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The mineralogy of the Bonanza silver deposit, Great Bear Lake, N.W.T. Diebel, John Keith 1948

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THE MINERALOGY OF THE BQMAEZA SILVER DEPOSIT GREAT BEAR LAKE N.W.'T.  A thesis submitted i n p a r t i a l  fulfillment  of the requirements f o r the degree of MASTER OF APPLIED SCIENCE In the Department of GEOLOGY AND GEOGRAPHY The University of B r i t i s h Columbia A p r i l , 1948.  JOHN KEITH DIEBEL  ACKNOWLEDGMENTS The writer i s indebted to Br. C. R i l e y of Vanoouver, who oolleoted the specimens and contributed valuable information concerning the geology, mineral deposits and general conditions i n the area. Special thanks are owing various members of the s t a f f of 'The Department of Geology and Geography f o r assistance received* and p a r t i c u l a r l y to Dr, H.0. Gunning, under whose superv i s i o n the work was carried out.  The technical assistance  given by Mr. J . A. Donnan i s g r a t e f u l l y acknowledged. Mr. R. G. MoOrosaan kindly did a l l the spectrographic analysis, using the Department of Physic's  spectrograph.  TABLE OF CONTENTS Page ABSTRACT INTRODUCTION by Dr. C. R i l e y GENERAL GEOLOGY  Table o f Formations. Bono Bay Group. , Cameron Bay Group.....  LNTRUSIVES General ., . Granodiorite. Granites......................... B a s i c Dykes and S i l l s . . . G i a n t Quartz V e i n s . STRUCTURAL GEOLOGY  .,  GEOLOGY OF THE BONANZA CLAIMS General. Sedimentary Rooks Granodiorite..................... Minera.// -ia.t/on  MINERAL DEPOSITS General MINERALOGY OF THE BONANZA GROUP G e n e r a l Statement................ Magnetite Hematite • Tetrahedrite.., A r g e n t i te Chalcopyrite Unknown Native S i l v e r  1 2 3 3 3 4 4 5 6 8 8 8 9  II  12 13 14 15 17 19 21 22 22  GANGUE MINERALS Quartz................. S e r i o i t i o Gangue................. Carbonate Gangue  25 28 28  ORIGIN OF THE DENDRITIC FORM OF SILVER....  29  SUMMARY OF MINERALOGY..,  33  PARAGENESIS  34  TABLE OF CONTENTS (float d)1  Page TEMPERATURE OF FORMATION  ,  36  ORIGIN OF THE SOLUTIONS  37  COMPARISON WITH OTHER DEPOSITS ....................  39  GENERAL  .  39  .............. •  40  COMPARISON WITH THE SILVER DEPOSITS AT COBALT, ONTARIO......  COMPARISON WITH THE ERZGEBIRGE DEPOSITS OF SAXONY AND CZECHOSLOVAKIA IN CENTRAL EUROPE COMPARISON WITH MISCELLANEOUS DEPOSTS...  41 43  CONCLUSIONS  44  BIBLIOGRAPHY  46  ILLUSTRATIONS F i g u r e I - G e n e r a l i z e d Map o f tae Echo Bay D i s t r i c t , N . W. T .  After page 1  P l a t e 1.  18  2.  18  3.  18  4i  18  5.  19  6.  19  7.  21  8.  21  9.  24  10.  24  11.  32  12.  32  4  ABSTRACT A study of the mineralogy of a suite of specimens, c o l lected "by Dr.C.Riley from the Bonanza s i l v e r deposit, has been made,  P a r t i c u l a r attention i s paid to the s i l v e r mineraliza-  tion and the o r i g i n of the dendritic structure,  A b r i e f ex-  amination of the wall rock a l t e r a t i o n i s included. The mineralogy of the deposit i s r e l a t i v e l y simple, cons i s t i n g of the following metallic minerals i n their order of abundance:  native s i l v e r , magnetite, hematite, tetrahedrite,  argentite, chalcopyrite,' and an unknown mineral. and cobalt-nickel minerals are absent.  Pitchblende  Magnetite and hematite  are r e s t r i c t e d to the wall rock and are not associated with the other metallic minerals.  The magnetite i s believed to be of  pyrometasomatic o r i g i n and related to a granodiorite intrusion, while the other metallic and gangue minerals, m) 1Lli 1.liesaggaafss L1 uii I.I P^s^^^feg, are considered to be of hydrothermal  origin.  The gangue minerals consist of quartz, s e r i c i t e , and carbonate. l i n e t y - f i v e percent of the native s i l v e r occurs as dendr i t e s and the other f i v e percent as replacement r i t e and chalcopyrite. developed.  Core replacement  of tetrahed-  by the s i l v e r i s well  The dendritic structure of the s i l v e r i s inherited  from quartz through replacement.  In a quartz gangue t h i s  structure appears to be controlled by rows of s p e c i a l l y oriented, doubly terminated, quartz prisms, while i n a s e r i c i t i c gangue the euhedral quartz grains, arranged i n a rude dendritic pattern, are the c o n t r o l l i n g factor. The mineral deposits of the Echo Bay area are compared with similar deposits throughout  the world.  INTRODUCTION by DR.  0. RILEY  Introduction. The ores described herewith were collected i"n June, 1932, by 0. R i l e y from the Bonanza s i l v e r prospect.  The only work  done at that time consisted of one shallow p i t on the vein and some s t r i p p i n g .  It was  therefore not possible to take a  complete suite of ores from the deposit.  The specimens, how-  ever, are probably representative of the main types of vein material.  They were taken for the purpose of study and des-  c r i p t i o n but opportunity to do such work was not available u n t i l Mr. J.K.. Diebel undertook the work during the winter of 1947-48.  