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Silver-base metal relationships in some British Columbia mines Robinson, Stephen Clive 1936

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SILVER - BASE METAL RELATIONSHIPS HI SOME  BRITISH COLUMBIA MINES S. C. ROB UTSON A Thesis submitted f o r the Degree of MASTER OF APPLIED SCIENCE i n the department of GEOLOGICAL ENGINEERING The U n i v e r s i t y of B r i t i s h Columbia A p r i l , 1936. CO IT T E N T S Page CHAPTER I -• 1. Int r o d u c t i o n .. ...... 1 2. Status of S i l v e r i n the Mining Industry • •. e..... •..«... •. 1 3 . Economic Considerations of the Various A s s o c i a t i o n s of S i l v e r 3 4. Summary of Methods Employed..o . . 3 J5. Summary of Results ............. 7 CHAPTER I I - 1. I n t r o d u c t i o n . 10 2. Deposits on the Western Flank of the Coast Range B a t h o l i t h . ...... 11 a * Anyox 12 b. B r i t a n n i a . ......... 12 c. Tyee, Coast Copper, Texada I s l a n d . . . . . . . 13 3 . Deposits on the Eastern Flank of the Coast Range B a t h o l i t h . . . . . . . 13 a. A t l i n D i s t r i c t . . . . . . . . . . 14 b. unuk Riv e r Area. 16 c. Premier. 17 d o B.C. S i l v e r . . . . . . . . . . . . . 20 e. T o r i c . 20 f. Hazelton D i s t r i c t 21 g. V i c t o r i a - E u r e k a . . . . . . . . . 22 4. Deposits across Southern B r i t i s h Columbia 23 a. The Horn S i l v e r Mine.... 23 b. Stump l a k e . . . . . . . . . . . . . . 23 c. Copper Mountain. 24 d e Beaverdell Camp......... 23 e. A l l e o Mining Company.... 27. f• Snowflake Mine.......... 29 g. Slocan Area............. 30 Mammoth Mine....... 32 h s B l u e b e l l lode........... 34 i . Nelson D i s t r i c t . . . . . . . . . % %. S u l l i v a n Mine............ 37 k. St. Eugene Mine......... 38 1. Other Argentiferous Deposits............. 38 CHAPTER I I I - 1, Introd u c t i o n 40 2. Geological D i s t r i b u t i o n ........ 40 a. Copper-Silver ores...... 41 b. Silver-Lead-Sine ores... 41 C O N T E N T S (continued) Page CHAPTER I I I (continued) 3<> Types of M i n e r a l Deposits.. ....... 42 a. Silver-Copper ores. ........ 42 b. S i l v e r - l e a d - Z i n c ores..,.. 43 c. "Dry" S i l v e r ores* . 4 5 d. Other D e p o s i t s * . . . . . . . . . 4.5 4. Persistence of Argentiferous Deposits at Depth................. 46 a. Copper-Silver ores,..,.... 46 b . Other Deposits J?. A s s o c i a t i o n of S i l v e r Deposits with Various Types of I n t r u s i v e s . . 50 6. The E f f e c t s of Supergene Forces... .51 CHAPTER IV - lo Intro d u c t i o n .................... • 54 2. A s s o c i a t i o n of S i l v e r with l e a d . . . 56 3* A s s o c i a t i o n of S i l v e r with Copper. 61 4. A s s o c i a t i o n of S i l v e r w i t h Z i n c . . . 64 5. A s s o c i a t i o n of S i l v e r wi th Other Base Metals............... 6? 6. A s s o c i a t i o n of S i l v e r with Gold... 67 CHAPTER V - 1. In t r o d u c t i o n ..................... 69 2. Mineralogy of S i l v e r i n B.C* ...... 69 3. Base-Metal A s s o c i a t i o n s of S i l v e r . 72 4. Types of Argentiferous Deposits..« 74 5. Depth and Zoning of S i l v e r Deposits.......... 74 6. Summary and Comparison o f Re s u l t s . 76 APPENDIX - Acknowledgments .......... i Bibliography ... i i ILLUSTRATIONS Page 1. Premier - Native S i l v e r intergrown with Galena. 19a 2. Premier - P y r i t e and Ruby S i l v e r . l ? a 3„ Premier - Ruby S i l v e r i n Quartz (Thin S e c t i o n ) . l ? a 4. Toric - Dissemination of M e t a l l i c M i n e r a l s . 20a 3 . Toric - M e t a l l i e s i n Quartz and B a r i t e (Thin Section) 20a 6 . A l l c o - Jamesonite between Galena and Tetrahedri te 28a 7» A l l c o - Weathered Galena, and C o v e l l i t e remaining i n place of Te t r a h e d r i t e . 28a 8. A l l c o - In c l u s i o n s i n etched Galena. 28a 9. Mammoth - In c l u s i o n s i n etched Galena (302 Stope). 33a 10. Mammoth - Inclusio n s i n etched Galena (701 S t o p e ) . 33a. 11. Mammoth - P y r r h o t i t e i n C a l c i t e (.701 Stope). 33a 12. B l u e b e l l - Etched Galena i n K n e b e l i t e . 34a 13« S u l l i v a n - D i s t r i b u t i o n o f minerals i n ore-body ( a f t e r S c h o f i e l d ) . 37a 14. D i s t r i b u t i o n of Metals about a B a t h o l i t h ( a f t e r Buddington) 30a - 1 -CHAPTER I . Introduction. Of the f i v e major metals mined i n B r i t i s h Columbia s i l v e r i s among the l e a s t important. Quantity and value of s i l v e r produced i n t h i s province are lower than f o r g o l d , l e a d , copper or, d o u b t f u l l y , z i n c . Yet s i l v e r occupies a p o s i t i o n unique among these metals i n i t s d i s t r i b u t i o n . l i k e g o l d , a very small quantity i n an ore i s required to make that ore of economic importance. In a deposit i n which other valuable metals are present the a d d i t i o n of an even smaller quantity of s i l v e r may make the d i f f e r e n c e between p r o f i t and l o s s i n i t s operation. But u n l i k e g o l d , s i l v e r appears i n a wide range of minerals, w i t h the r e s u l t that a s s o c i a t i o n s of s i l v e r with other metals and t h e i r minerals are often much cl o s e r and more d i s t i n c t than are those of gold. This d i f f e r e n c e i s , of course, due to the f a c t that s i l v e r i s chemically competent to react much more e a s i l y with various e l e c t r o l y t e s than g o l d . This o u t l i n e b r i e f l y i n d i c a t e s the possible import-ance of a study of s i l v e r and i t s a s s o c i a t i o n s i n B r i t i s h Columbia, a province i n which although i t i s a minor product, nevertheless, to borrow a p o l i t i c a l term, i t i s o f t e n the • r u l i n g m i n o r i t y ' f o r an i n d i v i d u a l mine« The Status of S i l v e r i n the Mining, Industry. In recent years the p r i c e of s i l v e r has shown wide and i n c o n s i s t e n t f l u c t u a t i o n s ; i n c o n s i s t e n t because the market -2~ f o r the metal i s predominantly a r t i f i c i a l 0 Although gold i s the more widely accepted basis of world exchange, s i l v e r also plays an important parte In e a r l i e r years the p r i c e of s i l v e r was l a r g e l y dependent on the welfare o f those countries which employed i t , i n part or i n whole, as the basi s f o r t h e i r currency, p a r t i c u l a r l y China. At present, however, t h i s use of s i l v e r has become so subordinate to the use of gold that the f l u c t u a t i o n of s i l v e r p r i c e s now a f f e c t s the f i n a n c i a l welfare of such nations; an instance of the " t a i l wagging the 4o g". For the past few years i t had been considered t h a t , as soon as the p r i c e of s i l v e r rose to 4.5-50 cents an ounce, the l a r g e r s i l v e r camps would reopen; that that p r i c e should provide a f a i r margin o f p r o f i t . In the past s i x t e e n months, l a r g e l y due to purchases of the United States t r e a s u r y , the pr i c e rose to w e l l above the f i g u r e mentioned and remained there f o r several months. Yet the s i l v e r mines of B r i t i s h Columbia showed almost no increase i n production. Ho b e t t e r i l l u s t r a t i o n of the modern place of s i l v e r i n the mining industry could be found® As a r e s u l t of the r i s e i n s i l v e r p r i c e s , a few base metal mines may have taken the opportunity to mine such parts of t h e i r deposits as could be operated p r o f i t a b l y only due to that r i s e * Those p r o p e r t i e s i n which s i l v e r was the primary product may have pushed production to the maximum. The s i g n i -f i c a n t fact remains that maintenance of a p r o f i t a b l e p r i c e of s i l v e r f o r nearly a year was not considered s u f f i c i e n t guarantee to warrant the reopening of i d l e s i l v e r mines. Therefore s i l v e r i n B r i t i s h Columbia i s e s s e n t i a l l y a by-24 product. To quote two a u t h o r i t i e s , De M i l l e , i n d i s c u s s i n g Canada's mineral production f o r 1 9 3 5 , s t a t e s , "A large amount of Canada's s i l v e r output i s now by-product, the greatest s i n g l e source i n 1935 being the S u l l i v a n mine, i n B. C." 2 Bateman concurs with t h i s statement, remarking, "8o°/0 of Canadian production i s by-product s i l v e r . While there has been some r e v i v a l of i n t e r e s t i n s t r a i g h t mines, i t i s doubtful i f the increased p r i c e w i l l have any m a t e r i a l e f f e c t i n i n c r e a s -ing production from t h i s source." I t s production i s dependent on that of metals f o r which the market i s more s t a b l e , I t s p o s i t i o n from the mine-operator's viewpoint i s analogous to that of second grade ore; important but too i n s t a b l e to be a safe b a s i s by i t s e l f f o r p r o f i t a b l e mining. Economic Considerations of the Various A s s o c i a t i o n s of S i l v e r . In the preceding s e c t i o n some ideas have been pre-sented regarding the p o s i t i o n of s i l v e r g e n e r a l l y ; under t h i s heading the d i f f e r e n c e i n value o f the s i l v e r , due to i t s various a s s o c i a t i o n s , w i l l be discussed, These d i f f e r e n c e s i n value are due to two major co n s i d e r a t i o n s . The more impor-tant of these i s the value of the metals with which s i l v e r i s associated. The second c o n s i d e r a t i o n i s the nature of t h i s a s s o c i a t i o n and i t s consequent amenability to cheap m i l l i n g processes. As an example of t h i s d i v e r s i t y o f s i l v e r values with various minerals, G a l l o w a y ^ gives the Ruth Hope mine. F i f t e e n percent of the s i l v e r at t h i s property i s associated - 4 -with the s i n e , the r e s t occurs f r e e or wi t h l e a d . A f t e r con-centrations the T s u l p h i d e s r are shipped to the smelter,. Cost of t r a n s p o r t a t i o n and treatment of the zin c concentrates and t h e i r included s i l v e r i s ju s t equal to t h e i r value. Therefore f i f t e e n percent of the s i l v e r values i n the ore i s so a s s o c i a -ted as to he worthless. The remaining e i g h t y - f i v e percent • 54 • supplements the net value o f the le a d . Sargent has c a r r i e d out a considerable amount of research work on the recovery of s i l v e r i n s i l v e r - l e a d - z i n c ores by f l o t a t i o n . To i l l u s t r a t e the divergence i n value of s i l v e r i n z i n c and l e a d concen-t r a t e s he gives the f o l l o w i n g f i g u r e s : Zinc Concentrate - Ag 20 oz./ton, Zn 50%, Pb Net value of s i l v e r i n t h i s concentrate 8 cents/ton. lead Concentrate - With the same amount of s i l v e r , the values f o r lead and zinc approximately reversed, the net value of s i l v e r i s 38 cents/ton. He then s t a t e s , " I t i s thus quite c l e a r that s i l v e r i n lead concentrates i s a great deal more p r o f i t a b l e than s i l v e r i n zinc concentrates." Warren has reported that t e t r a h e d r i t e , due to vagaries of f l o t a t i o n , tends to 'come up 1 with s p h a l e r i t e , where i t l o s e s much o f i t s value. Sargent has found the same to be true of the Slocan ores where the ruby s i l v e r s also come up with s p h a l e r i t e . He has, however, found that a f t e r the separation of the l e a d , the s i l v e r minerals may be p a r t l y f l o a t e d o f f . Together with the zin c product they are r e f l o a t e d and a f a i r l y clean separation of s i l v e r and zin c can be made. This i s pos s i b l e however, only when the s i l v e r minerals occur i n grains above 200 mesh and i n s u f f i c i e n t quantity to j u s t i f y the extra f l o t a t i o n circuit» S i l v e r tends to be recovered w i t h g o l d i n the larg e copper p l a n t s , much of i t i n the e l e c t r o l y t i c r e f i n i n g tanks* I t i s therefore a valuable a d d i t i o n to copper ores even i n small q u a n t i t i e s * The w r i t e r i s not conversant with the case of recovery of s i l v e r from t i n ores but i t must be s a t i s f a c -t o r y as the great mines of B o l i v i a , and, to a much l e s s e r extent, of Tasmania, are l a r g e l y dependent on s i l v e r values f o r t h e i r p r o f i t s . ^ Although the w r i t e r has not been able to obta i n comparative f i g u r e s on the value of s i l v e r a ssociated with the various metals, i t seems probable that i t i s valuable a s s o c i a -ted with l e a d , t i n , copper and gold , i n about that order. With z i n c , i t l o s e s most of i t s value due to expense o f recovery. These d i f f e r e n c e s i n value due to various a s s o c i a -t i o n s are i n themselves s u f f i c i e n t to j u s t i f y a considerable study of those a s s o c i a t i o n s i n an attempt to f i n d some s o l u -t i o n to the m i l l i n g and m e t a l l u r g i c a l problems i n v o l v e d . Summary of Methods Employed^ In a survey of papers devoted to s i l v e r i n B r i t i s h Columbia, the w r i t e r has been unable to f i n d one approaching the scope of t h i s t h e s i s . The occurrence o f the metal i n various parts of the province has been described too seldom by competent observers. U s u a l l y a d e s c r i p t i o n of s i l v e r deposits i s given but seldom are any deductions or inferences made from the facts» The w r i t e r has read as many papers bearing on every facet of the issue as time permitted and references to these papers are made by numbers r e f e r r i n g to the f u l l b i b l i o -graphy which i s appended* The d e s c r i p t i o n s o f pr o p e r t i e s are taken e n t i r e l y from published r e p o r t S o In order to make t h i s paper something more than a summary of other papers a considerable amount of time was devoted to the examination of s u i t e s of ores from deposits i n widely d i f f e r e n t parts o f the province. The ores were f i r s t s tudied megascopically w i t h the a i d of a hand lens and an attempt was made to deduce, from the texture and character, the type of deposit i t represented,. T y p i c a l sections of the ore from d i f f e r e n t l e v e l s were then made and pol i s h e d . Ores found to be too f r i a b l e to be amenable to the hand p o l i s h i n g l a p s were e i t h e r impregnated or polished on the super-polisher. Results from t h i s machine were not e n t i r e l y s a t i s f a c t o r y ; hence these studies could not be made i n s u f f i c i e n t d e t a i l . . From these p o l i s h e d surfaces determination of a l l the minerals observed was f i r s t attempted. The s i z e and asso-c i a t i o n of the various minerals was noted and a paragenesis drawn up f o r each deposit. F i n a l l y a rough determination o f the q u a n t i t i e s of d i f f e r e n t minerals was made i n sections representing the upper and lower l e v e l s of each property where specimens were a v a i l a b l e . The a s s o c i a t i o n of s i l v e r minerals was p a r t i c u l a r l y examined and an attempt made to ascr i b e s i l v e r values i n t h e i r order of importance to various minerals. By means o f etching the sections the occurrence of rather minute i n c l u s i o n s o f ~7-argentiferous minerals was studied. To supplement data thus acquired, some of the specimens were crushed and screened to a si z e s u f f i c i e n t to l i b e r a t e the l a r g e r p a r t i c l e s o f the various minerals. Products o f these minerals were then made by p i c k i n g them out of the screened ore. These picked products were then assayed to determine t h e i r s i l v e r content. P u r i t y of these products n e c e s s a r i l y v a r i e d considerably, p a r t l y due to shortage of m a t e r i a l and p a r t l y due to the general character of most of the ore. Samples were sent i n p r i m a r i l y to repre-sent t y p i c a l ore rat h e r than concentrations of various minerals o I t was not u n t i l l a t e i n the year that the w r i t e r found a reference d e s c r i b i n g the determination of s i l v e r minerals by etching w i t h intense l i g h t . ^ ~ Some attempt to master t h i s technique was made but time d i d not permit s u f f i -c i e n t research to obtain u s e f u l r e s u l t s . For determination o f s i l v e r minerals however, t h i s p a r t i c u l a r technique appears to be much superior to any known method f o r ores i n which s i l v e r minerals are too small i n s i z e f o r determination by other methods. The suggestion i s made to anyone proceeding w i t h study of s i l v e r minerals that they f i r s t acquire t h i s p a r t i c u -l a r technique. Summary of R e s u l t s . In undertaking to make labor a t o r y i n v e s t i g a t i o n of a s u f f i c i e n t number of ores to j u s t i f y a paper dependent on o r i g i n a l r e s u l t s , the w r i t e r found that he had g r e a t l y under-estimated the time required. As a r e s u l t , the f o l l o w i n g -8-summary i s based very l a r g e l y on a survey o f p u b l i s h e d f i e l d r e p o r t s . In ferences and c o n c l u s i o n s drawn from t h i s summary, toge ther w i t h the few f a c t s ob ta ined from the l a b o r a t o r y work done, comprise the o n l y o r i g i n a l work presented i n t h i s paper . 1, S i l v e r output o f B r i t i s h Columbia i s almost e n t i r e l y a b y - p r o d u c t . 2. The va lue o f the net r e t u r n s on the s i l v e r content o f an ore depends on the a s s o c i a t i o n o f the s i l v e r . 3» S i l v e r i s p r i m a r i l y a s s o c i a t e d w i t h l e a d , copper , g o l d , z i n c and t i n , approx imate ly i n that o r d e r . 4 . T e t r a h e d r i t e i s the most important e a r l y ( i n t ime o f d e p o s i t i o n ) source o f s i l v e r * j?. There are i n d i c a t i o n s tha t some o f the s i l v e r s u l p h o -s a l t s are d e r i v e d from t e t r a h e d r i t e by pr imary a l t e r a t i o n and r e p l a c e m e n t » 6. In the a s s o c i a t i o n o f s i l v e r w i t h copper , t e t r a h e d r i t e i s the most important m i n e r a l , f o l l o w e d by c h a l c o p y r i t e and i n one i n s t a n c e s t r o m e y e r i t e . 7. In the a s s o c i a t i o n o f s i l v e r w i t h l e a d , ga lena c a r r y -ing i n c l u s i o n s of a r g e n t i f e r o u s m i n e r a l s i s the o n l y important m i n e r a l . 8. The a s s o c i a t i o n of s i l v e r w i t h z i n c appears t o be due to the p r o x i m i t y i n the o r d e r o f d e p o s i t i o n , o f t e t r a h e d r i t e to s p h a l e r i t e . 9® R i c h s i l v e r - b e a r i n g shoots are c o n f i n e d to the upper l e v e l s o f ore d e p o s i t s i n t h i s p r o v i n c e . 