag/(Ag+Cu) The s i g n i f i c a n c e of these three r a t i o s w i l l be discussed l a t e r . The unusually bismuth-rich nature of several tetrahedrite- samples requires that the weight percent bismuth be considered (Figure 4.4.12) and therefore a new atomic r a t i o i s defined: X 4 =As/(As+Sb+Bi) A n a l y t i c a l data summaries for S i l v e r Queen tetrahedrite grains are i n Tables 4.4.1 to 4.4.4. 4.4.2 Single Grain Zonation in Tetrahedrites Tetrahedrites i n the Number Three and NG3 veins commonly dis p l a y o s c i l l a t o r y zoning on backscattered 126 electron photomicrographs (Figure 4.4.1). In most cases, the differences between i n d i v i d u a l zones represent the coupled su b s t i t u t i o n of Sb for As and Ag for Cu; zones that appear brighter on backscattered photos are more antimony- and s i l v e r - r i c h . In tetrahedrites from sample s i t e s 2CHN89-27, 3CHN89-88, 3CHN89-3, 1CHN89-117, and 3CHN90-1 (Appendix A), the v a r i a t i o n i n zone brightness i s associated with increasing B i contents (Figure 4.4.2), however, t h i s s i t u a t i o n i s r e l a t i v e l y uncommon (eg. Appendix C). Tetrahedrites throughout the Number Three system show a general outward trend from A s - r i c h cores to Sb-rich rims, with i n d i v i d u a l zones less than 5 microns i n width. A corresponding increase i n the value of X3 also occurs, with the outermost zones generally volumetrically less important than zones near the core (Tables 4.4.1 to 4.4.4). Zoning of Xi r a t i o s i s rare, with Zn/(Zn+Fe) tending to concentrate around 0.9 and showing l i t t l e v a r i a t i o n . A notable exception i s sample 3CHN89-46 (Figure 4.4.3), where X^ displays an i n i t i a l sharp drop before gradually climbing back to a value of 0.95. One should note, however, that sphalerite i s less abundant i n t h i s sample than i n any other on the. Number Three system (Figure 3.4.25), and both p y r i t e and tetrahedrite are widespread (Figures 3.4.24 and 3.4.26). Thus, less Zn may have been available to be p a r t i t i o n e d into the tetrahedrites. In general, no systematic trend from core to rim was noted for bismuth contents i n tetrahedrite, although i n two 127 F i g u r e 4.4.1 O s c i l l a t o r y zoned t e t r a h e d r i t e g r a i n from sample s i t e 2CHN89-19 (Appendix A) on t h e n o r t h e r n Number Three v e i n a t t h e i n t e r s e c t i o n o f t h e B u l k l e y c r o s s c u t and t h e South End d r i f t . I n c r e a s i n g b r i g h t n e s s c o r r e s p o n d s t o a d e c r e a s e i n t h e r a t i o As/(As+Sb+Bi) and an i n c r e a s e i n t h e r a t i o Ag/(Ag+Cu). S u r r o u n d i n g gangue i s m a n g a n o s i d e r i t e . S c a l e b a r on l o w e r l e f t o f photo. Figure 4.4.2 Tetrahedrite from sample s i t e 3CHN90-1 (Appendix A) on deep north Number Three vein. Scale bar on lower l e f t corner of photo. Table 4.4.1 Zonal analysis of tetrahedrite 3CHN90-1 Element 1 2 3 4 5 6 7 8 Cu 42 .92 42.94 42.54 43.04 42. 33 43. 27 42.56 42. 96 S 28 .13 27.97 27.65 27.42 27. 39 27. 82 27.89 27. 85 Zn 8 .13 8.05 7.92 8.10 7. 94 8. 07 8.09 7. 96 Fe 0 .61 0.62 0.58 0.61 0. 52 0. 60 0.61 0. 60 Sb 0 .33 0.17 0.17 0.41 0. 37 0. 27 0.31 0. 28 As 19 .17 18.77 18.02 18.37 17. 87 18. 98 18.70 18. 48 Pb 0 .00 0.00 0.09 0.00 0. 00 0. 00 0.00 0. 00 Ag 0 .21 0.39 0.35 0.42 0. 35 0. 30 0.31 0. 36 Bi 0 .22 1.45 2.83 1.82 2 . 64 0. 62 2.18 1. 36 Hg 0 .05 0.09 0.10 0.13 0. 00 0. 00 0.00 0. 00 Total 99 .77 100.5 100.3 100.3 99. 42 99. 94 100.6 99. 85 •Values given are element weight percents **S i t e numbers increase from core to rim 129 T a b l e 4.4.1 ( c o n t i n u e d ) 10 11 12 13 14 15 16 17 Cu 42.21 41.99 42.82 41.93 43.00 42.70 42.74 42.19 42.51 S 27.56 27.46 27.92 27.41 28.21 27.70 28.11 27.55 27.63 Zn 8.00 8.05 8.02 7.95 8.03 8.14 8.00 8.02 8.23 Fe 0.55 0.59 0.56 0.59 0.59 0.60 0.58 0.56 0.61 Sb 0.40 0.40 0.36 0.32 0.11 0.23 0.20 0.23 0.17 As 18.14 18.51 18.37 17.82 19.20 18.75 19.33 18.53 18.91 Pb 0.00 0.00 0.00 0.00 0.00 0.10 0.09 0.00 0.00 Ag 0.40 0.38 0.35 0.40 0.25 0.43 6.40 0.26 0.23 B i 3.00 2.47 1.76 3.08 0.43 1.70 1.13 2.28 1.28 Hg 0.00 0.13 0.21 0.00 0.00 0.00 0.00 0.04 0.06 Tot. 100.3 99.97 100.4 99.51 99.87 100.3 100.6 99.67 99.61 18 19 20 21 22 23 24 25 Cu 42.94 43.32 42.46 42 .85 42.75 43.14 42 .01 42 .78 S 27.46 27.87 27.67 28 .01 27.60 27.77 27 .76 27 .99 Zn 7.92 8.10 8.18 7 .85 7.91 8.06 7 .91 7 .92 Fe 0.58 0.64 0.63 0 .66 0.60 0.70 0 .60 0 .71 Sb 0.32 0.17 0.28 0 .38 0.43 0.22 0 .49 0 .25 As 18.34 19.67 18.16 19 . 10 18.66 18.86 18 .07 18 .87 Pb 0.07 0.15 0.00 0 .00 0.00 0.06 0 .14 0 .12 Ag 0.38 0.33 0.46 0 .32 0.31 0.29 0 .30 0 .24 B i 2.36 0.42 2.46 0 .44 1.53 0.15 2 .13 0 .34 Hg 0.07 0.00 0.00 0 .00 0.15 0.00 0 .04 0 .17 T o t a l 100.4 100.7 100.3 99 .59 99.93 99.24 99 .45 99 .38 130 r 2 0 . O O P 2 0 . 0 k U Figure 4 . 4 . 3 T e t r a h e d r i t e from sample s i t e 2CHN89-46 (Appendix A) on so u t h - c e n t r a l Number Three v e i n . Scale bar on lower l e f t corner of photo. Table 4.4.2 Zonal A n a l y s i s o f t e t r a h e d r i t e 2CHN89-46 1 2 3 4 5 6 7 8 9 Cu 43.51 41.31 42 .78 40. 65 41 .57 40.95 42 .38 42.71 42 .06 s 28.11 27.18 28 .26 26. 68 26 .85 26.50 27 .33 28.04 27 .71 Zn 8.43 8.10 6 .35 7. 28 7 .30 7.54 7 .50 7.59 7 .72 Fe 0.32 0.35 1 .95 0. 89 0 .89 0.65 1 .07 0.94 0 .82 Sb 0.11 10.28 0 .75 13. 12 10 .42 15.49 5 .53 2.60 3 .25 As 19.62 13.24 19 .06 10. 69 12 .49 9.37 15 .35 17.55 17 .25 Pb 0.00 0.00 0 .56 0. 00 0 .05 0.00 0 .12 0.59 0 .41 Ag 0.07 0.23 0 .10 0. 37 0 .19 0.20 0 .14 0.08 0 .00 B i 0.00 0.00 0 .05 0. 00 0 .00 0.07 0 .00 0.05 0 .00 Hg 0.00 0.00 0 .05 0. 07 0 .00 0.00 0 .00 0.00 0 .00 Tot. 100.2 100.7 99 .91 99. 77 99 .75 100.8 99 .42 100.2 99 .20 1 3 1 Figure 4 . 4 . 4 T e t r a h e d r i t e from sample s i t e 3 C H N 8 9 - 5 . Scale bar on lower l e f t corner of photo. Table 4 .4.3 Zonal Analysis of tetrahedrite 3CHN89-5 1 2 3 4 5 6 Cu 4 1 . 6 8 3 9 . 0 2 4 1 . 1 5 4 1 . 5 0 4 1 . 6 5 3 9 . 8 3 s 2 7 . 5 5 2 5 . 8 7 2 7 . 5 4 2 7 . 6 3 2 7 . 8 2 2 6 . 6 6 Zn 8 . 0 1 7 . 8 6 7 . 9 4 7 . 9 5 8 . 0 6 7 . 9 5 Fe 0 . 6 1 0 . 3 3 0 . 4 0 0 . 5 3 1 . 3 7 0 . 6 5 Sb 6 . 1 2 2 1 . 1 6 1 0 . 6 8 5 . 9 8 3 . 2 1 1 4 . 9 8 As 1 5 . 8 2 5 . 4 5 1 2 . 8 4 1 5 . 7 8 1 7 . 3 3 9 . 3 6 Pb 0 . 0 0 0 . 0 0 0 . 0 0 0 . 0 0 0 . 1 1 0 . 0 0 Ag 0 . 1 3 0 . 3 3 0 . 0 7 0 . 1 1 0 . 0 0 0 . 1 7 B i 0 . 0 0 0 . 1 8 0 . 1 5 0 . 0 8 0 . 1 7 0 . 1 2 Hg 0 . 0 6 0 . 0 0 0 . 0 0 0 . 1 5 0 . 0 0 0 . 0 0 Total 1 0 0 . 0 1 0 0 . 2 1 0 0 . 8 9 9 . 7 1 9 9 . 7 2 9 9 . 7 1 LO LO CO 4*. 0 meters 200 FIGURE 4.4.11 CONTOUR PLOT OFAal(Aa+Sb+Bd TETRAHEDRITE QRAIN'RIMS NUMBER THREE VEIN LONGITUDINAL SECTION meters 200 139 samples, the most B i - r i c h zones occurred over a small time period r e l a t i v e to the tetrahedrite mineralizing event (Figure 4.4.5). Samples were also analyzed for Pb and Hg, with both elements commonly below detection l i m i t s , and, where detected, showing no evidence of compositional trends (Tables 4.4.1 to 4.4.4; Appendix C). A problem which may a r i s e from a zone-by-zone analysis of tetrahedrite grains i s the p o s s i b i l i t y that adjacent zones may be excited by the beam during analysis and as a r e s u l t may give a "bulk" analysis from several zones rather than for the o r i g i n a l target. Such a problem would not be detectable i n the weight percent t o t a l s due to the compositional s i m i l a r i t i e s between the juxtaposed zones, and necessitates close comparison of Sb, As, and B i weight percents with the defined zones i n the photomicrographs. "Fuzzy" demarcations between zones, and anomalously high Zn, Fe, and Pb values were also found to be i n d i c a t i v e of " a n a l y t i c a l " interference from adjacent zones or phases. 4.4.3 Deposit-scale Variations in Tetrahedrite Composition In order to evaluate large scale tetrahedrite compositional v a r i a t i o n , various atomic r a t i o s were plotted on l o n g i t u d i n a l sections describing the d i s t r i b u t i o n of tetra h e d r i t e core and rim compositions. Four r a t i o s were found to be useful for t h i s purpose: Zn/(Zn+Fe), As/(As+Sb+Bi), Ag/(Ag+Cu), and weight percent bismuth (Figures 4.4.6 to 4.4.12). Average grain compositions were 140 found to be unrepresentative due to an i n a b i l i t y to determine appropriate three-dimensional weighting to the i n d i v i d u a l compositional zones. An attempt was made at using "marker elements" (Bi, Fe, Hg, and Pb) for developing a deposit-wide tetrahedrite "stratigraphy". This, however, was found to be impossible due to the sporadic occurrence of bismuthian tetrahedrites, which provided the best opportunity to correlate a p a r t i c u l a r mineralizing i n t e r v a l . Twenty-three tetrahedrite s i t e s on the Number Three and NG3 veins were analyzed and results are shown on manually contoured diagrams. The Zn/(Zn+Fe) r a t i o (Xi) displayed the le a s t amount of v a r i a t i o n of the plots ( Figures 4.4.6 and 4.4.7) fo r both cores and rims. Tetrahedrites within the Number Three vein have Zn/(Zn+Fe) r a t i o s mostly i n the 0.90 to 0.95 range, with the notable exception occurring i n the northernmost intersections of the vein. Samples from t h i s portion contained X^ values as low as 0.64 and are associated mineralogically with coarse grained, euhedral sphalerite and chalcopyrite. The occurrence of the most iron-enriched sphalerites with t h i s particular, zone i s also noteworthy and w i l l be discussed l a t e r . A second, less prominent zone of low Zn/(Zn+Fe) tetrahedrites occurs around sample s i t e s 3CHN89-24 and 3CHN89-44 (Appendix A) i n the southern portion of the vein and i s defined by both core and rim analyses. Samples from the two NG3 s i t e s containing abundant t e t r a h e d r i t e also showed r e l a t i v e l y low Zn/(Zn+Fe) r a t i o s . 141 The Ag/(Ag+Cu) (X3) and As/(As+Sb+Bi) (X4) r a t i o s are known to display strong p o s i t i v e c o r r e l a t i o n i n many natural systems (eg. Wu and Petersen,1977; Hackbarth and Petersen, 1984) and data c o l l e c t e d from the Number Three system support t h i s observation (Figure 4.4.13). In general, s i l v e r values are highest at the northernmost sample s i t e s on the vein, and i n a region centered on the decline i n t e r s e c t i o n i n the south end. Tetrahedrites from the l a t t e r portion of the vein are c l o s e l y associated with cosanguineous a i k i n i t e i n polished section and r e l a t i v e l y high gold and s i l v e r grades (Nowak, 1991). A second region of anomalously low Ag/(Ag+Cu) tetrahedrites occurs i n the deeper north portion of the vein, where tetrahedrite i s associated with galena and berryite (Figure 3.4.26) and precious metal grades are moderate. An occurrence of f r e i b e r g i t e , associated with polybasite and pyrargyrite, within material from sample 3CHN89-24 i s the only known occurrence of t h i s three phase assemblage i n the Number Three vein. D e f i n i t i o n of the anomalous zones i s r e f l e c t e d i n the As/(As+Sb+Bi) diagrams (Figures 4.4.10 and 4.4.11), with the most Sb-rich tetrahedrites occurring within the northernmost and topographically highest portion of the vein. 4.4.4 Tetrahedrites from Other Veins A number of other smaller veins at the S i l v e r Queen property were also sampled for tetrahedrites i n order to compare the compositional variations with those of the 142 Number Three system. Tetrahedrites from veins located furthest away from the Number Three vein, most notably the Owl and north Cole veins, contained unzoned grains with up to 18 weight percent s i l v e r . In the Owl vein, tetrahedrite occurs i n masses up to 3 mm. across (Figure 3.5.7), and i s associated with pyrargyrite and pearcite. One s i t e on the George Lake vein was also sampled (Appendix C), displaying r e l a t i v e l y low s i l v e r and high bismuth contents (up to 0.22 weight percent) and an association with an un i d e n t i f i e d s u l f o s a l t (berryite?) that bear a marked s i m i l a r i t y with material from sample s i t e 3CHN90-1 (Appendix A). The Portal and Camp vein systems were sampled i n several s i t e s , and a number of traverses across well zoned tetrahedrite grains were completed (eg. Figure 4.4.2). Camp vein material displayed the most spectacular examples of zoning, with i n d i v i d u a l tetrahedrites generally associated with pyrargyrite and pearcite grains as well. Portal vein material (including the Number Five vein) i s unusual due to the presence of t h i n compositional zones containing up to eight weight percent bismuth (Figure 4.4.5). Tetrahedrites from the Portal Three vein are enriched i n s i l v e r and are commonly found i n association with s i l v e r bearing phases such as m a t i l d i t e . 4.4.5 Bismuthian Tetrahedrites-An Unusual Occurrence The occurrence of elevated bismuth contents i n tetrahedrite has been reported only r a r e l y (eg. Oen and Figure 4 .4 . 5 : B a c k s c a t t e r e d e l e c t r o n photomicrograph of z o n a t i o n i n B i - c o n t e n t s i n t e t r a h e d r i t e from the Number F i v e v e i n (sample s i t e 1CHN89-117). B r i g h t e s t areas correspond t o h i g h e s t B i - c o n t e n t s . 144 K l e f t , 1976, Johnson et a l . , 1986) and apparently never within an epithermal vein system. Bismuth substitutes i n the semimetal s i t e with no apparent c o r r e l a t i o n with Sb or As contents (Johnson et a l . , 1986) (Figure 4.4.14). A c l u s t e r i n g of data points i n Figure 4.4.15 suggests the p o s s i b i l i t y of a moderate c o r r e l a t i o n between arsenic and bismuth, but i n general, bismuth data are widely scattered. Data from S i l v e r Queen are derived from three p r i n c i p a l s i t e s ; i n the deep North portion of the Number Three vein, i n the NG3 vein at sample s i t e 3CHN89-3, and i n the Number Five vein (Figure 4.4.5). In a l l three locales, the bismuthian tetrahedrite i s zoned and coexists with other bismuth-bearing phases such as b e r r y i t e . Bismuth contents are l o c a l l y up to 10 weight percent (Figure 4.4.14) and occur within tetrahedrites that are otherwise arsenic end-members and r e l a t i v e l y s i l v e r poor. In the most extreme cases (eg. sample s i t e 3CHN89-3; Appendix A ) , bismuthinite has apparently exsolved from the tetrahedrite and forms a s i g n i f i c a n t part of the Stage III assemblage (Figure 3.4.15). Other parts of the Number Three system also contain bismuth-bearing tetrahedrite, although, with a few exceptions, less than one weight percent i s present (Figure 4.4.12). 4.4.6 Discussion The presence of growth-zoned tetrahedrites at the S i l v e r Queen mine allows for better understanding of l a t e 1 . 2 0 r C Q t l + 0 . 8 0 (ft* ( 7 ) + in < \ 0 . 4 0 00 < o.o8< ** ' ' I ' ' ' ' ' ' I ' ' 0 0 0 . 1 0 * * * * * F I G U R E 4 . 4 . 1 3 Ag/(Ag+Cu) vs. As/(As+Sb+Bi) i i i i I i i i i I i i i i i i i i i I 0 . 2 0 0 . 3 0 0 . 4 0 g/(Ag+Cu if) £ o < _ Q in 12.00 r 8.00 4.00 0. * * * * * FIGURE 4.4.14 Bi Atoms vs'. Sb Atoms _ * m. a » I) H-»A t»i i i i I i i i i i i I I i I i i i i if I l l I L.I I i I *l I I I I I I I I I I I I I I I 0.50 r. 00 1.50 2.00 2.50 3.00 Bi Atoms 15.00 r 00 10.00 o •4—' < (7) ^ 5.00 * * * * * F I G U R E 4 . 4 . 1 5 Bi Atoms vs. As Atoms • * * \- * i i i I i i i i i i i i i I i i i i i i i i i I i i i i i i i i i I i i i i i i i i i I i i i i i I i i i I 00 0.50 1.00 1.50 2.00 2.50 3.00 Bi Atoms 148 stage evolution of hydrothermal f l u i d s within the Number Three system and associated veins (eg. Hackbarth and Petersen, 1984). Tetrahedrites show a wide v a r i a b i l i t y of compositions throughout the vein and contouring of important metal and semimetal r a t i o s reveals several d i s t i n c t i v e tetrahedrite "regions" over the length of the vein (Figures 4.4.6 to 4.4.12). Tetrahedrite has been described by several authors (eg. Springer, 1969; Johnson and Jeanloz, 1983; Sack and Loucks, 1985; O'Leary and Sack, 1987) as obeying the simple stoichiometry: { C u , A g ) 6 T R G [ ( C u , A g ) 2 / 3 ( F e , Z n ) 1 / 3 ] 6 T E T ( S b , A s , B i ) 4 S M ( S ) 1 3 described by O'leary and Sack (1987) as "corresponding to an i d e a l structure with 208 valence electrons per unit c e l l and f u l l occupancy of the 6 tr i g o n a l planar (TRG), 6 tetrahedral (TET), and 4 semimetal (SM) si t e s i n the 13-sulfur formula unit." Pb, Mn, Au, Cd, and Hg have also been i d e n t i f i e d as subst i t u t i n g i n the tetrahedral metal s i t e s , Te into the semimetal s i t e , and Se into the s u l f u r s i t e s (Johnson et al., 1986). In most natural systems, however, the binary substitutions of Fe for Zn, Ag for Cu, and As for Sb, are most prevalent (Johnson et al., 1986; Charlat and Levy, 1974). In the case of the Number Three vein, the substitution of B i for Sb and/or As i s also considered (through modification of the X 2 r a t i o ) i n order to accomodate s i g n i f i c a n t B i l e v e l s . Several authors have noted a strong p o s i t i v e c o r r e l a t i o n between Sb-As and Ag-Cu 149 substitutions (eg. Wu and Petersen, 1977; Johnson et a l . , 1986), with the most Sb-rich compositions generally, though not necessarily, associated with the highest s i l v e r values ( M i l l e r and Craig, 1983). Also present i s a p o s i t i v e c o r r e l a t i o n between Ag and Fe (Pattrick and H a l l , 1983), with a resultant equivalent c o r r e l a t i o n between Fe and Sb i n tetrahedrites (Raabe and Sack, 1984). Hackbarth and Petersen (1984) also noted that Cu- and As-enriched tetrahedrites p r e c i p i t a t e d p r e f e r e n t i a l l y r e l a t i v e to Sb- and Ag-rich v a r i e t i e s and were therefore more l i k e l y to be found nearer to the f l u i d source. One the goals of the S i l v e r Queen study, therefore, was to examine the use of tetrahedrite compositions i n understanding flow d i r e c t i o n and sources of ore f l u i d s . Results of tetrahedrite analyses from the Number Three system and associated veins support the coupled substitution of Sb for As, with Ag for Cu (Figure 4.4.13). The majority of tetrahedrite specimens, however, do not display the Ag-and Sb-rich cores noted for other deposits (eg. Hackbarth and Petersen, 1984). It may be that tetrahedrite mineralization d i d not i n i t i a t e u n t i l the hydrothermal cycle was declining,- an observation that i s supported by paragenetic r e l a t i o n s h i p s (Figure 3.4.22). The cooling hydrothermal c e l l , with the contraction of isotherms, therefore produced an e f f e c t i v e encroachment on the c e l l edge that resulted i n p r e c i p i t a t i o n of successively more Sb-r i c h compositions. In some tetrahedrite grains, i n d i v i d u a l 150 zones progress from an e a r l y Sb-rich core to a more As-rich rim, suggesting that o v e r a l l zonation i n tetrahedrite grains may be governed by a r a p i d l y f l u c t u a t i n g hydrothermal compositional environment than by simple variat i o n s i n p a r t i t i o n i n g from a homogeneous f l u i d . The almost exclusive association of i n t r i c a t e l y zoned tetrahedrite grains with highly brecciated wallrock or Stage I material could be the r e s u l t of highly variable or "chaotic" f l u i d c i r c u l a t i o n associated with f l u i d s moving through a breccia zone as opposed to a simple fracture (Figure 4.4.16). In general, the f i n e scale zoning and sharp boundaries indicate that the tetrahedrites did not s i g n i f i c a n t l y r e e g u i l i b r a t e with t h e i r parent solutions (Barton and Skinner, 1979), suggesting rapid deposition and l i t t l e d i f f u