Location. The Bonanza vein i s situated on Dowdell Point, about s i x miles south of the Eldorado Radium Mine on the eastern of Great Bear Lake.  The deposit should not be confused  shores with  the E l Bonanza prospect which i s about one half mile to the east (see Figure I ) . History. The Bonanza vein was Bine and E.C. Ltd.  discovered i n June, 1931, by G.A.  La  St.Paul, prospectors working for Eldorado Mines  A small amount of surface work was done i n 1931, and i n  1938 some underground work was been published.  done but no record of i t has  The property has, therefore, been inactive  most of the time since i t s discovery. Accessibility. The vein i s less than one h a l f mile on easy grade, from a  -ii small Day on Great Bear Lake.  Otherwise i t would be serviced  in the same manner as the Eldorado Mine - that i s , by r i v e r and lake boats, and by a i r . Climate. The climate of the country i s severebut not unpleasant. Winters are cold and dry;  the snowfall i s from three to four  feet.  Late winter and spring have long, clear and pleasant  days.  Summer i s short and f a l l commonly dreary.  The lake i s  open for navigation from July to October, Topography. 'The Great Bear Lake d i s t r i c t has unusually rugged topography f o r a pre-Cambrian area. feet above the lake l e v e l .  Rocky h i l l s r i s e about 1200  The Bonanza vein i s very l i t t l e  higher than the lake but the area immediately  to the north i s  rough and p r e c i p i t o u s . General Mining Conditiolis. E x p l o i t a t i o n of the Bonanza vein would offer no problems other than those to be expected from the remote l o c a t i o n and severe and protracted winter.  Timber, however, i s sparse and  stunted and already made scarcer by the long use of i t "by the Eldorado Mine.  Replacement by growth i s slow.  GENERAL GEOLOGY The  general geology  ed by D.F.  o f the Eoho Bay a r e a has been d e s o r i b -  K i d d (1932$, H.S.  R o b i n s o n (1933), G.M.  ( 1 9 3 9 ) , B. Murphy (1946) and o t h e r s .  Furnival  The f o l l o w i n g d e s c r i p -  t i o n i s a summary o f t h e i r work. The  g e n e r a l geology  i s shown i n F i g u r e I .  rooks a r e a complex s e r i e s o f v o l c a n i c and  The  oldest  sedimentary  rocks,  and p r o b a b l y i n t r u s i v e p o r p h y r i e s , known as the "Old Complex", On l i t h o l o g i c a l grounds, these e a r l y r o o k s a r e d i v i d e d i n t o two groups; and  the lower, member b e i n g c a l l e d the Eoho Bay  the upper member, the Cameron Bay  group.  group  TABLE OF FORMATIONS  1  Quaternary  i S i l t , clay, gravel, morainal material i i  Unoonformity Precambrian(?) iBasio dykes and s i l l s ;  large quartz veins  (Intrusive Contact)  Precambrian(?) 'J•Granite and other acid plutonic rocks •  i  (Intrusive Contact) Preoambrian  |Quartz d i o r i t e and granodiorite i  (Intrusive Contact ?) Sedimentary and volcanic complex subdivided into: (a) Cameron Bay group - conglomerate, t u f f , a r Precambrian  •  g i l l i t e , etc. unoonformity  •  (b) Eoho Bay group - porphyritic volcanics, a r g i l l i t e , quartzite, conglomerate, etc.  •— tuff,  -3 Eoho Bay Group: its  In 4U+H-U.- u p p e r part, the Eoho Bay group consists mainly of porphyries, at some places extrusives, with minor amounts of a r g i l l i t e and t u f f .  In the lower part of the group s i l i c e o u s  a r g i l l i t e , t u f f , quartzite, conglomerate are abundant.  and a l i t t l e limestone  The "base of the group has not been seen.  The  rooks have moderate to steep dips and s t r u c t u r a l l y appear to underlie the Cameron Bay group, though the contact has not been observed.  The presence i n the Cameron Bay conglomerate  of abun-?  dant pebbles of rooks similar to those i n the Echo Bay group, suggests there i s an unconformity between the  two.  i  Cameron Bay Group: The Cameron Bay group shows a uniform deposition of sediments;  f i r s t a poorly consolidated cobble conglomerate  with  some interbedded greywacke, followed by coarse g r i t , arkose and sandstone. ate.  One f e l s i t e flow i s interbedded with the conglomer-  The t o t a l thickness i s i n the v i c i n i t y of 3000 feet.  Vein quartz pebbles and a single granite pebble indicate that there may  have been a period of g r a n i t i c intrusion p r i o r to  the formation of the group. Intrusives - General: The Echo Bay and Cameron Bay groups have been intruded by acid and basic rocks. youngest  In chronological order from oldest to  they are: 1. Granodiorite to d i o r i t e  -42. D o w d e l l P o i n t g r a n i t e and L i n d s a y Bay g r a n i t e 3.  Diabase Dykes ( o l d e r )  4. Diabase Dykes and S i l l s  (younger)  Granodiorite: The  g r a n o d i o r i t e o c c u r s as i r r e g u l a r e l o n g a t e d s t o c k s i n -  t r u d i n g the Echo Bay and Cameron Bay groups.  