1 0 . Supergene enrichment and r e s u l t i n g h i g h grade supergene deposits have been removed by g l a c i a t i o n i n B r i t i s h Columbia* 1 1 . No epithermal s i l v e r deposits are known i n t h i s prov ince . Important deposits are almost a l l me sothermal, a few may be considered hypothermal* 12e The r i c h e s t s i l v e r producing d i s t r i c t s are found on the northeastern contact of the Coast Range b a t h o l i t h and i n southeastern B r i t i s h Columbia, 13« Many s i l v e r minerals, u s u a l l y considered to be super genej appear to be l a r g e l y hypogene i n deposits o f t h i s provinceo Notable among these are native s i l v e r and the. sulpho-salts* 14« In the s i l v e r - l e a d - z i n c deposits the order of deposi t i o n seems to be p y r i t e , s p h a l e r i t e , t e t r a h e d r i t e , galena, s i l v e r s u l p h o - s a l t s and nat i v e s i l v e r . This par-agenesis 38 agrees ex a c t l y with that postulated by Gui lds -10-CHAPTER I I . I n t r o d u c t i o n . D i s t r i b u t i o n of s i l v e r bearing deposits i n B r i t i s h Columbia coincides c l o s e l y with other ore bearing lode depos-i t s of the province* Governed almost e n t i r e l y by the presence of igneous rocks, the valuable deposits are found f l a n k i n g both sides of the Coast Range b a t h o l i t h and sc a t t e r e d among the l e s s continuous s e r i e s of b a t h o l i t h s across the southern end of the province. l i t t l e i s known o f the p o s s i b i l i t i e s o f the i n t e r i o r and northeastern parts of B r i t i s h Columbia and no great amount o f lode mining development has as yet taken place there. C e r t a i n g e n e r a l i z a t i o n s concerning the s i l v e r bear-ing deposits associated w i t h the Coast Range b a t h o l i t h have been o u t l i n e d by S c h o f i e l d . B r i e f l y , the western contact of the b a t h o l i t h i s notable for i t s copper-gold content; the eastern side f o r s i l v e r - l e a d - z i n c . In a paper on the f r a c t u r e systems of the province S c h o f i e l d f i n d s that IT.E. trending f i s s u r e s are commonly mi n e r a l i z e d with s i l v e r - l e a d - z i n c , whereas the JT.W. trending shear zones are t y p i c a l l y copper bearing. Camsell"^ has remarked a s i m i l a r segregation of metals and has found copper i n f i s s u r e s along the sides o f roof pendants and gold and s i l v e r i n f i s s u r e s across the ends of them. The w r i t e r had no t i c e d that along the eastern con-tact of t h i s b a t h o l i t h s i l v e r i s more common i n the north with gold predominating i n the south. Confirmation o f t h i s opinion was found i n Okulitoh's t h e s i s on the ore deposits of the - I l -ea s t e m contact of the batholith«, Dr. S c h o f i e l d has suggested that the chain of batho-l i t h s across southern B. C» i s a continuation o f the Coast Range b a t h o l i t h . He has also been able to show that the ten-dency towards segregation of minerals of copper on the south and s i l v e r - l e a d - z i n c on the north s t i l l a p p l i e s . In a bare majority o f instances t h i s i s true but there so many excep-t i o n s that the g e n e r a l i z a t i o n i s of doubtful value_ The s i l v e r bearing deposits to be discussed i n the remainder o f t h i s chapter are p r i n c i p a l l y those of which the w r i t e r has some knowledge or which have been f u l l y described i n the a c c e s s i b l e l i t e r a t u r e . Deposits on the Western Flank of the Coast Range B a t h o l i t h . This mineral b e l t , as pr e v i o u s l y s t a t e d , i s notable f o r the development o f copper and i r o n d eposits. The mineral-i z a t i o n i s commonly of hypothermal type and but l i t t l e s i l v e r has been found. Two or three small bodies of s i l v e r - l e a d - z i n c ore are known i n the northern i n t e r i o r o f Vancouver i s l a n d s and Dolmage reports the presence of s i l v e r i n appreciable quantity i n some ores o f Texada i s l a n d * Without question, however, the s i l v e r production o f t h i s mineral b e l t has come almost e n t i r e l y from the great copper mines of B r i t a n n i a , Anyox, Tyee and Coast Copper. The s i l v e r content of ore from these p r o p e r t i e s i s u s u a l l y low but i s of d e f i n i t e economic importance as a "sweetener". Probably the s i l v e r occurs as one of the complex sulphides, e i t h e r t e t r a h e d r i t e or stromeyerite, but apparently i n q u a n t i t i e s too -12-small f o r r e c o g n i t i o n under the microscopes. The deposits of the Hidden eree3c mine are found i n a large roof pendant of the Hazelton s e r i e s w i t h i n the b a t h o l i t h . The important deposits are r e s t r i c t e d to a b e l t of basic green-stone e Opinion d i f f e r s on the source of the ore; DoImage con-s i d e r s i t to be a product of the l a s t phases of the underlying g r a n o d i o r i t e but Hanson favours the greenstone as the parent magma. Bancroft however b e l i e v e s that m i n e r a l i z a t i o n con-tinued over a long i n t e r v a l so that the ore s o l u t i o n s came f i r s t from the basic magma and l a t e r from the g r a n o d i o r i t e • magma. Such an i n t e r v a l might e x p l a i n the d e p o s i t i o n of small amounts of a r g e n t i t e and na t i v e s i l v e r found i n the upper parts of the mine . At present the ore averages about l / p oz. of s i l v e r to the ton and 1»j>% copper. I t i s s i g n i f i c a n t , how-ever, that by 1?J2 the mine had produced more than f i v e m i l l -4 0 i o n ounces of s i l v e r . Ho mention i s made i n Hanson 5s report of the form i n which the s i l v e r i s found but i t s presence i n such small quantity seems to be t y p i c a l o f t h i s type of depos-i t . P y r i t e , p y r r h o t i t e , c h a l c o p y r i t e and magnetite make up the m e t a l l i c minerals i n that order o f abundance. At B r i t a n n i a somewhat s i m i l a r conditions obtain but zoning of the minerals i n d i c a t e s the main b a t h o l i t h as the 42 source of the ore. James places the deposits i n the meso-thermal range, but v a r i a t i o n from such minerals as b a r i t e and galena to magnetite and p y r r h o t i t e suggests "tele s c o p i n g " o f the zones. Galena and t e t r a h e d r i t e are among the l a t e s t minerals and occur remote from the b a t h o l i t h . The t e t r a -h e d r i t e has been proved by spectrographic analyses to contain -•-1-3-s i l v e r . Values i n s i l v e r are c o n s i s t e n t l y higher where these sulphides are most abundant and appear t o be l a r g e l y a s s o c i a -ted with blende and b a r i t e . Annual production of s i l v e r at B r i t a n n i a amounts to nearly 140,000 ounces. Although s i l v e r i s found both at Tyee and Coast Copper l i t t l e i nformation on i t s occurrence I s a v a i l a b l e . The Texada i s l a n d deposits are of i n t e r e s t as they are thought to provide evidence of two d i s t i n c t types of ore-bearing s o l u -t i o n s . Dolmage f i n d s that the e a r l i e r type was that contain-ing i r o n and copper, the l a t e r type c a r r y i n g copper and s i l v e r with l i t t l e i r o n . Again a long period of m i n e r a l i z a t i o n or more probably two periods i s i n d i c a t e d . Production from the various mines has been spasmodic w i t h r e s u l t a n t lack of d e f i n i t e s t a t i s t i c s on the various metals produced* Some ore shoots, however, carry quite important values i n s i l v e r . Deposits on the Eastern Flank of the Coast Range B a t h o l i t h . Many o f the deposits i n t h i s i n t e r i o r mineral b e l t are important p r i m a r i l y f o r t h e i r s i l v e r content. The major-i t y of them contain sulphides of s i l v e r , l e a d and zin c w i t h minor amounts of i r o n and copper. The lodes are almost e n t i r e l y of the f i s s u r e - f i l l i n g type and almost a l l f a l l i n t o the mesothermal range. Production of s i l v e r has been confined l a r g e l y to the Portland Canal area i n which Premier, B.C. S i l -ver and D o l l y Varden mines have been among the mo st important p r o p e r t i e s . Small and e r r a t i c shipments of argentiferous ore and concentrates have been made from the A t l i n and Hazelton d i s t r i c t s , and i n the south, from the V i c t o r i a Eureka property. -14-Lack of t r a n s p o r t a t i o n has hampered adequate prospecting and development along the i n t e r v e n i n g sections o f t h i s contact but s i l v e r - b e a r i n g ore has been proved to be almost continuous throughout i t s length* I t has been p r e v i o u s l y mentioned that s i l v e r tends to decrease and gold to increase towards the south. A t l i n D i s t r i c t . - In the e a r l y years of t h i s century r a p i d development of r i c h s i l v e r ores took place on Windy arm of Tagish lake» Of the mines developed the Venus and Montana properties are the most noteworthy, both o f them having produced a considerable tonnage of ore. Deposits of t h i s area are found i n metamorphosed sediments, i n porphyries and i n the g r a n i t e i t s e l f * The veins are f i l l e d w i t h a quartz gangue containing sulphides and native s i l v e r and copper i n varying amounts. The ore i s patchy and has proved u n s a t i s f a c t o r y f o r economic development. Usually the q u a r t z - f i l l e d f i s s u r e s are f a i r l y consistent but the contained sulphides tend t o be found only spasmodically. M e t a l l i c minerals reported are n a t i v e s i l v e r and copper, a r g e n t i t e , stephanite, t e t r a h e d r i t e , p y r a r g y r i t e , galena, c h a l c o p y r i t e , p y r i t e , a r s e n o p y r i t e , p y r r h o t i t e and s p h a l e r i t e , The s i l v e r values are l a r g e l y found i n minerals of that metal and values range up to |80 to the ton. Both galena and t e t r a h e d r i t e are i n v a r i a b l y argentiferous but be-cause the ore i s e s s e n t i a l l y of the 'dry* type a s s o c i a t i o n of s i l v e r w ith the base metals i s r e l a t i v e l y unimportant. The A t l i n - R u f f r i e r mine on Leonard mountain i s a more "15-recent development o f considerable i n t e r e s t * The country 21 ro ek, according to C o c k f i e l d , i s a g r a n i t e s a t e l l i t e of the Coast Range b a t h o l i t h . This has been cut by basic dykes, approximately h a l f l a b r a d o r i t e and h a l f femics i n composition The femics are l a r g e l y hornblende, so that C o c k f i e l d has described the dykes as hornblendites„ M i n e r a l i z a t i o n i s confined to f r a c t u r e s i n these dykes which apparently o f f e r e d s a t i s f a c t o r y zones of weakness 48 M c K i n i s t r y has found evidence o f four overlapping impulse periods o f m i n e r a l i z a t i o n s 1» Quartz, a r s e n o p y r i t e , p y r r h o t i t e and s p h a l e r i t e , i n order of de p o s i t i o n . 2. Galena and t e t r a h e d r i t e , quartz, p y r i t e , and chalco-p y r i t e. 3 ' P y r a r g y r i t e , c h a l c o p y r i t e and quartz, followed by carbonates, c h a l c o p y r i t e , b o r n i t e , a r s e n o p y r i t e , p y r a r g y r i t e and p r o u s t i t e . 4 . Carbonates, quartz and chalcedony. Argent i t e appears as a sooty substance where galena i s weathering, and as v e i n l e t s i n the p y r a r g y r i t e . C h a l c o c i t and c o v e l l i t e are found around the c h a l c o p y r i t e i n the weathered zone. The p y r a r g y r i t e i s considered to be primary because some o f the galena i s younger. Mc K i n i s t r y f i n d s that two periods of m i n e r a l i z a t i o n are d e f i n i t e l y i n d i c a t e d by t e x t u r a l r e l a t i o n s h i p s . He suggests that the telescoping of the high and low temperature minerals may have been due to the f a c t that the dykes were s t i l l warm when the e a r l y minerals were deposited and much -16-cooler at the time o f the l a t e r m i n e r a l i z a t i o n . S i l v e r values are l a r g e l y i n the t e t r a h e d r i t e and i n the galena hut no assays of e i t h e r of these minerals are a v a i l a b l e 0 • Unuk Ri v e r Area.- A few small samples o f ore from t h i s d i s t r i c t were studied i n p o l i s h e d s e c t i o n by the w r i t e r . Assay values o f t h i s ore are reported to run approximately $40 i n s i l v e r to the ton. Ho information was sent i n as regards the host rocks or type of deposit so the f o l l o w i n g summary i s based e n t i r e l y on laboratory examination. Megascopically the ore appears as t y p i c a l coarsely banded f i l l i n g of a v e i n . The quartz shows marked 'comb-s t r u c t u r e 5 of almost p a r a l l e l needles but without int e r v e n i n g vugs. The c h i e f m e t a l l i c s are p y r i t e and s p h a l e r i t e , which together with quartz make up almost a l l o f the specimens . examined. One noteworthy feature of the ore i s the colour and l u s t r e of the s p h a l e r i t e , which i n the hand specimen c l o s e l y resemble those of t e t r a h e d r i t e . Examination i n p o l i s h e d s e c t i o n showed the presence of an appreciable quantity of galena, and i n the s p h a l e r i t e , f i n e t h i n veins of a mineral which may be t e t r a h e d r i t e , but which due to i t s f i n e dissemination was impossible to i d e n t i f y . The paragenesis o f t h i s ore i s rather d i f f i c u l t to determine * The order of d e p o s i t i o n appears to have been: p y r i t e , quartz, s p h a l e r i t e , galena and t e t r a h e d r i t e . The poss-i b i l i t y of a second generation of p y r i t e i s i n d i c a t e d by long, very t h i n v e i n l e t s o f p y r i t e i n the s p h a l e r i t e . Under high power i t can be seen that these v e i n l e t s are composed of f i n e -17-euhedral g r a i n s . Normally the p y r i t e i s ranch shattered and cemented by the other minerals,. The w r i t e r was at a l o s s to account f o r the s i l v e r values reported as the t h i n v e i n l e t s of t e t r a h e d r i t e appeared i n s u f f i c i e n t to account f o r i t . Dr. Dolmage-^2 confirmed t h i s opinion and stated that these v e i n l e t s , even i f they consisted of native s i l v e r would not account f o r the s i l v e r content o f the ore* Upon examination of sections i n which galena was more abundant i t was found that there were i n c l u s i o n s o f another mineral w i t h i n the galena. These i n c l u s i o n s ranged up to 1 mm. i n s i z e and were thought to be argentite<> A colour d i f f e r e n c e was p e r c e p t i b l e between them and the f i n e v e i n l e t s . These t h i n v e i n l e t s , which probably account f o r the unusual l u s t r e of the s p h a l e r i t e , may be responsible also f o r some of the s i l v e r content. Lack of m a t e r i a l made assays of the s p h a l e r i t e and of the galena impossible, but such assays should provide i n t e r e s t i n g r e s u l t s . The Premier Mine.- Since 1921 t h i s mine has been one o f the most consistent and l a r g e s t producers of g o l d , s i l v e r and lead i n the province. S i t u a t e d on the eastern contact o f the b a t h o l i t h , i t i s nevertheless fortunate i n being close t o tidewater. Host rocks of the v i c i n i t y are various species of greenstone, a l l of J u r a s s i c age, intruded by stoekworks and s i l l s of g r a n o d i o r i t e porphyry. The depo s i t s are of .vein and replacement types and are found i n f r a c t u r e zones which are p a r t i c u l a r l y w e l l developed along the tuff-porphyry contacts. M i n e r a l i z a t i o n -18-i s also more intense i n the permeable porphyry of the upper l e v e l s , but f a l l s o f f where, i t i s found i n the l e s s permeable t u f f s of the lower l e v e l s . The ore i n the upper l e v e l s shows a wide d i v e r s i t y of minerals, but 700 feet lower only p y r i t e , s p h a l e r i t e , quartz and some galena remain. M e t a l l i c minerals reported by Burton"'*0 a r e . p y r i t e , s p h a l e r i t e , galena, t e t r a h e d r i t e , chalco-p y r i t e , eleetruin, argent i t e , poly b a s i t e , p y r a r g y r i t e , native s i l v e r and one or two other minerals which were too small to i d e n t i f y . He f i n d s evidence of two periods o f m i n e r a l i z a t i o n , the e a r l i e r one producing quartz, a d u l a r i a and p y r i t e , the second producing the remaining minerals i n successive but con-tinuous periods. The order of d e p o s i t i o n i s quartz, a d u l a r i a , p y r i t e , s p h a l e r i t e , galena , t e t r a h e d r i t e , c h a l c o p y r i t e , e l e c -trum, a r g e n t i t e and the s i l v e r s u l p h o - s a l t s . Burton has been able to show that there i s d e f i n i t e v e r t i c a l zoning of t e t r a h e d r i t e , electrum and the sulpho s a l t s . Tetrahedrite has seldom been recognized below the 650 l e v e l . I t i s quite commonly found as i n c l u s i o n s i n galena, but where i t i s massive, i t i s replaced by p o l y b a s i t e and native s i l v e r . Eleetrum i s more widely disseminated i n the ore but decreases sharply at depth. I t i s commonly found as rounded grains r e p l a c i n g galena, This i s a d i s t i n c t mineral and never grades i n t o n a t i v e s i l v e r ; as such Xindgren considers i t t o be c h a r a c t e r i s t i c of the epithermal zone. Po l y b a s i t e i s found both as a supergene and as a hypogene mineral but more commonly as the former. Where i t i s -19-hypogene i t i s found away from p o s s i b l e channels of downward c i r c u l a t i n g ground waters. There i t i s u s u a l l y intergrown with galena or p y r a r g y r i t e , but w i t h native s i l v e r n o t i c e a b l y absento Supergene p o l y b a s i t e i s commonly veined by n a t i v e 8ilver» P y r a r g y r i t e i s always hypogene and contemporary with galenas I t i s never found containing n a t i v e silver« Native s i l v e r i s considered by Burton and by most i n v e s t i g a t o r s of t h i s property to i n d i c a t e supergene e n r i c h -ment . However Dolmage has shown that i t i s primary i n the corresponding l e v e l s of the adjacent B 0C 0 S i l v e r property* The w r i t e r i n examining ore from the 200 l e v e l at Premier found native s i l v e r , d i s t i n g u i s h e d from electrum by etch t e s t s , intergrown with galena i n a manner suggesting hypogene o r i g i n . This a s s o c i a t i o n i s i l l u s t r a t e d i n f i g u r e (.1) . A r g e n t i t e , according to Burton, i s u s u a l l y hypogene, commonly r e p l a c i n g most of the other sulphides. I t weathers e a s i l y to a blade mass veined by n a t i v e s i l v e r . On the evidence of the electrum, a d u l a r i a , the 52 s u l p h o - s a l t s , which he quotes Ravicz as a s c r i b i n g to cool s o l u t i o n s s and f i n a l l y on evidence of the v e r t i c a l zoning, Burton concludes that the Premier i s , at l e a s t i n p a r t , an epithermal deposit® I t seems probable, however, that i t might more j u s t l y be described as leptothermal i n view of the r a p i d e x t i n c t i o n of low temperature minerals w i t h depth. C e r t a i n l y i t appears to be nearer the epithermal range than any other deposit found i n a s s o c i a t i o n w i t h the J u r a s s i c i n t r u s i v e s of the Coast Range bat h o l i t h o -19a F i g . ( 2 ) . F i g . O ) . Premier - P y r i t e & Ruby S i l v e r . Premier - Ruby S i l v e r i n Quartz (Thin S e c t i o n ) . Mag. x 130 Mag. x 130 - 2 0 -B® 0. S i l v e r * - This property i s o f i n t e r e s t due to i t s d i s t i n c t l y d i f f e r e n t m i n e r a l i z a t i o n to that o f Premier, despite the immediate proximity o f the two propertiesc M e t a l l i c minerals i n order of abundance are p y r i t e , galena, s p h a l e r i t e , n a t i v e s i l v e r ana. argent i t e (?) . Although 25 the specimens studied by Dolmage ^ came from the same horizon as the r i c h Premier ore, no t e t r a h e d r i t e , p o l y b a s i t e , stephan-i t e , c h a l c o p y r i t e nor ruby s i l v e r was recognized. The most common occurrence of a l l other minerals i n t h i s ore i s as i n c l u s i o n s i n the p y r i t e . Dolmage i n f e r s therefore that the native s i l v e r i s d e f i n i t e l y primary. This f a c t together w i t h the absence of'secondary copper minerals there leads him t o the conclusion that supergene enrichment at Premier i s not as important as i t i s g e n e r a l l y thought to be. This conclusion as p r e v i o u s l y noted was substantiated by evidence found by the w r i t e r i n examining Premier ore. The Toric Mine.