s i o n were taking place during l a t e Stage III mineralization. Tetrahedrites with the highest Ag/(Ag+Cu) and lowest As/(As+Sb+Bi) r a t i o s were found to occur i n the northernmost parts of the Number Three vein and i n veins most d i s t a l to the main system (Figures 4.4.8 to 4.4.11). These s i t e s are associated with narrow veining and a l t e r a t i o n zones, with abundant vuggy carbonate and vein pyrobitumen i n d i c a t i n g a. low-temperature environment of deposition. As a r e s u l t , the f l u i d source i s interpreted as being located towards the the southern part of the property, where more As-ri c h compositions are located. The Ag-Sb-rich zone centered around the decline may have resulted from several factors. Coprecipitation with 151 a i k i n i t e may have p r e f e r e n t i a l l y enriched the tetrahedrite mineralizing solutions i n s i l v e r r e l a t i v e to copper and thus given r i s e to more s i l v e r - r i c h forms, an observation which agrees with the less pronounced change i n the X4 r a t i o within the same area. Another possible mechanism for s i l v e r enrichment i n these tetrahedrites i s an abrupt change i n s a l i n i t y (eg. by b o i l i n g or d i l u t i o n ) . Sack and Loucks (1985) have demonstrated that f l u i d s f r a c t i o n a l l y p r e c i p i t a t i n g tetrahedrite along t h e i r flowpaths would undergo a marked increase i n s i l v e r content with only a 2% decline i n s a l i n i t y . The second anomalous zone, distinguished by low Ag-Sb contents, located i n the deep north portion of the Number Three vein, may have resulted from removal of s i l v e r from so l u t i o n by c o p r e c i p i t a t i o n with b e r r y i t e , or possibly from the presence of a second, smaller f l u i d source beneath the north portion of the vein. A p a r t i c u l a r point of note i s the presence of elevated bismuth contents and the coexistance with bismuthian mineralogies within both anomalous zones. The Zn/(Zn+Fe) r a t i o s are e s s e n t i a l l y constant for the bulk of the Number Three vein and only show s i g n i f i c a n t v a r i a t i o n i n the northernmost segment of the system, where the r a t i o X 2 i s as low as 0.65. P a t t r i c k and H a l l (1983) have noted an apparent c o r r e l a t i o n of Fe with Ag for l e v e l s of greater than two atoms, a s i t u a t i o n which i s present i n the north end material. A less plausible reason was noted by Wu and Petersen (1977), who found that tetrahedrite 152 Figure 4.4.16: Schematic diagram of environment of t e t r a h e d r i t e d e p o s i t i o n i n a v e i n b r e c c i a . T e t r a h e d r i t e g r a i n "A" r e c e i v e s a c o n s t a n t r e p l e n i s h m e n t of hydrothermal f l u i d s , t h e r e f o r e , zoning i s t i e d t o the e v o l u t i o n of the hydrothermal system. As a r e s u l t , z o n i n g developed w i l l be a g r a d u a l change i n one d i r e c t i o n d u r i n g the d u r a t i o n of one p u l s e . T e t r a h e d r i t e g r a i n "B" i s s u b j e c t to p e r i o d i c r e p l e n i s h m e n t d u r i n g a hydrothermal p u l s e . As a r e s u l t , the zoning p a t t e r n may show a tendency towards o s c i l l a t i o n due to v a r y i n g amounts of d e p o s i t i o n from " a c t i v e " and "stagnant" f l u i d s . T e t r a h e d r i t e g r a i n "C" i s l e a s t exposed to i n f l u x e s of hydrothermal s o l u t i o n s and evolves i n accordance to changing metal c o n t e n t s i n the ambient s o l u t i o n s . Zoning i s g r a d u a l , w i t h sudden changes or o s c i l l a t i o n s marking exposure t o l e s s e v o l v e d s o l u t i o n s (as the r e s u l t of t u r b u l e n c e ) . 153 associated with chalcopyrite i s enriched i n Fe. Leaching of the chalcopyrite was c i t e d as the mechanism of Fe enrichment. 4.5 Sphalerite Zonation 4.5.1 Introduction Sphalerites form an almost ubiquitous component of Stage II mineralization, and thus, as with the tetrahedrites, provided a valuable t o o l f o r evaluating f l u i d evolution. The most important facet of the sphalerite compositional data, however, i s the l o c a t i o n of anomalous contents of Ga, Ge, and In i n both a paragenetic context and on a vein-wide scale. Sampling and analysis of sphalerites was not as extensive as for the tetrahedrites; points were chosen from 12 widely separated and mineralogically d i s s i m i l a r s i t e s including 9 whole-grain traverses. Sample s i t e 3CHN89-5 (Appendix A), In p a r t i c u l a r , was chosen due to assays of 320 ppm Ga and nearly 2000 ppm Ge from a d r i l l i n t e r s e c t i o n . Complete analyses are given i n Appendix C and i n Tables 4.2.1 to 4.2.3. 4.5.2 Systematic trends in Sphalerite Zonation Sphalerite samples from the Number Three vein commonly display well defined growth-zoning or layering which was resolved i n r e f l e c t e d l i g h t microscopy into zones containing abundant minute chalcopyrite inclusions and fracture i n f i l l i n g s . Analysis across these layers detected l i t t l e v a r i a t i o n i n e i t h e r the i r o n contents or i n trace element l e v e l s . In general, s p e c i f i c periods of mineralization for any of the trace elements could not be determined. Ga, Ge, and In are near detection l i m i t s for most s i t e s examined, and Hg and Cd l e v e l s were found to be highly variable i n a l l samples. A sample traverse across sphalerite from sample s i t e 3CHN89-5, which displayed perhaps the best zoning observed, i s given i n Table 4.5.1. Two other traverses from samples displaying the highest Ga (3CHN89-1) and In (3CHN90-1) contents are also given i n Tables 4.5.2 and 4.5.3. In both cases, concentrations of the anomalous elements exceeded 0.5 weight percent l o c a l l y along the traverses. Sphalerites throughout the Number Three vein t y p i c a l l y have Fe contents of less than one weight percent with the single observed exception of sample s i t e 3CHN90-1 (Appendix A). This sample also contained the highest In contents noted i n the Number Three vein (Table 4.5.3) and was unique amongst sphalerite s i t e s evaluated i n that i t contained appreciable amounts of chalcopyrite inclusions within the Stage III assemblage. Eldridge et a l . (1988) have suggested that chalcopyrite "disease" w i l l grow by the replacement of the FeS component i n sphalerite; sphalerites from the v i c i n i t y of t h i s sample (and other areas?) thus may have had high Fe contents to begin with. A p a r t i c u l a r i l y noteworthy occurrence of high In assays i n the ch a l c o p y r i t e - r i c h Number Five vein suggests that chalcopyrite may be an important pathfinder for high In sphalerites. Fe-deficient sphalerites were also noted i n the northern Cole vein and Portal veins. 155 4.5.3 Discussion One of the important contributions of a study of the l o c i of Ga, Ge and In pertains to t h e i r paragenetic rel a t i o n s h i p s and the p o t e n t i a l for economic concentrations within the Number Three and associated veins. Gallium, germanium, and indium appear to be be concentrated within the sphalerites i n amounts up to 0.6 weight percent within the samples analyzed, but no single period of mineralization fo r any of the three metals was noted. Instead, peak concentrations were found to vary s p a t i a l l y within the vein, with the most notable example being the association of high In assays with sphalerites accompanying abundant chalcopyrite. High Fe contents i n these grains suggest that In mineralization may have been connected with Stage III chalcopyrite emplacement which le d to the development of extensive "chalcopyrite disease" i n sphalerites. K i e f t and Damman (1990) noted that primary In i n sphalerites from skarns i n c e n t r a l Sweden was remobilized into chalcopyrite and roquesite (CuInS2). In the Number Three system, the reverse action may have occurred, with In and Fe s u b s t i t u t i n g for Zn i n the sphalerite structure. A second p o s s i b i l i t y i s that the In-bearing sphalerite may represent a temporally disparate event r e l a t i v e to other sphalerites i n the Number Three vein, a hypothesis supported by sporadic occurrences of In-bearing material throughout the system and by the absence of In i n chalcopyrite. 156 Figure 4.5.1 Banded s p h a l e r i t e from sample s i t e 3CHN89-5, southern Number Three v e i n . M a t e r i a l from t h i s s i t e contained the highest Ge assays at the S i l v e r Queen mine. Scale bar i n lower l e f t corner. Table 4.5.1 Zonal Analyses of Sphalerite Sample 3CHN89-5 Element 1 2 3 4 5 6 7 8 Zn 66. 94 66. 52 66. 87 66. 14 66 06 66 05 67. 34 66 51 S 33. 28 33. 40 33. 21 33. 17 33 06 32 87 33. 20 32 98 Fe 0. 00 0. 00 0. 00 0. 00 0 00 0 00 0. 00 0 00 Mn 0. 00 0. 00 0. 00 0. 00 0 00 0 00 0. 00 0 .00 Cd 0. 12 0. 34 0. 26 0. 65 0 .72 0 46 0. 15 0 .12 Hg 0. 00 0. 00 0. 00 0. 00 0 .00 0 00 0. 00 0 .00 Ga 0. 00 0. 00 0. 00 0. 00 0 .05 0 03 0. 00 0 .00 Ge 0. 03 0. 00 0. 00 0. 00 0 .05 0 04 0. 00 0 .06 In 0. 00 0. 00 0. 00 0. 00 0 .00 0 00 0. 00 0 .00 T o t a l 100 .4 100 .3 100 .4 100 .0 99 .93 99 48 100 .7 99 .70 157 Table 4.5.1 (continued) Element c ) 10 11 12 13 14 15 Zn 66 21 66 .64 67 .41 67 .38 66 .89 66 .35 66 .01 S 33 16 32 .85 33 .27 33 .24 33 .16 33 .11 33 .04 Fe 0 00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 Mn 0 00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 Cd 0 37 0 .00 0 .00 0 .00 0 .54 0 .39 0 .75 Hg 0 00 0 .00 0 .00 0 .04 0 .07 0 .00 0 .00 Ga 0 00 0 .00 0 .00 0 .00 0 .00 0 .00 0 .00 Ge 0 03 0 .07 0 .00 0 .00 0 .05 0 .07 0 .00 In 0 00 0 .00 0 .00 0 .00 0 .10 0 .00 0 .00 Totals 99 80 99 .59 100.7 100.7 100.8 99 .96 99 .84 Element 18 21 22 25 28 33 37 Zn 65 .66 66. 69 66 .91 66 .42 66 .47 65 .91 66 .54 S 33 .42 33. 13 33 .07 33 .14 33 .40 33 .17 32 .93 Fe 0 .00 0. 00 0 .00 0 .00 0 .21 0 .22 0 .00 . Mn 0 .00 0. 04 0 .00 0 .00 0 .07 0 .15 0 .00 Cd. 0 .53 0. 10 0 .13 0 .04 0 .42 0 .40 0 .00 Hg 0 .00 0. 04 0 .00 0 .00 0 .00 0 .00 0 .00 Ga 0 .00 0. 03 0 .00 0 .00 0 .00 0 .00 0 .00 Ge 0 .04 0. 03 0 .08 0 .07 0 .00 0 .06 0 .00 In 0 .00 0. 00 0 .00 0 .00 0 .00 0 .00 0 .00 Total 99 .65 100 .1 100.2 100.2 100.6 99 .93 99 .51 * Values given are element weight percents ** S i t e numbers increase from rim to core *** Select analyses are given for s i t e s 18 to 37 i n d i v i d u a l r a t i o s (Figures 4.4.6 to 4.4.12). 158 Table 4.5.2 Zonal Analysis of Sphalerite sample 3CHN89-1 1 3 6 9 11 13 17 19 Zn 65.57 65.65 65.43 65.38 66 .32 66 .34 66 .81 66 .57 S 33.50 33.05 32.81 32.77 32 .98 33 .01 33 .00 32 .74 Fe 0.03 0.00 0.00 0.03 0 .04 0 .00 0 .00 0 .04 Mn 0.66 0.00 0.00 0.00 0 .00 0 .00 0 .11 0 .09 Cd 0.10 0.74 0.97 1.81 0 .94 0 .60 0 .12 0 .09 Hg 0.04 0.00 0.12 0.00 0 .00 0 .07 0 .00 0 .00 Ga 0.00 0.22 0.14 0.00 0 .00 0 .15 0 .15 0 .16 Ge 0.07 0.09 0.07 0.08 0 .00 0 .03 0 .00 0 .07 In 0.00 0.03 0.07 0.03 0 .00 0 .09 0 .00 0 .00 Total 100.0 99.79 99.65 100.1 100.3 100.3 100.2 99 .80 22 24 25 27 28 29 30 Zn 66.57 66.56 66.37 66. 23 66. 31 66. 10 66. 10 S 33.02 33.02 32.86 33. 11 33. 14 32. 85 32. 87 Fe 0.00 0.00 0.00 0. 00 0. 00 0. 00 0. 00 Mn 0.09 0.00 0.00 0. 52 0. 32 0. 00 0. 04 Cd 0.12 1.14 1.05 0. 06 0. 06 0. 71 0. 66 Hg 0.00 0.00 0.00 0. 11 0. 07 0. 00 0. 00 Ga 0.00 0.00 0.00 0. 05 0. 15 0. 10 0. 07 Ge 0.00 0.11 0.00 0. 00 0. 00 0. 05 0. 05 In 0.00 0.00 0.00 0. 00 0. 00 0. 03 0. 03 Total 99.81 100.9 100.3 100 .1 100 .1 99. 85 99. 88 Table 4.5.3 Zonal Analysis of Sphalerite sample NGV4,#1 1 2 4 5 7 8 9 11 Zn 63.38 63 .35 S 33.25 33 .36 Fe 2.63 2 .65 Mn 0.05 0 .05 Cd 0.22 0 .35 Hg 0.00 0 .00 Ga 0.00 0 .00 Ge 0.03 0 .00 In 0.20 0 .07 63.80 63.50 63.40 33.00 33.25 33.14 2.30 2.68 2.86 0.06 0.06 0.06 0.20 0.28 0.34 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.00 0.10 0.10 0.22 63.42 63.55 62.87 33.26 33.10 33.67 2.49 2.30 2.95 0.07 0.07 0.07 0.29 0.32 0.28 0.00 0.00 0.00 0.04 0.00 0.04 0.00 0.10 0.08 0.22 0.55 0.23 Total 99.79 99.84 99.51 100.3 100.0 99.78 99.99 100.2 •Values are given as element weight percents **Site numbers are across grain (NGV4,#1) and core to rim (3CHN89-1). Select analyses given for large traverses. 159 Germanium displays a more even d i s t r i b u t i o n i n the Number Three system and i s apparently contemporaneous with the main spha l e r i t e mineralizing event. Bernstein (1985) roughly characterized the geologic environment for high concentrations of Ge i n sphalerites and found that the highest concentrations of Ge were found i n l a t e stage, low temperature sp h a l e r i t e s , predominantly those hosted by sedimentary rocks. The higher temperature hydrothermal mineralization s i m i l a r to that present i n the Number Three vein tended to have lower Ge contents than "epigenetic" mineralizations. Incorporation of Ge into sphalerites was considered to be associated with low to moderate log ag 2 values, with other s u l f i d e s or independent Ge phases forming at a higher log a g 2 ( F i g u r e 4.5.2). Bernstein (1985) also suggested that Ge contained i n hydrothermal deposits may have been derived from one of two sources: a) f r a c t i o n a l c r y s t a l l i z a t i o n of igneous f l u i d s b) incorporation of Ge from country rocks, p a r t i c u l a r i l y those enriched i n organic matter. A p o s s i b i l i t y e x i s t s that independent Ge minerals are present i n some parts of the Number Three system because, germanium contents of sphalerites are too low to account for reported assays. Germanium may also be present i n trace amounts i n s i l i c a t e s and base metal s u l f i d e s from the Number Three vein, although t h i s probably could not account for the observed anomalous l e v e l s . 160 Gallium i s concentrated p r i n c i p a l l y i n sample 3CHN89-1 material and, l i k e Ge, appears to be a component of Stage II mineralization and not confined to any one event. Cadmium le v e l s i n the Number Three vein display patterns s i m i l a r to those of the three "semiconductor metals". Cadmium contents are highest i n sample 3CHN89-1, at 1.8 weight percent; the existence of independent Cd-bearing phases has not been ruled out. Sphalerites from sample 3CHN89-1 are also enriched i n Mn (up to 0.7 weight percent), with Mn contents varying inversely with Cd contents. In general, Hg contents i n sphalerite are below or near detection l i m i t s i n a l l parts of the vein. The r e l a t i v e l y Fe-deficient nature of S i l v e r Queen sphalerite i s unusual i n i t s continuity. A possible reason for low Fe contents i s the removal of Fe from the hydrothermal system by the c r y s t a l l i z a t i o n of p y r i t e preceding the main sphalerite mineralizing event. Paragenetic relationships support t h i s conclusion, with a widespread p y r i t e depositional event commonly noted to i n i t i a t e Stage II mineralization. 4.6 S u l f o s a l t and Electrum Chemistry 4.6.1 Introduction S u l f o s a l t s (other than tetrahedrite) and electrum form a volumetrically minor component of Stage III mineralization i n the Number Three and other systems at S i l v e r Queen; nevertheless, evaluation of the compositions of these phases was necessary i n order to confirm uncertain i d e n t i t i e s . A 161 less important aspect of s u l f o s a l t analysis was the p o s s i b i l i t y of comparison of s u l f o s a l t compositional change to tetrahedrite compositional v a r i a t i o n . Gemmel et al. (1989) have noted that s u l f o s a l t species such as the pearceite-polybasite series and the ruby s i l v e r s may display compositional trends s i m i l a r to coexisting tetrahedrites, with the p o t e n t i a l to develop a geothermometer i f enough f l u i d i n c l u s i o n analyses are available for the s u l f o s a l t m i neralization. In p a r t i c u l a r , i d e n t i f i c a t i o n of several phases was necessary i n order to account for anomalous s i l v e r contents within a number of the samples. Evaluation of these phases was undertaken p r i n c i p a l l y f or the purposes of species i d e n t i f i c a t i o n , with repeat analyses c a r r i e d out on electrum and b e r r y i t e grains i n order to define modal compositions for each. 4.6.2 Sulfosalt Compositions Seligmannite (Bernstein, 1987), berryite (Harris and Owens, 1973), and boulangerite (Marsden, 1985) are among the s u l f o s a l t phases previously noted at S i l v e r Queen. In a l l cases, the s u l f o s a l t assemblage corresponds with Stage III mineralization, with the greatest v a r i e t y of s u l f o s a l t species associated with chalcopyrite-bearing vein material and high s i l v e r grades. Minerals of the seligmannite-bournonite series appear to have the greatest s p a t i a l d i s t r i b u t i o n of the s u l f o s a l t s i n both the Number Three vein and i n several of the smaller veins (refer to Chapter 3). 162 The highly intergrown nature of seligmannite and bournonite i n the Number Three vein produced several d i f f i c u l t i e s during analysis, with interference from the host galena often producing unreasonably high t o t a l s . S.E.M. analysis coupled with three probe analyses allowed, however, for a rough determination of increasing Sb contents towards the northern portion of the vein. Tetrahedrite and seligmannite/ bournonite are commonly c l o s e l y associated s p a t i a l l y and temporally i n the Number Three system and therefore could provide an opportunity to evaluate changing hydrothermal conditions with adequate f l u i d i n c l u s i o n analyses through the construction of compositional t i e - l i n e s (e.g. Gemmel et a l , 1989). The f i r s t recorded Canadian occurrence of the mineral b e r r y i t e i s the S i l v e r Queen mine (Harris and Owens, 1973). The exact formula of berryite i s s t i l l uncertain, although compositionally the mineral f a l l s within the benjaminite s o l i d s o l u t i o n f i e l d described by Chang et a l (1988). The composition of b e r r y i t e from the Number Three vein (Table 4.6.1) shows a s l i g h t (2.5 wt.%) v a r i a t i o n i n B i content, and the formula calculated for the two "end members" appears to match c l o s e l y that determined by Harris and Owens (1973) for material from the same deposit. Some r e v i s i o n may be necessary due to the s l i g h t l y lower B i contents observed i n the new samples, which are probably the r e s u l t of improved p r e c i s i o n i n microprobe analyses. The high Ag contents observed i n the samples from the deep north portion of the 163 Number Three vein may also support an hypothesis that c o p r e c i p i t a t i o n of tetrahedrite and b e r r y i t e resulted i n p a r t i t i o n i n g of Ag p r e f e r e n t i a l l y into b e r r y i t e , producing unusually low Ag contents i n the tetrahedrite. The ruby s i l v e r s and minerals of the pearceite-polybasite series d i s p l a y a wide range i n compositions i n the Number Three and associated veins. Generally, end member pyrargyrite i s the predominant form of the ruby s i l v e r s , with more A s - r i c h compositions noted i n the southern portion of the Number Three vein and end member proustite i n the NG3. vein (Table 4.6.1). As for the seligmannite/bournonite series, the change i n compositions roughly p a r a l l e l s the tetrahedrite compositional changes and appear to r e f l e c t an increase i n Sb-substitution with increasing distance from the f l u i d source. An important fact' to consider i s that the proustite l o c a l i t y occurs at a lower elevation than any other vein i n t e r s e c t i o n on the property and therefore might be closest to the heat source. Minerals of the pearceite-polybasite series do not display any recognized systematic compositional trends i n the S i l v e r Queen system, a s i t u a t i o n that may p a r t i a l l y be the r e s u l t of the general s c a r c i t y of these minerals on the property. Compositions range from end member (arsenian) pearceite to arsenian polybasite, with one sample containing 3.21 weight percent B i substituting f o r Sb and As. Several samples from the Camp veins also contained trace quantities of B i , an occurrence which connects pearceite-polybasite 164 mineralization with much of the tetrahedrite event (which also contains appreciable B i ) . A i k i n i t e , m a t i l d i t e , and gustavite (?) were a l l i d e n t i f i e d i n s u l f o s a l t material from the Portal veins and Copper vein, with no unusual deviations from recognized formulae. The l a t t e r phase i s rare i n the veins and represents nearly complete Ag-Bi substitution of the l i l l i a n i t e - g u s t a v i t e s o l i d solution (Makovicky and Karup-Moller, 1977). Sb-bearing bismuthinite and cuprobismutite were i d e n t i f i e d i n association with bismuthian tennantites from the NG3 vein, from which they appear to have exsolved. Several other possible phases were also i d e n t i f i e d by backscattered electron imagery; although t o t a l s f o r these phases were low (90 to 97 wt.