A typioal speci-  men o f g r a n o d i o r i t e i s m a s s i v e , medium-grained, g r a n i t i c t u r e d and r e d d i s h t o g r e e n i s h - b r o w n i n c o l o u r . plagioclase  In thin section  (oligoolase to andesine), orthoclase,  quartz,  a u g i t e , b i o t i t e and i r o n o x i d e s a r e u s u a l l y p r e s e n t . r o c k s have caused an u n u s u a l l y round t h e i r b o r d e r s . quarter  tex-  These  g r e a t amount o f metamorphism  A t many p l a c e s , f o r a w i d t h o f one-  o f a m i l e o r more, the i n t r u d e d  r o c k s a r e r u s t y weath-  e r i n g , due t o d i s s e m i n a t e d p y r i t e , and c o n t a i n c h l o r i t e , magn e t i t e , b i o t i t e , epidote,  a c t i n o l i t e and r e d f e l d s p a r .  g r a n o d i o r i t e i s o l d e r , a t l e a s t , t h a n the D o w d e l l P o i n t  The granite,  because i t i s c u t by the g r a n i t e . Granites: The  Dowdell P o i n t g r a n i t e and the L i n d s a y Bay g r a n i t e do  not  occur i n contact  age  i s n o t known.  w i t h each o t h e r ;  thus t h e i r  relative  The Dowdell P o i n t g r a n i t e i s an e n t i a r e l y  massive, f r e s h - l o o k i n g , coarse-grained,  u s u a l l y somewhat p o r -  p h y r i t i c , b u f f t o p i n k , crumbly w e a t h e r i n g b i o t i t e g r a n i t e . The  L i n d s a y Bay g r a n i t e i s m a s s i v e , mediums-grained, r a t h e r  uni-  form i n appearance, w i t h l i g h t brown t o b u f f t o white t o p i n k  -5feldspars, quartz, b i o t i t e and, i n some places, hornblende. It i s occasionally s l i g h t l y porphyritic near the borders. dykes are minor d i f f e r e n t i a t e s of both granites.  Aplite  Pegmatites  are rare. Basic Dykes and S i l l s ; Basic dykes are widespread and cut rocks of a l l the four groups previously'described.  A few dykes d i f f e r l i t h o l o g i c a l -  l y from the more abundant type i n having some red feldspar and are p r o v i s i o n a l l y separated as an older type. These older dykes have been termed "gabbro" by Robinson (1933, p. 618).  'They are the youngest intrusive that can be  d e f i n i t e l y shown to be older than the pitchblende-silver mineralization.  Kidd (1932D, p.140) reports that thin sections from  two of these dykes show a rock with a medium even grain, also subhedral plagioclase grains (oligoclase to andesine), a l i t t l e orthoclase, quartz, augite and iron ore. The more abundant type of basic dyke i s widespread, genera l l y steeply dipping and up to 100 feet i n width. variable.  The trend i s  They are medium to fine-grained, and greenish-grey  to greenish-black  i n color.  In some instances the medium  grained parts have a diabasic texture. A f l a t - l y i n g dyke (or perhaps more than one) outcrops at many places.  It i s found as a series of isolated occurrences  that  may have been one continuous body.  It i s only 100 to 500 feet  thick but of great l a t e r a l extent.  It i s a quartz norite, which  in thin section shows conspicuous i n t e r s t i t i a l  micrographic  i n t e r g r o w t h s o f q u a r t z and f e l d s p a r , sill,  lithologioally this  o r f l a t - l y i n g dyke, i s s i m i l a r to the -more abundant  s t e e p l y - d i p p i n g b a s i o dykes and p r o b a b l y i s p a r t o f the same intrusive. S l a n t Q u a r t z Veins; fliWHiimi  the a r e a .  1 I r S t o o k w o r k s o f l a r g e q u a r t z v e i n s are common i n These v e i n s a r e l o c a l l y known as g i a n t q u a r t z v e i n s .  They range i n w i d t h from 50 t o 500 f e e t and have l e n g t h s up t o ten miles.  They c o n t a i n no f e l d s p a r n o r any a p p r e c i a b l e  t i t y of m e t a l l i c m i n e r a l s .  quan-  Their occurrence i n f a u l t s , w h i c h  out n e a r l y a l l the known igneous r o c k s , s u g g e s t s t h a t they a r e n o t r e l a t e d t o i n t r u s i v e s now exposed.  STRUCTURAL GEOLOGY I n the Eoho Bay d i s t r i c t the r o c k s of the s t r i k e n o r t h and s o u t h a t  G l a o i e r Bay and s w i n g s o u t h e a s t  s t r i k e about S.60°E. n o r t h of Contact L a k e . western edge o f a g e n t l e against  " O l d Complex" to  They form the  s y n c l i n e w h i c h has "been crumpled  the g r a n i t e a l o n g the shore of Great Bear L a k e , n o r t h  and s o u t h of Echo Bay.  E x c e p t n e a r the g r a n i t e b o d i e s ,  d i p s are u s u a l l y l e s s than 45 degrees; Bay group i s o n l y s l i g h t l y f o l d e d .  the  much o f the Cameron  Considering i t s proximity  t o so many i n t r u s i v e b o d i e s t h i s i s r a t h e r The a r e a i s broken by many f a u l t s ,  remarkable.  the m a j o r i t y of which  have r i g h t - h a n d o f f s e t s and s t r i k e about n o r t h e a s t .  Little  evidence has been found of major v e r t i c a l movement.  There  l a r g e q u a r t z v e i n s i n s e v e r a l o f the f a u l t s ,  are  and the c o i n c i d -  ence i n d i r e c t i o n between the system of q u a r t z v e i n s and the major f a u l t s s u g g e s t s t h a t many of the v e i n s may occupy f a u l t s . As some o f the l a r g e q u a r t z v e i n s cut the g r a n i t e ^ t h e possibly post-dates  the  faulting  granite.  