- S i t u a t e d on the K i t s a u l t R i v e r 17 miles from A l i c e arm, t h i s property i s reached by the tramway to the D o l l y Varden mine. The deposits were formed by f i l l i n g and replacement i n a sheared zone of massive b r e c c i a and f e l s i t e . 40 Hanson found that the r i c h e s t shoot was on the hanging w a l l , and has produced JO ,000 oz. of s i l v e r and 29,000 pounds of lead from 1900 tons o f ore. The ore i s a mixture o f b a r i t e , jasper, hematite, quartz and ankerite w i t h f i n e l y disseminated sulphides. The extremely f i n e g r a i n of these met a l l i e s renders them very d i f f i c u l t to determine. In order of abundance those recognized 20a F i g . ( 4 ) . Toric -Dissemination of M e t a l l i c M i n e r a l s . Mag. x 1200 F i g . ( 5 ) . Toric -M e t a l l i e s i n Quartz and B a r i t e (Thin Section;. Mag. x 200 -21-by the w r i t e r were hematite, galena, p y r i t e , . s p h a l e r i t e , n a t i v e s i l v e r and a "bluish-grey m i n e r a l , thought t o be p y r a r g y r i t e . In a p r i v a t e communication to the w r i t e r , Mr. Brennan stated that the s i l v e r values appeared to be most c l o s e l y associated wi th the b a r i t e but that where galena was abundant s i l v e r values were d i s a p p o i n t i n g . This was evident on examin-a t i o n of the specimens, because those w i t h the highest values i n s i l v e r contained much l e s s galena than those showing lower s i l v e r assays. Most o f the work was done on the specimens which gave the highest values i n s i l v e r , about 31 oz. to the ton. I t was found i n t h i n s e c t i o n t h a t the m e t a l l i c s tended to be concentrated where quartz appeared to form veins i n the b a r i t e , but much of the m e t a l l i c content was found i n the b a r i t e . The most s t r i k i n g f a c t , however, was the apparent r e s t r i c t i o n of the native s i l v e r to the b a r i t e . Hanson reports f i n d i n g the native s i l v e r as occurring as f l a k e s f i l l i n g small cracks and considers that i t i s secondary. This conclusion was substan-t i a t e d by evidence found by the w r i t e r . I t seems probable therefore that the supergene s i l v e r was p r e c i p i t a t e d by the b a r i t e along i t s cleavage planes« This i n turn would e x p l a i n the a s s o c i a t i o n o f the s i l v e r with b a r i t e , and i n contrast the low values where the m e t a l l i c s are more abundant. Several other minerals i n c l u d i n g a r g e n t i t e , proust-i t e and p o l y b a s i t e were reported by Mr. Brennan, but specimens containing them had not a r r i v e d at the time o f w r i t ing* Hazelton D i s t r i c t * - M i neral deposits o f t h i s area are -22-d i s t r i b u t e d about and w i t h i n s a t e l l i t e s of the Coast Range b a t h o l i t h e As a r u l e these deposits show ex c e l l e n t l o c a l zoning so that the s i l v e r deposits tend to be more widely scattered than those of metals deposited at higher tempera-tures* The deposits are of both wet and dry types but a l l of those developed as yet have proved to be too small o r too i r r e g u l a r t o be of economic importance. In many prope r t i e s e x c e p t i o n a l l y high values have been obtained but the quantity of ore i s smalls M i n e r a l i z a t i o n v a r i e s considerably but galena, sphal-e r i t e and t e t r a h e d r i t e are almost always present. S i l v e r values where they are high u s u a l l y i n d i c a t e the presence of the s i l v e r m i n e r a l s 5 but galena and t e t r a h e d r i t e are always argentiferous. V i c t o r i a - E u r e k a Mine.- This property i s one o f the few s i l v e r mines which have produced i n southwestern B r i t i s h Columbia* The mine was discovered about 1870 and some of the ore was so r i c h that i t could be packed by indians to Yale and shipped to smelters at San Francisco. The deposits are found i n a f r a c t u r e zone i n J u r a s s i c granodiorite and i n a small cap of o v e r l y i n g sediments«, Cairnes ' considers that they were associated w i t h l a t e Cre-taceous or Miocene intrusives= Tetrahedrite and the s i l v e r s u lpho-salts are the important s i l v e r - b e a r i n g minerals. Pyr-i t e , galena and s p h a l e r i t e are also present, the galena ca r r y i n g some s i l v e r . Deposits across Southern B r i t i s h Columbia,, Under t h i s heading the majority o f the province's s i l v e r — p r o d u c i n g p r o p e r t i e s may he l i s t e d * They are scattered i n sediments intruded "by the numerous rather discontinuous b a t h o l i t h s east to Kootenay lake® S i l v e r i s associated v a r i o u s l y with lead and z i n c , also i n 'dry T ores w i t h l i t t l e base metal content and i n one instance with copper* As i t would be d i f f i c u l t to f i n d a s u i t a b l e basis f o r f u r t h e r sub-d i v i s i o n the pr o p e r t i e s w i l l be discussed i n t h e i r approximate order from west to east _ The Horn S i l v e r Mine a - This property, s i t u a t e d southeast of Hedley, c o n s i s t s of one long v e i n . The f i s s u r e i s found p r i n c i p a l l y i n an a l k a l i syenite but continues i n t o hornblend-i t e . The w a l l s are very d i s t i n c t with very minor a l t e r a t i o n . The f i s s u r e i s f i l l e d wi th quartz and broken rock with the sulphides disseminated through them. M e t a l l i c miner-a l s i n the order of t h e i r d e p o s i t i o n are p y r i t e , s p h a l e r i t e and c h a l c o p y r i t e ; galena and t e t r a h e d r i t e ( ? ) ; hematite, 4 native s i l v e r and c a l c i t e . Bostock notes that a r g e n t i t e and py r a r g y r i t e are also reported. The s p h a l e r i t e i s very dark, suggesting a high i r o n content. Quartz i s rather coarsely c r y s t a l l i n e and vuggy. n a t i v e s i l v e r i s found i n f l a k e s among the other minerals, and i s p a r t i c u l a r l y a ssociated with p y r i t e * I t would thus appear to be of supergene o r i g i n . This deposit might be classed as belonging to the T d r y T type of ore as galena and s p h a l e r i t e are not found i n s o l i d bands. Stump l a k e . - These deposits are found about t h i r t y miles -24-south of Kamloops« Their t y p i c a l occurrence i s as quartz r e i n s i n a dark green diabase p o r p h y r i t e . They appear to have o r i g i n a t e d as the l a s t phases of i n t r u s i o n of an area of Juras-s i c g r a n i t e t o the west. ' The deposits are p r i m a r i l y quartz f i l l e d f i s s u r e s with f a i r l y good sulphide m i n e r a l i z a t i o n . Minerals recognized i n the order o f t h e i r d e p o s i t i o n are, quartz, p y r i t e , sphaler-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 , galena and c a l c i t e . Jameson-i t e i s also o c c a s i o n a l l y present. S i l v e r values run up to |400 to the ton. In the absence of true s i l v e r minerals, i t seems probable t h a t the galena,, and p a r t i c u l a r l y the t e t r a -h e d r i t e , must be h i g h l y a r g e n t i f e r o u s . Camsell 1^ states i n conclusion, "The veins of t h i s d i s t r i c t are of a type that have been formed at an intermediate depth by ascending thermal waters » " Copper Mountain.- As the name imp l i e s t h i s property was p r i m a r i l y operated f o r copper. During i t s period o f produc-t i o n , however, about 120 ,000 ozs. of s i l v e r were recovered annually, so that i t was one of the l a r g e r producers o f t h i s metal c The deposits are of contaot-metamorphic type, l y i n g p a r t l y i n the parent gabbro but more l a r g e l y i n the o v e r l y i n g v o l c a n i c s . The l a t t e r have been so metamorphosed as to resemble c l o s e l y the gabbro i t s e l f . Primary m e t a l l i c minerals are b o r n i t e , c h a l c o p y r i t e , p y r i t e , magnetite, c h a l c o c i t e , galena and s p h a l e r i t e . Small amounts of native s i l v e r and electrum were also noted, but - 2 5 -these together with the galena were i n s u f f i c i e n t i n Dolmage ?s opinion to account f o r the s i l v e r content of the ore. In t h i s regard Dolmage considers that s i l v e r must occur at Copper mountain and i n other large copper deposits of B, C. i n some i n v i s i b l e form, probably i n s o l i d s o l u t i o n , i n c h a l c o p y r i t e or one of the other m e t a l l i c minerals* This o p i n i o n i s o f i n t e r e s t as l i t t l e has been w r i t t e n about the occurrence of s i l v e r i n the copper deposits of the province. The Beaverdell Camp.- S i l v e r producing p r o p e r t i e s of t h i s camp are a l l concentrated on Wallace mountain. The ore i s very r i c h i n p a r t s but occurs i n narrow veins and shear zones, so that l a r g e production i s d i f f i c u l t . S i l v e r and a l i t t l e l ead are the two metals recovered but l e a d i s l i t t l e more than a by-product. The deposits are founci as shear zones, narrow veins and m i n e r a l i z e d f a u l t s , almost e x c l u s i v e l y i n quartz d i o r i t e of the Westkettle b a t h o l i t h . The Wallace formation was not 5 3 competent to maintain f i s s u r e s , and, according to Reineeke , formed a b a r r i e r impervious to the r i s i n g m i n e r a l i z i n g s o l u -t i o n s c As a r e s u l t t e l e s c o p i n g of the ore zones has occurred w i t h i n a narrow v e r t i c a l range of 1 0 0 0 f e e t . Both Reineeke and M c K i n i s t r y ^ b e l i e v e that the deposits at Carmi represent the s i l v e r - b e a r i n g ores o f Wallace mountain at depth. I f t h i s i s t r u e , the deposits of Beaverdell present a most i n t e r e s t i n g example of the changes i n m i n e r a l i z a t i o n o f argentiferous ores at depth. For t h i s reason a rough o u t l i n e o f minerals recog-nized at Carmi i s added. - 2 6 -M i lie r a 1 i z a t i o n of the S a l l y mine shows evidence of three d i s t i n c t impulse periods. M c K i n i s t r y has found that the main shear zones are min e r a l i z e d w i t h t y p i c a l mesothermal minerals* These ore "bodies have been cut by l a t e r f a u l t s which are themselves m i n e r a l i z e d w i t h ore which i s more char-a c t e r i s t i c o f the epithermal zone* The f o l l o w i n g l i s t of minerals in. the order of d e p o s i t i o n i s subdivided i n t o miner-a l s deposited i n the three periods. 1. Quartz, p y r i t e , a r s e n o p y r i t e , s p h a l e r i t e and galena. 2 * Quartz, p y r i t e , galena, t e t r a h e d r i t e , p y r a r g y r i t e . 3. Quartz, c a l c i t e , f l u o r i t e , p y r i t e , c h a l c o p y r i t e , poly-b a s i t e , a r g e n t i t e and na t i v e s i l v e r . Of these the f i r s t two are associated but the t h i r d type i s more c h a r a c t e r i s t i c o f the mi n e r a l i z e d f a u l t s . McKin-i s t r y b e l i e v e s that n a t i v e s i l v e r i s the only important super-gene mineral. In the Wellington mine 600 feet lower the sulpho-s a l t s are rat h e r sparse and s p h a l e r i t e i s more abundant 0 At Carmi, no sulpho-salts have been recognized, galena i s subor-dinate to s p h a l e r i t e and some molybdenite and ankerite have been founds S i l v e r values are very much lower and gold values are higher« Reinecke considers that the ores of Carmi are c h a r a c t e r i s t i c of great to moderate depth o f depositi o n * I t seems apparent then, that the v i c i n i t y of Beaverdell e x h i b i t s i n 1000 feet v e r t i c a l l y the range of metallogenetic zones from the epithermal down to the upper hypothermal. S i l v e r values i n the S a l l y mine occur p r i n c i p a l l y i n true s i l v e r minerals. The t e t r a h e d r i t e i s h i g h l y - 2 7 -a r g e n t i f e r o u s ^ 1 ) - ^ and may be more c o r r e c t l y termed f r e i b e r g -i t e . Much of the p y r a r g y r i t e i s c l o s e l y v e i n i n g the galena, and much of that mineral and a r g e n t i t e were found by the w r i t e r when etching the galena. As was p r e v i o u s l y no ted t h i s mine i s p r i m a r i l y a producer of s i l v e r , but i t would be i n t e r e s t i n g to f i n d whether the ore mineral changes to lead and f i n a l l y to gold at depth. A l l c o Mining Company.- The holdings of t h i s company are s t i l l i n the course of pre l i m i n a r y development. The property l i e s at the headwaters of S i l v e r Creek, 20 miles east o f Revelstoke. Country rock c o n s i s t s o f metamorphosed limestone and a black m e t a r g i l l i t e . These rocks form part o f Daly's B e I t i a n s e r i e s . Daly J had placed the only igneous i n t r u s i v e s of the area as p r e - B e l t i a n i n age , but on evidence of post-39 B e l t i a n deposits such as t h i s Gunning suggests that they may be J u r a s s i c . The deposits are found p a r t l y as m i n e r a l i z e d shear zones, and, i n the limestone, p a r t l y as replacements. Several d i s t i n c t ' v e i n s ? have been uncovered on the property which show signs o f leading to one c e n t r a l hub o f quartz. In only one v e i n however i s quartz found and i t contains much t e t r a -h e d r i t e and but l i t t l e galena or s p h a l e r i t e . Another v e i n i s almost s o l i d s p h a l e r i t e with p y r i t e and galena; the remaining veins are predominantly m i n e r a l i z e d by l e a d . Minerals that have been determined by the w r i t e r are quartz, p y r i t e , s p h a l e r i t e , t e t r a h e d r i t e , galena and Jameson-I t e ( ? ) . The jamesonite was recognized only i n the quartz v e i n TO d.S. l o r d . — — — - 2 8 -i t s determination was only p a r t i a l l y s a t i s f a c t o r y as i t occurred i n q u a n t i t i e s too small f o r the technique of micro-chemical a n a l y s i s . I t s r e l a t i o n s h i p to galena and tetrahed-r i t e i s shown i n f i g u r e (>)• Minerals were deposited i n the above order i n a l l veins on the property, although the f u l l l i s t was found only i n the quartz v e i n . Quartz appeared i n a l l the veins but i n very subordinate amount, u s u a l l y as euhedral c r y s t a l s . Much of the ore was h i g h l y o x i d i z e d so that i t was very d i f f i c u l t to pick clean specimens of the v a r i o u s minerals f o r assay. The t e t r a h e d r i t e i s h i g h l y a r g e n t i f e r o u s and c a r r i e s over 1000 oz. of s i l v e r to the ton. The galena was found to have numerous small i n c l u s i o n s of t e t r a h e d r i t e and another whiter mineral p o s s i b l y a r g e n t i t e . A picked and f a i r -l y clean sample o f t h i s galena assayed 95 oz. of s i l v e r per ton. S p h a l e r i t e was brown, i n d i c a t i n g low i r o n content, and ran only -§- oz. of s i l v e r to the ton. In the h i g h l y o x i d i z e d ore bands o f a brown earthy substance w i t h a tendency towards micaceous habit were n o t i c e d . Under the petrographic micros-cope t h i s m a t e r i a l was found to be p r i n c i p a l l y l i m o n i t e but-several hexagonal yellow prisms were noted. JTo opaque minerals suggestive o f m e t a l l i c habit were observed. Assays of t h i s m a t e r i a l averaged 18 oz. of s i l v e r to the ton. This would appear t o suggest the presence of some s i l v e r as the sulphate argento-_arosite, A d e f i n i t e sulphate t e s t was obtained but may have been due to the presence of a n g l e s i t e which was d e f i n i t e l y recognized. The s i l v e r may have been present as sooty a r g e n t i t e but was not recognized as such - 2 8 a -F i g . ( 6 ) . A l l c o -Jameson!te between Galena and Tetrahedrite. Mag. x 250 F i g . ( 7 ) . A l l c o - Weathered Galena, and C o v e l l i t e remaining i n place of Tetrahedrite. Mag. x 130 F i g . ( 8 ) . A l l c o - Inclus i o n s i n etched Galena. Mag. x 500 ~29~ under the microscopes This deposit appears to he p r i m a r i l y important f o r i t s l e a d content, I t i s p o s s i b l e also that z i n c may be pro-duced as one v e i n c a r r i e s much s p h a l e r i t e . S i l v e r assays on the surface quite commonly run over 100 oz. to the ton but i t i s expected that they w i l l f a l l o f f with depth. Figure (8) shows i n c l u s i o n s i n galena which appear to be o r i e n t e d along the cleavage planes and may be secondary* In the quartz v e i n , however, there i s no evidence of enrichment and therefore the values may be expected to continue at depth. Snowflake Mine.