%), a l l were found to be Cu-Pb-B i phases, possibly of the bismuthinite-aikinite s o l i d s olution s e r i e s . A m i s c i b i l i t y gap that exists within t h i s series below 300°C may be r e f l e c t e d within t h i s series because no compositions between 60 and 80 mole percent Bi2 S3 were noted (Harris and Chen, 1976). As a r e s u l t , an upper l i m i t on temperature might be applied to a region of the Number Three-NG3 system that i s close to the interpreted heat source. 4.6.3 Electrum Compositions Electrum i s the only observed Au-bearing phase at the S i l v e r Queen mine and thus generates a considerable degree of i n t e r e s t as to i t s locus and composition (see Chapter 3). Electrum from the Number Three vein and several smaller veins was, i n general found to be quite Ag-rich (560 to 760 Fine) and. to lack zoning i n i n d i v i d u a l grains (Table 4.6.2). The d i s t r i b u t i o n of electrum compositions throughout the Number Three system was not evaluated i n d e t a i l , although microscopy indicates a possible increase i n Au content toward the southern portion of the vein. S.E.M. analyses of several electrum grains defined no unusual trace elements and s l i g h t l y low t o t a l s are probably the r e s u l t of surface oxidation. 166 Table 4.6.1 Microprobe Analysis of S u l f o s a l t Compositions a.) Berryite S i t e A Si t e B Wt.% At. Ct. Wt.% At. Ct. Cu 6.19 9.14 6.37 9.58 S 17.34 52.21 17.52 52.19 Zn 0.00 0.00 0.00 0.00 Fe 0.22 0.38 0.04 0.06 Sb 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Pb 20.02 9.33 20.37 9.39 Ag 7.36 6.58 7.29 6.46 Bi 47.80 22.09 48.75 22.28 Hg 0.00 0.00 0.00 0.00 Total 98.92 100.37 S=ll Pb 2(Cu 1.9 fAg 1.4)Bi4. 7S 1 1 Pb 2(Cu 2,Ag 1 > 4 ) B i 4 . 7 s l l S i t e C Sit e D Wt.% At. Ct. Wt.% At. Ct Cu 6.43 9.47 6.30 9.51 S 17.69 51.58 17.44 52.20 Zn 1.23 1.76 0.00 0.00 Fe 0.24 0.41 0.00 0.00 Sb 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Pb 20.13 9.09 20.76 9.62 Ag 8.20 7.11 7.62 6.78 Bi. 46.01 20.59 47.60 21.87 Hg 0.00 0.00 0.00 0.00 Total 99.92 99.73 S=ll P b 1 . 9 ( C u 2 / A g 1 . 5 ) B i 4 . 4 S i 1 Pb 2(Cu 2 /Ag 1 • 4 ) B i 4 . 6 s l l S i t e A from sample s i t e 2CHN89-11 ; "Portal 10.5 " vein S i t e B from sample s i t e 3CHN90-2; Number Three vein S i t e C from sample s i t e 3CHN90-1; Number Three vein S i t e D from sample on Number Five vein * Karup-Moller (1966) gives Pb3 (Cu3 >5,Agi >5)Bi7 Sis for be r r y i t e formula. ** N u f f i e l d and Harris (1966). Harris and Owens (1973) gives Pb 2 (Cu fAg)3 B i s for b e r r y i t e formula. 167 3 . ) Pyrargyrite-Proustite series S i t e A Sit e B Wt. % At. Ct. Wt.% At. Ct. Cu 0.13 0.16 0.12 0.14 S 17.51 42.39 17.67 42.50 Zn 0.00 0.00 0.05 0.05 Fe 0.00 0.00 0.00 0.00 Sb 19.61 12.50 21.83 13.83 As 1.82 1.89 0.67 0.69 Pb 0.00 0.00 0.00 0.00 Ag 59.76 43.01 59.77 42.73 B i 0.00 0.00 0.13 0.05 Hg 0.00 0.00 0.00 0.00 Total 98.92 100.24 S i t e C Sit e D Wt.% At. Ct. Wt.% At. Ct. Cu 0.25 0.30 0.18 0.21 S 16.64 28.44 17.99 41.28 Zn 0.06 0.07 2.86 3.22 Fe 0.00 0.00 0.00 0.00 Sb 0.33 0.20 10.55 6.38 As 12.61 12.48 6.29 6.18 Pb 0.00 0.00 0.00 0.00 Ag 70.58 48.49 62.62 42.70 Bi 0.00 0.00 0.10 0.04 Hg 0.05 0.00 0.00 0.00 Total 100.53 100.61 Site A i s from sample s i t e 1CHN89 -65; Owl vein S i t e B i s from sample s i t e 3CHN89 -39; Camp veins S i t e C i s from sample s i t e 3CHN89 -1; NG3 vein S i t e D i s from sample s i t e 3CHN89 -24; Number Three vein. •General formula i s Ag 3 (Sb,As)S 3 168 c. ) Pearceite-Polybasite series S i t e A Si t e B Wt.% At. Ct. Wt.% At. Ct. Cu 11.30 12.79 3.31 4.11 S 16.51 37.04 14.01 34.55 Zn 0.00 0.00 0.56 0.68 Fe 0.44 0.56 0.00 0.00 Sb 0.34 0.20 6.88 4.47 As 6.57 6.31 1.54 1.63 Pb 0.00 0.00 0.00 0.00 Ag 64.40 42.95 74.37 54.53 Bi 0.26 0.09 0.07 0.03 Hg 0.05 0.02 0.00 0.00 Total 99.89 100.74 Si t e C Sit e D Wt. % At. Ct. Wt.% At. Ct. Cu 8.58 9.94 5.72 6.87 S 16.54 38.00 15.41 36.63 Zn 0.00 0.00 0.00 0.00 Fe 0.00 0.00 0.00 0.00 Sb 0.65 0.40 5.58 3.50 As 5.48 5.39 3.06 3.12 Pb 0.00 0.00 0.00 0.00 Ag 65.86 44.99 70.57 49.87 B i 3.21 1.13 0.00 0.00 Hg 0.00 0.00 0.00 0.00 Total 100.32 100.34 Sit e A i s from sample s i t e 2CHN89-48; "Jaxel" vein. S i t e B i s from sample s i t e 3CHN89-24; Number Three vein. S i t e C and s i t e D are from the Number Five vein. * General formula i s (Ag fCu)^g (As,Sb)2 S n 169 d.) Other Sulfosalts A i k i n i t e M a t i l d i t e -Wt.% At. Ct. Wt.% At. Ct. Cu 11.02 16.29 0.23 0.35 S 17.32 50.75 17.12 50.68 Zn 0.00 0.00 0.00 0.00 Fe 0.00 0.00 0.00 0.00 Sb 0.00 0.00 0.00 0.00 As 0.00 0.00 0.00 0.00 Pb 35.87 16.26 0.06 0.03 Ag 0.04 0.03 27.80 24.46 B i 36.37 16.35 53.78 24.42 Hg 0.00 0.00 0.06 0.03 Total 100.32 99.07 Bournonite Bismuthinite Wt.% At. Ct. Wt.% At. Ct. Cu 12.42 15.90 0.14 0.22 S 19.97 50.67 19.40 59.72 Zn 0.06 0.08 0.00 0.00 Fe 0.00 0.00 0.00 0.00 Sb 24.27 16.22 5.18 4.20 As 0.58 0.63 0.15 0.19 Pb 41.73 16.39 0.00 0.00 Ag 0.00 0.00 0.00 0.00 Bi 0.12 0.05 75.36 35.58 Hg 0.00 0.00 0.00 0.00 Total 100.15 100.30 A i k i n i t e and ma t i l d i t e samples are from the Number Five vein. Bournonite sample from sample s i t e 3CHN89-20; Number Three vein. Bismuthinite sample from sample s i t e 3CHN89-3; NG3 vein. 170 Gustavite (?) Geocronite Wt.% At. Ct. Wt.% At. Ct. Cu 0.19 0.30 0.00 0.00 S 16.95 54.80 1 17.66 53.74 Zn 0.00 0.00 0.08 0.13 Fe 0.00 0.00 0.00 0.00 Sb 0.00 0.00 7.21 5.78 As 0.00 0.00 5.95 7.75 Pb 23.67 11.85 68.90 32.46 Ag 8.60 8.27 0.00 0.00 Bi 49.91 24.76 0.17 0.08 Hg 0.00 0.00 0.00 0.00 Total 99.34 100.01 Cuprobismutite (best analysis) Wt.% At. Ct. Cu 17.40 22. 78 S 19.87 51. 56 Zn 0.16 0. 20 Fe 0.09 0. 13 Sb 3.52 2. 40 As 0.09 0. 09 Pb 0.00 0. 00 Ag 0.06 0. 05 Bi 57.27 22. 80 Hg . 0.00 0. 00 Total 98.45 Cuprobismutite i s from sample s i t e 3CHN89-3; NG3 vein. Geocronite i s from sample s i t e 3CHN89-1; NG3 vein. Gustavite (?) i s from sample s i t e 2CHN89-11; "Portal 10.5" vein. •General formula for gustavite given as Ag 3 Pb5 Bin s24 (Makovicky and Karup-Moller, 1977). ••General formula for geocronite given as Pb5 (As,Sb)2 Sg (Birnie and Burnham, 1976). 171 Table 4 . 6 . 2 Electrum Compositions Sample A B Wt.% At. Ct. Wt ..% At. Ct. Au 70.51 57.69 73 .73 62.18 Ag 28.22 42.15 24 .55 37.80 Hg 0.10 0.08 0 .00 0.00 Cu 0.00 0.00 0 .00 0.00 Total 98.86 98 .30 Sample C D Wt.% At. Ct:. Wt .% At. Ct. Au 76.18 64.76 56 .33 41.15 Ag 22.65 35.16 43 .47 57.76 Hg 0.00 0.00 0 .00 0.00 Cu 0.00 0.00 0 .48 (contam.?) Total 98.86 100 .28 Site A i s from Number Five vein Site B i s from sample s i t e 2CHN89 -4; Portal Three vein Site C i s from sample s i t e 3CHN90 -2; Number Three vein S i t e D i s from Number Five vein 172 5.0 DISCUSSION 5.1 Introduction The mineralogies of base- and precious-metal veins at the S i l v e r Queen mine are suggestive of r e l a t i v e l y low pressure and moderate temperature hydrothermal deposition. Open space f i l l i n g textures are present throughout the Number Three and associated veins, with no evidence of remobilization i d e n t i f i e d . Paragenetic studies have also indicated that mineralization proceeded through a series of stages, distinguished by variations i n the bulk mineralogy, textures, and o v e r a l l mode of deposition. In order to properly evaluate the evolution of thi s system, a number of questions must be answered: 1) What were the conditions of formation of the vein system, as defined by equilibrium pairings? 2) What was the mode of transport and deposition of the component metals during evolution of the hydrothermal system? 3) What were the c o n t r o l l i n g factors influencing the nature of the solutions? 4) What was the source of the metals? 5.)What was the d r i v i n g force, for f l u i d transport? 5.2 Conditions of Mineral Deposition Mineralization i n Stages I through III i s characterized by a diverse suite of phases, including p o t e n t i a l l y economic 173 concentrations of Au and Ag i n electrum and tetrahedrite. The close temporal and s p a t i a l associations of these minerals indicate that transport of the metals i n s o l u t i o n was through s i m i l a r processes, with deposition induced through a r e l a t i v e l y rapid change i n ambient conditions. As noted i n Table 5.2.1, transportation of the metals i s dominated by three p o t e n t i a l species, related to the pH and chloride content of the s o l u t i o n (Wood et a l . , 1983). At S i l v e r Queen, the abundance of l a t e vein hydrocarbons may be i n d i c a t i v e of the importance of organic ligands. as well, although the temperature of the solutions approaches the upper s t a b i l i t y l i m i t for most organic complexes (Barnes, 1979) . Conditions of deposition can be approximated c l o s e l y through the s t a b i l i t i e s of several observed s u l f i d e assemblages. The most important of these i s coexisting galena-matildite, a p a i r i n g that has been observed i n several c h a l c o p y r i t e - r i c h veins where Stage III mineralization i s most abundant. Craig (1967) noted that c h a r a c t e r i s t i c Widmannstaten-like textures formed through exsolution below 215 + 15° C , with complete s o l i d s o l u t i o n of Ag and B i i n PbS above the solvus. In samples from the Portal veins, galena-matildite intergrowths are observed within the outlines of a pre-existing bladed form which i s interpreted to represent the metastable Ag-Pb-Bi phase. If t h i s i s the case, the solutions o r i g i n a l l y deposited the metastable phase at temperatures s l i g h t l y greater than that Metal Low Chloride High Chloride Low PH H1qh £H Fe F e 2 + FeOH^, Fe(0H) 2 ' F e C , n 2 - " (n-O-3) In Zn 2 * ZnOH*. :n(0H) ;* : n c i n 2 - n (n-O-3) Pb P b 2 + POOH*; Pb(0H)2* PbCl„2- n (n-O-3) Bi B1(CH) 2 \ 3H0H) 3 ' 3iC1 n2-n (n-O-2) Au AuHS* or MAu(HS)2' Au(HS);- AuCl* Ag AgMS* or HAg(HS)2° Aa<HS)2- AgCl* Mo H2HoO« HM0O4- MoO«2~ Unchanged or Mo-blcareonate or -carbonate contolexes Sb Sb'(aQ), HSbSj, H2SbS«, Sb(0H) 2 + , SMOHlj* Unchanged TABLE 5.2.1 Speciation of Ore Metals i n Hydrothermal Solutions. [From Wood at a l (1983)] 175 of the solvus, with exsolution occurring as the phase cooled. Sakharova (1969) also suggests that m a t i l d i t e i n the absence of galena, but i n the presence of other coprecipitated Pb-bearing s u l f o s a l t s , may represent formation at temperatures less than 215° C. through the breakdown of chalcopyrite. M a t i l d i t e has been noted from one l o c a l i t y i n the Number Three system, but i s apparently the r e s u l t of replacement of berryite and i s not necessarily i n d i c a t i v e of. formation at subsolvus temperatures. Although they do not provide a d i r e c t approximation of temperature, other s u l f i d e / s u l f o s a l t assemblages give important information on the composition of the hydrothermal f l u i d s . The temperatures and pressures of the system at the time of deposition are not known, however, the value obtained from the galena-matildite assemblage can be regarded as a minimum. The presence of marcasite i n Stage I material i n the northernmost intersections from the Number Three vein constrains the early mineralization temperature i n the more d i s t a l segments of the Number Three vein at a maximum of 240° C. (Murowchick and Barnes, 1986). Preliminary f l u i d i n c l u s i o n work on e a r l y quartz and ba r i t e suggests maximum temperatures of 230 to 240° C , corresponding c l o s e l y with the temperatures obtained from marcasite and the galena-matildite p a i r i n g (M. Thomson, pers. comm. 1991). Estimates of pressure for the hydrothermal system of S i l v e r Queen mine are derived from comparisons with other 176 mineralizing systems of s i m i l a r temperature and environment. For the analysis of f l u i d compositional parameters, a temperature within 20° of 250° C , at a pressure of less than one kilobar (eg. Berger and Henley, 1989) w i l l be used. Lat e r a l temperature gradients are assumed to be n e g l i g i b l e over the length of the S i l v e r Queen system, i n accord with to the persistance of common paragenetic events over the ent i r e deposit, and r e l a t i v e l y small s i z e of the deposit compared with the probable si z e of the hydrothermal system (cf. Berger and Henley, 1989). Given an i n i t i a l temperature of 240° C. and pressure o f <1 kilobar, compositional parameters such as log ag 2, log aQ2 and pH can be constrained by coexisting mineral pairs (Figure 5.2.1). The assemblage pyrite-hematite-guartz i s p a r t i c u l a r l y widespread at S i l v e r Queen, forming a large percentage of the Stage I assemblage within the ce n t r a l section of the Number Three vein (refer to Chapter 3). A minimum log ag 2 of about -11 and log arj 2 of about -34.4 are implied by the coexistance of these two phases. In several intersections of the Number Three vein i n the deep central segment, an assemblage of pyrite+arsenopyrite+quartz a f t e r hematite has been i d e n t i f i e d . This indicates that a change i n log a,Q2 (independant of pH) from approximately -30 to s l i g h t l y less than -40 has taken place during the t r a n s i t i o n from the i n i t i a l specular hematite-dominated mineralogy to the l a t e r s u l f i d e assemblage (Figure 5.2.2). Within the Camp veins, the change i s more extreme, with pyrrhotite also - 8 b n + p y FIGURE 5.2.1 Log ag2~log aQ2 diagram showing the st a b i l i t y -f i e l d s of common hydrothermal minerals i n the presence of quartz. Temperature i s 250° C. with the standard states for S 2 and 0 2 as i d e a l diatomic gases at 1 atm. and 250° C.. From Barton et a l (1977), as applied to data from Creede. Note that S i l v e r Queen ores do not contain hydrothermal c h l o r i t e i n the vein assemblage; thus, the magnetite f i e l d i s not preempted by the c h l o r i t e f i e l d . 178 FIGURE 5.2.2 Log aQ2~pH diagrams showing common hydrothermal mineral s t a b i l i t i e s at 250° C. and log t o t a l s u l f u r of - 3 . Shaded f i e l d " I l a " represents low log ag 2 chalcopyrite-bearing assemblage. From Hayba e_£_aJL (1985), as applied to Summitville ores. . 250 °C F e - A s - S - O - H with excess Fe I : ! I i l i I 0 2 U 6 8 10 12 H PH FIGURE 5.2.3 Log aQ2 _pH diagram showing s t a b i l i t y f i e l d s of common hydrothermal m i n e r a l s and a r s e n i c s p e c i e s a t a temperature o f 250° C. and l o g ag2. of -2. From H e i n r i c h and Eadington (1986). Note t r a n s i t i o n from hematite assemblage t o p y r i t e - p y r r h o t i t e - a r s e n o p y r i t e assemblage a t lower l o g aQ2/ a s e x e m p l i f i e d by s e v e r a l of the Camp v e i n s . 180 occurring within the l a t e r s u l f i d e assemblage (Figure 5.2.2), and several peripheral veins (eg. the northernmost Cole vein i n t e r s e c t i o n , Barite vein) also display evidence of a s i m i l a r t r a n s i t i o n . The pH of each s i t e i s more d i f f i c u l t to determine, due to the near-complete replacement of hematite by p y r i t e i n most s i t e s (erasing p o t e n t i a l evidence that the assemblage passed through the magnetite s t a b i l i t y f i e l d ) . In the northernmost section of the Number Three vein and in. the Portal veins, the presence of primary marcasite i s instead used to estimate the pH of Stage I f l u i d s . Murowchick and Barnes, (1986) found that marcasite could be p r e c i p i t a t e d from pyrite-supersaturated f l u i d s at a pH of less than 5.4, with the pH of deposition dependent on the p o l y s u l f i d e species associated with Fe-transport. Minor amounts of marcasite are present i n several l o c a l i t i e s from the c e n t r a l Number Three vein as well, therefore, 5.4 i s regarded as a maximum pH for most Stage I assemblages. The pH. estimate i s i n agreement with the s t a b i l i t y f i e l d of k a o l i n i t e (Figure 5.2.2), found i n the a l t e r a t i o n assemblage at S i l v e r Queen mine. A p a r t i c u l a r i l y unusual Stage I mineral assemblage occurs within the Copper vein i n the Cole vein system, where hematite, magnetite, and p y r i t e coexist. On Figure 5.2.1, the assemblage plots on an invariant point at log ag 2 of about -11 and log a.Q2 °f about -34.4. The pH estimate (Figure 5.2.3) i s somewhat higher (6.5 to 7.0) than that determined from the presence of marcasite. 181 1 0 0 0 / T , °K FIGURE 5.2.4 Log ag2-Temperature diagram f o r s e l e c t e d s u l f o s a l t s u l f i d a t i o n c u r v e s . From C r a i g and Barton (1973). 182 The rare presence of coexisting b a r i t e and p y r i t e i n the southern section of the Number Three vein, the Camp veins, and the Chisholm veins i s in d i c a t i v e of r e l a t i v e l y s p e c i a l i z e d conditions e x i s t i n g i n the l a t t e r half of Stage I mineralization (eg. see Figure 5.2.2). The question of whether the s u l f i d e - s u l f a t e equilibrium was established cannot be evaluated s u f f i c i e n t l y u n t i l s u l f u r isotope studies are completed, and for the purposes of t h i s discussion the phases involved are assumed to be at equilibrium. Holland and Malinin (1979) noted that p r e c i p i t a t i o n of b a r i t e may be induced through simple cooling of the hydrothermal solutions. Ohmoto and Lasaga (1982) found, however, that the times required for s u l f a t e -s u l f i d e e q u i l i b r a t i o n were impractical for hydrothermal systems, instead proposing that mixing of the hydrothermal waters with a separate, r e l a t i v e l y oxidizing s o l u t i o n i s responsible f o r the s u l f i d e - s u l f a t e pairings observed at temperatures of below 350° C . Holland and Malinin (1979) considered t h i s process to involve p a r t i c u l a r i l y d e l i c a t e adjustments i n the so l u t i o n chemistry i n order to prevent resorption of s u l f i d e grains. Both barite and other phases which apparently p r e c i p i t a t e d under sulfate-dominant conditions (eg. hematite) display textural r e l a t i o n s with other s u l f i d e minerals that are suggestive of simple equilibrium as defined by Barton et al. (1963) and i t i s possible that s u l f a t e - s u l f i d e equilibrium was attained within the r e s e r v o i r f l u i d s before transport and deposition. 