The most prominent f a u l t i n the d i s t r i c t i s a t Cameron Bay ( F l g u r e l ) .  C o n t a c t s m e e t i n g i t appear to be d i s p l a c e d  about t h r e e m i l e s .  A l a r g e q u a r t z v e i n l i e s i n the  I n a d d i t i o n to the n o r t h e a s t t i o n s of o t h e r s t r u c t u r e s s t r u c t u r e s may r e p r e s e n t faulting.  faults,  fault.  t h e r e are  sugges-  t h a t t r e n d n o r t h and s o u t h . j o i n t i n g and f r a c t u r i n g r a t h e r  These than  They are i n d i c a t e d by n o r t h - s o u t h dykes o f c o n s i d -  -8erable  length. Geology of the Bonanza C l a i m s  General: The m i n e r a l i z a t i o n occurs i n banded sedimentary r o c k s the Eoho Bay g r o u p , a p p r o x i m a t e l y o n e - q u a r t e r  of  of a m i l e wide,  b o r d e r e d on the s o u t h by the D o w d e l l P o i n t g r a n i t e and on the n o r t h by a body of g r a n o d i o r i t e . Sedimentary Rooks-: The s e d i m e n t a r y r o c k s s t r i k e w e s t - n o r t h w e s t l y v e r t i c a l l y . They a r e ,  i n large p a r t ,  and d i p n e a r -  t h i n l y banded  cherts,  q u a r t z i t e s and a r g i l l i t e s , now l a r g e l y r e c r y s t a l l i z e d .  In  t h i n s e o t i o n they c o n s i s t p r i m a r i l y o f v e r y f i n e - g r a i n e d ,  re-  c r y s t a l l i z e d q u a r t z w i t h m i n o r amounts o f c h l o r i t e , green m i c a or h o r n b l e n d e , some c l o u d y a l t e r a t i o n ,  possibly a clay mineral,  Some. and e u h e d r a l g r a i n s of m a g n e t i t e ,  niiv+.n,* n  enough f i n e , d i s s e m i n a t e d hematite  to g i v e them a r e d d i s h c o l -  our.  The magnetite  bands  contain  c r y s t a l l i z e d l a t e since i t cuts i n t o a l l  the o t h e r m i n e r a l s . I n d i v i d u a l bands range from l e s s t h a n l / l 6 i n c h t o inch i n width.  The average g r a i n s i z e i s l e s s  t h a n 0 . 0 5 mm.  Some bands, p a r t i c u l a r l y i n the m i n e r a l i z e d zone, much s o f t e r , colour.  l/8  are  weather d i f f e r e n t i a l l y , and have a dark green  They c o n t a i n a l a r g e amount of f l a k y c h l o r i t e and a t  some p l a c e s much h e m a t i t e  and m a g n e t i t e .  Altered calcareous  The a l t e r a t i o n i s s i m i l a r to  beds.  They are p r o b a b l y that  oaused a t o t h e r p l a c e s by t h e g r a n o d i o r i t e .  A study of t h i n  s e c t i o n s o f these h i g h l y a l t e r e d s e d i m e n t a r y r o c k s shows w i d e s p r e a d development o f t a b u l a r t o f i b r o u s , g r e e n , s t r o n g l y p l e o c h r o i c , pennine c h l o r i t e w i t h anomalous b l u e colours, along with t y p i c a l greenish chlore(?) ohlorite. the groundmass,  Iron-stained  interference  to colourless  cleno-  carbonate predominates i n  Replacement o f t h e c h l o r i t e and c a r b o n a t e by  s u b h e d r a l g r a i n s o f m a g n e t i t e i s common.  R o s e t t e s and s t r i n g -  e r s o f h e m a t i t e a r e s c a t t e r e d t h r o u g h o u t much o f the rock.. I n one s e c t i o n t h e groundmass i s composed almost e n t i r e l y o f . minute shreds o f s e r i o i t e ( o r t a l o ? K length,  l e s s than 0.1 mm. i n  S e r i o i t e i s a l s o p r e s e n t t o a minor e x t e n t i n o t h e r  t h i n s e c t i o n s o f the a l t e r e d rock. following optical properties:  The s e r i o i t e has t h e  e l o n g a t e d s h r e d s , p a r a l l e l ex-  t i n c t i o n , t h i r d - o r d e r i n t e r f e r e n c e c o l o u r s and a mean i n d e x of r e f r a c t i o n , determined by means o f immersion o i l s , o f 1.57E. Granodiorite:* The  g r a n o d i o r i t e i s a b o r d e r phase o f a c o m p a r a t i v e l y  l a r g e i n t r u s i v e t h a t extends about f i v e m i l e s e a s t .  A speci-  men o f t h i s r o c k , t a k e n c l o s e t o t h e s e d i m e n t a r y c o n t a c t , was mode.ra.tely a  1 pli  a l t e r e d , d a r k , f i n e - g r a i n e d rook* w e l l m o t t l e d  p i n k f e l d s p a r g r a i n s and weathered t o a p i n k i s h - w h i t e  with  colour  f o r a d e p t h o f a p p r o x i m a t e l y l / 3 2 i n c h on t h e exposed s u r f a c e . £ 'The term g r a n o d i o r i t e , as used i n t h i s paper, r e f e r s t o ^ a ~ ^ ' lu,t L ILL 1 u u .ranging i n c o m p o s i t i o n from g r a n o d i o r i t e t o d i o r i t e . c  -10A t h i n s e o t i o n o f the same specimen i n d i c a t e d i t was a gammas* a i u i r l Lu w i t h the f o l l o w i n g m i n e r a l  composition:  O p t i c a l p r o p e r t i e s b y whioh the e s s e n t i a l mine r a l s were i d e n t i f i e d .  