- This property i s also on S i l v e r creek a few miles east of A l l c o . I t is- p a r t i c u l a r l y i n t e r e s t i n g be-cause t i n and s i l v e r are found i n the same deposit. Although t h i s a s s o c i a t i o n i s w e l l known i n B o l i v i a and Tasmania, the Snowflake i s the only such occurrence known i n B. 0 . The deposit occurs as a quartz f i l l e d shear zone i n B e l t i a n sediments. Sulphides are quite h e a v i l y scattered through the quartz. The quartz i s coarse and vuggy and the w a l l rocks but l i t t l e a l t e r e d , suggestive of low temperature d e p o s i t i o n . M e t a l l i c minerals recognized are p y r i t e , s p h a l e r i t e , galena, s t a n n i t e , c h a l c o p y r i t e , t e t r a h e d r i t e , p y r a r g y r i t e , n a t i v e s i l v e r and wolframite. Gangue minerals are quartz and s c h e e l i t e . Gunning ^ could f i n d no evidence of a break i n mi n e r a l ! z a t i o n , so that the a s s o c i a t i o n of minerals of both high and low temperatures of de p o s i t i o n i s d i f f i c u l t to explain- S i m i l a r deposits i n Tasmania are found i n the lower ~J'0-temperature b e l t , but m i n e r a l i z a t i o n seems to f i t Buddington's xenothermal zone most s a t i s f a c t o r i l y . The r i c h e s t shoot of t h i s deposit assayed, s i l v e r 43..5 oz,, lead 1 *5%, zinc G%, copper 6..5fc., t i n G%. Pure samples of s t a n n i t e were found t o contain no s i l v e r . The important argentiferous minerals are t e t r a h e d r i t e , galena and p y r a r g y r i t e * P y r a r g y r i t e i s more abundant i n the upper l e v e l s but i s d e f i n i t e l y primary. The Slocan Area,- This mining camp i s c e r t a i n l y the best known s i l v e r - p r o d u c i n g area i n the provinces, As such, i t merits some general d e s c r i p t i o n i n a d d i t i o n to d i s c u s s i o n of the Mammoth mine, whose ore has been examined by the w r i t e r . The large majority of producing p r o p e r t i e s i n the Slocan occur i n a large bay of sediments o f the Slocan s e r i e s w i t h i n i n t r u s i v e s of the West Kootenay b a t h o l i t h . A few p r o p e r t i e s are found i n the b a t h o l i t h i c rocks themselves but these tend to be s m a l l , and although r i c h i n s i l v e r are low i n lead and z i n c . The b a t h o l i t h dips below the Slocan sediments at a low angle; numerous p l u t o n i c stocks are found throughout the area. As a r e s u l t the sediments form only a t h i n l a y e r , but f r a c t u r e s may be continuous into the i n t r u s i v e rocks. Despite the proximity of these i n t r u s i v e s to the ore d e p o s i t s , very s i m i l a r m i n e r a l i z a t i o n i s found over a v e r t i c a l range of .5000 feet w i t h i n a very r e s t r i c t e d area. I t might be expected then that deposit s would tend to be uniform over that range, Cairnes""*" found, however, that i n any deposit, the shear zone tended to be continuous but the m i n e r a l i z e d shoots -31-were only discontinuous lenses. Although several instances are known where more than one lense of ore has been found i n any one shear zone, expense of prospecting u s u a l l y p r o h i b i t s development below the known ore shoot* Uglow studied these deposits ' i n an i n v e s t i g a t i o n of the o r i g i n of the gn e i s s o i d galena which i s a c h a r a c t e r i s t i c feature of those r i c h i n lead*, He concluded that the ore was o r i g i n a l l y deposited i n a normal shear zone. The deposits were then disrupted by l a t e r movements so that the o r i g i n a l band of ore was broken into lenses separated by areas o f gouge and broken rock* 1 Both Bateman and Oairnes f i n d that argentiferous deposits of the area f a l l n a t u r a l l y into three groups on the basis of t h e i r mineral content. These groups cannot be sharp-l y d i s t i n g u i s h e d one from another but form a continuous s e r i e s . 1, The dry type of ore i s composed almost e n t i r e l y of quartz. I t contains small amounts of r i c h s i l v e r minerals and some gold but p r a c t i c a l l y no lead or z i n c . 2, This group contains s i l v e r as the most important mineral w i t h values also i n lead and z i n c . The quartz gangue occupies most of the deposit but contains important amounts of lead and z i n c . 3, This i s the 'wet 1 type of s i l v e r - l e a d - z i n c ore, with abundant base metals and l i t t l e quartz. S i l v e r minerals are not conspicuous, the s i l v e r values being associated with galena and to a minor extent with s p h a l e r i t e . The s i l v e r - l e a d ore grades i n depth to predominant zinc ore c a r r y i n g l i t t l e s i l v e r and f i n a l l y to s l i g h t l y a u riferous p y r i t e . - 3 2 -Gairnes has found that these three types grade i n t o each other. The dry ore was deposited f u r t h e s t from the parent magma, the wet ore nearer to i t . The p y r i t i f e r o u s lodes appear to he t y p i c a l of the highest temperature of dep o s i t i o n of those outcropping i n the d i s t r i c t . In an imposing l i s t o f minerals recognized i n the d i s t r i c t Cairnes regards the f o l l o w i n g as "being d e f i n i t e l y a r g e n t i f e r o u s : 1. A r g e n t i t e - commonly found i n small amount, may be both hypogene and supergene. 2. Galena - i n v a r i a b l y c a r r i e s s i l v e r . 3® Tetrahedrite - always a r g e n t i f e r o u s , c a r r i e s up to 2000 oz. of s i l v e r to the ton. 4. P o l y b a s i t e - r a r e , i n small q u a n t i t i e s . j>« P y r a r g y r i t e - f a i r l y common, u s u a l l y supergene. 6. Sp h a l e r i t e - u s u a l l y low i n s i l v e r , but i n one instance c a r r i e d 3*8 oz. to the ton, and 0.07^ copper. 7• Native S i l v e r - very widespread, u s u a l l y supergene, mostly i n dry ores. 8. Stephanite - r a r e , i n small q u a n t i t i e s . 9 • C e r a r g y r i t e - i n one mine, as rods and pl a t e s i n s p h a l e r i t e . 12 The Mammoth Mine.- This deposit i s of the 'wet' type, with galena s l i g h t l y predominant over s p h a l e r i t e . The proper-t y l i e s i n the upper basin of A r i s o n creek north of S i l v e r t o n creek. The lode i s a mineralized shear zone 30 to 40 feet - 3 3 -wide, which has been traced f o r n e a r l y a m i l e . Workings have opened up the ore body over a v e r t i c a l range of n e a r l y 600 feet which corresponds to about 800 along the d i p . The deposit c o n s i s t s of a f i l l i n g of quartz and sulphides cementing the mass of crushed and broken rock with which the f i s s u r e i s f i l l e d . There i s but l i t t l e change i n the tenor of the ore at depth as compared wi t h no. 3 l e v e l . Galena i s more abun-dant i n the upper l e v e l s but s p h a l e r i t e i s s l i g h t l y predominant at depth. P y r r h o t i t e was recognized i n c a l c i t e gangue from the seventh (bottom) l e v e l . ( F i g . 11) . Minerals recognized by the w r i t e r i n order of abundance are , quartz, galena s s p h a l e r i t e , c a l c i t e , a n k e r i t e , t e t r a h e d r i t e , p y r i t e , c h a l c o p y r i t e , p y r r h o t i t e and a r g e n t i t e ( ? ) . I t was impossible to obtain the r e l a t i o n s h i p of a l l these minerals to each other but the apparent order of d e p o s i t i o n was quartz, p y r i t e , ( p y r r h o t i t e ) , s p h a l e r i t e , t e t r a h e d r i t e ; galena, c h a l c o p y r i t e and argent i t e ( ? ) ; ( a n k e r i t e ) and c a l c i t e . This l i s t of minerals might be s l i g h t l y enlarged i f ore from the weathered zone had been examined, but the a v a i l a b l e samples were a l l unaltered. Nothing from above the t h i r d l e v e l was a v a i l a b l e f o r inspect i o n . S i l v e r values v/ere shown by assay to be almost r e s t r i c t e d to the galena and t e t r a h e d r i t e . S p h a l e r i t e con-t a i n e d only a trace of s i l v e r , i n a picked, almost pure sample. Galena was found to contain large i n c l u s i o n s of t e t r a h e d r i t e and smaller but more numerous blebs of a r g e n t i t e ( ? ) . A n o t i c e -able decrease i n the s i z e and quantity o f these i n c l u s i o n s was F i g . ( 9 ) . Mammoth -Incl u s i o n s i n etched. Galena. ( 3 0 2 Stope} Mag. x 500 F i g . ( 1 0 ) . Mammoth - In c l u s i o n s i n etched Galena. ( 7 0 1 Stope) Mag. x 500 F i g . ( 1 1 ) . Mammoth - P y r r h o t i t e i n C a l c i t e , ( 7 0 1 Stope) Mag. x 130 _ 5 4 -found i n galena from the seventh l e v e l . Tetrahedrite was i n v a r i a b l y veined by c h a l c o p y r i t e so that i t was impossible to pick a pure product of the l a t t e r . Assay r e s u l t s from picked products were as f o l l o w s : 1. Gneissic s t e e l galena - elev. .5600 - 125.0 oz/ton. 2. F o l i a t e d cube galena - " 5210 - 8 3 . 4 4 " " 3* Clean cube galena - " 5600 - 3 3 . 4 4 " " 4 . Impure t e t r a h e d r i t e - " 5600 -1273.0 " " 5» Clean s p h a l e r i t e • - " 5030 - . 0 . 4 " " A s e c t i o n made of m a t e r i a l from which the clean cube galena had been picked, showed n o t i c e a b l y fewer and smaller i n c l u s i o n s than were found i n the ma j o r i t y of specimens of that mineral. 55 B l u e b e l l Lode.- This large replacement deposit has been the s i t e of three mines, the B l u e b e l l , Kootenay Chief and Cumfort p r o p e r t i e s . I t i s much the most important deposit of the Ainsworth camp. The deposit was formed by replacement of a limestone band i n B e l t i a n sediments. M i n e r a l i z i n g s o l u t i o n s were blocked by an impervious pegmatite dyke which was intruded between the limestone and the o v e r l y i n g q u a r t z i t e . As a r e s u l t the s o l u t i o n s were forced into e x i s t i n g open f i s s u r e s i n the limestone, but were l o c a l l y blocked by f i s s u r e s f i l l e d w i t h impermeable gouge. The r e s u l t i n g deposit i s l a r g e l y replacement i n type with concentration of ore along these o r i g i n a l f i s s u r e s . Important metals are s i l v e r and lead with a minor - 3 4 a -F i g . ( 1 2 ) . B l u e b e l l - Etched Galena i n K n e b e l i t e . Mag. x 130 - 3 5 -amouiit of z i n c . Minerals recognized i n the ore are native s i l v e r , n a t i v e copper, galena, marmotite, p y r i t e , p y r r h o t i t e , marcasite, k n e b e l i t e , quartz, f l u o r i t e , c a l c i t e , angle s i t e and some e e r u s i t e . Hypogene m i n e r a l i z a t i o n appears to the w r i t e r to show no evidence of a break i n de p o s i t i o n . Although the ore was mined f o r i t s lead and s i l v e r content, i t s most noticeable feature i s the abundance of i r o n minerals. Of these p y r i t e and p y r r h o t i t e are the most common and represent much the l a r g e s t percentage of m e t a l l i c minerals i n the ore. That o r i g i n a l s o l u t i o n s contained much i r o n i s c l e a r l y shown by the appearance of the ferrous s p h a l e r i t e or marmotite. The ore i s h i g h l y weathered, p a r t i c u l a r l y along channels permeable to c i r c u l a t i o n of surface waters. This o x i d a t i o n i s found i n f i s s u r e s at the bottom of the mine. 500 feet below the surface and 400 feet below the present l e v e l of Kootenay l a k e . This f a c t suggests that at one time the surface of the lake must have been much lower. S i l v e r values are very l a r g e l y associated w i t h galena, but Mr. F o w l e r ^ informed the w r i t e r that s i l v e r values i n the lead coneentrate were higher per u n i t o f lead than i n the run of mine ore. This would suggest that much of the lead was l o s t i n f l o t a t i o n , and also that the lead that was l o s t d i d not carry much s i l v e r . I t seems probable there-fore that the s i l v e r l i b e r a t e d by o x i d a t i o n of the galena must have been l a r g e l y p r e c i p i t a t e d on the. unaltered galena below. Assays c a r r i e d out by C u r r i e ^ , however, tend to ref u t e Mr. Fowler's statement. Assays of picked galena (1J Currie,J.M. Geology ? Rept., U.B.C., 1933» - 3 6 -averaged 84.0% l e a d and 21.65 oz. of s i l v e r . Assays of the ore showed 7.4% l e a d , 29.6% i r o n , 5.3% zinc and 2.8 oz. of s i l v e r per ton. From these f i g u r e s the galena appears to con-t a i n only 70% of the s i l v e r . As a r e s u l t of these c o n f l i c t i n g r e s u l t s i t i s d i f f i c u l t to form an accurate estimation of the true occurr-ence of s i l v e r . I t may be j u s t l y i n f e r r e d , however, that almost a l l of the s i l v e r was o r i g i n a l l y i n the galena. An assay made of a clean marmot i t e product by the w r i t e r showed l e s s than 1 oz. of s i l v e r to the ton. Nelson D i s t r i c t . - Some deposits i n the v i c i n i t y of 45 Nelson, described by Leavy , are of i n t e r e s t i n view of t h e i r mineral a s s o c i a t i o n s , They are f i s s u r e veins i n s c h i s t s , limestone, and g r a n i t i c rocks of the Nelson b a t h o l i t h . M inerals recognized are native g o l d , native s i l v e r , n a t i v e copper, p y r a r g y r i t e , p y r i t e , c h alcopyrite , b o r n i t e , t e t r a h e d r i t e , stromeyerite, molybdenite, galena, s p h a l e r i t e , p y r r h o t i t e , magnetite and secondary copper minerals. The gangue i s l a r g e l y quartz but s c h e e l i t e , garnet, b a r i t e and epidote are also present. Deposits are d i v i d e d i n t o three groups on t h e i r valuable metal content: 1. GoId-Silver. Small quartz veins containing p y r i t e , s c h e e l i t e , c h a l c o p y r i t e , s p h a l e r i t e and galena. Deposits i n -d i c a t i v e of high temperature and s i l v e r values are low. 2. Copper-Gold-Silver. Chalcopyrite and weathered copper minerals are found i n gangue of quartz and c a l c i t e . No galena ~37~ or s p h a l e r i t e i s mentioned. Assays show 5.5% copper, 0.21 oz. g o l d , and 2.5 oz. of s i l v e r . The s i l v e r apparently must he associated with the c h a l c o p y r i t e . 3 . Silver-Copper. M e t a l l i c minerals are t e t r a h e d r i t e , p y r a r g y r i t e , stromeyerite, c h a l c o p y r i t e , p y r i t e and galena. S i l v e r values i n t h i s group are higher than i n the preceding ones hut are r a t h e r patchy. The S u l l i v a n Mine.- Very l i t t l e information i s a v a i l a b l e i n regard to t h i s property, despite i t s l a r g e production of s i l v e r , lead and z i n c . The deposit i s p r i m a r i l y a replacement i n q u a r t z i t e of the Aldridge s e r i e s . There i s only one main lode which reaches over s i x t y feet i n thickness i n some p a r t s . M e t a l l i c minerals i n the order of t h e i r abundance are p y r i t e , p y r r h o t i t e , galena, s p h a l e r i t e , jamesonite, and some c h a l c o p y r i t e . Gangue minerals include garnet, pyroxene, b i o t i t e , muscovite, quartz and l i t t l e c a l c i t e . The ore i s g e n e r a l l y rather f i n e - g r a i n e d and shows a tendency towards zoning of minerals (Figure ( 1 3 )). The f a c t that the garnet, d i o p s i d e , a c t i n o l i t e and muscovite are found only i n the ore body and not i n the host rocks i n d i c a t e s that the s o l u t i o n s deposited the ore at high temperature. 57 S c h o f i e l d reports that the ore runs about 4 oz. i n s i l v e r to one per cent l e a d . Mr. F o w l e r ^ informed me that the galena c a r r i e s about 20 oz. of s i l v e r to the ton. As p r e v i o u s l y mentioned l i t t i e information i s a v a i l a b l e but at the time of S c h o f i e l d * s examination S u l l i v a n had produced over one m i l l i o n ounces of s i l v e r and nearly 53 m i l l i o n pounds of -37a-7 quartzites garnet dtqosrfe gaiena.gamet zone zJncb/ende and zone (banded) (banded) garnet 20 feet chert Figure 13. Diagrammatic longitudinal section of Sullivan ore-body. F i g . (13). S u l l i v a n - D i s t r i b u t i o n of minerals i n ore-body ( a f t e r S c h o f i e l d ) . l e a d . Today the S u l l i v a n i s s a id to be the w o r l d ' s l a r g e s t l e a d - z i n c p r o d u c e r . S t® Eugene M i n e . - Th i s p r o p e r t y i s somewhat s i m i l a r t o the S u l l i v a n but i s a t rue v e i n . The d e p o s i t s are t y p i c a l o f s l i g h t l y lower temperature o f d e p o s i t i o n . As might be expected they are somewhat h i g h e r i n s i l v e r per u n i t percentage o f l e a d . Ore bod ie s are found as l a r g e d i s c o n t i n u o u s l e n s e s i n the main shear zone© M e t a l l i c m i n e r a l s are g a l e n a , s p h a l e r i t e , some p y r i t e and pyr rhot i t e , c h a l c o p y r i t e , magnet i t e , jamesonite and n a t i v e s i l v e r . Gangue m i n e r a l s are much the same as at S u l l i v a n . S i l v e r i s a g a i n a s s o c i a t e d p r i m a r i l y w i t h the g a l e n a . Produc-t i o n at the time of S c h o f i e l d ' s v i s i t was 5 i m i l l i o n ounces o f 56 s i l v e r and 225 m i l l i o n pounds o f l e a d * Other A r g e n t i f e r o u s D e p o s i t s . - I f an attempt were made to d e s c r i b e a l l the s i l v e r b e a r i n g mines or mining camps of B r i t i s h Co lumbia , the l i s t would i n c l u d e a very l a r g e m a j o r i t y o f a l l the mines i n the p r o v i n c e . Of these a few are worth b r i e f mention h e r e . The Phoenix camp was operated p r i m a r i l y f o r copper . Go ld and s i l v e r va lue s amounted to o n l y § 1 . 0 0 per t o n and , 46 a c c o r d i n g to l e r o y , were e n t i r e l y a s s o c i a t e d w i t h the c h a l -c o p y r i t e . N e v e r t h e l e s s the d i s t r i c t had produced n e a r l y three m i l l i o n ounces of s i l v e r at the time of h i s examinat ion . The Ross land camp was an important g o l d producer e a r l i e r i n the century but c a r r i e d c o n s i d e r a b l e va lues i n s i l v e r . A s s o c i a t i o n o f the s i l v e r was not e s t a b l i s h e d but the - 2 9 -very general d i s t r i b u t i o n of the metal combined with only occasional appearance of galena point to some other a s s o c i a -t i o n . Rossland's production of s i l v e r t i l l the end of 1905 amounted to 1,700,000 ounces as compared with 1,200,000 ounces 7 of gold. The Monarch mine at F i e l d c a r r i e s only low values i n s i l v e r but i s of i n t e r e s t as being the only mine i n the Rocky mountains. The lardeau d i s t r i c t contains many small mines about which only sketchy information was obtained from EmmonsT p a p e r , ^ Several high assays were quoted which showed that galena and p a r t i c u l a r l y t e t r a h e d r i t e were the important and o f t e n r i c h , s i l v e r - c a r r y i n g minerals. -40-OHAPTER I I I . Introduction,, The general d i s t r i b u t i o n of the various types of argentiferous deposits i n the province corresponds c l o s e l y to that of B r i t i s h Columbia's mining camps. Cursory i n s p e c t i o n of the areas represented by mines discussed i n the previous chapter i n d i c a t e s that s i l v e r i s found wherever mining of any consequence has taken place. The types of deposit i n which s i l v e r i s found show a corresponding d i v e r s i t y o f character. These conclusions might be expected when i t i s remembered that s i l v e r i n B r i t i s h Columbia i s mined p r i m a r i l y as by-product. When s i l v e r deposits are subdivided on the b a s i s o f t h e i r base-metal a s s o c i a t i o n , a f a i r l y r e g u l a r d i s t r i b u t i o n and type of deposit becomes apparent f o r each s u b d i v i s i o n . I t i s necessary therefore i n d i s c u s s i o n of the general g e o l o g i c a l features of s i l v e r , to group the deposits under the heading of the asso-c i a t e d base metal. Geological D i s t r i b u t i o n . There i s no evidence i n t h i s province to suggest an o r i g i n f o r the s i l v e r - b e a r i n g lodes other than the g e n e r a l l y aceepted hypothesis that these deposits were formed by the l a t e s t phases of igneous i n t r u s i o n or e x t r u s i o n . A very large majority of a l l productive lodes i n B r i t i s h Columbia are gene-t i c a l l y associated with the Jurasside r e v o l u t i o n . As a r e s u l t , metallogenetic zoning of deposits l a r g e l y governs ; i t h e i r d i s t r i b u t i o n . Many minor anomalies to t h i s general ! I I -41-system of zoning e x i s t . They are thought by the w r i t e r to represent more than one impulse period o f m i n e r a l i z a t i o n ; e v i -dence of two such periods i s found i n widely scattered areas. In the southern b e l t l a t e r a l zoning i s not so e a s i l y recog-n i z e d , due to the haphazard arrangement of the b a t h o l i t h s . In t h i s b e l t however, v e r t i c a l zoning i s w e l l i l l u s t r a t e d ; examples from Beaverdell and the Slocan have been discussed. a. Copper-Silver Pres.