183 A second p o s s i b i l i t y i s that times for mineral deposition were r e l a t i v e l y protracted and s u f f i c i e n t l o c a l equilibrium-was attained i n the observed s i t e s (Ohmoto and Lasaga, 1982) . Stage II mineralogies, dominated by carbonate minerals and sphalerite, provide fewer opportunities to evaluate the conditions during mineral deposition. Coexisting sphalerite and p y r i t e or pyrrhotite may provide information about log aS2 ( e9* Figure 5.2.1), but coprecipitated sphalerite and p y r i t e were not p o s i t i v e l y i d e n t i f i e d within the Number Three assemblage. Sphalerite at S i l v e r Queen i s generally very Fe-poor, and from Figure 5.2.1 and Tables 4.5.1 to 4.5.3, log a£2 for much of the Number Three vein i s about -10 i f p y r i t e saturation was achieved. Barton et al. (1977) noted that abrupt increases i n Fe-content i n sphalerites from the OH vein at Creede corresponded to f l u i d pulses of r e l a t i v e l y reducing chemistry. At S i l v e r Queen, no such Fe-r i c h zones have been i d e n t i f i e d , suggesting that r e l a t i v e l y constant o x i d i z i n g conditions (induced perhaps by mixing with cooler meteoric waters) persisted. Bernstein (1985) has suggested that high Ge contents i n sphale r i t e , such as those present at Silver. Queen mine, are i n d i c a t i v e of a low to moderate log ag2 environment. Arnorsson (1984), however, found that Ge remained i n sol u t i o n i n a mixing environment such as that proposed for the S i l v e r Queen system. Ge p r e c i p i t a t i o n was favoured by simple conductive cooling, suggesting that such a process 184 may have been responsible for the deposition of Ge-bearing sphalerites i n the Number Three system. If the e f f e c t of conductive cooling was s u f f i c i e n t to induce p r e c i p i t a t i o n of Ge, then the r e s u l t may r e f l e c t an i n a b i l i t y to maintain ambient vein temperatures, and perhaps the i n i t i a t i o n of a decline i n hydrothermal a c t i v i t y . The deposition of carbonate minerals during Stage II and much of Stage III (Figure 3.4.22) was sensitive to changes i n dissolved CO2 content of the solutions and pH (Holland and Malinin, 1979). S o l u b i l i t i e s for a l l carbonates are also lowered with increasing temperature (Fournier, 1985). In the Number Three vein, the abundance of carbonate increases with increasing distance from the source of f l u i d s (Figures 3.4.23 and 3.4.25), i n d i c a t i n g that deposition was independent of temperature gradient. Furthermore, the abrupt changes i n CO2 content required for carbonate p r e c i p i t a t i o n cannot be generated without CO2 loss through b o i l i n g . As a r e s u l t , the deposition of carbonate minerals i s proposed to represent e i t h e r a change i n pH caused by mixing with more neutral, oxidized waters (or by H + metasomatism associated with wallrock a l t e r a t i o n [Holland and Malinin, 1979]). The mineral assemblages generated during Stage III mineralization are the most complex at the S i l v e r Queen mine i n terms of composition and d i s t r i b u t i o n . A l l of the Au, Ag, B i , Sb, As and Cu, and most of the Pb minerals are associated with t h i s stage and as a r e s u l t numerous opportunities are available to evaluate solution chemistry 185 during t h i s stage. The conditions of deposition are interpreted to have been variable over short periods of time, as i s evidenced by the presence of " o s c i l l a t o r y zoned" tetrahedrite-tennantite i n some lo c a l e s . These s i t e s may represent l o c a l e s where f l u i d compositions were highly anisotropic due to i n t e r a c t i o n with brecciated vein or wallrock material. The fahlores have e a r l i e r (Chapter IV) been interpreted to display possible evidence of a shrinking hydrothermal c e l l and o v e r a l l present an outward trend towards i n c r e a s i n g l y evolved (Sb-rich) compositions. In several grains, however, the zone to zone t r a n s i t i o n s are sharp, and rather than displaying a t r a n s i t i o n from one composition to another, appear to have been abrupt. The turbulent nature of the f l u i d flow i n a brecciated environment may r e s u l t i n l o c a l variations i n the a b i l i t y of the f l u i d s to deposit tetrahedrite-tennantites. As a r e s u l t , the grains may d i s p l a y sharp zonal boundaries with small-scale compositional variations, but w i l l r e f l e c t the developing whole-vein chemistry across the width of the grain. Hackbarth and Petersen (1984) proposed that compositional v a r i a t i o n s within single grains may be due to f r a c t i o n a l c r y s t a l l i z a t i o n , with compositional heterogeneity generated by varying exposure to more or less evolved f l u i d s . I f t h i s i s indeed the case, then a r e l a t i v e l y large degree of compositional v a r i a t i o n could be expected for the Stage III f l u i d s . 186 Cu-bearing phases (tetrahedrite-tennantite, seligmannite-bournonite and chalcopyrite) are the most widespread of the Stage III assemblages. A number of constraints can thus be applied, to the depositional conditions as implied by t h e i r presence. Figure 5.2.1 plots the boundary for the chalcopyrite to pyrite+bornite t r a n s i t i o n at a log ag 2 value of about -8.6. S i m i l a r i l y , the t r a n s i t i o n from enargite to tetrahedrite i s placed at a log aS2 value of approximately -9.7, with neither of the phase changes affected by log arj 2 and to a lesser extent, pH v a r i a t i o n . In the S i l v e r Queen mine, the phase enargite has not been i d e n t i f i e d , and bornite has been noted as rare inclusions i n p y r i t e at the southern extent of the Number Three vein. As a r e s u l t , the value of log ag 2 present during Stage III mineralization i s constrained by an upper l i m i t of about -9.7. To evaluate the lower l i m i t s f or log ag 2 values, s u l f i d a t i o n curves f o r proustite and m a t i l d i t e are consulted (Figure 5.2.4). At 250° C , the t r a n s i t i o n from the assemblage argentite+realgar to proustite occurs at a log ag 2 of -12.5, whereas the t r a n s i t i o n from silver+bismuth to mat i l d i t e occurs at -16. The s t a b i l i t y of proustite and mat i l d i t e i n the Number Three system thus constrains the lower l i m i t of log ag 2 at about -12.5. The l a s t major constraining element provided by Stage III mineralogies i s the presence of the assemblage galena+anglesite i n the Portal veins, Lead vein, Number Two vein, and Owl vein. These veins represent systems that are among the most d i s t a l 187 to the "source" as defined by tetrahedrite compositions (Chapter IV) and thus may represent the most oxidized areas i n the S i l v e r Queen system due to interactions with d i l u t e oxidized meteoric waters. A maximum log an,2 °f -31.4 (Figure 5.2.1) i s i n f e r r e d f o r t h i s assemblage. 5.3 Evolution of the Hydrothermal System The epithermal veins at S i l v e r Queen developed along a series of near v e r t i c a l fractures i n response to upward and l a t e r a l movement of hydrothermal f l u i d s , possibly generated by "seismic pumping" (Thomson and S i n c l a i r , 1991) or by simple pluton driven convective motion (eg. Barton et a l . , 1977). An association with Unit 6 dykes may have also contributed to the l o c a l l i z a t i o n of mineralizing solutions. I n i t i a l f l u i d i n c l u s i o n and C 1^ isotope studies by Thomson (pers comm.) indicate that f l u i d s were dominantly meteoric i n o r i g i n , with temperatures of up to 240° C . From mineral assemblage evaluation, the heat source that drove the f l u i d s i s located at depth i n the southern section of the mine area (Figure 2.3.1), with the southern end of the Number Three system representing the vein segment closest to the heat source. Fluids are interpreted to have undergone a large degree of l a t e r a l motion due to the o v e r a l l outward mineralogical zonation away from the south-central block of the S i l v e r Queen area, l a t e r a l v a r i a t i o n i n fahlore compositions i n the Number Three vein (Chapter IV), and changes i n the character of mineralization from south to G e l precipi tates Fibrous crystals Very f i n e crystals Ske le ta l crysta ls Sec tor - zoned crysta ls I Select ive replacement. Del icate growth banding, 1 Large crystals S A T U R A T I O N = EQUIL IBRIUM Select ive etching M i ld etching Deep etching Tota l r emova l FIGURE 5.3.1 Textural properties i n d i c a t i v e of degree saturation. From Barton e t a l (1977). At S i l v e r Queen, p y r i t e and spha l e r i t e display textural v a r i a t i o n s that probably r e l a t e d to degree of saturation. 189 FIGURE 5.3.2 S o l u b i l i t y of b a r i t e contoured on a temperature-salinity diagram, showing predicted t r a j e c t o r i e s for b o i l i n g and mixing. pH i s set at 5.5. From Hayba fit, a l -(1985). 190 north. Of p a r t i c u l a r note i s the change i n form of Stage I py r i t e and.Stage II sphalerite from south to north i n the Number Three vein (refer to Figure 5.3.1). In the south, sphalerite and p y r i t e are c h a r a c t e r i s t i c a l l y colloform or as fine grained aggregates, i n d i c a t i v e of a high degree of supersaturation f o r these two phases. Towards the north, the textures appear to represent decreasing degrees of supersaturation, u n t i l near equilibrium textures are developed i n the northernmost in t e r s e c t i o n s . F i n e l y laminated carbonate occurring i n the northern segments of the Number Three structure i s also i n d i c a t i v e of a d i s t a l p o s i t i o n i n the. hydrothermal system. Examples of undersaturation are minor, i d e n t i f i e d by the absence of p a r t i c u l a r phases (eg. p y r i t e i n Stage III) rather than by di s s o l u t i o n . The p o t e n t i a l complexes involved i n the transport of metals i n the hydrothermal system are summarized i n Table 5.2.1. Chloride contents i n f l u i d inclusions are inconclusive, although r e l a t i v e l y low s a l i n i t i e s are commonly found i n inclusions within s p h a l e r i t e . In most hydrothermal systems, Zn transport i s accomplished by a chloride complex (Reed and Spycher, 1985) rather than a b i s u l f i d e complex, as may be the case for some other metals. As a r e s u l t , the values obtained for NaCl equivalent percent (<6 molal) may, therefore, represent a mixed value rather than the s t a r t i n g value for the solutions. Another point of note involves the transport of Pb, which at the temperatures 191 indicated f o r the Number Three vein, occurs dominantly as a carbonate complex (Reed and Spycher, 1985). In the S i l v e r Queen system, transport of the remainder of the economic metals (Cu, Ag, Au, Cd, and Hg) may have been accomplished by s u l f i d e / s u l f a t e or chloride complexing. Transportation of Ge, Ga, In, and the semimetals was probably accomplished by hydroxyl complexes (Arnorsson, 1984; Heinrich and Eadington, 1986; Crerar et a l . , 1985) Ore deposition at Owen Lake appears to have been dependent on a number of factors. Precious metal grades are elevated and r e l a t i v e l y consistent (Nowak, 1991) i n the deeper southern segment of the Number Three vein. The increase i n o v e r a l l Auand Ag grades corresponds to two s i g n i f i c a n t features: (1) the change i n d i r e c t i o n or "bend" in: the vein, where s t r u c t u r a l control of the vein o r i e n t a t i o n switched from one j o i n t set to another, and (2) the approximate l i t h o l o g i c boundary between the feldspar porphyry unit and the more porous fragmental rocks. The former point i s important i n that a s i m i l a r e f f e c t i s seen throughout the S i l v e r Queen area; east-west trending veins are dominated by Stage III assemblages and tend to be enriched i n Ag-bearing minerals r e l a t i v e to the more extensive northwest trending veins. This e f f e c t could be representative of opening along the second fracture set towards the end of Stage II mineralization, with Au and Ag grades influenced by the enrichment i n Stage III mineralization r e l a t i v e to e a r l i e r assemblages. More 192 e s s e n t i a l to the deposition of elevated l e v e l s of Au and Ag, however, may be the e f f e c t of the host l i t h o l o g y on the nature of the metal-bearing solutions. Au and Ag contents increase dramatically i n response to crossing into the fragmental rocks, although vein thickness apparently decreases towards the south (Nowak, 1991). Mineralogically, the assemblage at t h i s point i s distinguishable by the appearence of a i k i n i t e and argentian tetrahedrite i n Stage III mineralization. These changes i n the character of the ore could be linked to a change i n the permeability of the host rocks. Cheng et a l . (1991) have noted a r e l a t i v e l y abrupt increase i n the width of the strongly a l t e r e d envelope which corresponds roughly to the p o s i t i o n of the contact with the fragmental rocks. Furthermore, disseminated Stage II and Stage III s u l f i d e s are present throughout the a l t e r e d tuffaceous rocks, suggesting that f l u i d s were able to c i r c u l a t e i n the wallrock and deposit s u l f i d e well into Stage I I I . From these observations, one might i n f e r that wallrock plays an important r o l e i n determining the solution chemistry of a l l mineralizing episodes where the mineralization was hosted by the fragmental rocks. As the solutions passed from the tuffaceous rocks into the less permeable and less altered feldspar porphyry and microdiorite units, pH buffering, of the f l u i d s by the wallrock became less important and mineral deposition was c o n t r o l l e d by simple cooling and d i l u t i o n . 193 Mineral deposition at S i l v e r Queen i s proposed to have been i n i t i a t e d by i n t e r a c t i o n and mixing of two separate f l u i d s . An o r i g i n by b o i l i n g (eg. Reed and Spycher, 1985; Drummond and Ohmoto, 1985) i s rejected due to the frequently coarse grained nature of the ore, preliminary f l u i d i n c l u s i o n analyses, lack of bladed c a l c i t e , the lack of c o r r e l a t i o n between carbonates and precious metals, and depth of formation of the system. The heated mineralizing f l u i d s t r a v e l l e d along fractures u n t i l mixing with a cooler, less s a l i n e meteoric water occurred, r e s u l t i n g i n a temperature decrease at a near constant or s l i g h t l y increasing pH. The temperature decline would reduce the s o l u b i l i t i e s of the s u l f i d e (or chloride) species by one or more orders of magnitude while having a much lesser e f f e c t on metal concentrations (Reed and Spycher, 1985). L a t e r a l v a r i a t i o n s i n mineralogy i n the vein system would be c o n t r o l l e d by the s t a b i l i t i e s and concentrations of the metal complexes (Susak and Crerar, 1982). Barnes (1963, 1975) and Likhachev (1975) defined a generalized hydrothermal zoning sequence outward from the f l u i d source as Fe-Ni-Sn-Zn-Pb-Ag-Au-Sb-Hg fo r both b i s u l f i d e and chloride complexed metals. Barnes (1975) noted however, that chloride complexed metals were less l i k e l y to follow the proposed sequence, r e s u l t i n g i n variations i n the outward sequence of mineral deposition. At S i l v e r Queen, the o v e r a l l paragenetic sequence could represent the zoning pattern proposed by Barnes (1975), with l e a s t soluble and most 194 concentrated Fe-sulfides and bari t e occurring e a r l i e s t paragenetically, followed by sphalerite (Zn), galena (Pb), and s u l f o s a l t s (Ag, Sb, As). In the extreme case, interactions with cooler, o x i d i z i n g groundwaters could lead to the p r e c i p i t a t i o n of sulfate phases i n the "peripheral" veins (eg. Figure 5.3.2). At S i l v e r Queen, the veins which are interpreted to have been most d i s t a l from the heat source (Camp, Chisholm, and eastern Cole veins) do contain abundant b a r i t e and s i l v e r minerals within t h e i r assemblages which may represent t h i s e f f e c t . A s i m i l a r s i t u a t i o n has been proposed fo r the OH vein at Creede, where b a r i t e (and associated s i l v e r mineralization) occurs, toward the southern* end of the vein where f l u i d i n c l u s i o n s a l i n i t i e s and temperatures are lowest (Hayba et a l . , 1985). In summary, the hydrothermal system i s interpreted to have been i n i t i a t e d as an expanding c e l l of heated meteoric waters. Metal transport i s uncertain, with b i s u l f i d e or chloride complexing expected to be the dominant mode of. transport f o r base- and precious-metals. The heated waters reacted almost immediately with cooler, more ox i d i z i n g meteoric waters, r e s u l t i n g i n a zone of quartz-pyrite-barite i n the southern section of the system, moving northward into a hematite-pyrite-quartz assemblage where su l f a t e was the dominant s u l f u r species. At the maximum extent of the hydrothermal c e l l , p y r i t e and quartz were the dominant phases p r e c i p i t a t e d , with ba r i t e and p y r i t e formed towards the margins of the system where the e f f e c t of the cooler 195 waters was more important. The e f f e c t of the expanding c e l l i s expressed i n the assemblage change from hematite to py r i t e to pyrite-pyrrhotite-arsenopyrite, r e f l e c t i n g the increasingly reducing nature of the solutions. As sulfate was reduced to s u l f i d e (coupled with oxidation of Mn^ to MnJ ), H was extracted from the solutions (Holland and Malinin, 1979), r e s u l t i n g i n an increase i n CO3 concentration and concomittant carbonate p r e c i p i t a t i o n . Deposition of the carbonate, coupled with collapse of the hydrothermal c e l l and associated cooling, resulted i n d e s t a b i l i z a t i o n of the zinc chloride complex and p r e c i p i t a t i o n of sphalerite. Continued i n t e r a c t i o n of the f l u i d s with the cooler meteoric waters lowered the s o l u b i l i t i e s of other metals, r e s u l t i n g i n the p r e c i p i t a t i o n of Stage III s u l f i d e s and gold. Gold deposition took place near p y r i t e grain surfaces, where exposure to f l u i d s undersaturated with respect to p y r i t e caused d i s s o l u t i o n . Iron released by from the grain sufaces was oxidized to Fe^ +, whereas gold was reduced from Au + to Au° and deposited near the p y r i t e grain surface. Zonation i n the vein was controlled by the. amount of opening the vein experienced during mineralization, the nature of the wallrock, and the r e l a t i v e s t a b i l i t i e s of the metal species i n solution. The source of the metals i n the mineralizing solutions i s at present uncertain. Analyses of vein bitumen (Stage IV) by Thomson et al. ( i n prep.) display carbon is o t o p i c values ranging from -25.7 to -29 per m i l , suggesting a t e r r e s t r i a l 196 o r i g i n for the carbon. Elevated Ge contents i n sphalerite are also suggestive of metal derivation from sedimentary rocks containing organic matter (eg. Bernstein, 1985). Furthermore, preliminary f l u i d i n c l u s i o n r e s u l t s indicate that s a l i n i t i e s were r e l a t i v e l y low and that f l u i d s were dominantly of meteoric o r i g i n . Late Cretaceous sedimentary rocks containing substantial amounts of organic matter are known to occur i n the region, i n p a r t i c u l a r to the west of the study area on the slopes of Mt. Nadina (Lang, 1929). As a r e s u l t , organic-bearing sediments are suggested to have been an important, i f not the dominant, metal contributor to the hydrothermal solutions. 