Mineral Orthoclase  26  Hornblende  15  i n d e x l e s s than balsam; untwinned; b i a x i a l w i t h l a r g e 2V g r e e n - p l e o o h r o i o ; b i r e f r i n g e n c e * 0.20; maximum e x t i n c t i o n a n g l e i n l o n g i t u d i n a l s e c t i o n s = 13°;  b i a x i a l n e g a t i v e w i t h 2V about 70°.  Biotite  15  p l e o c h r o i s m ; s t r o n g e s t a b s o r p t i o n when t h e cleavage  t r a c e s were p a r a l l e l t o t h e v i b r a t i o n  plane o f the lower n i c o l . Plagioolase (Andesine)  15  Quartz  10  Chlorite  10  Magnetite Apatite Sericite Some c l a y mineral  10  maximum e x t i n c t i o n a n g l e o f a l b i t e t w i n s i n s e c t i o n s normal t o 0/0 " 16°; i n d e x g r e a t e r than balsam; b i a x i a l n e g a t i v e w i t h 2V about 80°„ uniaxial positive  -11In thin section the rock i s moderately altered.  About 80 per-  cent of the feldspar, p a r t i c u l a r l y orthoclase, has altered to s e r i c i t e and a cloudy a l t e r a t i o n product, probably one of the clay minerals. mm.  Small, fresh remnants of plagioclase, about  i n diameter, are f a i r l y abundant.  of hornblende to b i o t i t e are evident. altered to c h l o r i t e .  0.1  A l l stages of a l t e r a t i o n Some of the b i o t i t e has  Much of the magnetite i s along cleavage  planes of the b i o t i t e thus suggesting i t i s secondary a f t e r the a l t e r a t i o n of hornblende. primary o r i g i n was seen.  Very l i t t l e magnetite of possible Both hornblende and b i o t i t e are con-  spicuously embayed along t h e i r margins by grains of quartz and ' feldspar, and i n addition, commonly contain isolated inclusions v  of these minerals.  The writer has interpreted the above r e l a -  tionships as i n d i c a t i n g replacement of the hornblende and biot i t e by quartz and feldspar. the  A few seams of c h l o r i t e traverse  rock. The contact between the granodiorite and the sedimentary  rocks i s very i r r e g u l a r and the intrusive contact appears to dip;.south at a low angle under the sedimentary rocks;  this  may account f o r the extensive a l t e r a t i o n of the intruded rock. Specimens of the Dowdell Point granite were not available and thus no study could be made of the granite and i t s a l t e r a tion effects. Mineralization: Dr. G. S i l e y has supplied the following.description of the  ore zone: "Bonanza Number 5 showing oocurs i n a brecciated and  -12she<x.red  z o n e  ally.  SO  me 20 feet wide, s t r i k i n g N. 20° W. and.dipping  vertiGr  The zone, l i e s . w i t h i n banded sedimentary rocks just at  t h e i r contact with a granodiorite to the north.  The sediment-  ary rocks strike N. 20° to 25° W. and vary i n dip from 65° S.W.  to v e r t i c a l .  They consist of banded oherts, quartzites  and a r g i l l i t e s a l l highly metamorphosed and fractured." "The granodiorite i s altered i n the same manner." "The  chief mineral i n the vein i s native s i l v e r i n quartz  and c a l c i t e lenses and stringers.  Locally, the s i l v e r forms  25 percent of the lenses and' stringers.  Magnetite and hema-  t i t e are abundant gangue minerals and appear to be e a r l i e r than the s i l v e r . " "Some distance to the south of the zone, coarse-grained, pink granite i s i n t r u s i v e into the sedimentary rocks along a c l e a r l y defined contact." MINERAL DEPOSITS General. The mineralization* of economic interest i n the Echo Bay IS  d i s t r i c t ss*e s i l v e r and pitchblende.  The p r i n c i p a l deposits  are shown i n Figure I. Pitchblende occurs i n the area at Labine Point and Lake and also at Hottah Lake, 110 miles to the,„south.  Contact It i s  frequently i n botryoidal, oolloform or dendritic forms.  Mag-  n e t i t e , cobalt and n i c k e l minerals, native bismuth, argentite, ohalcopyrite, tetrahedrite, galena, and native s i l v e r are  com-  -13monly associated with the  pitchblende.  S i l v e r occurs at most of the pitchblende Camsell River* 35 miles to the south.  deposits and at  It i s usually i n the  native state i n the form of dendrites or fine wires.  Tetra-  hedrite, cobalt and n i c k e l minerals, and argentite are c l o s e l y associated with the native s i l v e r . Copper i s widespread i n the area but of no economic importance.  It i s found i n a l l deposits, usually as chalcopy-  r i t e , bornite, chalcocite, tetrahedrite or c o v e l l i t e . Like copper, the cobalt and n i c k e l minerals are of widespread occurrence but of l i t t l e direct economic importance. They are found as smaltite-chloanthite, skutterudite, cobalti t e , n i c c o l i t e , and g e r s d o r f f i t e . The more important deposits occur i n breociated and shear-, ed zones. calcite.  The gangue minerals  comprise quartz, b a r i t e , and  Much of the carbonate i s manganiferous. Mineralogy of the Bonanza Group  General Statement: Microscopic  study was made of 20 polished sections and  thin sections from the Bonanza group.  