- This type of ore predominates along the western contact of the Coast Range b a t h o l i t h . A l -though the s i l v e r content i s low, development of large ton-nages of ore have rendered i t s production important. In t h i s western b e l t , Anyox, Coast Copper, Texada, B r i t a n n i a and Tyee may be mentioned. Other examples of t h i s a s s o c i a t i o n are found at Telkwa, Copper mountain, and Phoenix. b. Silver-Lead-Zinc Pres.- With t h i s type, f o r purposes of d e s c r i b i n g the d i s t r i b u t i o n , the s o - c a l l e d f d r y ' ores of s i l v e r may be included. In the northern part of the eastern contact of the Coast Range b a t h o l i t h t h i s "white-metal" ore forms much the l a r g e s t part of the m i n e r a l i z a t i o n . South of Hazelton however, gold ore becomes more important. A second large area i n which these metals form the primary products of the mining industry i s i n the Kootenays. Three main camps may be mentioned, Slocan, Ainsworth and, i n the eastern Kootenays, the S u l l i v a n and St. Eugene mines. Other important occur-rences of these metals are found at B e a v e r d e l l , the V i c t o r i a -Eureka property of the Coquihalla and the Monarch mine i n the Rockies. - 4 2 -The one property i n which s i l v e r i s associated with t i n i s found at the same e l e v a t i o n and w i t h i n a few miles of the A l l c o mine i n which s i l v e r i s found with lead and z i n c . P r o p e r t i e s i n which gold i s found and i n which some s i l v e r i s almost always present, are so scattered through the province that no general account of t h e i r d i s t r i b u t i o n need he made here* In general then, s i l v e r i s found associated w i t h cop-per on the western side of the Coast Range b a t h o l i t h , and w i t h lead and zinc along the northeastern c o n t a c t c The copper asso-c i a t i o n i s more important i n the western and southern parts of the southern mineral b e l t o S i l v e r w i t h lead and z i n c i s found most commonly along the northern side and p a r t i c u l a r l y at the eastern end of t h i s b e l t © Types of M i n e r a l Deposits. S i l v e r i n B r i t i s h Columbia i s found i n ore bodies which vary from rather high-temperature metasomatic deposits to the lower temperature f i s s u r e - f i l l e d veins- As with the d i s t r i b u t i o n , the types of argentiferous deposits are best t r e a t e d separately under the headings of t h e i r base-metal a s s o c i a t i o n s . a. Silver-Copper Pres.- In general such deposits are c h a r a c t e r i s t i c a l l y formed close to the parent magma under f a i r -l y high conditions of temperature and pressure. I t i s d i f f i -c u l t to assign these b i g copper deposits to any p a r t i c u l a r type. They appear to be composite of metasomatism, replacement - 4 3 -and f i l l i n g o f sheared and s h a t t e r e d zones , l i n d g r e n ^ l i s t s them as be ing i n the me sothermal zone , and d e s c r i b e s them as v e i n - l i k e rep lacement s . The country rock i s u s u a l l y much a l t e r e d , a c c o m p a n i e d by p y r i t i z a t i o n and s i l i e i f i c a t i o n . Much country r o c k , u s u a l l y a s s i m i l a t e d i n p a r t , i s found i n the ore The d e p o s i t s are commonly i r r e g u l a r i n shape occupy ing o n l y par t o f the sheared zones i n which they are found . Of the copper d e p o s i t s c a r r y i n g va lues i n s i l v e r , which are s i t u a t e d i n sou thern B r i t i s h Columbia , two are worth some d e s c r i p t i o n . At Copper Mounta in the ore bodies were formed by contact-metamorphism. The ore i s found p a r t i a l l y i n the o v e r l y i n g v o l c a n i c s and p a r t i a l l y i n the parent gabbro• The Phoenix and Greenwood l o d e s were formed by igneous emana-t i o n s t r a v e r s i n g the l imes tone from s tocks o f g r a n o d i o r i t e one and o n e - h a l f mile's d i s t a n t . They f a l l i n t o an anomalous c l a s s i f i c a t i o n o f pyrometasomatic d e p o s i t s not r e l a t e d to c o n t a c t s . D e p o s i t s i n which the s i l v e r oc curs w i t h copper i n the form of t e t r a h e d r i t e commonly c o n t a i n much l e a d and z i n c and wi11 be d i s c u s s e d under the s i l v e r - l e a d - z i n c head ing . b . S i l v e r - L e a d - Z i n c P r e s . - These d e p o s i t s i n c l u d e the l a r g e s t number o f s i l v e r - p r o d u c i n g mines i n the p r o v i n c e ; t h e i r p r o d u c t i o n o f s i l v e r i s much l a r g e r than that of a l l o ther groups combined. Wide d i v e r s i t y o f occurrence o f these ores e x i s t s , from the upper mesothermal to the hypothermal zones . No g e n e r a l i z a t i o n w i l l s a t i s f a c t o r i l y cover a l l these d e p o s i t s . The Premier mine i n i t s lower l e v e l s may be j u s t l y i n c l u d e d i n t h i s group. Pre bod ie s are found as s tock works -44-and veins with minor a l t e r a t i o n of the v e i n - w a l l s . The A t l i n -Ruffner property and the wet ores of the Slocan have many features i n common. Ore bodies are found as discontinuous lenses i n well-marked f i s s u r e s . They appear to have been formed by f i s s u r e f i l l i n g w i t h but l i t t l e a l t e r a t i o n of the w a l l rocks. The A t l i n - R u f f n e r lodes are found i n dykes w i t h i n the i n t r u s i v e s , but the 'wet! ores of the Slocan are r e s t r i c t e d to the sediments. Uglow suggests that i n the Slocan these ores were deposited as continuous veins and that subsequent movement broke them in t o l e nses. V/ith the Slocan group most of the small deposits o f the eastern contact of the Coast Range batho-l i t h show many features i n common. The Ainsworth deposits are t y p i c a l l y replacement ores i n limestone. Some coneentration of the ore by f i s s u r e s i s recognized but i n general the ore bodies are c h a r a c t e r i s t i c of replacement. A few s i m i l a r deposits are known i n the northern i n t e r i o r of Vancouver I s l a n d . The Monarch mine at F i e l d i s also p r i m a r i l y of t h i s type. In the hypothermal range the S u l l i v a n and, doubtful-l y , the St. Eugene mines may be included. The S u l l i v a n i s e s s e n t i a l l y a replacement i n q u a r t z i t e and contains most of the determinative minerals of t h i s type. R e s t r i c t i o n of high temperature minerals to the ore i s the best c r i t e r i o n of the temperature of d e p o s i t i o n because they cannot be a t t r i b u t e d to a metamorphic o r i g i n . The St. Eugene i s of decidedly lower temperature and i s much nearer the true v e i n type. I t s asso-c i a t i o n s , however, i n d i c a t e that i t i s b e t t e r classed with the S u l l i v a n than with the Slocan group. -45-Oo 'Dry" S i l v e r Pres.- The d i s t i n c t i o n "between t h i s group and the preceding one i s seldom e a s i l y defined. I t r e s t s p r i m a r i l y upon a much greater proportion of quartz and corres-ponding diminution of lead and zinc minerals. These deposits are g e n e r a l l y considered to have been formed at lower tempera-tures and. more remote from the b a t h o l i t h than the 'wetV ores. As a camp the deposits of Beaverdell f a l l i n t o t h i s group. M i n e r a l i z a t i o n by lead and zin c i s much more abundant than that by s i l v e r . The s i l v e r minerals, however, are so much more abundant than i n the wet ores that s i l v e r i s the primary metal sought. Very l i t t l e a l t e r a t i o n of the v e i n w a l l s i s found and the ore appears to have been deposited very l a r g e l y as v e i n f i l l i n g . Vuggy quartz and a tendency towards banding i n d i c a t e normal r a t h e r low temperature v e i n deposits. Some-what s i m i l a r ore i s found i n the upper l e v e l s of Premier and i n the 'dry' ores of the Slocan, In almost every instance these deposits appear to grade i n t o the le a d - z i n c type at depth. d. Pther Deposits.- Two of the deposits mentioned i n the previous chapter cannot be placed i n any of the categories just o u t l i n e d . The To r i c mine i s dependent almost e n t i r e l y on i t s s i l v e r content. M e t a l l i e s are very scarce i n the high grade ore, i n which s i l v e r values are associated w i t h b a r i t e . The deposit i s found on the hanging w a l l of a large shear zone and was formed by f i l l i n g and replacement. The only comparable ore body i s found at B r i t a n n i a where s i l v e r i s also found asso-c i a t e d with b a r i t e and jasper. The other anomalous deposit i s that of the B.C. S i l v e r mine. S i l v e r values are l a r g e l y due to n a t i v e s i l v e r o c c u r r i n g as i n c l u s i o n s i n p y r i t e . The lode i s almost e n t i r e l y made up of quartz and p y r i t e with some galena and s p h a l e r i t e also found as i n c l u s i o n s i n the p y r i t e . P e rsistence of Argentiferous Deposits at Depth. Mining experience i n t h i s province has e s t a b l i s h e d the b e l i e f that s i l v e r values do not p e r s i s t at depth. The number of properties i n which such values have, i n p a r t , j u s t -i f i e d mining to a depth of over 1000 feet i s but a small pr o p o r t i o n of the t o t a l . I t i s not always easy to make a j u s t estimate of the v e r t i c a l extent of s i l v e r - b e a r i n g lodes because the depth to which mining may be p r o f i t a b l y c a r r i e d on i s u s u a l l y dependent more on the associated base metal than on the s i l v e r content. The depth of the argentiferous lodes v a r i e s widely with the base metal a s s o c i a t i o n of the s i l v e r . a. Silver-Copper Deposits.- Ore bodies of t h i s type are g e n e r a l l y very i r r e g u l a r i n shape. The ore i s u s u a l l y made up of disseminated m e t a l l i c s i n the gangue and country rock, so that the l i m i t s of such a deposit are a r b i t r a r i l y f i x e d by economic f a c t o r s rather than n a t u r a l f e a t u r e s . In general, s i l v e r values decrease sharply over the f i r s t 300-.500 feet and then remain more or l e s s constant. There i s therefore no reason to expect that they would decrease very much at depth. However, these deposits are so formed t h a t they are u s u a l l y developed l a t e r a l l y r ather than v e r t i c a l l y , w i t h a depth l i m i t e s t a b l i s h e d by the percentage of disseminated copper. The - 4 7 -depth to which these ore bodies extend appears to have been l i m i t e d l a r g e l y by s t r u c t u r a l features o f t h e i r d e p o s i t i o n . Although workings of these deposits may extend over 2000 f e e t , m i n e r a l i z a t i o n does not show evidence of v e r t i c a l c o n t r o l o f d e p o s i t i o n , but suggests that d e p o s i t i o n took place at any a v a i l a b l e place i r r e s p e c t i v e of e l e v a t i o n . In sho r t , these copper deposits c a r r y i n g s i l v e r , tend to show greater l a t e r a l than v e r t i c a l extent, so that depth from a t e c h n i c a l viewpoint i s i n s u f f i c i e n t to be in f o r m a t i v e . b. Other Deposits.- A comparatively d e f i n i t e r e l a t i o n e x i s t s between the remaining groups of argentiferous deposits. I t seems probable, i n view of the evidence a v a i l a b l e from Premier, Beaverdell and the Slocan, that the r i c h dry ores of s i l v e r give place i n depth to the poorer, wet ores of s i l v e r and l e a d . Yet i n B r i t i s h Columbia t h i s succession has not l e d to a deposit i n which s i l v e r and lead values together warranted mining to a depth greater than 1500 f e e t . The only exception to t h i s statement i s the S u l l i v a n mine which as prev i o u s l y stated i s of hypothermal d e p o s i t i o n . The majority of proper-t i e s i n the Slocan, at Beaverdell and i n the Salmon r i v e r d i s t r i c t have become too impoverished to be worth mining below the tenth l e v e l . The average property such as these u s u a l l y returned high s i l v e r values near the surface which s t e a d i l y decreased with depth. Commonly the s i l v e r i s the most impor-tant mineral near the surface, then lead becomes important, and f i n a l l y zinc and i r o n with an increase i n quartz are found i n the lower l e v e l s . Very often t h i s succession i s complete -48-w i t h i n a maximum range of 1 2 0 0 f e e t . In attempting to e x p l a i n these phenomena several p o s s i b i l i t i e s present themselves. S i l v e r and lead, are among the l a t e s t metals to be deposited. There i s evidence i n many deposits to suggest that they were introduced considerably l a t e r than the i r o n and z i n c . This has r e s u l t e d i n some t e l e -scoping of zones so that the two metals are found i n small q u a n t i t i e s with i r o n and z i n c . The remainder o f the s i l v e r and lead then appear to have been deposited s l i g h t l y more remote from the source. Most of these deposits i n d i c a t e d e p o s i t i o n under a f a i r l y steep temperature gradient, p o s s i b l y occasioned by heavy erosion having taken place i n the i n t e r v a l between i n t r u s i o n and m i n e r a l i z a t i o n . The majority of these deposits were formed l a r g e l y by v e i n - f i l l i n g , o ften i n w e l l developed f i s s u r e s i n which the ore deposits are found occupying only a small part of the a v a i l a b l e space. Several w r i t e r s have commented on t h i s phen-omenon , p a r t i c u l a r l y i n de s c r i b i n g the Slocan d i s t r i c t . Uglow suggests that there the f i s s u r e s were o r i g i n a l l y narrower and almost e n t i r e l y m i n e r a l i z e d , but subsequent movement has broken the ore i n t o lenses. Nearly a l l w r i t e r s on t h i s d i s t r i c t point out the p o s s i b i l i t y that when one lens i s exhausted ex-p l o r a t i o n at depth may re v e a l the presence of another. Cert-a i n l y a few examples are known i n which two such lenses have been found to outcrop i n the same f i s s u r e . The f a c t however remains that r a p i d impoverishment at depth i s a feature of nearly a l l these deposits. They are a l l classed as me sothermal and as such would be expected to a t t a i n depths up to two or three thousand f e e t . Another point of i n t ere st i s that such deposits i n one d i s t r i c t where they are a l l g e n e t i c a l l y associated w i t h the same i n t r u s i v e , may vary up to f i v e thousand feet i n r e l a t i v e distance from i t . For example, i n the Slocan area such deposits are thought to he l a t e d e r i v a t i v e s of an underlying b a t h o l i t h , yet they vary 4000-^000 feet i n e l e v a t i o n w i t h no d i s t i n c t i v e d i f f e r e n c e i n m i n e r a l i z a t i o n . Cairnes considers the 'dry 1 ore to be lower i n temperature of d e p o s i t i o n there than the 'wet' ore, yet he shows that the dry ore i s found w i t h i n the g r a n i t i c rocks but the wet ore i s never so found. Such i n c o m p a t i b i l i t y of phen-omena can best be explained by a break i n m i n e r a l i z a t i o n with subsequent cooling of host rocks and lessening of pressure by erosive denudation of the o v e r l y i n g s t r a t a . The w r i t e r has been unable to f i n d a s a t i s f a c t o r y e x p l a n a t i o n f o r the r a p i d reduction of values i n depth of these de p o s i t s . The only s o l u t i o n seems to l i e i n the time required by m i n e r a l i z a t i o n coupled with s t r u c t u r a l features that may have allowed almost complete d e p o s i t i o n of s i l v e r and lead w i t h i n 1.500 f e e t . Where replacement has played the major part i n the o r i g i n of a deposit, i t s dimensions i n depth are r e s t r i c t e d by the l i m i t s o f the host rock amenable to replacement« The depo-s i t s at Ainsworth are an ex c e l l e n t example. No l i m i t has yet been reached at S u l l i v a n but d e p o s i t i o n has been l a r g e l y con-t r o l l e d by s t r a t i g r a p h y and development has been more l a t e r a l than v e r t i c a l , although the p o s i t i o n of the i n t r u s i v e source i n r e l a t i o n to t h i s deposit i s not yet known. I t may be ' - 5 0 -therefore that the development i s d i r e c t l y approaching the i n t r u s i v e along the l i n e o f the ore-body. A s s o c i a t i o n of S i l v e r Deposits with Various Types of I n t r u s i v e s , Nearly a l l the mineral deposits o f the province are at present thought to be associated w i t h J u r a s s i c i n t r u s i v e s . The bulk of these p l u t o n i c rocks are compo sed of g r a n o d i o r i t i e and quartz d i o r i t e , but others ranging from gabbro to gr a n i t e are a t t r i b u t e d to the same period of i n t r u s i o n . In southeast-er ern Alaska Buddington has found evidence which, i n h i s o p i n i o n , i n d i c a t e s a s s o c i a t i o n of c e r t a i n types of m i n e r a l i z a -t i o n with each d i f f e r e n t i a t e of the parent magma. He.asso-c i a t e s the copper deposits with d i o r i t e and gr a n o d i o r i t e and the s i l v e r - l e a d - z i n c deposits with quartz monzonite. Along the western f l a n k of the Coast Range b a t h o l i t h , most of the s i l v e r - b e a r i n g copper deposits are associated with g r a n o d i o r i t e . On the eastern contact the s i l v e r - l e a d - z i n c ores appear to have had t h e i r source i n a magma which produced g r a n o d i o r i t e and quartz d i o r i t e . In the southern b e l t t h i s type of ore i s associated with p l u t o n i c s ranging from gr a n i t e to g r a n o d i o r i t e , but the copper ores are found with gabbro and g r a n o d i o r i t e . From t h i s b r i e f summary there would appear to be no consistent r e l a t i o n s h i p between one type of ore and a corres-ponding i n t r u s i v e . There does not appear to be any p a r t i c u l a r preference shown by these deposits f o r any p a r t i c u l a r type of host rock providing i t i s competent to maintain f i s s u r e s . Some preference i s , of course, i n d i c a t e d i n those properties - 5 0 a -F i g . (14). D i s t r i b u t i o n of Metals about a B a t h o l i t h ( a f t e r Buddington). -51-i n which replacement has played a large part i n formation of the ore bodies. The copper deposits tend to show a f f i l i a t i o n w i t h the more basic p l u t o n i c s ; the s i l v e r - l e a d - z i n c ores appear to be more commonly associated with the a c i d types. The E f f e c t s of Supergene Forces. S i l v e r deposits are probably the type most generally associated with secondary enrichment. I t has been shown by 5% 22 Ravicz and Cooke that s i l v e r i s more e a s i l y d i s s o l v e d by downward c i r c u l a t i n g waters than most other metals. Both the above authors agree that f e r r i c sulphate and s u l p h u r i c a c i d are e x c e l l e n t solvents of s i l v e r and that ferrous sulphate i s a good p r e c i p i t a n t of native s i l v e r . Cooke shows that the a c t -i o n of d i l u t e s u l p h u r i c a c i d on the common sulphides produces hydrogen sulphide which reacts w i t h the s i l v e r to form second-ary a r g e n t i t e . Ravicz f u r t h e r mentions the a l k a l i n e