5.4 Comparison with Other Vein Deposits Table 5.4.1 summarizes the defining factors f o r " a d u l a r i a - s e r i c i t e " and "acid-sulfate" type epithermal deposits, with the S i l v e r Queen system included f o r comparison. The S i l v e r Queen veins do not f a l l neatly into e i t h e r category, perhaps a r e s u l t of the nature of the metal source and probable i n t e r a c t i o n of two disparate f l u i d s during mineral deposition. In general, the S i l v e r Queen system more c l o s e l y resembles an Adularia-sericite-type environment, with the absence of adularia and the presence of. bismuthinite being the most notable exceptions. Of the major producing epithermal d i s t r i c t s , the one most c l o s e l y resembling S i l v e r Queen i s Creede, with i t s s i m i l a r l i t h o l o g i e s , host-mineralization age relationships and vein 197 mineralogies. In p a r t i c u l a r , Creede i s also proposed to have originated i n part as the r e s u l t of i n t e r a c t i o n between two f l u i d s of disparate temperature and composition. As with Creede, barite-Ag-mineral-rich veins are located near the periphery of the S i l v e r Queen system, where mineralizing f l u i d s experienced a greater influence from cooler oxidizing groundwaters. The absence of c h l o r i t e i n the veins, and adularia i n the a l t e r a t i o n (perhaps due to a sustained low pH), however, distinguishes the S i l v e r Queen system from the ores at Creede. TABLE 5.4.1 Comparative Anatomy of Volcanic-Hosted Spithermal Deposits.  Type A: A d u l a r i a - s e r i c i t e 1.)Host Rock s i l i c i c to intermediate volcanics 2.)Ore/host age re l a t i o n s ages of ore and host d i s t i n c t 3.)Mineralogy Fahlores, argentite c h l o r i t e common selenides present Mn gangue present no bismuthinite 4.)Alteration s e r i c i t i c to a r g i l l i c abundant adularia occasional k a o l i n i t e 5.)Temperature 200 to 300° C. 6. ) S a l i n i t y 0 to 13 wt% NaCl equiv. 7.)Source of s u l f i d e s u l f u r Leaching of wallrocks deep i n system 198 Type B: Acid- s u l f a t e 1. )Host Rock 2. )Ore/host age rel a t i o n s 3. ) Mineralogy 4. ) A l t e r a t i o n 5. )Temperature 6. ) S a l i n i t y 7 .)Source of s u l f i d e s u l f u r rhyodacite t y p i c a l s i m i l a r ages for ore and host enargite, p y r i t e c h l o r i t e rare no selenides Mn-minerals rare bismuthinite present advanced a r g i l l i c extensive hypogene alunite no adularia 200 to 300° C. 1 to 24 wt% NaCl equiv. probably magmatic S i l v e r Queen veins 1. )Host Rocks 2. )Ore/host age re l a t i o n s 3. ) Mineralogy 4. ) A l t e r a t i o n 5. )Temperature 6. ) S a l i n i t y 7 . )Source of s u l f i d e s u l f u r intermediate volcanics/intrusives 20 Ma difference Fahlores abundant, rare acanthite abundant early p y r i t e and b a r i t e no c h l o r i t e i n veins no selenides abundant Mn-carbonates trace bismuthinite S e r i c i t i c to a r g i l l i c no adularia or alunite 230 to 280° C. <10 wt% NaCl equiv. possibly from organic-rich tuffaceous volcanics/sediments 199 6.0 PRACTICAL ASPECTS OF MINERALOGIC STUDIES 6.1 INTRODUCTION An important consequence of mineralogical studies at the S i l v e r Queen mine i s the provision of data concerning the form and occurrence of economic mineralization i n the veins. A number of p o t e n t i a l l y valuable commodities are present i n the S i l v e r Queen veins, and the aim of t h i s chapter i s to further elaborate on how these resources might be located and developed i n the most e f f i c i e n t manner. Two p r a c t i c a l aspects of the mineralization w i l l be discussed: (1) The d i s t r i b u t i o n and l i b e r a t i o n c h a r a c t e r i s t i c s of important phases and phase associations, including p o t e n t i a l problems with recovery of s i g n i f i c a n t minerals. (2) The delineation of, and exploration for, a d d i t i o n a l ore reserves as predicted through e x i s t i n g mineralogic trends. The Number Three vein system, including the NG3 vein extension, i s the most important of the known veins at S i l v e r Queen. The vein system i s open at the south and at depth, and provides the best opportunity to expand e x i s t i n g reserves. Other vein systems w i l l be considered, and a base for future comparison of vein systems on the property w i l l be provided. Gold, s i l v e r , and zinc are the metals with the greatest economic po t e n t i a l at S i l v e r Queen, and the d i s t r i b u t i o n and 200 r e c o v e r y " o f these p a r t i c u l a r metals i s of c r i t i c a l importance. P o t e n t i a l l y important r e s o u r c e s of l e a d and copper are a l s o p r e s e n t throughout the v e i n system as galena, c h a l c o p y r i t e , and t e t r a h e d r i t e . A d d i t i o n a l l y , a number o f l e s s important byproduct metals, i n c l u d i n g g a l l i u m , germanium, indium, cadmium, and bismuth are a l s o somewhat e r r a t i c a l l y d i s t r i b u t e d w i t h i n the d e p o s i t . 6.2 Occurrence and B e n e f i c i a t i o n o f Economic M i n e r a l s The m a j o r i t y o f p o t e n t i a l l y economic metals i n the Number Three v e i n system are p r e s e n t as s u l f i d e s (Table 6 .1 .1 ) , w i t h e l e c t r u m b e i n g the o n l y economic n o n - s u l f i d e phase i d e n t i f i e d . Electrum, the o n l y Au m i n e r a l i d e n t i f i e d , c o n t a i n s e f f e c t i v e l y 100% of the Au and perhaps 5% of the Ag pre s e n t i n the Number Three and a s s o c i a t e d systems (Tables 6.1.1 and 6 .1 .2 ) . I t g e n e r a l l y occurs as rounded i n c l u s i o n s l e s s than 30 microns i n diameter (Table 6 .1 .2) . L a r g e r g r a i n s , some of which are v i s i b l e i n hand specimen, were found i n the abnormally Au- and A g - r i c h P o r t a l Three and Number F i v e v e i n s ( F i g u r e 3 .5 .8 ) . In most cases, electrum occurs i n galena o r intergrown g a l e n a - A g - s u l f o s a l t masses, commonly c l o s e l y a s s o c i a t e d w i t h f i n e - g r a i n e d p y r i t e (eg. F i g u r e 3 .4 . 18 ) . Electrum may a l s o occur i n s p h a l e r i t e , p y r i t e , t e t r a h e d r i t e , c h a l c o p y r i t e o r even as i s o l a t e d g r a i n s i n t e r s t i t i a l t o gangue q u a r t z . Most should r e p o r t t o a Pb-concentrate (given t h a t s u f f i c i e n t s e p a r a t i o n from f i n e - g r a i n e d p y r i t e has been a c h i e v e d - r e f e r t o Table 6 .1 .1) . 201 S i l v e r i s d i s t r i b u t e d throughout a number of s u l f i d e minerals that mostly represent Stage III mineralization. Argentian tet r a h e d r i t e i s the most important Ag-bearing phase within the Number Three, George Lake, and Cole Lake systems, containing up to 90% of the Ag i n these systems (Table 6.1.1). In the Camp and Chisholm systems, argentian tetrahedrite occurs with s i g n i f i c a n t quantities of other Ag-bearing phases, notably pyrargyrite and pearceite (Table 6.1.1). Tetrahedrite i s replaced by other Ag-sulfides as the most important Ag-bearing mineral i n the Portal veins (matildite, gustavite, berryite, pearceite) and NG3 vein (proustite, Ag-Pb-Sb s u l f o s a l t ) . In a l l veins, Ag-bearing minerals are c l o s e l y associated with, galena and chalcopyrite. Tetrahedrite masses commonly cut (Figure 3.4.9) or are intergrown with (Figure 3.4.6) other Stage III phases, with grain sizes averaging about 0.1 to 0.3 mm.. Much of the Ag would report to a Cu-concentrate, dominated eithe r by chalcopyrite or tetrahedrite. In d i s t a l systems such as the Camp and Chisholm veins, the elevated Ag-content of the mineralogy (see Chapters 3 and 4) combined with grain sizes up to several mm. (eg. Figure 3.5.7) allows for much easier recoveries of Ag-bearing phases. Contamination of the Cu-concentrate i n a l l cases would mostly be the r e s u l t of galena inclusions with or along the margins of the larger tetrahedrite masses. In sample s i t e 3CHN89-1 (Appendix A) i n the deep south NG3 vein, Ag-bearing phases occur as f i n e -grained intergrowths and inclusions i n massive galena (Table 202 6.1.1). As a r e s u l t , Ag (and Au) should report e n t i r e l y to the Pb-concentrate. Recovery of base metals (Cu, Pb, and Zn) from Number Three vein ores w i l l be easiest with vein material from the northernmost and southernmost extensions of the system. In the north, the coarse-grained, euhedral nature of galena and sphalerite (Table 6.1.1) should allow for r e l a t i v e l y easy l i b e r a t i o n and high recovery, with gangue mineralogy dominated by r e l a t i v e l y s o f t carbonate minerals. Within the cha l c o p y r i t e - r i c h zone, Zn-,Cu- and Pb- phases mostly are intimately intergrown (eg. Figure 3.4.5), with the appearence of the Cu-Ag-Pb-Bi phase b e r r y i t e presenting the spec i a l problem of providing a poten t i a l contaminant for both the Pb- and the Cu-concentrates. Berryite from t h i s part of the vein i s commonly intergrown with or replaced by galena (Figure 3.4.11), but most of the smaller b e r r y i t e grains are contained i n chalcopyrite or sphalerite (Figure 3.4.5), creating a p a r t i c u l a r i l y complex d i s t r i b u t i o n for much of the Ag and Pb i n the deep, northern part of the Number Three vein. Toward the south, the complex mineral assemblage i s replaced by simpler, commonly coarse-grained mineralogies (Table 6.1.1) including sphalerite and galena. Unfortunately, material i n the central segment of the Number Three vein i s dominated by hard quartz and p y r i t e gangue, and galena from t h i s section of the vein i s scarce and mostly locked i n p y r i t e . Sphalerite from the cen t r a l part of the Number Three vein i s more abundant and easier to 203 recover; with the greater vein widths, the central section represents a p o t e n t i a l l y important reserve of Zn (eg. Nowak, 1991). Further south, the percentage of sphalerite, galena, and tetrahedrite i n the vein increases. Grain sizes are much smaller than i n the north, although sphalerite masses are commonly up to several mm. i n diameter. Galena i s t y p i c a l l y intergrown with tetrahedrite (Figure 3.4.6), a i k i n i t e , or seligmannite, necessitating f i n e r grinding sizes to eliminate the problem of Cu- and Pb-mineral contamination. Approximately 10% of the galena i n the southern part of the vein i s t i g h t l y locked i n sphalerite or fine-grained p y r i t e masses, probably forming the greatest source of Pb loss during processing. South of the decline area, the degree of intergrowth with galena appears to decrease. Within the NG3 vein, l i b e r a t i o n of base-metal s u l f i d e s i s improved. Masses of galena, sphalerite, and tetrahedrite are la r g e r and less intergrown (Table 6.1.1) i n the NG3 vein, with Cu-bearing phases l a r g e l y absent from the southernmost and deepest i n t e r s e c t i o n (3CHN89-l-see Appendix A). Sample s i t e 3CHN89-1 i s e s p e c i a l l y important i n that the base-metal assemblage consists of two phases: galena, which contains a l l of the Ag and Au, and sphalerite, which also contains appreciable quantities of Ga, Cd, Ge, and In (Table 4.5.2). Contamination from intergrown phases i n t h i s i n t e r s e c t i o n i s almost n i l , and the gangue mineral assemblage includes a large amount of carbonate. 204 Concentrations of base-metal s u l f i d e s i n other structures at S i l v e r Queen are much less important economically, either because of lack of d e f i n i t i o n of availa b l e reserves (as i n the George Lake vein) or because of predominance of precious-metal-bearing phases (as i n the Camp and Po r t a l veins). The George Lake and Cole Lake veins contain the largest potential reserves outside of the Number Three system, and much delineation remains to be done. In the George Lake vein, b e n e f i c i a t i o n would be d i f f i c u l t due to the interlocked nature of the major s u l f i d e species (including pyrite)(Table 6.1.1). Furthermore, fine-grained quartz i s present throughout much of the known vein, creating p o t e n t i a l problems with s u l f i d e l i b e r a t i o n . In the southern segment of the vein, s u l f i d e grain s i z e increases, with i n d i v i d u a l tetrahedrite grains up to 1 mm. across. The Cole vein i s si m i l a r to the north end of the Number Three system, with very coarse-grained (Table 6.1.1) euhedral galena and sphalerite generally present i n a so f t , dominantly carbonate gangue. In the south, the Cole shear contains larger amounts of tetrahedrite and p y r i t e , and base-metal s u l f i d e s become much more interlocked (and ease of vein d e f i n i t i o n declines where the vein i s intersected as a series of c l o s e l y spaced s t r i n g e r s ) . In other systems at S i l v e r Queen, base-metal s u l f i d e s become less important with a corresponding increase i n the Ag-mineral content. Galena, chalcopyrite, and sphalerite are the most abundant phases (Table 6.1.1) and occur commonly as 205 r e l a t i v e l y coarse, euhedral grains or as masses intergrown with s u l f o s a l t s (eg. Portal veins). The l a t t e r occurrence creates p o t e n t i a l d i f f i c u l t i e s where the precious metal-bearing minerals are intergrown with more than one base-metal phase, thus p o t e n t i a l l y d i s t r i b u t i n g the Au or Ag to more than one concentrate. This problem i s p a r t i c u l a r i l y prominant i n the Portal veins, where m a t i l d i t e (AgBiS2) i s intergrown with galena and, less commonly, chalcopyrite. Unusual metals, including Ga, Ge, In, and Cd, are p o t e n t i a l l y important byproducts from the processing of base-metal s u l f i d e ores at S i l v e r Queen. Microprobe analyses of sphalerites (summarized i n Chapter 4) have indicated that anomalous l e v e l s of Ga (0.4 wt. % ) , Ge (0.3 wt. % ) , In.(0.7 wt. % ) , and Cd (1.8 wt. %) substitute for Zn or Fe within sphalerites from S i l v e r Queen. Indium was found to be most enriched i n sphalerite from chalcopyrite-bearing vein material (Table 4.5.3), and thus the presence of chalcopyrite may be regarded as a pathfinder for anomalous In l e v e l s . Ga, Ge, and Cd were more unevenly di s t r i b u t e d , with the greatest contents noted i n sphalerites from sample 3CHN89-1 (Appendix A) on the deep southern NG3 structure. The amenability of the sphalerite from t h i s s i t e to b e n e f i c i a t i o n (eg. Table 6.1.1) and the elevated contents of the metals Ga, Ge, Cd, and to a lesser extent In, suggests a p o t e n t i a l l y large untested resource of these metals i n the NG3 vein. Ge- and Ga-rich sphalerite was also found i n the southern part of the Number Three vein (Table 4.5.1). 206 6.3 Recommendations for Future Exploration Mineralogic studies have indicated that the heat source that drove f l u i d c i r c u l a t i o n i s located at depth towards the southern edge of known mineral deposits at S i l v e r Queen. Tetrahedrite analyses also suggest that the ore f l u i d had a l a t e r a l , south-to-north component during mineralization, with the most Ag- and Au-rich mineralization occurring within the fragmental rocks at the southern end of the Number Three system. If the fragmental rocks d i d i n fact influence the deposition of Au from hydrothermal f l u i d s , then perhaps the best opportunity to extend proven reserves i s within the fragmental rocks. This suggestion i s supported by scattered, r e l a t i v e l y high-grade vein intersections on the NG3 structure. Vein material from the southernmost and deepest d r i l l hole on the NG3 vein (sample s i t e 3CHN89-1) i s mineralogically simple, with few observable problems, with b e n e f i c i a t i o n and anomalous levels of Pb, Zn, Ge, Ga, In, Cd, Au, and Ag. Thus, the part of the S i l v e r Queen property with the greatest potential, for future exploration i s the area centered around, and to the south of, the sample 3CHN89-1 (Appendix A) . Exploration i n t h i s area has been n e g l i g i b l e due to a th i c k cover of overburden, but there i s no obvious reason that the Number Three-NG3 structure shouldn't continue to the south of the known inte r s e c t i o n s . S i m i l a r i l y , the p a r a l l e l George Lake structure may display s i m i l a r mineralogic trends to the Number Three vein, and thus develop higher grade intersections further south from 207 presently known vein l i m i t s . Exploration for high-grade Ag resources should also be undertaken i n the area surrounding the Camp vein system, and i n the region surrounding sample s i t e 3CHN89-66 north of the Cole vein (Figure 2.3.1). The appearence of Ag-minerals such as pyrargyrite suggests a pronounced Ag-enrichment towards the margins of the system, and t h i s should be taken into consideration when exploring for Ag-rich veins. 208 Table 6.1.1: Economic Mineralogy of the S i l v e r Queen Property Vein Phase % of Max. Grain Liberation* Opaques size North gn 2-5% 2mm. lib'n(80)=0.1mm #3 coarse-grained Minor contam. from cpy, t t - t n t t - t n 0-5% 1mm. Reports to Cu-con. due to fine-grained, locked nature. s i 30-80% >lcm. lib'n(90)=lmm. minor contam. from cpy, t t , and gn. cpy 0-20% > 1cm. lib'n(90)=0.1ram Often t i g h t l y locked with py. Cpy cpy 10-60% >lcra. lib'n(90)=0.1mm Section Abundant contam #3 from s u l f o s a l t s and gn. s i 2-30% >lcm. lib'n(80)=0.1ram Abundant contam from a l l other phases. gn 0-10% 1cm. lib'n(80)=0.08 mm. About 20% i s locked i n s i and cpy. ber 0-2% 0.4mm. lib'n(50)=0.05 mm. Often c l o s e l y assoc. with galena. t t - t n 0-5% 1mm. Locked i n cpy-see cpy entry. aik <1% 0.05mm. Locked i n cpy-see cpy entry. Central cpy 0-3% 0.06mm. Locked i n s i #3 (50%) and i n tt-tn(50%) gn 5-15% 3mm. lib'n(70)=0.08 mm. Contains abundant f i n e -grained py. 209 s i 20-50% 5mm. lib'n(80)=0.08 mm. Minor contam. from cpy and gn inclusions. t t - t n 0-2% 0. 8mm. lib'n(60)=0.05 mm. Always i n ass'n. with gn. s e l <1% 0.05mm. Locked i n gn. South gn 3-15% 1mm. lib'n(70)=0.08 #3 mm. Often quite locked with t t -tn and py. aik 0-2% 0. 1mm. lib'n(70)=0.05 mm. Well locked with gn. t t - t n 2-10% 1mm. lib'n(75)=0.05 Losses to Pb-con. expected. s i 10-40% 1mm. lib'n(80)=0.1mm Contam. from gn cpy, and aik. pb 0-1% 0.05mm. Locked i n s i . f r cpy pyg s e l 0-1% 0. 1mm. Locked i n gn. NG3 gn 10-40% >lcm. lib'n(80)=0.1mm Hosts minor amounts of s u l f o s a l t s . s i 40-60% >lcm. lib'n(90)=0.25 mm. Rela t i v e l y free of inclusions. t t - t n 0-10% 0. 8mm. lib'n(90)=0.08 mm. Weakly to moderately locked with gn. cpy 0-2% 0.05mm. Locked i n s i and gn. Pr 0-2% 0.06mm. Locked i n gn. geoc Ss Twinkle gn 0-5% 0. 6mm. lib'n(80)=0.07 Zone mm. Weakly locked with s i and t t - t n . t t - t n 0-8% 1mm. lib'n(80)=0.07 mm.-see gn. 210 s i 2-10% 1mm... lib'n(80)=0.08 mm. Contam. from py and t t . cpy <1% 0.0 3mm. Locked i n s i and t t - t n . Portal mtd/ 5-35% 3mm. lib'n(80)=0.1mm gn Intimately intergrown and are thus considered together. gust/ 0-5% 0. 5mm. Lib'n as for ber gn/mtd. t t - t n / 0-5% 0. 6mm. Locked i n cpy. pc cpy 5-40% >lcm. lib'n(80)=0.1mm. Contam. from mtd/gn and py. s i 10-30% 1cm. lib'n(80)=0.1mm Rel. i n c l u s i o n -free. Camp PC 1-10% 3mm. l i b ' n highly variable-approx the same as for t t - t n . pyg 0-5% 0.2mm. Locked i n pc. t t - t n 0-10% 2mm. lib'n(80)=0.08 f r mm. Commonly quite intergrown with. pc and pyg. gn 5-30% 0. 