Physical and  16  optical  c h a r a c t e r i s t i c s coupled with etch reactions were used f o r mineral determinations.  A l l the m e t a l l i c minerals, except f o r  native s i l v e r , hematite and magnetite, were considered  too  small to be i s o l a t e d into pure samples large enough for spectroscopic or micro-chemical analysis.  Two  spectroscopic  •-14-  analyses were made of native s i l v e r . Magnetite  (ffe^O^: •  The magnetite  i s abundant i n 1}he altered wall rock and the  banded sedimentary rocks but i s conspicuously lacking i n the veins or stringers of quartz or c a l c i t e .  It occurs as euhed-  r a l to subhedral grains and as i r r e g u l a r stringers or massive patches replacing the country rock.  Remnants of carbonate,  quartz, ohlorite, and s e r i c i t e are found i n the massive magnetite.  In some cases the massive magnetite has i r r e g u l a r d i s -  seminations of tabular pennine c h l o r i t e grains i n i t , a texture s i m i l a r i n appearance to "diabasic".  giving  The magnetite -  i s commonly rimmed and cut by stringers of hematite.  In thin  sections of the. fine-grained, banded sedimentary rocks, magnet i t e i s found as scattered, small, euhedral grains cutting into the r e c r y s t a l l i z e d s i l i c e o u s groundmass. In a l l cases examined the magnetite  i s l a t e r than the  country rock a l t e r a t i o n but i s the e a r l i e s t metallic mineral present.  It i s generally accepted that the majority of the  magnetite (1)  i s related to the granodiorite intrusion.  Dr. C.  R i l e y states that i n the Echo Bay d i s t r i c t , and also immediatel y to the south, i t i s more the rule than the exception, to find magnetite as disseminations, patches or veins adjacent to the granodiorite contact but i n the intruded rock. (1) B i l e y , 0.: Oral Communication,  1948.  -15^ Hematite (ffe Q<*): g  Hematite i s w i d e s p r e a d i n the d e p o s i t hut n o t as a b u n dant as some o f the hand specimens might i n d i c a t e .  These  specimens have a r e d d i s h tone s u g g e s t i n g a l a r g e p r o p o r t i o n o f hematite,  but when they are examined c a r e f u l l y the r e d d i s h  tone i s found to be due to the d o m i n a t i n g r e d c o l o u r of a few narrow hematite  s t r i n g e r s whosej.pqwder has covered the  o f the specimen.  surface  >  Hematite commonly o c c u r s as t i n y i r r e g u l a r seams, up t o l / l 6 i n c h i n w i d t h , c u t t i n g or rimming the m a g n e t i t e . the rook i s b r e c c i a t e d  Where  i t i s common f o r the a n g u l a r p i e c e s  to  be cemented by c a r b o n a t e c o n t a i n i n g much f i n e l y - d i v i d e d hematite.  The a l t e r e d r o c k u s u a l l y c o n t a i n s  hematite,  f i n e l y disseminated  or r o s e t t e s o f the same m i n e r a l , a l o n g f r a c t u r e s  i n t e r s t i t i a l t o the m i n e r a l g r a i n s .  Ohert and carbonate v e i n -  l e t s commonly c o n t a i n enough d i s s e m i n a t e d hematite g i v e them a r e d d i s h c o l o u r .  "dust'*  to  The same a p p l i e s f o r some of  s i l i c e o u s bands i n the f i n e - g r a i n e d , banded sedimentary Hematite was n o t found t o be a s s o c i a t e d m e t a l l i c m i n e r a l s other than magnetite;  w i t h any o f  any c h e r t  the  rocks. the  or carbonate  t h a t c o n t a i n e d hematite was u s u a l l y v o i d of m e t a l l i c s . faot,  or  This  however, may not have much s i g n i f i c a n c e as K i d d and Hay-  cock (1935, p . 9 0 5 ) ,  and F u r n i v a l (1939, p.751) found t h a t  h e m a t i t e was q u i t e commonly a s s o c i a t e d  a t L a b i n e P o i n t and a t  C o n t a c t Lake w i t h v a r i o u s oopper and s i l v e r m i n e r a l s . The hematite  is definitely later  t h a n the m a g n e t i t e  and  16appears to be e a r l i e r than the native s i l v e r since the veins containing s i l v e r cut hematitio country rock.  It i s possible  that the hematite may be of two generations! the f i r s t one f i l l i n g fractures i n the magnetite and altered rock and acting as a cement along with carbonate f o r the brecciated material, and the second generationuappearing with the chert and carbonate stringers.  However, since no direct evidence was found  substantiating the theory of two generations of hematite, i t i s probably best to assume one generation l a t e r than the magnetite and e a r l i e r than the s i l v e r . The best evidence f o r hydrothermal o r i g i n of the hemat i t e i n the area i s presented by Murphy (1946, p.436) i n the following passage:  "The a l t e r a t i o n of the rocks and veins  i n the v i c i n i t y of the Eldorado mine 'is prominent, and the 'baked  1  appearance of a l l formations, except the l a t e r diabase,  has been frequently remarked.  