carbon-ates as good solvents of Sb 2S_ and As 2S_. He f i n d s that by t h e i r a c t i o n on the s u l p h o - s a l t s , the antimony or arsenic i s d i s s o l v e d and a r g e n t i t e l e f t as a secondary product. He then concludes: "These experiments supported by f i e l d observations j u s t i f y the conclusion that the s u l p h o - s a l t s of s i l v e r may be primary i n deposits formed at shallow depths, but are general-l y secondary i n deposits formed at intermediate or greater depths." This statement corroborated by the f a c t that s i l v e r values are commonly much higher i n the upper l e v e l s of most mines appear to i n d i c a t e a considerable amount of secondary enrichment i n B r i t i s h Columbia. Quite apart from whether such - 5 2 -i s the case, the r i c h e r parts of the ore-bodies i n t h i s province seldom reach depths of more than 200 to 500 f e e t . Palmer and Bast i n ^ have found that galena and s p h a l e r i t e are poor p r e c i p i t a n t s of s i l v e r . This f a c t i s o f i n t e r e s t because i n the r i c h e r parts of these deposits the galena u s u a l l y c a r r i e s higher values i n s i l v e r than i t does i n the lower l e v e l s . Further, these higher values appear under the microscope to be due l a r g e l y to rounded blebs of t e t r a -h e d r i t e . However, some i n c l u s i o n s of a r g e n t i t e i n galena do suggest e i t h e r mechanical unmixing or secondary d e p o s i t i o n . (Figures (8) and ( 9 ) ) . Modern o p i n i o n , l a r g e l y based on mineragraphic study of polished s e c t i o n s , a t t r i b u t e s l e s s importance to secondary enrichment. Dolmage has discussed the subject at Premier and B.C. S i l v e r and has reached the con-c l u s i o n that much of the native s i l v e r there i s o f hypogene o r i g i n . This s i l v e r was noted as rounded grains i n galena by the w r i t e r , and by Dolmage i n p y r i t e . Dolmage f u r t h e r draws a t t e n t i o n to the absence of secondary copper minerals at Premier. I t has been the experience of the w r i t e r that much of the native s i l v e r appears to be supergene but that i n nearly every instance the sulpho-salts were hypogene. Some enr i c h -ment of these ores at the surface i s probably due to concen-t r a t i o n of sooty a r g e n t i t e i n the secondary lead and zinc minerals. Evidence of the appearance of a non-metallic a r g e n t o - j a r o s i t e at A l l c o has already been mentioned. D e f i n i t e supergene a c t i o n has reached a depth of 500 feet at Ainsworth and Premier and to l e s s e r depths at other mines. This a c t i o n , however, i s almost wholly confined - 5 2 -to the f i r s t 50 or 100 feet and to f i s s u r e s through which c i r c u l a t i o n of surface waters i s f a c i l i t a t e d . In general, supergene enrichment of s i l v e r deposits i n B r i t i s h Columbia might be expected to be important. The necessary i r o n minerals are always present, the r a i n f a l l i s s u f f i c i e n t and f i s s u r e s f o r c i r c u l a t i o n are quite p l e n t i f u l . I t i s , however, an estab-l i s h e d f a c t that the argentiferous deposits of the province are s i n g u l a r l y l a c k i n g i n the zones of o x i d a t i o n and concentration which so commonly mark them elsewhere. Two p r i n c i p a l reasons f o r t h i s may be suggested. The groundwater table i n many parts of the province i s u s u a l l y close to the surface. I t seems d i f f i c u l t to envisage c i r c u l a t i o n of solvent s o l u t i o n s below t h i s l e v e l ; therefore p r e c i p i t a t i o n of secondary minerals would be expected there* The second and most general-l y accepted theory i s that the f a i r l y recent g l a c i a l scouring to which a l l parts of the province have been subjected, has removed a l l previous o x i d i z e d and enriched zones. The time elapsed since g l a c i a t i o n i s inadequate f o r subsequent forma-t i o n of such zones. -.54-CHAPTER IT. Int r o d u c t i o n . I t i s the purpose of the w r i t e r to discuss i n t h i s chapter the a s s o c i a t i o n of s i l v e r with various base metals and t h e i r common minerals. The average mine operator i s not so much i n t e r e s t e d i n m i n e r a l o g i c a l d e t a i l of t h i s a s s o c i a -t i o n , except where i t i s possible to improve h i s recovery thereby, as i n the a c t u a l a s s o c i a t i o n of s i l v e r with the various minerals. Modern research'* 0 »^' ^ j , l a s s n o w n quite c l e a r l y that the amount of s i l v e r i n s o l i d s o l u t i o n or other a s s o c i a t i o n w i t h common base metal minerals, such that the s i l v e r content might be considered inherent i n that mineral, i s very low. Mining and e x i s t i n g m i l l i n g p r a c t i c e , however, have produced r e s u l t s that are d i f f i c u l t to r e c o n c i l e with research f i n d i n g s . Although the w r i t e r cannot hope, on the bas i s of h i s b r i e f study of a few s u i t e s of B r i t i s h Columbia ores, to reach valuable or o r i g i n a l conclusions, i t i s hoped that compilation of r e s u l t s obtained may be of i n t e r e s t i n comparison with those of e x i s t i n g papers. Probably the greatest d i f f i c u l t y f a c i n g those who wish to determine the a s s o c i a t i o n of s i l v e r w i t h various metals and minerals, i s the question of laboratory methods. Two main avenues of approach have been used: examination of n a t u r a l ores and synthesis and subsequent examination of a r t i f i c i a l ores. Of these the former would appear to be the more p r a c t i c a l . At present knowledge of conditions c o n t r o l -l i n g d e p o s i t i o n of minerals i s very l a r g e l y h y p o t h e t i c a l i n - 5 5 " nature and i s based almost e n t i r e l y on study of n a t u r a l ore. U n t i l more d e f i n i t e data can be obtained i t would appear to be somewhat abortive to attempt to reproduce n a t u r a l conditions of dubious a u t h e n t i c i t y i n the la b o r a t o r y . Occasional reference may be made to r e s u l t s of the synthetic type of research but the w r i t e r ' s laboratory work consisted only of examination of n a t u r a l ores. Two methods were used to obtain s i l v e r content o f , and a s s o c i a t i o n with various minerals. The most gen e r a l l y used method i s that of examination of polished sections under r e f l e c t e d l i g h t . Minerals were determined by etch reactions on the polished s u r f a c e , by hardness, c o l o u r , isotropism and by micro chemical a n a l y s i s of minute p a r t i c l e s removed by a sharp needle from the polished surface. Determination o f paragenesis of the minerals was c a r r i e d out as f a r as possible on c r i t e r i a of amount of f r a c t u r i n g , veining of one mineral by another and to a l e s s extent by c r y s t a l form. -The second method i s more s t a t i s t i c a l i n nature and c o n s i s t s of assaying picked specimens of various minerals f o r t h e i r s i l v e r content« The work e n t a i l e d i n p i c k i n g these clean minerals from crushed and screened samples o f ore, requires much time and patience. I t i s g r e a t l y f a c i l i t a t e d i f samples of ore c o l l e c t e d i n the f i e l d are chosen to contain as much of one pure mineral i n each as i s p o s s i b l e . The w r i t e r was handicapped by the ne c e s s i t y of p i c k i n g samples of each mineral from t y p i c a l specimens of mixed, sometimes f i n e -65 grained, ore. Warren has shown that the s i l v e r content of any one pure mineral from various parts of one deposit i s p r a c t i c a l l y constant. As a r e s u l t i t i s possible to choose the e a s i e s t ore specimen from which to pick the mineral sample. The A s s o c i a t i o n of S i l v e r w i t h Lead. I t has been common p r a c t i c e among base metal miners of North America to quote the s i l v e r content of t h e i r ore i n terms of ounces of s i l v e r to each uni t or one per cent of le a d . This p r a c t i c e has i t s o r i g i n i n the b e l i e f , engendered by almost u n i v e r s a l experience, that where lead i s present and s i l v e r content i s not e x c e p t i o n a l l y h i g h , the s i l v e r i s c l o s e -l y a s s o ciated with l e a d . The nature of t h i s a s s o c i a t i o n , how-ever, i s f a r from being the same i n every deposit. In the various ore s u i t e s studied galena and, of very much l e s s importance, jamesonite, were the only two hypogene minerals of lead which were recognized. Jamesonite was present i n such minor amounts that i t s possible s i l v e r content could not be determined. However, the f a c t that i t i s ne a r l y always among the l a s t minerals to be depo s i t e d suggests the p o s s i b i l i t y of i t s i n c l u d i n g s i l v e r by replacement of some other e a r l i e r a r g entiferous mineral. I t s chemical composi-t i o n i s c l o s e l y analogous to that of the s i l v e r sulpho-salts and, i n the instance of a few of them, c r y s t a l l i z a t i o n i n the monoclinic system completes the conditions necessary f o r isomorphism. Dana repor t s such an argentiferous v a r i e t y of jamesonite under the name owyheeite. In t h i s regard bournon-i t e and c o s a l i t e are even more favourable and i t would be i n t e r e s t i n g to assay samples f o r s i l v e r . I t i s , however, with galena that most of the s i l v e r -51-' appears to be associated. Several w r i t e r s , notably Hissen and Hoyt- 5 0, G u i l d ^ and W a r r e n h a v e i n v e s t i g a t e d the p o s s i b i l i t y of s i l v e r e x i s t i n g i n s o l i d s o l u t i o n i n galena. With increas-ing p r e c i s i o n and accuracy the amount of s i l v e r so e x i s t i n g has been successively shown to be smaller. At present i t seems impossible f o r more than 0.1% of s i l v e r to e x i s t as sub-micro-scopie p a r t i c l e s or i n s o l i d s o l u t i o n i n galena. Warren y f i n h i s work on the Combination and Groundhog mines, has reduced t h i s f i g u r e to about 0.015% which amounts to 15.2 oz. per.ton of galena. When assays o f galena are higher than t h i s f i g u r e , i t i s u s u a l l y p o s s i b l e to detect i n c l u s i o n s of some d e f i n i t e s i l v e r mineral on etching with HC1 fumes. Of the specimens of galena so t r e a t e d only one f a i l e d to show such i n c l u s i o n s . This specimen came from the Great Bear lake deposits and assayed about 4 oz. of s i l v e r per ton. In p i c k i n g specimens of galena f o r assay i t has been the experience o f the w r i t e r that the ' c l e a n e s t f samples show the smallest values i n s i l v e r . The f o l l o w i n g l i s t shows assay r e s u l t s from samples of picked galena made by the w r i t e r . D e s c r i p t i o n of the picked samples accompanies the f i g u r e s , and i n a few instances photographs showing the i n c l u s i o n s are noted. Source of Ore D e s c r i p t i o n of Picked Sample Figure No. Assay f o r S i l v e r Oz. per ton. Mammoth -Stope 302 S t e e l galena impure product 125.0 « it i t F a i r l y clean cube galena (9) 33.44 » " 701 F o l i a t e d impure cube galena (10) 83.44 A l l c o - No. 1. Weathered f a i r l y clean galena (8) 95.68 Premier -Stope 30 clean cube galena 45*84 - 5 8 -From these r e s u l t s i t w i l l be no tea that although the amount of i n v i s i b l y contained s i l v e r i n galena may be con-stant i n one deposit, the amount of associated s i l v e r v a r i e s widely. This variance depends of course on the quantity of i n c l u s i o n s , t h e i r s i ze and t h e i r composition. In the Mammoth mine l a r g e blebs of included t e t r a h e d r i t e , and numerous small blebs of a r g e n t i t e (?) were very common i n the s t e e l galena. The cube galena contained much l e s s t e t r a h e d r i t e but more a r g e n t i t e ( ? ) . These i n c l u s i o n s as shown by f i g u r e (§) exhib-i t evidence of cleavage c o n t r o l by the galena. As a r e s u l t the w r i t e r b e l i e v e s they may be supergene i n o r i g i n . S i m i l a r cleavage c o n t r o l i s evident i n specimens from the A l l c o property, f i g u r e ( 8 ), and from the ITnuk River area. In ore from the 6 0 0 l e v e l of the Mammoth mine, however, the i n c l u -sions are rounded and show complete lack of regular o r i e n t a -t i o n , as do samples from below the supergene zone at Premier. At the Toric mine Brennan-^ reports that s i l v e r values are not associated with galena. This i s noteworthy because galena i s the most abundant sulphide. A cursory examination of the ore and comparison with the appended assays q u i c k l y confirmed Mr. Brennan"s r e p o r t . The ore i s very f i n e - g r a i n e d , f i g u r e ( 4 ) , so that i t was impossible to assay galena samples. Etching w i t h HOI fumes was u n s a t i s f a c t o r y due to the f i n e dissemina-t i o n , but no i n c l u s i o n s could be observed. This i s a l l the more i n t e r e s t i n g as p y r a r g y r i t e was determined i n the ore but d i s s o c i a t e d from the galena. Further, secondary native s i l v e r was never n o t i c e d among the m e t a l l i c s but always i n the b a r i t e . At Ainsworth, St. Eugene and the S u l l i v a n mine s i l v e r i s apparently almost r e s t r i c t e d to the galena® Various t h e o r i e s have been advanced to e x p l a i n the presence of these argentiferous i n c l u s i o n s i n galena, rr 66 Wagner and others have suggested that they are due to unmixing on s o l i d i f i c a t i o n o f the galena. That i s , the s i l v e r minerals are soluble i n galena i n the l i q u i d state but only at high temperatures i n the s o l i d . Therefore they separate i n t o minute i n c l u s i o n s when the s o l i d galena cools by mechanical unmixing. I t i s quite p o s s i b l e that some of the s i l v e r mineral might be segregated i n p a r t i c l e s so minute that they could not be detected under the microscope, o r i t may be . solub l e i n l i m i t e d quantity i n the galena, at room temperature. S c h w a r t z ^ f i n d s that l i m i t e d s o l u t i o n i s possible but d i s -agrees with the unmixing theory on the grounds that galena normally does not show cleavage or c r y s t a l c o n t r o l over i t s i n c l u s i o n s . A second theory i s that the argentiferous i n c l u s i o n s are soluble i n the l i q u i d but to a much smaller degree i n the s o l i d . Whether t h i s suggestion can be divorced from the p o s s i b i l i t y that galena and i t s i n c l u s i o n s are deposited simultaneously i s a matter of some doubt. 38 The t h i r d suggestion i s that supported by Guild He has made a very thorough study of s i l v e r and i t s a s s o c i a -t i o n s and has found that associated minerals tend to be deposited i n a d e f i n i t e order. This order f o r s i l v e r - l e a d -zinc deposits i s , p y r i t e , s p h a l e r i t e , t e t r a h e d r i t e , galena, s u l p h o - s a l t s and native s i l v e r . He then states that the t e t r a h e d r i t e i s replaced by the galena, leaving small blebs of i t w i t h i n the galena- The w r i t e r was unable to decide whether Gui l d a t t r i b u t e d a r g e n t i t e i n the galena to the s i l v e r content of the replaced t e t r a h e d r i t e , G u i l d , however, states that the presence of other s i l v e r s u l p h o - s a l t s i n the galena i s u s u a l l y i n the form of v e i n l e t s and i n d i c a t e s l a t e r enrichment. This l a s t statement i s not i n accord with the w r i t e r ' s f i n d i n g s , as p y r a r g y r i t e and p o s s i b l y p o l y b a s i t e were determined as rounded i n c l u s i o n s i n galena from the Premier. Galena from the Bounty mine shows almost an intergrowth with p y r a r g y r i t e and con-t a i n s many rounded blebs of the l a t t e r . These blebs, however, are most common near masses of p y r a r g y r i t e which may be v e i n i n g the galena. I t i s the opinion of the w r i t e r that Guild's explan-a t i o n of blebs of t e t r a h e d r i t e i n the galena i s s a t i s f a c t o r y . In a f a m i l y as uniform i n character as that of the sulpho-s a l t s i t i s d i f f i c u l t to e x p l a i n presence of the argentiferous v a r i e t i e s as blebs i n galena i f they are of l a t e r deposition unless they are primary a l t e r a t i o n products of the t e t r a -h e d r i t e . One f u r t h e r important question i s l e f t , that of the f i n a l d e p o s i t i o n of the s i l v e r when galena weathers. Appar-e n t l y i t i s not found i n a n g l e s i t e or c e r u s i t e and so must e i t h e r be deposited as a supergene mineral lower i n the deposit, or remain as sooty a r g e n t i t e or native s i l v e r . One s e c t i o n of A l l c o ore, f i g u r e ( 7 ) , shows quite c l e a r l y the weathering of the galena. A few b r i g h t species i n the weathered zone appear only near the unweathered mineral and disappear away from i t . This suggests that they are the l a s t -61-v e s t i g e s of unweathered galena. Tetrahedrite can he seen a l t e r e d to c o v e l l i t e but there i s no i n d i c a t i o n of any s i l v e r mineral remaining. S i l v e r i s quite e a s i l y s o l u b l e , p a r t i c u -l a r l y i n the presence of ferrous i r o n and so i s probably c a r r i e d down, Removal of s i l v e r by downward moving s o l u t i o n s i s g r e a t l y f a c i l i t a t e d by the moderate annual p r e c i p i t a t i o n which p r e v a i l s i n t h i s province. The A s s o c i a t i o n of S i l v e r with Copper. Copper minerals are more v a r i e d and more numerous than minerals of l e a d . Three copper minerals, c h a l c o p y r i t e , t e t r a h e d r i t e and stromeyerite, are reported from various parts of the province as c a r r y i n g s i l v e r . Although the a s s o c i a t i o n of s i l v e r with copper i s not widely appreciated i t i s funda-mentally more important than a s s o c i a t i o n with lead. The c o p p e r - s i l v e r a s s o c i a t i o n i s important i n two main types of ores. She b i g copper deposits of B r i t i s h Colum-b i a a l l carry small values i n s i l v e r . Such values are o f d e f i n i t e economic importance, often being the determining f a c t o r i n deciding what parts of a deposit may be economically designated as ore. The w r i t e r has not had the opportunity to examine specimens of these copper ores f o r t h e i r s i l v e r con-26 t e n t . Dolmage a t t r i b u t e s the s i l v e r content of these b i g copper deposits to the c h a l c o p y r i t e . C e r t a i n l y the uniformity of s i l v e r assays i n these large deposits does point to asso-c i a t i o n with c h a l c o p y r i t e . However, s i l v e r i s u s u a l l y reported as having been more abundant i n the upper l e v e l s where argentiferous minerals were commonly reported. I t would be —62— i n t e r e s t i n g to determine whether such minerals were of secondary o r i g i n s The second group of deposits i n which the s i l v e r copper a s s o c i a t i o n i s important includes those lodes i n which t e t r a h e d r i t e i s an important