6mm. lib'n(80)=0.05 mm. Common as inclusions i n t t - t n . s i 10-20% 3mm. lib'n(90)=0.1mm Minor contam. from cpy and gn cpy 1-2% 0.2mm. Locked i n s i . CC <1% 0.04mm. Locked i n py ac and to lesser bn extent s i . George cpy 0-10% 1mm. lib'n(50)=0.05 Lake mm. Well locked i n s i and t t - t n s i 30-50% >lcm. lib'n(90)=0.2mm Widespread contam. from cpy and py. gn 1-3% 0. 8mm. Well locked i n 211 py(50%) and i n tt-tn(50%). t t - t n 1-5% 0. 5mm. lib'n(75)=0.05 mm. Contains inclusions of other s u l f i d e s , ber <1% 0.06mm. Locked i n cpy. Cole cpy 0-20% >lcm. for Cu-vein: lib'n(80)=0.06 mm, otherwise locked i n s i . aik 0-3% 2mm. Locked i n gn. mtd gn 5-40% >lcm. lib'n(80)=0.15 mm. Material i n Cu-vein i s intergrown with aik and mtd. pc <1% 0.05mm. Locked i n gn. pyg t t - t n 0-5% 0.2mm. lib'n(75)=0.04 f r Commonly well locked with gn and Fe-sulfides s i 30-60% >lcm. For Cu-vein: lib'n(80)=0.05 mm. Otherwise lib'n(90)=0.2mm Abundant i nc1's of cpy, gn, and t t - t n Chisholm/ s i 10-40% 0. 5cm. lib'n(80)=0.1mm Owl Re l a t i v e l y free of i n c l ' s . t t - t n 1-3% 0 .5cm. lib'n(90)=0.1mm f r Commonly contains pyg inclusions. gn 1-8% 1cm. l i b ' n as for t t - t n . Contains abundant pyg and pc i n c l ' s . pc 0-2% 0.05mm. Locked i n gn pyg and t t - t n . cpy #2 s i 20-60% 1cm. lib'n(90)=0.3mm Abundant inclusions of cpy, gn, and 212 t t - t n . gn 2-3% 0.2mm. Locked i n s i and with t t - t n and py. pc-pb <1% 0.0 3mm. Locked i n t t - t n pr-pyg t t - t n 1% 0. 1mm. as for gn. cpy 2-3% 0.15mm. as for gn. *"lib'n ( 8 0 ) " refers to the property that 80% of the observed grains would be l i b e r a t e d at the p a r t i c l e s i z e l i s t e d afterward. Individual mineral abbreviations are as follows: cpy= chalcopyrite gn= galena sl= sphalerite bn= bornite py= p y r i t e tt-tn= fahlores ac= acanthite fr= f r e i b e r g i t e pr= proustite geoc= geocronite gust= gustavite mtd= ma t i l d i t e pb= polybasite pc= pearceite pyg= pyrargyrite aik= a i k i n i t e ber= be r r y i t e sel= seligmannite ss= Ag-Sb-Pb s u l f o s a l t 213 Table 6.1.2; Electrum Occurrence; S i l v e r Queen Property Vein Grain Size Host/No. of Grains Recovery North #3 <15u galena(5) pyrite(1) gangue(1) much of galena containing the electrum would report to Cu-concentrate . #3-Cpy-rich section <70u pyrite(7) chalcopyrite(5) galena(4) Central #3 <15u galena(7) p y r i t e ( l ) galena i s d i f f i c u l t to li b e r a t e due to a f i n e -grained nature South #3 <25u galena(20) sphalerite(5) fahlores(3) electrum i n galena i s commonly c l o s e l y assoc. with f i n e -grained pyrite May r e s u l t in. losses up to 20% of elec. NG3 <30u galena(7) sphalerite(2) fahlore(1) as for South #3 Portal <160u galena-mat i l d i t e ( 56) pyrite(6) chalcopyrite(3) fahlore(1) abundant and easy to recover Camp <20u pyrite(1) chalcopyrite(1) electrum i n cpy would be l o s t to py r i t e ( t a i l s ) #5 <50u galena-matildite(36) chalcopyrite(4) abundant and easy to recover. George Lake <20u pyrite(2) sphalerite(2) s i g n i f i c a n t loss to t a i l s expected. 214 Chisholm/ Owl <15u galena(4) elec. assoc. with Ag-rich minerals, but may be d i f f i c u l t to l i b e r a t e . Cole <20u pyrite(2) galena(4) fahlore(1) occurrence i n py r i t e i s probably unusual for Cole veins. #2 <25u sphalerite(15) gangue(3) easy recovery due to single locus nature, but spotty d i s t r i b u t i o n . 215 7 .0 SUMMARY AND CONCLUSIONS Base- and p r e c i o u s - m e t a l - b e a r i n g v e i n s a t the S i l v e r Queen mine, southeast of Houston, B r i t i s h Columbia, have been e v a l u a t e d i n terms of mineralogy and m i n e r a l p a r a g e n e s i s . V e i n systems g e n e r a l l y occur a l o n g northwest t r e n d i n g and l e s s commonly east-west f a u l t s . G e n e r a t i o n of through going f r a c t u r e s i s commonly a s s o c i a t e d w i t h dyke i n t r u s i o n . M i n e r a l i z a t i o n i s i n the form of (open space f i l l i n g ) c r u s t i f o r m s u l f i d e s and gangue m i n e r a l s w i t h i n the f r a c t u r e s . M i n e r a l assemblages w i t h i n the v e i n s are grouped i n t o f o u r p a r a g e n e t i c s t a g e s , each w i t h a d i s t i n c t i v e mineralogy. Stage I i s r e p r e s e n t e d by f i n e - g r a i n e d p y r i t e and q u a r t z m i n e r a l i z a t i o n , u b i q u i t o u s i n the l a r g e s t (Number Three) v e i n as w e l l as l e s s e r s t r u c t u r e s . B a r i t e , s v a n b e r g i t e , and h i n s d a l i t e r each peak abundance i n the southern p a r t s of the Number Three and NG3 v e i n s , and i n s i l v e r - r i c h v e i n s l o c a t e d near the margins of the known system. Hematite i s most abundant i n Stage I m a t e r i a l near the c e n t r a l segment of the Number Three v e i n and i n a few s m a l l e r v e i n s , w h i l e m a r c a s i t e i s most abundant i n the n o r t h p a r t o f the Number Three v e i n . Stage I I m i n e r a l o g i e s are dominated by massive s p h a l e r i t e and l a y e r e d carbonate m i n e r a l s , w i t h minor amounts of p y r i t e , q u a r t z , and galena. The carbonates are dominated by manganese-bearing s p e c i e s ( r h o d o c h r o s i t e and 216 manganosiderite) i n the north and calcium-magnesium species i n the south. Stage I I I , however, i s far more complex. The mineralogy i s most commonly galena, chalcopyrite, electrum, and tetrahedrite-tennantite (fahlores). S u l f o s a l t s , most notably b e r r y i t e within the c h a l c o p y r i t e - r i c h zone i n the north Number Three vein, and a i k i n i t e i n the v i c i n i t y of the "bend" i n the Number Three vein, are also abundant i n Stage I I I . Stage IV i s volumetrically minor and consists of quartz, pyrobitumen, and c a l c i t e . Minor element trends i n sphalerite and tetrahedrite were examined i n order to better assess the nature of the mineralizing f l u i d s and the d i s t r i b u t i o n of the elements. Tetrahedrites were found to be compositionally zoned with respect to Sb, As, B i , Ag, and Cu on both single grain and deposit-wide scales. Unusually B i - r i c h v a r i e t i e s were also noted. Sphalerites were found to be less well zoned compositionally, and most grains analyzed were found to be quite Fe poor. Gallium, Germanium, and Indium were found to be present i n appreciable quantities i n sphalerites from S i l v e r Queen, although no d i s t i n c t zoning pattern was recognized. The S i l v e r Queen veins are proposed to have formed i n an environment s i m i l a r to that proposed by Hayba et al. (1985) for epithermal veins at Creede, Colorado. Fluids t r a v e l l i n g along fractures mixed with cooler, more oxidized meteoric waters, r e s u l t i n g i n deposition of Stage I mineralogies. A change i n pH from a c i d towards neutral 217 resulted i n carbonate and sphalerite deposition, followed by de s t a b l i z a t i o n of metal-ligand complexes and p r e c i p i t a t i o n of Stage I I I . Data from tetrahedrite analyses and mineral assemblages suggests that the heat source d r i v i n g the system i s present at depth and to the south of the Number Three vein. The presence of Ga, Ge, and In i n anomalous amounts i s suggestive of a (non-exposed or removed) organic-rich unit as a metal source. Development of the S i l v e r Queen deposits has centered around p o t e n t i a l l y economic concentrations of Au, Ag, Pb, Zn, and Cu. A l l of the Au and much of the s i l v e r i s i n the form of 60 to 70 f i n e electrum, as grains generally less than 50 microns i n diameter. An important consideration-for removal of the electrum i s i t s host; much of the electrum occurs i n galena that i s associated with fine-grained p y r i t e . S i l v e r i s also present i n tetrahedrites and s u l f o s a l t s . Future exploration and development at S i l v e r Queen mine i s recommended to be concentrated i n the southern part of the project area, i n the v i c i n i t y of the NG 3 vein. Fragmental rocks are apparently condusive to the deposition of precious metals and material from the southernmost i n t e r s e c t i o n on the structure indicates a r e l a t i v e ease of recovery. Furthermore, the width of the a l t e r a t i o n halo i s seen to expand markedly towards the southern end of the Number Three vein, suggesting a possible increase i n proximity to the heat source. 218 8.0 REFERENCES Armstrong, R.L. (1988): Mesozoic and e a r l y Cenozoic magmatic evolution of the Canadian C o r d i l l e r a ; Geol. soc. Amer. spec. Paper 218, pages 55-91. Arnorsson, S. (1984): Germanium i n Icelandic geothermal systems; Geochim. et Cosmochim. Acta, v o l 48, pages 2489-2502. Barnes, H.L. (1975): Zoning of ore deposits: Types and Causes; Trans. Royal Soc. Edinburgh, v o l 69, pages 295-311. Barnes, H.L. (1979): S o l u b i l i t i e s of Ore Minerals in Geochemistry of Hydrothermal Ore Deposits, Barnes, H.L.,ed., New York, pages 404-460. Barton, P.B. J r . , Bethke, P.M. and Roedder, E. (1977): Environment of ore deposition i n the Creede Mining D i s t r i c t , San Juan Mountains, Colorado: Part I I I . Progress toward in t e r p r e t a t i o n of the chemistry of the ore-forming f l u i d for the OH vein. Econ. Geol., vol 72, pages 1-24. Barton, P.B. J r . , Bethke, P.M. and Toulmin, P., I l l (1963): Equilibrium i n ore deposits; Mineral. Soc. Am. Spec. Paper No. 1, pages 171-185. Barton, P.B. J r . and Skinner, B.J. (1979): S u l f i d e Mineral S t a b i l i t i e s in Geochemistry of Hydrothermal Ore Deposits, Barnes, H.L., ed., New York, pages 278-403. Berger, B.R. and Henley, R.W. (1989): Advances i n the understanding of Epithermal Gold-Silver deposits, with special reference to the Western United States; Econ. Geol., Mon. 6, pages 405-419. Bernstein, L.R. (1985): Germanium geochemistry and mineralogy; Geochim. et Cosmochim. Acta, v o l 49, pages 2409-2422. Bernstein, L.R. (1987): Mineralogy and Petrography of some ore samples from the S i l v e r Queen Mine, near Houston, B r i t i s h Columbia; Unpublished Report by Mineral Search, 380 Willow Road, Menlo Park, CF 94025, Aug. 1, 1987, 13 pages. Bi r n i e , R.W. and Burnham, CW. (1976): The c r y s t a l structure and extent of s o l i d solution of Geocronite. Am. Mineral., v o l 61, pages 963-970. 219 Carter, N.C. (1981): Porphyry Copper and Molybdenum Deposits, West-central B r i t i s h Columbia; British Columbia Ministry of Energy, Mines and Petroleum Resources, B u l l e t i n 64, 150 pages. Chang, L.L.Y., Wu, D. and Knowles, CR. (1988): Phase re l a t i o n s i n the system Ag2S-Cu2S-PbS-Bi2S3; Econ. Geol., v o l 83, pages 405-418. Charlat, M. and Levy, C. (1974): Substitutions multiples dans l a se r i e Tennantite-Tetrahedrite; B u l l . Soc. fr. Mineral. Crystallogr., v o l 97, pages 241-250. Cheng, X., S i n c l a i r , A.J., Thomson, M.L. and Zhang, Y. (1991): Hydrothermal a l t e r a t i o n associated with the S i l v e r Queen polymetallic veins at Owen Lake, Central B r i t i s h Columbia (93 L/2); British Columbia Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1990, Paper 1991-1, pages 179-183. Church, B.N. (1970): Nadina ( S i l v e r Queen); British Columbia Ministry of Energy, Mines and Petroleum Resources, Geology, Exploration and Mining 1969, pages 126-139. Church, B.N. (1971): Geology of the Owen Lake, Parrott Lakes and Goosly Lake area; British Columbia Ministry of Energy, Mines and Petroleum Resources, Geology, Exploration and Mining 1970, pages 119-125. Church, B.N. (1973): Geology of the Buck Creek area; British Columbia Ministry of Energy, Mines and Petroleum Resources, Geology, Exploration and Mining 1972, pages 353-363. Church, B.N. (1973b): Code Fen; British Columbia Ministry of Energy, Mines and Petroleum Resources, Geology, Exploration and Mining 1972, pages 373-379. Church, B.N. (1984): Geology of the Buck Creek T e r t i a r y O u t l i e r ; British Columbia Ministry of Energy, Mines and Petroleum Resources. Unpublished 1:100,000 scale map. Church, B.N. (1985): Update on the Geology and Mineralization i n the Buck Creek area-the Equity S i l v e r Mine r e v i s i t e d (93 L/1W); British Columbia Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1984, Paper 1985-1, pages 175 -187. 220 Church, B.N. and Barakso, J . J . (1990): Geology, Lithochemistry and Mineralization i n the Buck Creek area, B r i t i s h Columbia; British Columbia Ministry of Energy, Mines and Petroleum Resources. Paper 1990-2, 95 pages. Craig, J.R. (1967): Phase r e l a t i o n s and mineral assemblages i n the Ag-Bi-Pb-S system; Mineral. Deposita, v o l 1, pages 278-306. Craig, J.R. and Barton, P.B. J r . (1973) Thermochemical approximations for s u l f o s a l t s ; Econ. Geol., v o l 68, pages 493-506. Crerar, D.A., Wood, S.A., Brantley, S.L. and Bocarsly, A. (1985): Chemical controls on s o l u b i l i t y of Ore-forming minerals i n hydrothermal solutions; Can. Mineral., v o l 23, pages 333-352. Drummond, S.E. and Ohmoto, H. (1985): Chemical evolution and mineral deposition i n b o i l i n g hydrothermal systems; Econ. Geol., v o l 80, pages 126-147. Eldridge, C.S., Bourcier, W.L., Ohmoto, H. and Barnes, H.L. (1988): Hydrothermal innoculation and incubation of the Chalcopyrite disease i n Sphalerite; Econ Geol, v o l . 83, pages 978-989. Fournier, R.O. (1985): The behavior of s i l i c a i n hydrothermal solutions; J?ev. Econ. Geol., v o l 2, pages 45-72. Fryklund, V.C. and Fletcher, J.D. (1956): Geochemistry of Sphalerite from the Star Mine, Couer d'Alene D i s t r i c t , Idaho; Econ. Geol., v o l 51, pages 223-247. Gemmel, J.B., Zantop, H. and B i r n i e , R.W. (1989): S i l v e r S u l f o s a l t s of the Santo Nino Vein, F r e s n i l l o D i s t r i c t , Zacatecas, Mexico; Can. Mineral., vol 27, pages 401-418. Hackbarth, C.J. and Petersen, U. (1984) A f r a c t i o n a l c r y s t a l l i z a t i o n model for the deposition of argentian Tetrahedrite; Econ. Geol., v o l 79, pages 448-460. Harris, D.C. and Chen, T.T. (1976): Crystal chemistry and re-examination of nomenclature of sulphosalts i n the aikinite-bismuthinite s e r i e s ; Can. Mineral., v o l . 14, pages 194-205. Harris, D.C. and Owens, D.R. (1973): Berryite, a Canadian occurrence. Can. Mineral., v o l 11, pages 1016-1018. Hayba, D.O., Bethke, P.M., Heald, P and Foley, N.K. (1985): Geologic, mineralogic, and geochemical c h a r a c t e r i s t i c s of Volcanic-hosted epithermal precious-metal deposits; Rev. Econ. Geol., v o l 2, pages 129-167. Heinrich, C.A. and Eadington, P.J. (1986): Thermodynamic predictions of the hydrtothermal chemistry of Arsenic, and t h e i r s i g n i f i c a n c e for the Paragenetic sequence of some Cassiterite-Arsenopyrite-Base metal s u l f i d e deposits; Econ. Geol., vol 81, pages 511-519. Holland, D.H. and Malinin, S.D. (1979): The S o l u b i l i t y and Occurrence of the Non-Ore Minerals in Geochemistry of Hydrothermal Ore Deposits, Barnes, H.L., ed., New York pages 461-508. Hood, C.T., Le i t c h , C.H.B. and S i n c l a i r , A.J. (1991): Mineralogic v a r i a t i o n observed at the S i l v e r Queen mine, Owen Lake, Central B r i t i s h Columbia (93 L/2); British Columbia Ministry of Energy, Mines and Petroleum Resources Geological Fieldwork 1990, Paper 1991-1, pages 185-191. Johnson, N.E., Craig, J.R. and Rimstidt, J.D. (1986): Compositional trends i n Tetrahedrite. Can. Mineral., v o l 24, pages 385-397. Johnson, M.L. and Jealoz, R. (1983): A Brillouin-zone model for compositional v a r i a t i o n i n Tetrahedrite; Am. Mineral., v o l 68, pages 220-226. Karup-Moller, S. (1966): Berryite from Greenland; Can. Mineral., v o l . 8, pages 414-423. K i e f t , K. and Damman, A.H. (1990): Indium-bearing Chalcopyrite and Sphalerite fron the Gasborn area, West Bergslagen, central Sweden; Mineral. Mag., vol 54 pages 109-112. Krogh, T.E. (1973): A low-contamination method for hydrothermal decomposition of Zircon and extraction of Uranium and Lead for isotopic age determinations; Geochim. et Cosmochim. Acta, v o l . 37, pages 485-494. Lang, A.H. (1929): Owen Lake Mining Camp, B r i t i s h Columbia; Geological Survey of Canada Summary Report 1928, Part A, pages 62A-93A. Leitch, C.H.B., Hood, C.T., Cheng, X. and S i n c l a i r , A.J. (1990): Geology of the S i l v e r Queen Mine area, Owen ^Lake, Central B r i t i s h Columbia (93 L ) : British Columbia Ministry of Energy, Mines and Petroleum Resources Geological Fieldwork 1989, Paper 1990-1, pages 287-295. 222 Leitch, C.H.B., S i n c l a i r , A.J., Cheng, X. and Hood, C.T. (1991-in press): Structural character of epithermal polymetallic veins and bearing on g e o s t a t i s t i c a l studies at the S i l v e r Queen Mine, near Owen Lake, West-Central B r i t i s h Columbia; C.I.M. Bulletin. L e i t c h , C.H.B., S i n c l a i r , A.J. and Godwin, C.I. (1991-in press): A Galena Lead isotope study of polymetallic deposits i n the Buck Creek area, c e n t r a l B r i t i s h Columbia; Can. Inst. Min. Metall. Geol. Quart.. Likachev, A.P. (1975): Redeposition of ore-producing and petrogenetic components by aqueous solutions; Geochemistry International, v o l 12, pages 101-113. Macintyre, D. (1985): Geology and Mineral Resources of the Tahtsa Lake D i s t r i c t , West-central B r i t i s h Columbia; British Columbia Ministry of Energy, Mines and Petroleum Resources, B u l l e t i n 75, 82 pages. Macintyre, D.G. and Desjardins, P. (1988): Babine Project (93 L/15); British Columbia Ministry of Energy, Mines and Petroleum Resources Geological Fieldwork 1987, Paper 1988-1, pages 181-193. Makovicky, E. and Karup-Moller, S. (1977): Chemistry and crystallography of the L i l l i a n i t e homologous serie s . II.. D e f i n i t i o n of new minerals: Eskimoite, V i k i n g i t e , Ourayite and Treasurite. Redefinition of Schirmirite and new data on the L i l l i a n i t e - G u s t a v i t e s o l i d solution s e r i e s ; Neues Jahrb. Mineral. Abh., v o l 131, pages 56-82. Marsden, H.W. (1985): Some aspects of the Geology, Mine r a l i z a t i o n , and Wallrock A l t e r a t i o n of the Nadina Zn-Cu-Pb-Ag-Au vein deposit, North-central B r i t i s h Columbia; Unpublished B.Sc. Thesis, University of B r i t i s h Columbia, Vancouver, Canada, 90 pages. M i l l e r , W.J. and Craig, J.R. (1983): Tetrahedrite-Tennantite series compositional v a r i a t i o n s i n the Cofer Deposit, Mineral D i s t r i c t , V i r g i n i a ; Can. Mineral., v o l 68, pages 227-234. Murowchick, J.B. and Barnes, H.L. (1986): Marcasite p r e c i p i t a t i o n from hydrothermal solutions. Geochim. et Cosmochim. Acta, v o l 50, pages 2615-2630. Nowak, M.S. (1991): Ore Reserve estimation, S i l v e r Queen Vein, Owen Lake, B r i t i s h Columbia; Unpublished M.A.Sc. Thesis, University of British Columbia, Vancouver, Canada, 224 pages. 223 N u f f i e l d , E.W. and Harris, D.C. (1966): Studies of mineral sulpho-salts. XX. Berryite, a new species; Can. Mineral., vol 8, pages 407-413. Oen, I.S. and K i e f t , C. (1976): Bismuth-rich Tennantite and Tetrahedrite i n the Mangualde Pegmatite, Portugal; Neues Jahrb. Mineral. Monatsh., pages 94-96. Ohmoto, H. and Lasaga, A.C. (1982): Kinetics of reactions between aqueous sulfates and sulfide s i n hydrothermal systems. Geochim. et Cosmochim. Acta, v o l 46, pages 1727-1745. O'Leary, M.J. and Sack, R.O. (1987): Fe-Zn exchange reactions between Tetrahedrite and Sphalerite i n natural environments; ContriJbs. Min. Petrol., v o l 96, pages 415-425. Pa t t r i c k , R.A.D. and H a l l , A.J. (1983): S i l v e r s u b s t i t u t i o n into synthetic Zinc, Cadmium, and Iron-Tetrahedrites; Mineral. Mag., v o l 47, pages 441-451. Petersen, E.U., Petersen, U. and Hackbarth, C.J. (1990): Ore Zoning and Tetrahedrite compositional v a r i a t i o n at Orcopampa, Peru; Econ. Geol., v o l 85, pages 1491-1503. Raabe, K.C. and Sack, R.O. (1984): Growth zoning i n Tetrahedrite from the Hocking Mine, Alma, Colorado; Can. Mineral., v o l 22, pages 577-582. Reed, M.H. and Spycher, N.F. (1985): B o i l i n g , Cooling and Oxidation i n epithermal systems. A numerical modelling approach; Rev. Econ. Geol., v o l . 