In both rocks and veins, the  a l t e r a t i o n has given r i s e to widespread  discolouration by  hematite and the o b l i t e r a t i o n of o r i g i n a l textures. called red a l t e r a t i o n , undoubtedly  This so-  related to the quartz-  hematite period of mineralization, affects the quartzose rocks most severely, but, where a l t e r a t i o n i s intense, there i s l i t t l e selectivity.  The rocks are then reduced to a dense,  reddish 'jasperoid'. The exact nature of the a l t e r a t i o n has not been determined, but quartz, hematite, magnetite,  seri-  c i t e , c h l o r i t e , and carbonate are obvious constituents.  -17-  "Going away from the mine, the degree of a l t e r a t i o n f a l l s off, hut the mineralization i s so pervasive that i n no oase oan i t he said that examination has been carried beyond the zone of a l t e r a t i o n .  The d i s t r i b u t i o n of the a l t e r a t i o n points  to the mine as being a centre of mineralization i n the d i s t r i c t , and indicates that the veins and a l t e r a t i o n have a common hydrothermal source.  In a geophysical examination of the  area, Brant has noted an unusually high magnetite content of the rocks on Labine Point.  The percentage of magnetite  de-  creases away from the mine, thus giving further evidence as to the locus of mineralization." The above description i s comparable to the s i t u a t i o n at Bonanza mine and thus i t i s l o g i c a l to assume that the hemat i t e at Bonanza i s also hydrothermal. Tetrahedrite Tennantite  (50ugS.3(Ouffe)S.SSbgSgi}: (SGugS.SfGuFejS.gAsp.S^):  The physical and chemical properties of tetrahedrite and tennantite are so s i m i l a r that chemical or spec&rographic analysis must be resorted to i n order to distinguish between them.  Although tetrahedrite (or tennantite) i s widespread  in the polished sections, i t was never found i n s u f f i c i e n t quantity to enable a spectrographic sample to be isolated.  In  the remaining part of t h i s paper this mineral s h a l l be c a l l e d tetrahedrite, with the understanding that i t may be tennantite. Tetrahedrite appears i n more than 50 percent of the polish-.  -18* ed sections, but only as sparsely disseminated small  grains.  Usually the mineral could barely be distinguished under low power and was revealed lenses.  only -by high power or o i l of immersion  The largest single piece of tetrahedrite i s shown  i n Plate I, where the width of the mineral i s about 0.5 mm. Tetrahedrite  i s c l o s e l y associated primarily with native  and argentite, and to a minor extent with chaloopyrite unknown pinkish-cream mineral.  silver  and an  With the exception of chalco^  pyrite, i t i s older than a l l the metallio minerals with which i t i s associated.  Argentite  consistently replaces  tetrahedrite  andj invariably, i r r e g u l a r islands of the mineral are found within argentite, as i l l u s t r a t e d i n Plates I I and III. The argentite replacement most commonly starts on the borders of the: tetrahedrite, and advances very rapidly along easiest channels, such as fractures.  - •  The s i l v e r replacement of tetrahedrite generally begins at the core of the mineral and advances towards the rim.  In  many cases remnant rims of tetrahedrite, p a r t i a l l y rimmed by argentite, can be seen bordering s i l v e r (Plates I and IV). Edwards (1947, p. 97) c i t e s core replacement by s i l v e r as occurring at Oobalt, Ontario, KQnigsberg, Norway and Contact Lake i n the Eoho Bay d i s t r i c t . l H H H " l l , n  1*1  PJ  i n n i i i i n  l . n  IIUJJIM  I.Twi l,Ml.''nlnii1r'1 1,11, IIIII  will i i l l  t l i n  u u l m  iiii  u b  r n u n  iiiil  r  Silver  i,Ljilm.I.LLII.IIL  u  n  ) m 1  111 Mini 0  M  I)  ^ ^ ^ t e i ^ ^ M a ^ ^  »•  n,  ol Liim Lria-b-jfa-  P r n . n l . u r n  nmj>  M M !  1  M . ^ " " " ' "  =  1  Occasionally under  high power.silver can be seen replacing tetrahedrite from the  x 204 Plate I Core replacement of tetrahedrite by s i l v e r i n a s e r i c i t i c gangue.  Plate I I Islands of tetrahedrite and s i l v e r i n argentite.  The gangue i s mostly s e r i c i t e ,  x  1250  Plate I I I  Argentite r e p l a c i n g t e t r a h e d r i t e . t l l e  Note  s i l v e r beginning to replace the a r g e n t i t e .  x  P l a t e IV  204  S i l v e r rimmed by t e t r a h e d r i t e (dark gray) and a r g e n t i t e ( l i g h t gray).  This i s thought  to be an advanced stage of core replacement.  outer borders i n much ^he  same manner as the-argentite  does.  A few small remnants of tetrahedrite were f ound i n s i l v e r i n several of the polished Tiny 'snake r-l i k e in one polished  1  sections. ve i n l e t s of tetrahedrite were found-,!  section, with t h e i r borders being replaced  a pinkish-cream, unknown mineral and,  by  occasionally, by argen-  t i t e (Plate V). Intimate association of chalcopyrite and seen i n only one section. l y replaced  tetrahedrite  was  The chalcopyrite has been d e f i n i t e -  by tetrahedrite.. The grey mineral rim3 the  p y r i t e with the replacing front advancing into the  chalco-  chalcopyrite  along the easiest channels, very similar t o the replacement of tetrahedrite by argentite.  