argentiferous mineral. This group contains nearly a l l the r i c h e r base metal deposits and most of the r i c h 'dry' ore deposits of the province. Tetra-h e d r i t e i s widely disseminated and i s the only r i c h s i l v e r mineral which commonly p e r s i s t s to depth. Two samples of t h i s grey copper were picked and assayed. A f a i r l y clean sample wi t h some jamesonite from the A l l c o quarts v e i n ran 1,114.0 oz. of s i l v e r per ton. Another sample with much intergrown c h a l c o p y r i t e from the upper l e v e l s of the Mammoth mine assayed 1 ,273.0 oz. of s i l v e r . Neither of these r e s u l t s i s p a r t i c u l a r l y h i g h , as they average only 4.2% s i l v e r , whereas Dana reports up to 30% as the maximum a r g e n t i -(1) ferous content. l o r d , working on picked specimens of t e t r a -h e d r i t e from B r i t i s h Columbia and the Yukon, reported several samples which contained over 5% s i l v e r . The s i l v e r content of 3 8 t e t r a h e d r i t e , according to G u i l d , i s due to an isomorphous molecule i n the min e r a l , i n other words, i s i n s o l i d s o l u t i o n . This f a c t appears to be undisputed; l o r d could f i n d but l i t t l e d i f f e r e n c e i n the pro p e r t i e s of t e t r a h e d r i t e r i c h i n s i l v e r and i n t e t r a h e d r i t e low i n s i l v e r . G u i l d b e l i e v e s that m i n e r a l i z a t i o n of the r i c h e r s i l v e r deposits i s eff e c t e d by continuous deposition and successive replacement by the l a t e r minerals. Although he does \1) Lord, CJ..S7 Master's Thesis, U.B.C. [ - 6 5 -not make the d e f i n i t e statement that the s i l v e r s u l p h o - s a l t s are d e r i v e d from the e a r l i e r t e t r a h e d r i t e , the sugges t ion o f suoh hypogene replacement and a l t e r a t i o n may he j u s t l y i n f e r r e d . I f t h i s were so i t might be expected that wherever f hypogene s i l v e r s u l p h o - s a l t s were f o u n d , t e t r a h e d r i t e should be found a l s o . A survey o f the d e p o s i t s d e s c r i b e d i n t h i s paper shows t h a t whenever the s i l v e r s u l p h o - s a l t s are found t e t r a h e d r i t e i s a l s o p r e s e n t . I t i s i n t e r e s t i n g to note the d i f f e r e n c e i n m i n e r a l i z a t i o n o f the h i g h grade lodes o f Premier and the ne ighbour ing B . C . S i l v e r d e p o s i t . In Premier t e t r a h e d r i t e and a v a r i e t y of s i l v e r s u l p h o - s a l t s - some o f them secondary - are f o u n d , but at B . C . S i l v e r , d e s p i t e the h i g h s i l v e r content o f the l o d e , t e t r a h e d r i t e i s absent and the s i l v e r s u l p h o - s a l t s are c o r r e s p o n d i n g l y l a c k i n g . Thus the p o s s i b i l i t y , t h a t the s i l v e r s u l p h o - s a l t s both o f hypogene and supergene o r i g i n are l a r g e l y d e r i v e d from a r g e n t i f e r o u s t e t r a -h e d r i t e , f i n d s c o n f i r m a t i o n i n the d e p o s i t s o f B r i t i s h Colum-b i a . The t h i r d m i n e r a l i n which s i l v e r and copper are a s s o c i a t e d i s s t r o m e y e r i t e . Reference to o n l y one occurrence o f the m i n e r a l i n t h i s p r o v i n c e has been found by the w r i t e r . T h i s was i n l e r o y ' s d e s c r i p t i o n o f some s i l v e r copper 45 d e p o s i t s i n the v i c i n i t y of N e l s o n . I t i s p o s s i b l e that an i n t e n s i v e examinat ion o f ore from some o f the 1arger copper mines i n the p r o v i n c e would d i s c l o s e the presence o f t h i s m i n e r a l and thus account fo r the s i l v e r content . The c h a r a c t e r i s t i c occurrence of s t romeyer i t e i s as an in te rg rowth w i t h o t h e r copper s u l p h i d e s , so that i t might be e a s i l y overlooked. In conclusion, i t appears that i n B r i t i s h Columbia the a s s o c i a t i o n of s i l v e r and copper, p a r t i c u l a r l y i n t e t r a -h e d r i t e , i s of primary importance. I t has been shown that t h i s mineral i s the e a r l i e s t argentiferous compound to be deposited, and that much of the s i l v e r i n other minerals, such as galena and the s i l v e r s u l p h o - s a l t s , i s derived from i t . The deposits discussed i n t h i s paper appear to substantiate G u i l d ' s statement that t e t r a h e d r i t e i s the most important primary source of s i l v e r . Due to the great tonnage mined i n the large copper deposits of the province, the doubtful asso-c i a t i o n of s i l v e r w i t h c h a l c o p y r i t e i s also important. Dol-mage assigned the s i l v e r content of these ores to the chalco-p y r i t e on the grounds that the observed s i l v e r minerals were 65 i n s u f f i c i e n t to' account f o r assay values. Warren , however, has found that c h a l c o p y r i t e c a r r i e s from 0.006% to 0.009% s i l v e r which amounts to a maximum of 2.6 oz. of s i l v e r per ton of pure c h a l c o p y r i t e . This would not appear to be s u f f i c i e n t to s a t i s f y the assay r e s u l t s e i t h e r . C h a l c o c i t e , however, has been shown to carry up to 0.4% s i l v e r and i f present i n any quantity would more e a s i l y provide the known s i l v e r content. The A s s o c i a t i o n of S i l v e r with Zinc. In base metal mining the d i s t r i b u t i o n of s i l v e r values between the lead and zinc i s a matter of considerable importance. The a s s o c i a t i o n of s i l v e r with zinc i s rather d i f f i c u l t to e x p l a i n . In the w r i t e r ' s knowledge there i s no common mineral containing both z i n c and s i l v e r . The a s s o c i a t i o n cannot be accounted f o r , as i n the case o f l e a d , by replacement of e a r l i e r a r g e n t i f e r o u s m i n e r a l s , because i t has been the exper ience of the w r i t e r that s p h a l e r i t e i s always e a r l i e r than the s i l v e r m i n e r a l s . . There remains , t h e r e -f o r e , the p o s s i b i l i t y o f the p r e f e r e n t i a l a s s o c i a t i o n o f some l a t e r a r g e n t i f e r o u s m i n e r a l o r m i n e r a l s w i t h one or more z i n c m i n e r a l s . In ore d e p o s i t s d i s c u s s e d i n t h i s paper o n l y three z i n c m i n e r a l s have been r e p o r t e d . Of t h e s e , s p h a l e r i t e i s o f hypogene o r i g i n , smi thson i t e i s supergene, and ca lamine , due to i t s common a s s o c i a t i o n w i t h s m i t h s o n i t e , may be g e n e r a l l y c o n s i d e r e d to be a l s o of secondary o r i g i n . So f a r as the pr imary d e p o s i t s are concerned t h e n , s p h a l e r i t e i s the o n l y z i n c m i n e r a l which needs d i s c u s s i o n . A few samples o f s p h a l e r i t e , a l l o f them p e r f e c t l y c l e a n , were assayed by the w r i t e r . Of these the samples from C o r k - P r o v i n c e and B l u e b e l l were r a t h e r h i g h i n i r o n , that from A l l c o was low i n i r o n . 1. A l l c o #5 c l e a n blende 0.5 o z . A g / t o n . 2. C o r k - P r o v i n c e " marmotite 0.5 " " " 3. B l u e b e l l u 1 1 . 0 . 9 1 1 " " These f i g u r e s check wi th W a r r e n ' s ^ r e s u l t s and show q u i t e d e f i n i t e l y that the amount o f s i l v e r which may be con-s i d e r e d to be i n h e r e n t l y a s s o c i a t e d w i t h s p h a l e r i t e i s n e g l i -g i b l e . Indeed i t i s the w r i t e r ' s o p i n i o n that the t r a c e o f s i l v e r found i s probab ly due to i n c l u s i o n s o f another m i n e r a l . 55 I t i s o f i n t e r e s t to n o t e , however, tha t S c h o f i e l d r e f e r s to r e p o r t s from Cork-Prov ince which s t a t ed that s p h a l e r i t e had -66-been known to assay 3% s i l v e r . From the Ruth Hope property ore has been shipped, i n which according to Galloway^, 13% 0 f the s i l v e r values were found with the z i n c . These are but a few examples but from many proper t i e s come reports of varying values i n s i l v e r associated with the z i n c . G u i l d has compiled a general order of depo s i t ion f o r minerals i n s i l v e r - l e a d - z i n c ores. The w r i t e r has been able to f i n d no s i g n i f i c a n t d e v i a t i o n from t h i s order, which i n abbreviated form i s as f o l l o w s : s p h a l e r i t e , t e t r a h e d r i t e , galena, s i l v e r s ulpho-salts and jamesonite ( ? ) . In view of t h i s order of d e p o s i t i o n the obvious argentiferous mineral which might be expected to be associated with s p h a l e r i t e i s t e t r a h e d r i t e . In h i s mineralogy o f the Beaverdell camp, Reinecke says t e t r a h e d r i t e i s intergrown with galena and to a l a r g e r extent, with s p h a l e r i t e . I t has been the w r i t e r ' s experience that t e t r a h e d r i t e i s more commonly associated with galena, but that i t i s commonly concentrated along the con-t a c t of galena and s p h a l e r i t e , This phenomenon was noted i n ores from Premier, A l l c o and Mammoth. The best explanation f o r the s i l v e r content of s p h a l e r i t e seems to be that s p h a l e r i t e and t e t r a h e d r i t e are deposited at much the same time. Tetrahedrite seems to be more e a s i l y replaced by galena than s p h a l e r i t e . Therefore tetrahedrite,which i s f a i r l y w e l l intergrown with s p h a l e r i t e , would be l e s s l i k e l y to be replaced by galena, or i f i t were, would tend to enrich the galena which i t s e l f would then be c l o s e l y intergrown with the s p h a l e r i t e and so provide the l a t t e r ' s s i l v e r content. In deposits which e x h i b i t the banded - 6 7 -s t r u c t u r e a s c r i b e d to f i s s u r e - f i l l i n g , the s p h a l e r i t e would be found nearer the w a l l s with t e t r a h e d r i t e next to i t and f i n a l -l y galena and the s i l v e r s u l pho-salts near the centre* Warren - repor t s that the a c t i o n of t e t r a h e d r i t e i n f l o t a t i o n i s r a ther i n c o n s i s t e n t , and that i t frequently comes o f f with the s p h a l e r i t e . This f a c t would of course tend to substantiate the b e l i e f that a considerable p o r t i o n of the s i l v e r values are associated with the s p h a l e r i t e . A s s o c i a t i o n of S i l v e r with Other Base Metals. Ti n . The Snowflake mine i s the only property i n the province i n which t i n and s i l v e r are associated. A r g e n t i -ferous minerals are t e t r a h e d r i t e , ruby s i l v e r and galena. The t i n occurs as starmite which i s contemporaneous with sphaler-i t e . Ruby s i l v e r and t e t r a h e d r i t e are found i n the galena and s t a n n i t e . Pure sta r m i t e , however, does not contain s i l v e r at t h i s property. Explanation of the a s s o c i a t i o n of s i l v e r with s t a n n i t e seems to again r e s t i n the time of d e p o s i t i o n , as was the ease i n s i l v e r ' s a s s o c i a t i o n with z i n c . The ruby s i l v e r may p o s s i b l y be considered as a hypogene a l t e r a t i o n production of the t e t r a h e d r i t e . No break i n the sequence of m i n e r a l i z a -t i o n i s i n d i c a t e d so that the presence of s i l v e r cannot be explained,by two periods of m i n e r a l i z a t i o n . The deposit i s t y p i c a l of v e i n f i l l i n g rather than replacement, and might be 9 classed with Buddington's xenothermal / group. A s s o c i a t i o n of S i l v e r with Gold. Although t h i s chapter was p r i m a r i l y intended to -68-d i s e u s s d i s t r i b u t i o n o f s i l v e r w i t h the base m e t a l s , t h i s l a s t a s s o c i a t i o n seems best d e s c r i b e d h e r e . Gold and s i l v e r are found toge ther o n l y i n e lec trum and some t e l l u r i d e s , Of the l a t t e r o n l y the bismuth v a r i e t y , t e t r a d y m i t e , i s common i n B r i t i s h Columbia , so they need not be f u r t h e r c o n s i d e r e d , E l e c t r u m i s known i n the p r o v i n c e from the Premier mine where i t i s an important ore m i n e r a l . There i t i s c o n cent ra ted i n the upper l e v e l s but has been found i n g r e a t l y reduced q u a n t i t y i n the lower l e v e l s . I t never grades i n t o n a t i v e s i l v e r ; the boundar ies between the two are sharp ly marked when etched w i t h F e C l ^ , N e a r l y a l l n a t u r a l g o l d , whether from p l a c e r or lode d e p o s i t s , i s a l l o y e d w i t h some s i l v e r . A l though the s i l v e r v a l u e s from such d e p o s i t s are low as compared w i t h g o l d , these d e p o s i t s are worthy o f mention as sources o f an a p p r e c i a b l e amount o f s i l v e r . I t would.be imposs ib le to d e s c r i b e a l l these d e p o s i t s i n t h i s paper , but i t i s s u f f i c i e n t to p o i n t out that q u i t e a l a r g e amount o f g o l d i s produced i n B r i t i s h Columbia and a l l o f i t c a r r i e s s i l v e r , i n amounts up to 10?,. CHAPTER V . I n t r o a u c t i o n a Due to the wide scope o f f e r e d by the sub ject o f t h i s paper , c o n c l u s i o n s drawn from the r e s u l t s of l e s s than one y e a r ' s work on i t must n e c e s s a r i l y be l i m i t e d to the few broad g e n e r a l i z a t i o n s which seem j u s t i f i e d , toge ther w i t h a few more d e t a i l e d r e s u l t s * These l a t t e r r e s u l t s should be cons idered o n l y as s c a t t e r e d m a t e r i a l which shou ld be supplemented by f u r t h e r work i n the l a b o r a t o r y and l i b r a r y . From them i t i s not p o s s i b l e to draw l o g i c a l c o n c l u s i o n s because they r e p r e -sent o n l y a l i m i t e d number o f d e p o s i t s . They a r e , however, i n c l u d e d f o r r e f e r e n c e o f o ther s who may be i n t e r e s t e d i n com-p i l i n g a more complete a n a l y s i s o f t h i s s u b j e c t . Most o f the m a t e r i a l to f o l l o w has been more f u l l y covered i n prev ious chap te r s but i s o u t l i n e d here i n more conc i se form. M i n e r a l o g y of S i l v e r i n B , G.." 1. N a t i v e S i l v e r . Thi s m i n e r a l i s commonly found i n the upper p a r t s o f most a r g e n t i f e r o u s d e p o s i t s . I t i s u s u a l l y secondary but i s found i n hypogene ore at Premier and B . C. S i l v e r . I t i s the most important ore m i n e r a l at the T o r i c m i n e « 2. N a t i v e G o l d . T h i s minera l i s mentioned only because o f the smal l amount o f s i l v e r which i t n e a r l y always c o n t a i n s . E l e c t r u m . E l e c t r u m i s found only at the Premier mine jk F o l l o w i n g Dana ' s c l a s s i f i c a t i o n . -70-and at Copper Mountain i n t h i s p r o v i n c e . I t i s hypogene and q u i t e d i s t i n c t from n a t i v e s i l v e r . I t i s found i n a l l l e v e l s o f the Premier mine hut i s ve ry much more abundant i n the upper p a r t ® 4 . A r g e n t i t e . A l t h o u g h i t i s w i d e l y d i s seminated i n many s i l v e r d e p o s i t s of the p rov ince a r g e n t i t e i s o n l y o f minor importance as an ore o f s i l v e r . I t i s both hypogene and supergene , i n the sooty form i s a common weathering product o f a r g e n t i f e r o u s g a l e n a . 5« Galenas Th i s i s not a t rue s i l v e r m i n e r a l but i n B r i t i s h Columbia i s n e a r l y always a r g e n t i f e r o u s * The s i l v e r i s u s u a l l y i n the form of minute i n c l u s i o n s o f a r g e n t i t e , t e t r a h e d r i t e and the s u l p h o - s a l t s . I t i s s i g n i f i c a n t that specimens showing few i n c l u s i o n s are low i n s i l v e r . Evidence i n ores o f t h i s prov ince supports G u i l d ' s statement that the maximum s i l v e r content of c l e a n ga lena i s not over O . l f . . I t i s , however, from an economic s t a n d p o i n t , the most important s i l v e r - c a r r y i n g m i n e r a l i n the p r o v i n c e . 6. S p h a l e r i t e . Th i s m i n e r a l i s f r e q u e n t l y repor ted to be a r g e n t i f e r o u s . In the few samples a s sayed , the t r a c e o f s i l v e r o b t a i n e d was probab ly due to i n c l u s i o n s of o ther m i n e r a l s . When s p h a l e r i t e i s a r g e n t i f e r o u s i t probably con-t a i n s some t e t r a h e d r i t e . 7. C h a l c o p y r i t e . Dolmage a t t r i b u t e s most o f the s i l v e r va lues i n the b i g copper d e p o s i t s to some a s s o c i a t i o n w i t h c h a l c o p y r i t e , p o s s i b l y s o l i d s o l u t i o n . 8. S t r o m e y e r i t e . Only one occurrence i s known i n B r i t i s h Co lumbia . I t i s r e p o r t e d by l e r o y from the Ne l son a r e a . - 7 1 -9* Tetrahedrite (and F r e i b e r g i t e ) . This i s the most important e a r l y mineral of s i l v e r i n the deposits of t h i s provinceo I t i s found most commonly i n the lower temperature deposits. 1 0 o P y r a r g y r i t e . Nearly always associated with tetrahed-r i t e , t h i s mineral appears to be primary but some secondary occurrences are reported. 1 1 . P r o u s t i t e . Reported from the Toric mine but not i d e n t i f i e d by the w r i t e r . I t i s also reported from the Slocan but not by Cairnes. No d e f i n i t e a n a l y s i s of t h i s mineral has been reported, so that i t s occurrence i s somewhat doubtful. 1 2 . Stephanite. The only d e f i n i t e occurrence of t h i s mineral i s reported by Cairnes from the Anna mine and one or two other p r o p e r t i e s i n the Slocan but i t has been noted from the Portland Canal area. I t i s t y p i c a l of the r i c h dry ores, and may be both hypogene and supergene. I J . P o l y b a s i t e . Next to p y r a r g y r i t e t h i s mineral appears to be the most common s i l v e r sulpho-salt i n the province. I t i s reported from Premier, Beaverdell and the Slocan. I t i s u s u a l l y associated with the other sulpho-salts i n the r i c h e r upper l e v e l s of the low temperature deposits. According to Cairnes i t i s probably secondary but not n e c e s s a r i l y super-gene * I t i s thought 1 0 be primary at Beaver d e l l , and at Premier i s known to be d e f i n i t e l y hypogene and supergene. . , I d e n t i f i c a t i o n o f these s i l v e r sulpho-salts i s d i f f i c u l t , so that others, not mentioned, may be present but not recognized. I t i s p a r t i c u l a r l y d i f f i c u l t to determine the minute i n c l u s i o n s i n galena, some of which may be one or more - 7 2 -of these s u l p h o - s a l t s . 14. C e r a r g y r i t e i s reported by Cairnes from the U t i c a mine i n the Slocan where i t occurs as rods i n s p h a l e r i t e . 