2, pages 249-272. Sack, R.O., Ebel, D.S. and O'Leary, M.J. (1987): Tennanhedrite thermochemistry and metal zoning, in Helgeson, H.C., ed., Chemical transport i n metasomatic processes; Amsterdam, D. Reidel Pub. Co., pages 701-731. Sack, R.O. and Loucks, R.R. (1985): Thermodynamic properties of Tetrahedrite-Tennantites: Constraints on the independence of the Ag-Cu, Fe-Zn, Cu-Fe and As-Sb exchange reactions; Am. Mineral., v o l 70, pages 1270-1289. Sakharova, M.S. (1969): A f i n d of Beta-Matildite i n Eastern Transbaikal. DokladyAkad. Nauk SSSR, v o l . 189, pages 418-420. Souther, J.G. (1977): Volcanism and tectonic environments i n the Canadian C o r d i l l e r a ; A second look; Geol. Assoc. Canada, Special Paper 16, pages 3-24. 224 Springer, G. (1969): Electron probe analyses of Tetrahedrite; Neues Jahr. Mineral. Mont., pages 24-32. Stacey, J.S. and Kramers, J.D. (1975): Approximation of t e r r e s t r i a l Lead isotope evolution by a two-stage model; Earth and Planetary Science Letters, v o l . 26, pages 207-221. Steiger, R.H. and Jager, E. (1977): Subcommision on Geochronology: Convention on the use of decay constants i n Geo- and Cosmochronology; Earth and Planetary Science Letters, v o l . 36, pages 359-362. Streckeisen, A.L. (1967): C l a s s i f i c a t i o n and Nomenclature of Igneous rocks; Neues Jahr. Mineral. Abh., v o l 107, pages. 144-214. Susak, N.J. and Crerar, D.A. (1982): Factors c o n t r o l l i n g zoning i n hydrothermal ore deposits; Econ. Geol., v o l 77, pages 476-482. Thomson, M.L. and S i n c l a i r , A.J. (1991): Syn-hydrothermal development of fractures i n the S i l v e r Queen Mine area, Owen Lake, Central B r i t i s h Columbia; British Columbia Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1990, Paper 1991-1, pages 191-197. Tipper, H.W. and Richards, T.A. (1976): Jurassic Stratigraphy and History of North-central B r i t i s h Columbia; Geological Survey of Canada, B u l l e t i n 270, 73 pages. Wood, S.A., Crerar, D.A. and Borsik, M. (1983): S o l u b i l i t y of a multi-phase s u l f i d e system i n hydrothermal chloride solutions. Geol. Soc. Amer.Abstr. Programs, v o l . 15, page 722. Wu, I. and Petersen, U. (1977): Geochemistry of Tetrahedrite -Tennantite at Casapalca, Peru; Econ. Geol., v o l 72, pages 993-1016. i A P P E N D I X A SAMPLE S I T E LOCATIONS APPENDIX A Part i t Surface Sample Sites •surface sample locations are provided i n Figure A - l i n pocket* Part l i t Underground Sample Sites Sample Material Location 2CHN89-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 2.-11 2-12 2-13 2-14 2-15 2-16 2-17 2-18 2-19 2-20 2-21 2-22 2-23 Vein section Vein section Unit 6 Dyke Vein sample Unit 4-weak a l t ' n Unit 6 Dyke Unit 6 Dyke A l t ' d Unit 4 Unit 6 Dyke A l t ' d Unit 5 Vein section Fresh Unit 4 Unit 7 Dyke Unit 6 Dyke Unit 6 Dyke Fresh Unit 4 Unit 7 Dyke Vein section Vein sample Unit 6 Dyke Vein section Unit 6 Dyke Portal One vein P o r t a l Two vein Portal Three vein v i c i n i t y P o r t a l Three vein 50 m. NE of Portal Three vein 120 m. NE of Portal Three vein 150 m. NE of Portal Three vein Near Portal Nine vein Near P o r t a l Nine vein 20 m. NE of Portal Nine vein P o r t a l 10.5 vein 30 m. NE of Portal Eleven vein. 40 m. NE of Portal Eleven vein 50 m. NE of Portal Eleven vein 200 m. SW of Number Three vein i n Bulkley Crosscut 180 SW of Number Three vein i n Bulkley Crosscut 80 m. SW of Number Three vein i n Bulkley Crosscut Number Three vein at Bulkley Crosscut North end d r i f t . — Vein i n Number Three hangingwall Near S i t e 2-20 i n North end d r i f t Number One vein Near Number One vein 227 2-24 Chalcedonic vein 2-25 Fresh Unit 4 2-26 Vein section 2-27 Vein section 2-28 Chalcedonic vein 2-29 Unit 6 Dyke 2-30 Vein section 2-31 Vein section 2-32 Unit 7 Dyke 2-33 Unit 8 Dyke 2-34 Vein section 2-35 Vein section 2-36 Vein section 2-37 Vein section 2-38 Vein section 2-39 Vein section 2-40 A l t ' d Unit 5A 2-41 A l t ' d Unit 2 2-42 P y r i t i c v e i n l e t 2-43 A l t ' d Unit 3 2-44 Fresh Unit 4 2-45 Vein section 2-46 Unit 7 Dyke 2-47 Vein section 2-48 Vein section Near Number One vein Between Number One and Number Two veins Number Two vein Number Three vein at Number One Crosscut North end face 2nd crosscut, leaving North end d r i f t (into Number Three vein H.W) Number Three vein, i n North end d r i f t where vein reappears i n d r i f t Footwall vein, at northernmost exposure in- underground workings 120 m. SE of Bulkley Crosscut i n South End d r i f t Near S i t e 2CHN89-32 Number Three vein 300 m. SE: of Bulkley Crosscut i n South End d r i f t Number Three vein near southernmost exposure. Number Three vein at "bend", South End d r i f t M3 vein exposure, South End d r i f t Footwall vein i n 2750 sub-level Footwall vein near Site 2CHN89-38 South End d r i f t South End d r i f t , i n 1989 crosscut Near South End face South End d r i f t , i n 2nd major d r i f t SE of Bulkley Crosscut Bulkley Crosscut face George Lake vein, at Bulkley Crosscut Near S i t e 2CHN89-45 George Lake vein at Bulkley Crosscut "Jaxel" vein at Bulkley Crosscut 228 2-49 2CHN90-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 2-11 2-12 2-13 2-14 Vein section Vein section Vein section Vein section Vein section Vein section Vein section Vein section Vein section Vein section. Vein section Grab sample Chalcedonic Vein Vein section Vein section Veinlet i n Bulkley Crosscut, 60 m. SW of "Jaxel" vein Veinlet i n Number Three vein hangingwall North End d r i f t Number Three vein at: North End face "Portal 11.5" vein, i n Portal Eleven d r i f t P ortal Eleven vein Portal Ten vein Portal Nine vein Portal Five vein Portal Four vein Portal Three vein Portal Two vein Portal Three vein Near S i t e 2CHN90-9 Number Three vein 100 m. SE of North End face "Portal 12" vein NE of Portal Eleven d r i f t 229 P a r t I I I ; Underground D r i l l Hole Sample L i s t Sample DDH Interval Vein 3CHN89-1 NG 3 1433' 1439' NG3 3-2 NG 4 1941.5' 1942.7' — . 3-3 80-1 377' 380' NG3 3-4 NFX-1 1387' 1387'8" — 3-5 87-U-19 1.9' 3.7' No. 3 3-6 88-S-53 258'9" 261'8" Cole 3-7 88-S-54 311'5" 313'4" Cole 3-8 88-S-54 387'2" 394'4" Cole 3-9 88-S-58 608' 616' No. 3 3-10 88-S-53 187'6" 189' Cole 3-11 88-S-51 482'2" 483'8" Cole 3-12 88-S-ll 304' 307' Camp 3-13 88-S-26 104'10" 106'6" Camp 3-14 88-S-ll 550'4 " 553'8" Camp 3-15 88-S-12 364' 366'5" Camp 3-16 88-S-ll 170' 172'8" Camp 3-17 88-S-ll 286'3" 294'2" Camp 3-18 88-U-53 308' 318' No. 3 3-19 88-U-15 333'5" 336'10" No. 3 3-20 88-U-24 460' 465' No. 3 3-21 88-U-7 337'4" 338'8" No. 3 3-22 89-U-8 252' 252.5' _ 3-23 89-U-8 297' 298.3' — . . . 3-24 89-U-8 261.5' 264.5' No. 3 3-25 89-U-3 285'10" 292' No-. 3 3-26 89-U-8 228.2' 230' 3-27 89-U-3 240'2" 241'10" — . 3-28 88-S-47 600'1" 602'2" G.L. 3-29 88-S-49 181' 182' Cole 3-30 88-S-46 215'5" 216'1" — 3-31 88-S-52 286' 289' Cole 3-32 88-S-47 399'8" 400'11" — 3-33 88-S-47 316' 320' 3-34 88-S-46 383'6" 383'11" — . 3-35 88-U-46 265' 267' G.L. 3-36 87-U-15 152'2" 153'4 " NG3. 3-37 87-S-10 248' 253' Camp 3-38 87-U-15 149' 151' NG3 3-39 87-S-13 278' 281'2" Camp 3-40 87-S-9 11' 18.5' Camp 3-41 87-S-8 162' 168' Camp 3-42 89-U-2 220' 220.5' — • 3-43 88-U-42 227' 232' No. 3 3-44 88-S-33 166'4" 16.6/10" No, 3 3-45 88-S-44 170' 171'3" No. 3 3-46 88-S-44 172'8" 175'1" No. 3 3-47 88-U-74 387' 392' No. 3 3-48 S-32 166.8' 167.5' _ 3-49 S-33 111' 114' _ 3-50 S-32 228.5 231.5' — 3-51 84-15 230'3" 231'3" Twinkle 3-52 88-S-29 467'6" 470' Camp 3-53 88-S-5 70' 76' — 3-54 88-S-20 300'10" 304'3" Camp 3-55 88-S-5 212'8" 214' Camp 3-56 88-S-23 189' 191'4" Camp 3-57 87-S-2 327.5' 336' Switchb 3-58 87-S-2 307.5' 309' Switchb 3-59 88-S-46 503'6" 505' — 3-60 88-S-50 247'5' 249'10" Cole 3-61 88-S-46 236'3" 237'3" — 3-62 88-S-49 384'9" 386'3" Cole 3-63 87-S-5 169.3' 171' Camp 3-64 BU 107 627' 633.5' No.l 3-65 BU 107 216' 221' No. 2 3-66 NGF 8 404'4" 412' Cole 3-67 NGF 8 1848' 1848.5' — 3-68 NGF 5 1962' 1962.8' _ 3-69 NGF 5 845' 845.5' — 3-70A BU 100 14' 16' No .3 3-7 OB S-19 283.2' 288.4' Portal 3-71 88-U-37 293.3' 298.5' No. 3 3-72 88-U-30 214.9' 218.7' No. 3 3-73 88-U-58 334' 335' No. 3 3-74 87-U-5 159' 160'6" No. 3 3-75 87-U-18 43.5' 44.1' No. 3 3-76 87-U-12 81.9' 82.6' No. 3 3-77 NGF1 126.9' 127.7' Cole 3-78 NGF1 777.4' 782.3' Cole 3-79 NGF1 442' 449.1' Cole 3-80 BSR85-1 114.7' 115.2' — 3-81 2-72 462.8' 464.2' G.L. 3-82 4-72 281' 286.3' G.L. 3-83 BSR85-2 31.5' 33.5' — 3-84 S-22 262.3' 264' Switchb 3-85 S-25 158.5' 163' "S-26" 3-86 BU 5 86' 93.5' No. 3 3-87 BU 159 172.5' 176.5' No. 3 3-88 UG74-3 303.5' 304.2' No. 3 3-89 PH 7 288.8' 290.2' G.L. 3-90 NGF 7 246.5' 247.2' Cole 3-91 NGF 7 376' 376'3" Cole 3-92 NGF 7 401.5' 402.4' Cole 3-93 F-X-l 71' 73.1' Cole 3-94 NFX-1 1426' 1426'3" — -3-95 NFX-1 973' 973'3" _ 3-96 K2 125' 125'1" — 3-97 UG81-12 130'4" 132'4" No.. 3 -3-98 88-U-26 309'7" 311'7" No. 3 3-99 88-U-21 321'9" 331' No. 3 3-100 88-U-67 321' 324' No. 3 3-101 88-U-50 148' 151'10" No. 3 3-102 88-U-56 393' 398'5" No. 3 3-103 88-S-45 293'10" 295' No. 3 3-104 F-5 250.9' 251.2' Cole 3-105 F-9 229' 229.7' Cole 3-106 NGV 1 724.8' 733.5' No. 3 3CHN90-1 NGV 4 941.7' 943.5' No. 3 3-2 BU 158 47' 48' No. 3 3-3 88-U-17 311' 314' No. 3 3-4 UG81-18 200.8' 202.5' No. 3 3-5 88-U-76 435'5" 438'5" No. 3 3-6 UG81-15 147.3' 153.6' No. 3 3-7 88-U-8 234'1" 237'11" No. 3 3-8 88-U-31 235'5" 247' No. 3 3-9 88-U-55 339'5" 341' No. 3 3-10 88-S-57 641'8" 650' No. 3 3-11 88-S-30 147'7" 150' No. 3 3-12 88-U-3 322'8" 323'3" No. 3 APPENDXA LONGITUDINAL SECTION OF NUMBER THREE VEIN SHOWING SAMPLE SUE POSITIONS KEY _ sample site 1989 sample 1990 sample surface cx underground sample (sea baton*) Lettered Sample Key ai2CHN9Q-2 b:2CHN90-13 c:2CHN89-27 d:2CHN8940 e: 1CHN89-83 t: 1CHN8942 g:1CHN89-82 h:2CHN39-19 i:2CHNa*34 j: 1CHN8941 ft 1CHN8940 1:1CHNB9-78 m: 1CHN89-77 n: Decline that p:2Ctm9-3S q: 2CHN89-36 meters 200 Sampling Labels: 2CHN8&35 Sample Location "CH. Nadina, 1989" Sample Number 1= surface 2= underground 3= drill hole to LO to APPENDIX B PARAGENETIC DIAGRAMS FOR MINERALIZED STRUCTURES AT SILVER QUEEN MINE VEIN: George Lake SECTION: Central THICKNESS: 60 cm. SAMPLES: 3CHN89-81, 3CHN89-82 STAGE 1 // ill \ rv tt-tn py -*mmm— qzA — qzB cpy — 9n si e/ec — cbA — • a. ) Elec occurs as Irregular Inclusions In py. b. ) QzB is fine-grained and grayish. c. ) The gn-tt-tn-cpy+ qzA, cb assemblage occurs as fracture Infflllngs In py and wallrock. VEIN: George Lake SECTION: South THICKNESS: 30 cm. SAMPLES: 3CHN89-81 STAGE 1 II III qz pyA sl cb pyB tt-tn cpy gn a.) sulfides in this section may have been remobilized. Tt-tn, cpy and gn Infill fractures In sl and py. Cb and tt-tn also interstitial to qz. VEIN: George Lake? SECTION: Emit Creek THICKNESS: Siliceous Zone (2 m wide) SAMPLES: 1CHN90-2 STAGE 1 MH CD he tt-tn py * cpy si elec — a. ) Qzis very fine-grained. Cb is probably calcite. b. ) Sulfides are disseminated in quartz. He is principally after mafics. VEIN:JaxBt SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 2CHNB9-48 STAGE 1 III he pyA cpy — — si — elec — pc — gn qz — — cb pyB -a. ) Elec occurs as two 30 micron grains with pc and cbA in a fracture in cpy. b. ) Gn occurs as inclusions in py. VEIN: Portal One SECTION: Total vein THICKNESS: 25 cm. SAMPLES: 2CHNB9-1 STAGE II Ill slA — cb py — qz cpy _ ttA — sIB — ttB gnA — mtd — e/ec — UN#1 — a.) two distinct bands (hangingwall sphalerite and footwall carbonate) predominate. Later sulfides are concentrated near the footwall of the carbonate band. VEIN: Portal Two SECTION: Total vein THICKNESS: 30 cm. SAMPLES: 2CHN89-2, 2CHN90-10 STAGE II III ba py sl qzA qzB cb gn mtd po aspy tt-tn cpy elec a. ) brecciated wallrock noted with this vein. Ba is bladed. b. ) Gn and mtd form myrmekitic intergrowths. Tt-tn is localized around py grains in cpy, and as fracture infillings. VEIN: Portal Three SECTION: Total vein THICKNESS: 30 cm. SAMPLES: 2CHN90-9, 2CHN89-4 STAGE 1 II III coA — cbB — SLA cpyA qzA pyA tnA cpyB — tnB — sIB 11 ltd — ber — gn — tnC — elec — mc — pybit a. ) locally up to 5-e% gn-mtd masses. Intergrowths are myrmokttfc to Wldmannstaten and frequently fracture fill chalcopyrftB. Elec Is spotty, in grains up to 160 microns. Late sulfosalts commonly Interstitial to quartz b. ) Pyrobitumen In vugs In cb and qz. c. ) no layering noted In cb and qz. VEIN: Portal Four SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 2CHN90-B STAGE 1 II /// N py qzA cb ba qzB — • -gn slA sIB tt-tn cpy qzC a. ) QzC Is a fracture fining phase cutting all other minerals. b. ) vein occupies breccia zone with abundant fine-grained galena. c. ) Chalcopyrite occurs as Inclusions on the margins of galena masses VEIN: Portal Five SECTION: Total vein THICKNESS: 18 cm. SAMPLES: 2CHN90-7 STAGE 1 II III rv mcA — qzA — aspy — qzB si cb mcB — cpy — gn — tt-tn — qzC — a. ) vein is weakly layered and dominated by coarse-grained sphalerite. b. ) QzC is a late, fracture infilling phase and also fills vugs in carbonate gangue. VEIN: Portal Nine SECTION: Total vein THICKNESS: 25 cm. SAMPLES: 2CHN90-6 STAGE 1 II /// qz ba py si cb gn tt-tn - — cpy — a. ) QzA is sparry and lines wallrock fragments. Bladed barite is apparently earlier than qzA. b. ) Paragenesis determined from hand sample. VEIN: Portal Ten Z^°\ SECTION: Total vein THICKNESS: 25 cm. SAMPLES: 2CHN90-5 STAGE\ 1 II Ill qzA mc — slA — cbA — pyA cbB — cbC — -qzB — ba — sIB — pyB — qzC — sIC pyC gn — cbD — sID — cpy tt-tn a.) vein material Is well layered. VEIN: 'Portal 10.5" SECTION: Total vein THICKNESS: 8 cm. SAMPLES: 2CHN89-11 STAGE 1 // III qz py ber cpy — . . . cb elec — gn — gust tn — pc — a. ) narrow vein with no layering and visible sutfosait concentrations. b. ) Berryite occurs as lath shaped grains in a matrix of gustavite. Galena replaces both phases. VEIN: 'Portal Twelve' SECTION: Total vein THICKNESS: 10 cm. SAMPLES: 2CHN90-14 STAGE 1 II /// pyA — qzA ba — pyB — -qzB — cbA — cbB — qzC — sl — gn — a. ) Paragenesis determined from hand sample. Dominated by massive pyrite band near center. b. ) PyA-qzA brecciated, with interstices filled by qzB-cbA material. Both cbB and qzC cut ail other phases. VEIN: Mae One SECTION: Total vein THICKNESS: 20 cm. SAMPLES: 1CHN89-49 to 1CHN6&-B2 STAGE 1 II Ill rv pyA — ba — slA — qz cb — gn elec — sIB — pc-pb tt — pyg — pyB a. ) Pyg, tt, and pc-pb occur as vermiform to Irregular Inclusions In gn. Elec also noted (near pyA grains) In galena. b. ) PyB Is a fracture Infilling phase cutting all other minerals. VEIN: Mae Two SECTION: Total vein THICKNESS: 25 cm. SAMPLES: 1CHN89-55, 1CHN90-4 STAGE II III IV ba qz si cpy tt-tn bour cbA cbB UN#1 py gn cbC aspy elec pyg angl a. ) Ba blades are abundant and usually occur In qz. Aspy and py have overgrown/replaced a pre-existing bladed phase. b. ) Gn and associated phases were noted to replace a particular py-aspy-rfch band In si. c. ) Bour rarely occurs as myrmekttic Intergrowths In gn. VEIN: Colo SECTION: North (NGFB) THICKNESS: 140 cm. SAMPLES: 3CHN89-66 STAGE II III rv qzA slA gnA cbA ba qzB qzC cpy tt fret sIB pyB elec gnB pc-pb cbB aspy a. ) crustform aspy and pyA occur on pre-existing bladed phase which has been replaced by frei, gn, anrl c/ b. ) SlA and GnA are massive, coarse- grained phases within a distinct band, c) Elec and pc-pb occur within frei grains. d. ) Ba Is In bladed form e. ) Cpy and tt are more abundant In wallrock, where they cut and replace pyrite. VEIN: Lead SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 1CHN89-36 STAGE 1 II III pyA — ba slA • qz gn — eiec pc — UN#1 — tt-tn — pyB — cpy — cb a. ) SI and gn are quite coarse-grained (to several mm.) b. ) Pc and UN#1 are closely associated, occurring Intergrown with tt-tn masses near the margins of largo gn grains or Intergrown with gn. c. ) PyB noted as fracture Infillings In si VEIN: Barite SECTION: Total vein THICKNESS: 30 cm. SAMPLES: 1CHN89-20, 1CHN89-37, 3CHN89-31 STAGE 1 II Ill N py UN#1 ba — aspy qz 31 cbA cbB — cpy gn pc-pb U-tn UN#2 _ a. ) py and aspy overgrow and replace an unidentified bladed phase (hematite?) that pre-dates barite. b. ) Tt-tn and pc-pb occur as inclusions near the margins of galena grains. c. ) UN#2 Is possibly supergene (acanthtte?). VEIN: Bear SECTION: Total vein THICKNESS: 25 cm. SAMPLES: 1CHN89-22 to 1CHN89-26 STAGE 1 he mt • py — mc — sl ba — • qz cpy tt-tn gn cbA pc-pb — a.) massive specuiarite and bladed barite dominate this vein. Gn may contain several sulfosalts (including pc-pb) but Is relatively rare. VEIN: Cole Shear SECTION: Total vein THICKNESS: 30 cm. SAMPLES: 1CHN69-13, 1CHN89-14 STAGE i II in qzA cbA ba qzB — cbB — sl — tt-tn — sef-bour — gn — cpy — py —— a.) CbA and cbB are similar In appearence, but apparently paragenetically different CbA forms a prominant band with ba blades along one margin. VEIN: NG6 SECTION: Total vein THICKNESS: 20 cm. SAMPLES: 1CHN89-30, 3CHN89-90 STAGE II III IV cb ba qz sl gn cpy pyA tt-tn UN#1 pyB a. ) Cb gangue Is interstitial to euhedral sphalerite grains. Cpy replaces zoned sl along zonal boundaries. b. ) Tt-tn occurs as fracture tnfilllngs In sl and cpy. c. ) Bladed ba Is locally abundant and very coarse grained, d. ) UN#1 is a low-reflectance oxide species associated with py and cb. VEIN: Copper SECTION: Total vein THICKNESS: 40 cm. SAMPLES: 3CHN69-79 STAGE 1 II Ill IV he — mt mc py aik mtd elec — tt-tn pc-pb gn sl — cbA — cbB cbC — 02 — cpy — a. ) many of the later sulfides occur Interstitially to helmt and other gangue minerals. b. ) Gn, aik and mtd occur throughout the section as symplectic intergrowths. These phases and tt-tn also occur as "rims* surrounding py or mc. c) Mc appears to pseudomorph py In several instances, but does not display other paragenetic relationships. VEIN: Camp (Ruby Silver) SECTION: Total vein THICKNESS: 20 cm. SAMPLES: 3CHN89-37, 3CHN89-39 STAGE II III IV qzA qzB ba cb pyA pyB pybit si gn tt pc pyg pyC bn cpy UN#1 qzC ac cv cc a. ) Bn, ac, cvlcc, and cpy occur as Inclusions In py. Py Is commonly brecciated. b. ) Vermltomt Inclusions of cpy, py, and gn occur In the cores of large tt grains. c. ) Pc, pyg, and tt are Intergrown with galena throughout d. ) QzA occurs as crusttform overgrowths on brecciated wallrock. Also as fine-grained aggregates overgrown bv VEIN: Camp SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 3CHNB9-15, 3CHNB9-14, 3CHNB9-16, 3CHN89-17 STAGE 1 II Ill rv qzA — cbA pyA — pyB — aspyA po — pybtt — cbB — cbC gn — sl cpy — pc — frei — elec — ba — qzB aspyB pyC cbO — aspyC — pyO — a. ) the vein contains crusttform aspyA and pyB over a pre-existing bladed phase. AspyB and pyC form rims around qz and sl with later Interstitial sulfides. b. ) Bladed ba and daisy qz are also present c. ) vein Is well layered and cored by cbD. AspyC and pyO are fine-grained massive bands near the vein core. VEIN: Camp SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 3CHN89-13 STAQt III ba cbA cbB cbC aspyA pyA si gn tt-tn cpy pyblt UN#1 cbD cbE pyB aspyB po cbF qzA cbG qzB a. ) Cbln this section Is well banded. b. ) Pyln some places pseudomorphs aspyA. VEIN: -SECTION: Total vein THICKNESS: 10 cm. SAMPLES: 3CHNB9-80 STAGE 1 II Ill ba qzA cbA — — • • cbB cbC -pyA — qzB — si — gn tt-tn cpy pyB — a.) Ba blades display drusy qz rims followed by collltorm and sparry cb. VEIN: Camp SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 3CHN80-40 STAGE 1 // /// rv qz — ba cbA — pyA — cbB UN#1 —— pyB — • si cpy — pybtt — po aspy — UN#2 — UN#3 gn a. ) Qz Is a final vug-infilling phase. CbA, si and UN#1 occur as masses (breccia?) In a cbB and qz matrix. The cbA-sl-UN#1 association Is very similar