1.5• A r g e n t o - j a r o s i t e . This mineral was t e n t a t i v e l y determined by the w r i t e r from o x i d i z e d ore of the A l l c o mine. These oxides were examined under the microscope and yellow hexagonal p l a t e s were noted but m e t a l l i c s were absent. Assays of t h i s m a t e r i a l amounted to 20 oz. of s i l v e r per ton. P o s i -t i v e sulphate t e s t s f u r t h e r confirmed the determination. One or two other s i l v e r - b e a r i n g minerals, such as s y l v a n i t e , have been b r i e f l y mentioned by various w r i t e r s , but no d e f i n i t e confirmation of t h e i r determination was given. Such minerals are at best only c u r i o s i t i e s and are unimportant i n any of the p r o p e r t i e s known to the w r i t e r . Base-Metal A s s o c i a t i o n s of S i l v e r . Copper. Tetrahedrite i s the mo st important primary mineral of s i l v e r i n deposits of B r i t i s h Columbia. I t i s found, however, with s i l v e r and lead but seldom with copper ores. Chalcopyrite i s thought by Dolmage to carry the bulk of the s i l v e r values i n the copper ores. Cairnes mentions the a s s o c i a t i o n of c h a l c o p y r i t e with t e t r a h e d r i t e i n the Slocan. The w r i t e r has not examined the copper ores and can make no other suggestion as to the mineral a s s o c i a t i o n of s i l v e r . Stromeyerite has been i d e n t i f i e d i n only one property. Lead. S i l v e r values associated with galena are almost e n t i r e l y accounted f o r by i n c l u s i o n s of argentiferous - 7 3 -m i n e r a l s . One specimen o f ga lena from Great Bear l a k e , examined by the w r i t e r , s h o w e d no i n c l u s i o n s ; assay r e s u l t s ^ showed a s i l v e r content o f o n l y 4 o z . per t o n . The importance o f the s i l v e r a s s o c i a t i o n w i t h l e a d i s best e x p l a i n e d by replacement o f s i l v e r m i n e r a l s by g a l e n a , and p r e f e r e n t i a l replacement o f ga lena by l a t e r s i l v e r m i n e r a l s . Galena i s the l a t e s t base metal m i n e r a l to be d e p o s i t e d and so i s most commonly a s s o c i a t e d w i t h the s i l v e r m i n e r a l s which are a l so l a t e i n d e p o s i t i o n . E c o n o m i c a l l y l e a d i s the most important base metal w i t h which s i l v e r i s a s s o c i a t e d . F o r t u n a t e l y i t i s a l s o the best metal f o r t h i s a s s o c i a t i o n from m e t a l l u r g i c a l and economic s t a n d p o i n t s . Z i n c . The s i l v e r content o f s p h a l e r i t e i s a t t r i b u t e d 11 53 by C a i r n e s and o ther s to the pre ference shown f o r i t by t e t r a h e d r i t e . The w r i t e r has found evidence o f t h i s a s s o c i a -t i o n i n s e v e r a l o r e s . However t e t r a h e d r i t e seems to be most h e a v i l y d e p o s i t e d a long boundar ies o f s p h a l e r i t e and g a l e n a . I n c l u s i o n s o f ga lena i n s p h a l e r i t e commonly c o n t a i n minute i n c l u s i o n s of s i l v e r m i n e r a l s and probab ly represent r e p l a c e -ment of e a r l i e r t e t r a h e d r i t e . T i n . The Snowflake mine i s the only ore depos i t i n B r i t i s h Columbia i n which s i l v e r i s found w i t h t i n . S i l v e r m i n e r a l s are found most abundantly where the s t a n n i t e and ga lena are most abundant. S tanni te i t s e l f conta ined no s i l v e r . In c o n c l u s i o n i t may be s a i d tha t the s i l v e r (1) R i d l a n d , C . G e o l . 9 Rept . , U . B . C . , 1936. -74-a s s o c i a t i o n s of the v a r i o u s ores i n order of economic import-ance and abundance are l e a d , z i n c , copper, gold and t i n . Of these r e l a t i o n s h i p s , only the copper mineral t e t r a h e d r i t e c a r r i e s a l a r g e inherent s i l v e r content. Galena, s p h a l e r i t e and s t a n n i t e are important f o r the mechanically admixed s i l v e r minerals which they commonly contain. Galena i s always argen-t i f e r o u s i n B r i t i s h Columbia, but no specimens were seen by the w r i t e r that d i d not contain a r g e n t i f e r o u s i n c l u s i o n s . S p h a l e r i t e i s normally very low i n s i l v e r ; a l l assays of pure samples of t h i s mineral were very low i n s i l v e r . The s i l v e r content of a l l base metal ores i n t h i s province, w i t h the p o s s i b l e exception of the low-grade d e p o s i t s , i s very l a r g e l y due to the presence of d e f i n i t e s i l v e r minerals. The amount of s i l v e r held i n s o l i d s o l u t i o n or other i n v i s i b l e form i n the common minerals i s very s m a l l . Types of Argentiferous Deposits. S i l v e r i s found most abundantly i n deposits of v e i n f i l l i n g type. I t i s also found i n considerable amount i n r e -placement de p o s i t s . The only occurrence i n B r i t i s h Columbia In a pyrometasomatic deposit i s at Copper Mountain. The r i c h e s t s i l v e r deposits are those of lowest temperature. No d e f i n i t e epithermal s i l v e r deposits are known i n B r i t i s h Colum-b i a . The majority of them are i n the mesothermal range and a few are of hypothermal o r i g i n . Depth and Zoning of S i l v e r Deposits. The s i l v e r - b e a r i n g copper ores are found as i r r e g u l a r -75-b o d i e s , l y i n g i n shear zones and a long beds amenable to r e -placement . These d e p o s i t s are so i r r e g u l a r i n shape that development i s more l a t e r a l than v e r t i c a l , and hence no great depths (more than 1500 f ee t ) have been reached . Some s i l v e r m i n e r a l s , a r g e n t i t e and n a t i v e s i l v e r , are commonly found near the s u r f a c e , but at depth va lue s are low and f a i r l y c o n s t a n t , w i t h no d e f i n i t e s i l v e r m i n e r a l s v i s i b l e . The grea t replacement depos i t of S u l l i v a n and sma l l e r ones at A i n s w o r t h , show very l i t t l e d i f f e r e n c e i n s i l v e r va lues at d e p t h , apar t from the s e c o n d a r i l y e n r i c h e d zone c lo se to the s u r f a c e . Depth can mean l i t t l e i n such a depos i t as the m i n e r a l i z a t i o n probab ly a l l took p l a c e under n e a r l y i d e n t i c a l c o n d i t i o n s from beg inn ing to end. The r i c h d r y ores are n e a r l y always found i n v e i n s . These ore bod ie s tend to grade w i t h but l i t t l e increa se i n depth i n t o the s i l v e r - r i c h l e a d o r e s , i n which the s i l v e r decreases and z i n c i n c r e a s e s at d e p t h . The l a s t stage o f t h i s zoning tha t may be t r a c e d i s the p y r i t e - q u a r t z ore w i t h some s p h a l e r i t e , p o s s i b l y some g o l d and l i t t l e s i l v e r . T h i s s e r i e s extends from the top to the bottom of the mesothermal range . A l though such a s u c c e s s i o n o f zones seems very s a t i s f a c t o r y i n t h e o r y , there i s no one i n s t a n c e i n which the v a r i o u s zones have a l l been found i n a cont inuous s e r i e s o f f i s s u r e s . U s u a l -l y , one type of ore occurs near the top o f a mountain, the second a mi l e or two away and nearer the parent p l u t o n i c s , and so f o r t h . I n any p a r t i c u l a r r e g i o n t h i s s u c c e s s i o n i s much compl i ca ted by m i n e r a l o g i c a l l y s i m i l a r d e p o s i t s being found at -76-g r e a t l y v a r y i n g d i s t a n c e s from the source . Yet no one o f these d e p o s i t s appears to extend to much over 1000 feet i n . d e p t h . The w r i t e r suggests that the e x p l a n a t i o n of such anomalies l i e s p a r t l y i n the governing s t r u c t u r e s , f i s s u r e s , e t c . , which a l l o w f a i r l y r a p i d expansion of s o l u t i o n s and r e s u l t i n g concent ra ted bod ie s o f o r e . The other important f a c t o r s are the l e n g t h o f time over which m i n e r a l i z a t i o n has taken p l a c e and the p o s s i b i l i t y o f more than one impulse per -i o d o f m i n e r a l i z a t i o n accompanying the parent i n t r u s i o n . I n -d i c a t i o n s o f s t r u c t u r a l c o n t r o l are v e r y common to t h i s type o f s i l v e r depos i t and r e s u l t s i n s m a l l bodies o f ore which f i l l o n l y p a r t s o f the a v a i l a b l e f i s s u r e s . D e f i n i t e s t r u c t u r a l i n d i c a t i o n s of two p e r i o d s of m i n e r a l i z a t i o n are found i n f a u l t s c u t t i n g the ore b o d i e s , which themselves have been more l a t e l y m i n e r a l i z e d . At P r e m i e r , i n the Uhuk R i v e r area and i n the S l o c a n sudden changes i n compos i t ion o f the ore suggest s i m i l a r breaks i n m i n e r a l i z a t i o n . Summary and Comparison o f R e s u l t s . I n a paper such as t h i s , whose data are incomplete and c o n c l u s i o n s l a c k i n g i n d e t a i l , comparison with r e s u l t s o b t a i n e d elsewhere i s probab ly the most i n t e r e s t i n g f e a t u r e . I t has been found that i n the e s s e n t i a l mineralogy o f s i l v e r and i n the pa ragenes i s , the depos i t s o f the s i l v e r -l e a d type c l o s e l y approximate the g e n e r a l i z a t i o n s made by G u i l d . T e t r a h e d r i t e i s u s u a l l y the important e a r l y s i l v e r m i n e r a l . I t i s f o l l o w e d and p a r t l y r e p l a c e d by ga lena and i t s a s s o c i a t e d a r g e n t i t e . There are d e f i n i t e a l though not -77-u n i v e r s a l i n d i c a t i o n s that the l a t e r s i l v e r s u l p h o - s a l t s , a r g e n t i t e and p o s s i b l y n a t i v e s i l v e r , may i n part have been d e r i v e d from the e a r l i e r t e t r a h e d r i t e and a r g e n t i f e r o u s galena by hypogene a l t e r a t i o n . Th i s theory was f i r s t formulated by G u i l d , p a r t l y on evidence from ores from S locan c i t y . The w r i t e r has n o t i c e d that n a t i v e s i l v e r i s very l a r g e l y a t t r i b u -22 t e d to supergene a g e n c i e s , but as Cooke has shown, s i l v e r i s e a s i l y d i s s o l v e d i n f e r r i c su lphate s o l u t i o n and p r e c i p i t a t e d i n n a t i v e forms by many common s u l p h i d e s , i t seems qu i te p o s s i b l e that s i m i l a r c o n d i t i o n s may have a p p l i e d to the magmatic s o l u t i o n s . C e r t a i n l y much o f the n a t i v e s i l v e r i n B r i t i s h Columbia pre sent s the appearance o f an hypogene miner-a l under the mineragraphic microscope . As i n par t s o f U t a h ^ , the a c t u a l form of a s s o c i a -t i o n of s i l v e r w i t h the base-metals i s l a r g e l y d i s s e m i n a t i o n o f s m a l l , o f t e n minute q u a n t i t i e s o f s i l v e r minera l s among the base metal o r e s . The common preference fo r l e a d r a t h e r than z i n c i s c h a r a c t e r i s t i c o f d e p o s i t s i n t h i s p r o v i n c e . The amount of s i l v e r a s s o c i a t e d w i t h copper i s so smal l that no v a l u a b l e comparison can be made w i t h G u i l d ' s s i l v e r - c o p p e r t y p e . R e s u l t s of assays and m i c r o s c o p i c a l examinat ion 65 c l o s e l y correspond to those obta ined by Warren y i n the western U . S . A . , France and S p a i n . B r i e f l y , t h e amount o f s i l -v e r i n h e r e n t l y c o n t r o l l e d by base metal ores i s very s m a l l . The m i n e r a l s i n the order of t h e i r inherent s i l v e r content appear to be t e t r a h e d r i t e , g a l e n a , c h a l c o p y r i t e and s p h a l e r -i t e . T e t r a h e d r i t e probably conta ins s i l v e r as an isomorphous - 7 8 -molecule; Lord reports analyses showing 23% s i l v e r from the Yukon,' Galena when fre e from i n c l u s i o n s appears to carry up to 0,1% s i l v e r and c h a l c o p y r i t e up to 0,0013%. Sphalerite when free from i m p u r i t i e s shows only a t r a c e . Most s i l v e r deposits i n other countries have been notable f o r the r i c h zone of cementation, and i n dry c l i m a t e s , f o r valuable o x i d i z e d deposits. In B r i t i s h Columbia such zones are very shallow, and but s l i g h t l y r i c h e r than the o r i g i n a l ore. Heavy r a i n f a l l and a f a i r l y shallow water table have been p a r t l y responsible f o r lack of r i c h o x i d i z e d ore and f o r the shallow zone of cementation r e s p e c t i v e l y . However' the time a v a i l a b l e f o r enrichment by supergene forces has been r e s t r i c t e d to t h a t , elapsed since g l a c i a t i o n . Nearly a l l w r i t e r s agree that the p r i n c i p a l reason f o r the common lack o f such enrichment i n B r i t i s h Columbia i s the removal of those zones by the i c e . Enrichment since that time has been very meagre. AGEHOWLEDGMMTS. The w r i t e r was f i r s t indebted to D r . Warren f o r sugges t ing the s u b j e c t , and subsequent ly f o r h i s i n t e r e s t and c o n s t r u c t i v e c r i t i c i s m . S ince i t s i n c e p t i o n t h i s paper has undergone many changes i n p r e s e n t a t i o n of i t s sub ject mat ter , l a r g e l y due to h i s sugge s t ions . The methods used were e s s e n t i a l l y those employed by D r . Warren i n h i s own work on s i m i l a r sub j e c t s . To D r . Dolmage the w r i t e r wishes to tender h i s g r a t i t u d e f o r many communications r e g a r d i n g p r o p e r t i e s i n a l l p a r t s of the p r o v i n c e , and f o r much p r a c t i c a l i n s t r u c t i o n i n m i c r o s c o p i c t e c h n i q u e . Mr . J . M . Cummings made p o s s i b l e much o f the l a b o r a t o r y work through long hours o f master ing the p o l i s h i n g machines and microchemica l a n a l y s i s . He was a l so k i n d enough to take most o f the photographs and to s u p e r i n t e n d the r e s t . I t would be imposs ib le to enumerate the many d i s c u s s i o n s w i t h , and c r i t i c i s m s from f e l l o w students which form such an i n d i s p e n s a b l e par t o f graduate work. Mr . B i s h o p , o f the department of M i n i n g , devoted two days to making and checking assays of the p i c k e d m i n e r a l s . - i i -BIBLIOGRAPHY No. Author l o Bateman, A.M. S i l v e r - l e a d Deposits of the Slocan D i s t -r i c t . Ee. Geol. xx, 554 . 2 . Bateman, G.C. Gold and S i l v e r i n Canada. C.I.M. & M. B u l l . Oct. 1935« 3« Bancroft,J.A. Coast and Islands o f B r i t i s h Columbia. G.S.C Mem. 2 5 . 4 . Bostock, H.S. The Home S i l v e r Mine„ G.S.C. Summ.Rept. 1927 A. 5© Bremian, C V . Personal communication. 6. Brewer, W.M. Some Ore Deposits of the Coast Range. C . I . M . & Mo B u l l . Nov. 1922. 7. Brock, R.W. Pre l i m i n a r y Report on the Rossiand Min-ing D i s t r i c t . G.S.C. Pah. No. 959. G.S.C. Summ.Rept, 1906. 8 . Buddington,A.F. V a r i a t i o n s of Types of M i n e r a l i z a t i o n of Coast Range I n t r u s i v e s . E c 0 Geol. x x i i , p .1580 9 . n n High Temperature Mi n e r a l Deposits at Shallow to Moderate Depths. Ec. Geol. xxx, p.205« 10. Burton Mineralogy of the Premier Mine. Ec. Geol. x x i , 5 8 6 . 1 1 . Cairnes, C.E. Slocan Mining Camp. G.S.C. Mem. 173° 12. " " Descriptions of P r o p e r t i e s , Slocan Mining Camp. G.S.C. Mem.l84« 1 3 . " " The Coquihalla Map-Area. G.S.C.Mem.139» 14. " " Pemberton Area, l i l l o o e t , G.S.C. Summ.Rept. 1924 A . » 11 Notes;,on the'Slocaho.- CI®K®.&.Me B u l l . Feb, 1927. 16. Cairnes, D.D9 Portions of the A t l i n D i s t r i c t . G.S.C. Mem. 37» 17- Camsell, C. S i l v e r at Stump Lake. G.S.C. Summ. Rept. 1919 B. - i i i -l 8 ® 2 0 . 2.X « 22 © 2 3 . 24. 2,5 ® 2 6 . 2 7 . 2 8 . 2 9 . 3 0 . 31« 3 2 . 33 • 34 . 55-36 • Camsell, G, Chapman & Stephens Cockfield,W.E« Cooke, H.C. Daly, R. A. De M i l l e , J.B. Dolmage, V. II it n 11 11 it it 11 n it tt 11 n it Emmohs, H^ W. Emmons, S.F. Fowler, S.S. Galloway, J»D. Tulameen D i s t r i c t . G.S.C. Summ. Rept. 1909. Reconnaissance along the l i n e of the P.G.E. Rly. G.S.C. Summ. Rept. I 9 1 7 B. An Isomorphous Molecule with Galena. Ec. Geol. x x v i i i , p.6 8 5 . S i l v e r - l e a d Deposits of A t l i n . G.S.C. Summ. Rept. 1925 A. The Secondary Enrichment of S i l v e r Ores. Jour, of Geol. x x i , p. 1. Reconnaissance from Revelstoke to Golden, G.S.C. Summ. Rept. c i r c a I909. Canada's Mineral Production f o r I935. E. & M. J . Feb. I936. High-Grade S i l v e r - G o l d Ore from the B.C. S i l v e r Mine. C.M.J. 45, Ho.30, p.7111. Geology and Ore Deposits of Copper Mount-ain© G.o.C© Mem.171© Copper-Silver Veins of Telkwa D i s t r i c t . Ec. Geol. x i i i j p.349. The Marble Bay Mine, Texada Is l a n d . Ec. Geol. x v i , p.3 7 2 . The Chilko Lake Area. G.S.C. Summ. Rept. 1924 A. The Western M i n e r a l B e l t of B. C. C.M.J. 4 5, Ho. 2 6 . Reconnaissance up the Portland Canal. G.S.C. Summ. Rept. 1922 A. Personal Communication. Mineral Resources of the lardeau. CM.I.J. x i i , p.453» Enrichment of Sulphide Ores. U.S.G.S. B u l l . 5 2 9 . Personal Communication. S i l v e r , i n B r i t i s h Columbia. B.C. Miner, May 1935° - i v -37e Graton, L.C. Depth Zones i n Ore Deposition,, Ec, Geol, x x v i i i , p.513, 38. G u i l d , H. The Mineralogy of S i l v e r Deposits* Eco Geol, x i i , p.303. 39. Gunning, H.C. A T i n - S i l v e r Vein at Snowflake Mine, Ec, Geol. x x v i , p .215. 40. Hanson, G.S. The Portland Canal Area, G.S.C, Mem. 175. 41. I r v i n g and Bancroft. U.S.G.S, B u l l s 478, p.56. 42. James, H.I. • B r i t a n n i a Beach Map-Area. G.S.C. Mem,158. 4 3 . K e r r , F.E. The Coast Range B a t h o l i t h . Proc. & Trans. Roy.Soe.Can, 1932,p.305<> 44. Leach, W.W. The Skeena River D i s t r i c t . G.S.C. Summ. Rept. I 9 0 9 . 45* l e r o y ^ O.E. Geology of Helson Map-Area. G.S.C. Summ.Rept. 1911. 46. " " Geology and Ore Deposits of Phoenix Boundary D i s t r i c t . G.S.C. Mem. 21. 47. McConnell,R.G. Windy Arm D i s t r i c t , Tagish Lake. G.S.C. Summ, Rept, I 9 0 5 . 48. McKinistry,H.E. Silver-Lead-Zinc Veins at A t l i n . E. & M.Jo 125, Mar. 24, I928. 49. " " S i l v e r M i n e r a l i z a t i o n at Beaverdell. Ec. Geol. xx, p.434. 50. Hissen, L. & Hoyt. Argent if e r o u s Galena. Ec. Geol. x, p.172. 51. O ' N e i l l , J . J . Ore Deposits of Hazelton D i s t r i c t . G.S.C. Mem. 110, 52. Ravicz, L.G. Experiments i n Enrichment of S i l v e r Ores. Ec. Geol. x, p,368. 53. Reineeke , L. Ore Deposits of Beaverdell Map-Area. . G.S.C. Mem. 79-54. Sargent , H. The S i l v e r Problem i n M i l l i n g S i lver-Lead-Zinc Ores. C.M.J. 55, p.112. 55. S c h o f i e l d , S . J . Geology and Ore Deposits of Ainsworth Mining Camp. G.S.C. Mem. 117. 5 6 . 57* 5 8 . 59» 6 0 . 61 a 62 . 6 3 e 65 « 66 * 6 7 . S c h o f i e l d , S . J . O r i g i n of S i l v e r - L e a d D e p o s i t s o f Eas t Kootenay* E c . G-eoI. v i i , p . 3 5 1 ° " " Geology of the Cranbrook A r e a . G . S . C . Mem. 1 1 2 . " " (and Hanson) The Salmon R i v e r A r e a . G . S . C . Mem. 1 3 2 . Schwartz Stephens , M.M. Teas , L . P . Uglow, W . l . V a l l a n c e , J , Warren, H . Y . Wagner L i n d g r e n , W. P r i v a t e Manuscr ip t 1 9 3 2 . M e c h a n i c a l Unmixing i n Ore M i n e r a l s . S c . G e o l . x x v i , p .759« E f f e c t o f L i g h t on P o l i s h e d Surfaces o f S i l v e r M i n e r a l s . A n n . M i n e r a l . 1 6 , p o 5 5 2 © The R e l a t i o n o f S p h a l e r i t e to the Other S u l p h i d e s . T r a n s . A . I . M . E . 5 9 s P» 6 8 . G n e i s s i c Galena from the S l o c a n . E c . G e o l . x i i , p.643<> The Standard M i n e , S i l v e r t o n . C ® I . M . J . 14, p.212® D i s t r i b u t i o n of S i l v e r i n Base-Meta l Ore s . T r a n s . A . I . M . M . E . 1 15 , p . 8 1 . A S i l v e r Depos i t o f the T r a n s v a a l . E c . G e o l . x i x , p . 6 5 4 . ' M i n e r a l D e p o s i t s ' - 1 9 3 3 ° 

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