to that observed in the Portal 11.5 vein. b. ) Po similar In occurrence to that seen with cpy in Portal 11.5 vein. c. ) PyA and aspy often appear In bladed form. The two phases commonly surround masses of cbA-sl-UN#1. d.) UN#2 and UN#3 occur In gn, the latter as myrmekttic Intergrowths with a reflectance of about 38-40. e. ) Pybtt commonly associated with grains of UN#1. Pybtt fragments were noted in a cbB matrix. VEIN: Twinkle zone SECTION: Total vein THICKNESS: 1-3 cm. SAMPLES: 3CHN89-51 STAGE 1 II III py _ Si gn U-tn cpy qz a.) the Twinkle zone is actually a zone of stringer and disseminated sulfide mineralization. VEIN: Camp SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 3CHNB9-52 STAGE 1 II HI ba cbA sl — pybtt — • po — pyA cpy tt-tn gn cbB — aspy — pyB — a. ) CbA Is well zoned. CbA and sl fragments occur in a CbB matrix. b. ) Ba is bladed and pre-dates all other phases. c.) PyB and aspy surround pyA and po fragments and appear to replace an.unknown bladed phase. PyA and po form grains outwardly zoned to po. d.) Cpy, sl, tt-tn and gn all fracture Infill pyA, pyB, aspy and po. VEIN: -SECTION: Total vein THICKNESS: 15 cm. SAMPLES: 3CHN89-83 STAGE 1 II IIIIIV pyA po aspyA pyB cbA ba cbB cbC gn sl pyc aspyB cbD cbE — a. ) PyA Is quite massive and fine-grained material with rare ba In vugs. b. ) Cb Is banded and zoned; CbE displays breccia textures and has been replaced along partings by aspyB and pyC. c. ) AspyA occurs as laths in pyB. Ba is bladed habit VEIN: Number One SECTION: North THICKNESS: 20 cm. SAMPLES: 3CHNB9-64, 1CHN89-84 STAGE 1 II Ill cbA — qzA — cbB qzB — pyA — pyB — sl 9" — tt-tn cpy aspy — pr-pyg _____ a. ) vein Is well banded and cored by late sulfides. b. ) QzA Is sparry. VEIN: Number Two SECTION: North Segment THICKNESS: 30 cm. SAMPLES: 3CHN89-65 STAGE 1 II Ill IV he --slA — • sIB pyA pyB — aspy pybit — qzA — qzB _ cpy bour pr-pyg gn — tt po qzC pyC — — cbA — . . . . cbB — a. ) vein material Is well layered. Some aspy-pyB shows crustiforrn overgrowth and replacement of a pre-existing bladed phase, probably hematite. b. ) Pr-Pyg and bour Intergrown with galena VEIN: -SECTION: Total vein THICKNESS: 20 cm. SAMPLES: 1CHNB9-87 STAGE 1 If/Ill pyA — qzA slA — ba — qzB — pyB — sIB — cbA cbB — cbC cbD — pyC gn cpy — tt-tn — SIC • siD aspy UN#1 sallg pr-pyg a.) Vein Is well layered. Sellg-bour and pr-pyg occur as Intergrowths In gn. VEIN: Footwail SECTION: Atlmak Raise THICKNESS: 50 cm. SAMPLES: 2CHNB9-38, 2CHNB9-39 STAGE 1 Ill si pyA — cpy tt-tn pyB — aloe — cb — gn qzA qzB — a.) Tt-tn tonus a matrix tor si and py breccias. Tt-tn cuts and Is cut by cpy. VEIN: -SECTION: Total vein THICKNESS: 20 cm. SAMPLES: 2CHN89-20 STAGE 1 II /// pyA — tt-tn si cpy cb qz pyB — gn —— he — a. ) PyB Is a coltomorphio form that has been partially replaced by tt-tn and cpy. b. ) Cpy and tt-tn brecclate and fracture Infill si and pyA c. ) SI and he have been replaced by cpy as well. d. ) Tt-tn is concentrated In a 2 cm. wide layer in the vein core. Minor phases may be present In gn. VEIN: -SECTION: Total vein THICKNESS: 1.5 cm. SAMPLES: 3CHN89-96 STAGE II III N qzA qzB cbA cbB ba gypsum pyA sl tt-tn cpy gn pyB a.) veintet is well layered and has sharp contacts with the wallrock. Mn staining suggests that carbonate is manganoan. VEIN: -SECTION: Total vein THICKNESS: 30 cm. SAMPLES: 3CHN89-2 STAGE 1 ll III qzA — py — — cbA — cbB — — sl qzB cbC — gn — tt cpy a.) cpy occurs as fracture InHlllngs cutting all other phases. Abundance of cpy Is unusual for the south part of the property. APPENDIX C MICROPROBE ANALYSES 256 APPENDIX C: MICROPROBE ANALYSES PART I i TETRAHEDRITES Sample 3CHN89-101 Sit e 1 2 3 4 5 Cu 35.69 36.03 38.61 38.68 35.42 S 25.16 25.40 26.38 26.69 24.80 Zn 7.91 7.56 7.88 8.06 7.68 Fe 0.17 0.20 0.17 0.21 0.10 Sb 24.59 21.63 16.35 15.21 24.30 As 2.68 4.67 8.50 9.59 3.42 Pb 0.00 0.00 0.00 0.00 0.00 Ag 3.58 3.13 1.24 1.64 3.68 Bi 0.35 0.14 0.00 0.00 0.00 Hg 0.14 0.00 0.00 0.19 0.00 Total 100.28 98.78 99.13 100.26 99.39 Sample 2CHN89-2 Sit e 1 2 3 4 5 Cu 36.08 40.01 40.14 40.69 41.03 S 25.32 27.49 27.79 27.77 27.94 Zn 6.67 5.53 6.07 6.33 7.61 Fe 1.17 2.66 2.21 2.24 1.26 Sb 25.11 9.16 8.34 6.26 3.39 As 2.43 13.22 14.12 15.28 17.30 Pb 0.00 0.00 0.00 0.00 0.00 Ag 2.26 0.75 0.67 0.40 0.20 Bi 0.00 0.00 0.00 0.00 0.00 Hg 0.00 0.00 0.00 0.00 0.15 Total 99.05 98.88 99.35 99.00 98.88 257 Sample 1CHN89-83 Sit e 1 2 3 Cu 33 .61 33 .15 33 .32 S 24 .99 24 .49 24 .57 Zn 6 .99 7 .13 7 .05 Fe 0 .75 0 .61 0 .65 Sb 24 .73 25 .11 25 .85 As 2 .53 2 .25 1 .61 Pb 0 .00 0 .00 0 .00 Ag 6 .15 6 .97 6 .41 B i 0 .00 0 .00 0 .00 Hg 0 .14 0 • 29 0 .17 Total 99 .88 99 .99 99 .65 Sample 3CHN89-36 Si t e 1 2 3 4 5 Cu 41.32 42 .36 41 .83 41 .82 40. 27 S 27.26 27 .82 27 .79 27 .86 26. 88 Zn 8.15 8 .10 8 .33 8 .39 8. 19 Fe 0.28 0 .52 0 .58 0 .49 0. 17 Sb 8.07 4 .22 3 .82 4 .43 12. 07 As 14.64 16 .87 17 .18 16 .81 11. 59 Pb 0.00 0 .00 0 .00 0 .00 0. 00 Ag 0.41 0 .25 0 .22 0 .27 0. 85 Bi 0.00 0 .00 0 .00 0 .00 0. 00 Hg 0.00 0 .00 0 .00 0 .00 0. 09 Total 100.13 100 .15 99 .76 100 .08 100. 11 Sample 1CHN89-65 Sit e 1 2 3 Cu 24.37 26.37 23.47 S 23.33 24.39 23.16 Zn 4.31 4.07 4.41 Fe 2.26 2.62 2.04 Sb 25.66 17.29 20.59 As 1.44 6.96 4.16 Pb 0.00 0.00 5.08 Ag 18.61 17.38 17.32 Bi 0.00 0.00 0.10 Hg 0.00 0.09 0.00 Total 99.97 99.22 100.35 258 Sample 3CHN89-3 (Grain I) Sit e 1 2 3 4 5 6 Cu 41.60 40.49 40.64 41.35 41.16 40.40 S 27.54 26.61 26.84 27.08 27.36 26.62 Zn 6.44 6.76 7.09 6.86 6.60 7.28 Fe 1.78 1.31 1.12 1.36 1.56 1.00 Sb 6.38 11.77 13.01 7.71 6.81 13.45 As 15.06 11.50 10.89 14.33 16.84 10.67 Pb 0.00 0.00 0.00 0.00 0.00 0.00 Ag 0.24 0.29 0.34 0.25 0.26 0.46 Bi 0.32 0.19 0.10 0.10 0.16 0.26 Hg 0.00 0.11 0.00 0.00 0.17 0.00 Total 99.36 99.02 100.03 99.04 100.91 100.13 S i t e 7 8 9 10 11 12 Cu 40.13 40.92 41.02 41.60 41.20 41.18 S 26.51 26.72 26.71 27.27 27.00 27.26 Zn 7.28 7.13 7.22 7.06 7.31 7.23 Fe 0.89 1.12 0.90 1.06 1.11 1.12 Sb 13.31 9.35 11.96 7.37 6.19 7.94 As 10.80 14.30 12.16 15.68 14.68 14.26 Pb 0.09 0.00 0.00 0.00 0.00 0.00 Ag 0.36 0.32 0.15 0.22 0.23 0.20 Bi 0.28 0.10 0.00 0.24 2.12 0.23 Hg 0.00 0.08 0.00 0.00 0.00 0.00 Total 99.67 100.04 100.18 100.49 99.82 99.45 Sample 3CHN89-76 Sit e 1 2 3 4 5 6 Cu 38.16 37.71 39.57 38.70 40.45 41.00 S 26.22 26.16 26.79 26.41 27.03 27.94 Zn 7.98 7.77 8.25 8.08 8.06 8.81 Fe 0.41 0.41 0.59 0.49 0.67 0.63 Sb 17.29 18.52 10.93 13.80 5.44 3.19 As 8.40 7.13 12.35 10.16 15.21 17.28 Pb 0.00 0.00 0.00 0.00 0.00 0.00 Ag 2.20 2.44 1.28 1.96 0.87 0r53 B i 0.07 0.00 0.00 0.29 0.99 0.54 Hg 0.00 0.00 0.00 0.00 0.10 0.00 Total 100.71 100.14 99.76 99.91 98.82 99.91 259 Sample 3CHN89-2 Si t e 1 2 3 4 5 6 Cu 36.74 39.94 40.57 40.97 41.69 41.87 S 25.16 26.99 26.74 27.51 28.11 27.72 Zn 8.15 7.56 7.75 8.26 7.62 7.12 Fe 0.33 0.83 0.74 1.23 1.45 1.64 Sb 21.79 8.95 10.90 3.13 0.77 1.71 As 5.26 13.98 12.52 17.31 19.32 18.69 Pb 0.00 0.00 0.00 0.00 0.00 0.00 Ag 2.23 0.79 1.08 0.47 0.35 0.33 Bi 0.00 0.00 0.06 0.00 0.13 0.00 Hg 0.00 0.00 0.00 0.00 0.00 0.00 Total 99.69 99.06 100.36 98.91 99.46 99.11 Sample 2CHN89-45 Sit e 1 2 3 Cu 43.60 40.81 42.85 S 28.37 27.75 28.38 Zn 6.27 6.58 8.06 Fe 1.68 1.43 1.07 Sb 0.00 10.40 0.06 As 18.99 12.45 19.69 Pb 0.82 0.00 0.00 Ag 0.20 0.22 0.06 Bi 0.15 0.08 0.12 Hg 0.05 0.00 0.00 Total 100.14 99.72 100.30 Sample 3CHN89-87 Si t e 1 2 3 4 5 Cu 37.42 38.16 38.00 38.18 37.96 S 25.04 25.49 25.63 25.57 25.54 Zn 7.39 7.26 7.37 7.23 7.22 Fe 0.41 0.57 0.59 0.60 0.52 Sb 24.68 20.94 21.79 20.41 20.96 As 2.57 5.53 4.88 6.26 5.43 Pb 0.00 0.00 0.06 0.00 0.00 Ag 2.16 1.60 1.82 1.45 1.68 Bi 0.18 0.00 0.00 0.00 0.00 Hg 0.00 0.00 0.17 0.00 0.00 Total 99.83 99.55 100.32 99.70 99.30 260 Sample 3CHN89-20 Site 1 2 3 4 5 6 Cu 41.95 39.12 37.76 37 .93 37 .07 38 .20 S 28.09 26.09 25.28 25 .62 25 .00 25 .60 Zn 8.40 8.33 8.01 8 .25 7 .97 7 .83 Fe 0.69 0.17 0.21 0 .23 0 .21 0 .21 Sb 0.32 14.89 21.75 20 .83 22 .87 19 .89 As 19.09 9.28 4.62 5 .25 4 .37 6 .16 Pb 0.52 0.00 0.00 0 .00 0 .00 0 .00 Ag 0.30 1.42 1.93 1 .99 2 .40 2 .26 Bi 0.10 0.08 0.00 0 .07 0 .00 0 .07 Hg 0.00 0.00 0.00 0 .00 0 .00 0 .00 Total 99.46 99.36 99.62 100 . 15 99 .88 100 .22 Site 7 8 9 Cu 37.59 37.46 38.25 S 25.25 24.86 25.48 Zn 8.01 7.97 8.51 Fe 0.15 0.18 0.17 Sb 22.10 23.68 20.17 As 4.51 3.83 5.85 Pb 0.00 0.00 0.00 Ag 2.21 2.26 1.76 Bi 0.19 0.21 0.00 Hg 0.00 0.00 0.12 Total 100.01 100.47 100.30 Sample 3CHN89-21 Site 1 2 Cu 34.73 35.80 S 24.39 24.96 Zn 7.21 7.20 Fe 0.35 0.43 Sb 26.80 25.71 As 1.26 2.29 Pb 0.00 0.00 Ag 4.05 3.30 Bi 0.17 0.12 Hg 0.00 0.00 Total 98.96 99.82 261 Sample 3CHN89-44 Sit e 1 2 3 Cu 40.99 39.46 41.55 S 27.87 26.85 27.56 Zn 8.04 7.98 8.19 Fe 1.59 1.47 1.05 Sb 0.99 7.85 3.56 As 18.67 13.89 16.95 Pb 0.42 0.13 0.00 Ag 0.54 1.80 0.74 Bi 0.09 0.11 0.12 Hg 0.00 0.00 0.08 Total 99.20 99.53 99.79 Sample 3CHN89-24 (Grain I) Sit e 1 2 3 Cu 42.13 41.15 41.40 S 27.68 27.07 27.41. Zn 7.81 7.76 7.70 Fe 1.31 0.74 0.80 Sb 3.05 8.79 6.65 As 17.01 13.74 15.21 Pb 0.00 0.00 0.00 Ag 0.36 0.72 0.42 Bi 0.00 0.15 0.00 Hg 0.00 0.00 0.00 Total 99.35 100.09 99.58 Sample 3CHN89-97 Site 1 2 3 4 5 6 Cu 37.95 38.73 36.26 38.07 37 .67 35 .42 S 25.93 26.08 24.96 25.78 25 .77 24 .78 Zn 7.89 8.01 7.74 7.27 7 .64 7 .36 Fe 0.16 0.29 0.20 0.33 0 .30 0 .37 Sb 18.47 15.46 22.59 18.08 18 .31 23 .52 As 7.42 8.94 3.98 6.73 7 .09 3 .16 Pb 0.00 0.00 0.00 0.00 0 .00 0 .00 Ag 2.49 2.34 3.72 2.92 2 .91 4 .48 B i 0.58 0.65 0.68 0.22 0 .41 1 .18 Hg 0.09 0.00 0.00 0.09 0 .00 0 .00 Total 100.96 100.52 100.12 99.50 100 .09 100 .28 262 Sample 1CHN89-117 Sit e 1 2 3 4 5 Cu 42.34 38.86 39.27 40.00 42.04 S 28.21 26.05 26.53 26.44 28.26 Zn 6.05 6.88 7.10 7.18 6.79 Fe 2.42 1.11 1.12 1.05 1.96 Sb 0.05 0.70 0.08 0.08 0.12 As 19.35 14.36 15.58 15.84 19.43 Pb 0.00 0.00 0.00 0.00 0.00 Ag 1.19 2.85 2.30 1.91 0.96 Bi 0.00 8.49 7.78 6.78 0.00 Hg 0.00 0.13 0.09 0.00 0.00 Total 99.61 99.43 99.84 99.30 99.61 Sample 2CHN89-26 Sit e 1 2 3 4 Cu 35.99 39.25 40.57 40.51 S 25.65 27.02 28.06 27.52 Zn 6.20 7.18 7.03 6.86 Fe 2.50 2.55 3.12 2.78 Sb 20.31 11.62 5.27 4.08 As 5.57 11.27 15.22 16.98 Pb 0.00 0.00 0.00 0.00 Ag 4.04 1.09 0.46 0.72 Bi 0.00 0.00 0.00 0.10 Hg 0.00 0.15 0.00 0.04 Total 100.25 100.12 99.81 99.60 Sample 2CHN89-11 Sit e 1 2 Cu 42.55 42.74 S 28.37 28.29 Zn 2.59 6.21 Fe 5.51 2.08 Sb 0.00 0.13 As 19.73 19.62 Pb 0.00 0.00 Ag 0.34 0.12 Bi 0.08 0.00 Hg 0.00 0.00 Total 99.17 99.19 263 Sample 3CHN89 -7OB (Two Grains: 1,2 and 3,4,5, 6,7) Sit e 1 2 3 4 5 6 7 Cu 42.51 42.33 33.48 34.70 34.33 33.26 33.13 S 28.10 28.31 24.97 25.29 25.31 24.73 24.65 Zn 7.54 6.23 5.40 5.72 6.49 5.34 5.66 Fe 1.28 2.79 1.89 2.17 1.18 2.09 1.91 Sb 0.00 0.27 24.25 22.13 21.69 24.01 25.02 As 19.06 19.09 2.65 4.41 4.21 2.31 2.16 Pb 0.00 0.00 0.00 0.00 0.00 0.07 0.00 Ag 0.71 0.73 6.54 4.66 6.04 6.92 6.52 Bi 0.00 0.00 0.00 0.05 0.00 0.08 0.27 Hg 0.09 0.00 0.06 0.04 0.00 0.00 0.00 Total 99.31 99.82 99.26 99.17 99.25 98.82 99.33 Sample 3CHN89-19 Sit e 1 2 3 4 5 Cu 37.45 38.99 37.36 38.88 36.37 S 26.03 26.46 25.62 26.84 25.24 Zn 7.50 7.79 7.56 7.62 7.66 Fe 0.52 0.40 0.78 1.03 0.69 Sb 22.90 18.26 22.69 14.66 23.48 As 4.04 6.96 4.21 9.73 3.49 Pb 0.00 0.00 0.00 0.00 0.00 Ag 1.68 1.40 1.79 1.13 2.80 Bi 0.14 0.00 0.00 0.13 0.16 Hg 0.00 0.00 0.09 0.10 0.00 Total 100.25 100.26 100.11 100.11 99.86 Sample 3CHN89-100 Sit e 1 2 Cu 33.34 38.71 S 25.07 26.30 Zn 6.84 7.89 Fe 0.51 0.31 Sb 19.67 13.12 As 5.45 10.88 Pb 0.00 0.00 Ag 7.30 2.54 B i 0.06 0.08 Hg 0.09 0.00 Total 98.32 99.83 Sample 2CHN90-2 Site 1 2 Cu 36.69 35.57 S 25.45 25.30 Zn 4.84 5.58 Fe 2.35 1.80 Sb 24.43 25.71 As 3.09 2.37 Pb 0.00 0.00 Ag 2.60 2.99 Bi 0.00 0.00 Hg 0.00 0.13 Total 99.46 99.46 Sample 3CHN89-98 Sit e 1 2 3 Cu 39.11 38.71 38.62 S 26.87 26.70 27.06 Zn 7 .73 7.75 7.88 Fe 0.35 0.33 0.37 Sb 10.71 12.08 12.24 As 12.47 11.53 11.42 Pb 0.00 0.00 0.00 Ag 1.43 1.79 1.81 B i 0.18 0.06 0.14 Hg 0.00 0.00 0.04 Total 98.86 98.97 99.58 Sample 2CHN89-27 Site 1 2 3 4 5 6 Cu 42.63 41.36 42.10 42.13 42.27 41.30 S 28.56 27.66 28.41 28.16 28.23 27.69 Zn 6.80 8.40 8.28 8.59 8.51 8.72 Fe 1.60 0.67 1.01 0.67 0.94 1.10 Sb 0.04 0.08 0.00 0.00 0.03 0.00 As 19.68 17.77 19.21 18.54 19.38 17.45 Pb 0.00 0.00 0.00 0.00 0.00 0.00 Ag 0.43 0.55 0.34 0.49 0.40 0.52 Bi 0.08 3.58 0.86 2.23 0.25 3.56 Hg 0.00 0.11 0.06 0.11 0.04 0.04 Total 99.80 100.17 100.29 100.91 100.03 100.41 265 Sample 3CHN89-66 Sample 3CHN89-3 (Grain Site 1 Site 1 2 Cu 25.50 Cu 39.90 39.22 S 24.14 S 27.17 26.41 Zn 6.15 Zn 3.98 4.39 Fe 2.24 Fe 3.16 2.33 Sb 20.71 Sb 11.29 16.17 As 4.60 As 11.37 6.90 Pb 0.00 Pb 0.00 0.00 Ag 17.32 Ag 0.47 0.70 Bi. 0.00 Bi 1.31 3.84 Hg 0.00 Hg 0.18 0.13 Total 100.66 Total 98.82 100.07 Sample 3CHN89-3 (Grain III) Sample 3CHN89 -3 (Grain IV) S i t e 1 2 Site 1 2 3 Cu 38.87 39.26 Cu 40.13 46.96 42.63 S 25.89 26.97 S 26.22 32.42 28.65 Zn 6.71 7 .24 Zn 3.74 0.33 3.40 Fe 1.19 1.27 Fe 3.13 1.12 4.33 Sb 3.49 8.26 Sb 10.55 2.48 2.71 As 12.84 13.40 As 11.02 17.31 18.43 Pb 0.00 0.00 Pb 0.00 0.00 0.00 Ag 0.38 0.25 Ag 0.65 0.00 0.25 Bi 9.99 2.18 Bi 4.56 0.15 0.20 Hg 0.00 0.00 Hg 0.32 0.00 0.00 Total 99.36 98.83 Total 100.32 100.75 100.66 Sample 3CHN89-88 Sample 3CHN89-15 Sit e 1 2 _ Site 1 Cu. 40.43 41.72 Cu 26.36 S 27.72 29.00 S 23.68 Zn 7.12 7.70 Zn 0.70 Fe 2.53 1.83 Fe 6.28 Sb 0.11 0.00 Sb 26.64 As 17.37 18.69 As 1.02 Pb 0.00 0.00 Pb 0.00 Ag 0.49 0.24 Ag 16.32 Bi 4.23 0.74 Bi 0.00 Hg 0.13 0.00 Hg 0.00 Total 100.12 99.92 Total 101.02 Sample 2CHN89-19 Sample 2CHN89-34 Sit e 1 Si t e 1 2 Cu 39.71 Cu 37.88 41.59 S 26.45 S 25.76 28.23 Zn 7.78 Zn 7.77 7.70 Fe 0.73 Fe 0.21 0.62 Sb 14.34 Sb 20.95 0.89 As 9.61 As 5.25 18.68 Pb 0.00 Pb 0.00 0.00 Ag 0.14 Ag 0.79 0.12 Bi 0.11 Bi 0.00 0.18 Hg 0.10 Hg 0.00 0.00 Total 98.98 Total 98.64 98.01 Sample 3CHN89-24 (Grain II) Sample 2CHN90-9 Si t e 1 Site 1 2 Cu 19.50 Cu 35.58 36.63 S 22.03 S 25.31 25.80 Zn 6.48 Zn 7.52 7.66 Fe 1.23 Fe 0.19 0.17 Sb 23.62 Sb 20.36 17.70 As 1.53 As 6.10 6.96 Pb 0.00 Pb 0.16 0.28 Ag 24.61 Ag 3.60 2.99 B i 0.00 Bi 0.04 0.08 Hg 0.05 Hg 0.07 0.00 Total 99.04 Total 98.95 98.27 Sample 3CHN89-79 Sit e 1 Cu 41.51 S 28.47 Zn 6.40 Fe 2.29 Sb 0.00 As 19.51 Pb 0.00 Ag 0.47 Bi 0.13 Hg 0.00 Total 98.79 267 Part l i t Sphaler i tes Sample 3CHN89-66 S i t e 1 2 3 4 5 6 Zn 66.42 66.38 66.47 65.59 65.96 66.10 S 33.33 33.29 33.40 33.22 33.11 33.12 Fe 0.11 0.10 0.21 0.43 0.23 0.15 Mn 0.05 0.03 0.07 0.34 0.07 0.00 Cd 0.36 0.45 0.42 0.38 0.41 0.39 Hg 0.00 0.00 0.00 0.00 0.00 0.00 Ga 0.00 0.00 0.00 0.00 0.00 0.00 Ge 0.06 0.00 0.00 0.00 0.04 0.04 In 0.00 0.00 0.00 0.00 0.00 0.00 T o t a l 100.33 100.26 100.60 99.96 99.83 99.83 S i t e 7 8 9 10 11 12 Zn 66.25 65.19 66.34 66.23 65.99 66.54 S 33.40 33.17 33.37 33.14 33.19 32.93 Fe 0.08 0.22 0.40 0.23 0.34 0.00 Mn 0.00 0.15 0.00 0.04 0.14 0.00 Cd 0.41 0.40 0.42 0.40 0.43 0.00 Hg 0.00 0.00 0.00 0.00 0.00 0.00 Ga 0.00 0.00 0.00 0.00 0.00 0.00 Ge 0.00 0.06 0.03 0.00 0.06 0.00 In 0.00 0.00 0.00 0.00 0.00 0.00 T o t a l 100.16 99.93 100.58 100.09 100.14 99.51 Sample 3CHN89-20 S i t e 1 2 3 4 5 6 Zn 63.18 65.35 65.74 65.86 65.58 65.37 S 33.11 33.21 33.27 33.15 33.21 33.22 Fe 2.55 0.68 0.00 0.00 0.00 0.00 Mn 0.07 0.00 0.00 0.00 0.00 0.00 Cd 0.00 0.06 0.17 0.14 0.28 0.64 Hg 0.00 0.00 0.07 0.00 0.00 0.04 Ga 0.04 0.00 0.00 0.00 0.00 0.00-Ge 0.00 0.00 0.00 0.00 0.00 0.07 In 0.00 0.00 0.00 0.00 0.04 0.08 T o t a l 98.98 99.34 99.27 99.20 99.11 99.42 268 Site 7 8 9 10 11 12 Zn 65.80 65.29 66.04 65.82 66.06 65.39 S 32.90 33.03 33.21 32.97 33.18 33.08 Fe 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.44 0.56 0.11 0.38 0.20 0.54 Hg 0.00 0.00 0.00 0.05 0.00 0.06 Ga 0.00 0.00 0.00 0.00 0.00 0.00 Ge 0.05 0.05 0.00 0.03 0.03 0.00 In 0.10 0.19 0.00 0.07 0.00 0.18 Total 99.31 99.14 99.42 99.34 99.48 99.28 Site 13 14 15 16 17 18 Zn 65.80 65.70 66.12 65.40 65.33 65.91 S 32.97 32.73 33.29 32.98 33.43 32.84 Fe 0.00 0.00 0.00 0.46 0.69 0.21 Mn 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.29 0.71 0.13 0.39 0.17 0.34 Hg 0.00 0.00 0.00 0.00 0.07 0.00 Ga 0.03 0.03 0.00 0.00 0.00 0.00 Ge 0.07 0.05 0.00 0.00 0.07 0.05 In 0.05 0.09 0.00 0.00 0.00 0.00 Total 99.21 99.31 99.56 99.23 99.77 99.38 Sample 3CHN89-20 (continued) Site 19 20 21 22 23 24 Zn 66.06 63.25 65.55 66.28 65.96 66.27 S 33.28 33.57 33.03 33.24 32.94 33.17 Fe 0.47 2.51 0.29 0.23 0.31 0.05 Mn 0.00 0.00 0.00 0.00 0.00 0.04 Cd 0.14 0.00 0.15 0.08 0.23 0.24 Hg 0.00 0.00 0.00 0.00 0.00 0.00 Ga 0.00 0.00 0.00 0.00 0.00 0.00 Ge 0.03 0.00 0.09 0.05 0.00 0.00 In 0.00 0.00 0.00 0.00 0.00 0.03 Total 99.99 99.37 99.12 99.87 99.44 99.82 269 Sample 3CHN89-36 Site 1 2 3 4 5 6 Zn 66.65 66.12 66.17 66.34 66.30 66.64 S 33.09 32.92 33.04 32.97 33.01 33.04 Fe 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.09 0.07 0.43 0.34 0.21 0.08 Cd 0.17 0.18 0.36 0.30 0.34 0.38 Hg 0.00 0.00 0.00 0.00 0.00 0.00 Ga 0.00 0.00 0.00 0.00 0.00 0.04 Ge 0.00 0.00 0.00 0.00 0.04 0.00 In 0.03 0.00 0.00 0.07 0.00 0.00 Total 100.03 99.36 100.03 100.05 99.91 100.22 Si t e 7 8 9 Zn 65.93 65.81 66.28 S 32.95 33.20 33.04 Fe 0.00 0.00 0.00 Mn 0.00 0.14 0.06 Cd 0.68 0.29 0.30 Hg 0.00 0.08 0.00 Ga 0.00 0.00 0.00 Ge 0.00 0.03 0.06 In 0.00 0.00 0.00 Total 99.64 99.55 99.73 Sample 2CHN89-4 Sit e 1 2 3 4 Zn 64.88 65.71 65.50 65.28 S 33.26 33.05 33.24 33.17 Fe 0.98 0.24 0.43 0.28 Mn 0.00 0.00 0.00 0.00 Cd 0.34 0.42 0.42 0.42 Hg 0.00 0.00 0.00 0.00 Ga 0.00 0.05 0.00 0.00 Ge 0.03 0.00 0.10 0.08 In 0.00 0.10 0.04 0.00 Total 99.51 99.59 99.74 99.23 270 Sample 3CHN89-18 Sit e 1 2 3 4 5 6 Zn 66.64 65.88 66.24 66.26 66.77 66.75 S 33.03 32.98 33.10 33.10 32.99 32.99 Fe 0.00 0.00 0.00 0.00 0.00 0.00 Mn 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.44 0.60 0.53 0.52 0.42 0.42 Hg 0.06 0.00 0.07 0.00 0.00 0.00 Ga 0.00 0.03 0.04 0.04 0.00 0.00 Ge 0.07 0.05 0.06 0.00 0.00 0.00 In 0.04 0.00 0.00 0.00 0.00 0.00 Total 100.31 99.57 100.06 99.98 100.20 100.18 S i t e 7 8 Zn 66.62 66.73 S 33.07 33.06 Fe 0.00 0.00 Mn 0.00 0.00 Cd 0.35 0.35 Hg 0.00 0.00 Ga- 0.00 0.00 Ge 0.00 0.07 In 0.00 0.00 Total 100.07 100.28 Sample 2CHN89-27 S i t e 1 65.83 33.04 0.89 0.00 0.44 0.00 0.00 0.07 0.00 100.31 Zn S Fe Mn Cd Hg Ga Ge In Total - Sample 3CHN89-21 S i t e 1 2 3 4 5 Zn 66.03 66.67 65.62 66.23 66.69 S 33.32 33.20 33.07 33.36 32.64 Fe 0.46 0.44 0.52 0.57 0.43 Mn 0.00 0.00 0.00 0.28 0.00 Cd 0.82 0.37 0.54 0.36 0.55 Hg 0.00 0.00 0.00 0.07 0.04 Ga 0.00 0.00 0.00 0.03 0.00 Ge 0.00 0.03 0.00 0.05 0.03 In 0.00 0.00 0.04 0.00 0.00 T o t a l 100.65 100.73 99.81 100.96 100.39 Sample 1CHN89-83 S i t e 1 2 3 4 5 6 Zn 65.97 66.19 66.73 66.40 66.37 66.06 S 33.10 33.17 33.03 33.06 33.04 32.75 Fe 0.32 0.32 0.30 0.33 0.31 0.30 Mn 0.00 0.00 0.00 0.00 0.00 0.00 Cd 0.50 0.51 0.47 0.59 0.46 0.48 Hg 0.00 0.07 0.04 0.00 0.00 0.04 Ga 0.00 0.03 0.03 0.00 0.00 0.00 Ge 0.06 0.03 0.00 0.00 0.00 0.00 In 0.00 0.00 0.00 0.03 0.00 0.00 T o t a l 99.98 100.34 100.60 100.43 100.20 99.64 Sample 2CHN90-2 Best Analys i s S i t e 1 Zn 64.27 S 33.34 Fe 0.32 Mn 0.00 Cd 0.51 Hg 0.00 Ga 0.03 Ge 0.00 In 0.00 T o t a l 98.53 272 Sample 3CHN89-97 S i t e 1 2 Zn 65.84 66.68 S 32.96 32.88 Fe 0.00 0.00 Mn 0.00 0.00 Cd 0.08 0.00 Hg 0.00 0.00 6a 0.00 0.00 Ge 0.06 0.03 In 0.04 0.00 T o t a l 99.01 99.67 273 Part I I I : Miscellaneous Sulfide Analyses *A11 analyses done using s u l f o s a l t routine **Values are weight percents. For several galena samples, atom counts generally show Ag=Bi, suggesting a possible unresolvable intergrown matildite component Sample 3CHN89-79 (Galena) Sample 3CHN89-79 Site 1 Site 1 Cu 0.00 Cu 33.42 S 14.32 S 34.55 Zn 0.00 Zn 0.00 Fe 0.04 Fe 31.50 Sb 0.00 Sb 0.00 As 0.00 As 0.06 Pb 82.85 Pb 0.00 Ag 1.20 Ag 0.00 Bi 2.47 Bi 0.25 Hg 0.00 Hg 0.09 Total 100.88 Total 99.91 Sample 3CHN89-88 (Galena) Sample 2CHN89-45 Sit e 1 2 Site 1 Cu 0.98 0.48 Cu 34.42 S 13.69 14.07 S 35.06 Zn 0.14 0.00 Zn 0.00 Fe 2.01 0.00 Fe 30.42 Sb 0.06 0.00 Sb 0.00 As 0.00 0.00 As 0.00 Pb 76.75 80.99 Pb 0.00 Ag 1.90 1.24 Ag 0.06 Bi 3.86 3.72 Bi 0.21 Hg 0.00 0.00 Hg 0.00 Total 99.42 100.54 Total 100.23 (Chalcopyrite) 

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