A poor example of this i s shown  in the upper part of Plate VI. Tetrahedrite  occurs in the same gangues as s i l v e r , namely*  carbonate, quartz and The  sericite.  following i s a summary of the tests used to i d e n t i f y  tetrahedrite: Colour ( i n polished section): Hardness:  Steel grey.  C *.  Crossed N i c o l s : Etch Tests:  Isotropic.  HNO , HCl., FeClg, KOH, K O I , and HgClg a l l g  negative. Miscellaneous: Argentite  Triangular p i t s i n some of the mineral.  (AggS):  Argentite  i s intimately associated with, but not quite so  • • •• Plate V  x 1250.  * "Snake-like" stringer of tetrahedrite rimmed by the unknown mineral i n a s e r i c i t i c gangue.  x 204  Plate VT partly  Chalcopyrite be 1 life replaced by s i l v e r and tetrahedrite (dark gray).  The dark back-  ground i s the quartz gangue.  - 2 0 -  abundant as tetrahedrite.  The two minerals have practically  the same occurrence^and t h e i r relationships have already been described. S i l v e r and argentite have much the same relationships as s i l v e r and tetrahedrite except that the s i l v e r i s more commonly associated with the l a t t e r ;  however, this may be because  of the r e l a t i v e abundance of the two minerals.  Plate II shows  s i l v e r replacing argentite from the core outwards,and Plate I I I shows i t replacing argentite from the border inwards.  Argen-  t i t e , with imbedded islands of tetrahedrite, occasionally i s completely rimmed by s i l v e r . In some instances argentite i s found with chalcopyrite. but i n these cases tetrahedrite i s usually present also.  Some  replacement of the chalcopyrite by argentite may have taken place but the invariable presence of tetrahedrite as well suggests that a good deal of the argentite replaced r i t e and not chalcopyrite.  tetrahed-  The unknown pinkish-cream mineral  was not found associated with argentite. It i s possible that some of the argentite i s supergene though p o s i t i v e evidence on t h i s point was not found. The tests by which argentite was i d e n t i f i e d are as- f o l lows: Colour ( i n polished section): Hardness:  B -•  Crossed Nicols:  Isotropic.  Light grey.  -21Btoh Tests: HNOg - d e f i n i t e bluish-green HCl  - commonly negative;  KCN  - stains brown  tarnish  oooasional  tarnish  FeClg- dark s t a i n HgOlg- d e f i n i t e irridesoent s t a i n KOH  - negative  Ohaloopyrite (OuFeSpj.: Chalcopyrite  i s rather scarce i n the polished sections.  It appears i n only three out of the 20 sections and i n only p o s s  one of these i s i t  in  nn r r i  H  / b/<e. i imt.  .vim m l  i.nnn  to determine i t s  associations and r e l a t i v e age. Generally the chalcopyrite oocurs as isolated small grains, about 0 . 1 mm. i n diameter, scattered throughout the gangue and not p a r t i c u l a r l y associated with any of the other m e t a l l i c minerals.  Whenever chalcopyrite does occur with the  other metallics i t i s decidedly, and i n some instances  exten-  s i v e l y , replaced by them, e s p e c i a l l y by tetrahedrite.  Silver  occasionally replaces the chalcopyrite as core replacement (see Plate VI).  Three i r r e g u l a r grains of chalcopyrite are  shown i n Plate VII with three patches of unknown pinkishcream mineral at the bottom of the photomicrograph. Chalcopyrite was i d e n t i f i e d by the following means: Colour^in polished section): Hardness:  C•  Brass yellow.  x 204 Plate VII Chalcopyrite  and t h e unknown  m i n e r a l i n a s e r i c i t i c gangue.  Plate VIII A t y p i c a l s i l v e r dendrite i n a q u a r t z gangue.  J  -22-  Grossed N i c o l s :  S l i g h t l y anisotropic.  Etch Tests:  -  M O „ - irridesoent tarnish o  KCN  - very l i g h t tarnish  HOI, FeClg, KOH and HgClg ~ negative. Unknown Pinkish-Oream Mineral: ,  An unknown pinkish-oream mineral oocurs sparsely i n two  of the polished sections.  As already mentioned i t s relation-?  ships are: (1) as replacement rims on tetrahedrite (see Plate V). (2) as isolated blebs scattered throughout the section (see Plate VII). A l l that can be said of the unknown's r e l a t i v e age i s that i t i s younger than tetrahedrite. Properties of the unknown mineral are: Colour ( i n polished section): Hardness:  Pinkishr-cream.  C .  Crossed l i c o l s :  ;•  •  .  Isotropic.  Etch Tests: HHOg, FeClg, HgClg - very l i g h t tarnish. HCl, KCfi, KOH - a l l negative. lative Silver  (Ag.):  Native s i l v e r i s the most abundant and widespread m e t a l l i c mineral  i n the polished sections and hand specimens.  found i n a l l sections of the vein material.  It i s  With the exception  of hematite and magnetite, i t i s the only m e t a l l i c mineral that can be seen i n megascopic examination.  Ninety-five per-  cent of the silver'occurs either as individual, dendrites or in a dendritic pattern.  The other f i v e percent appears as  isolated blebs and seams, and as replacements of tetrahedrite, argentite or chalcopyrite.  The gangue minerals, i n order of  abundance, comprise quartz, s e r i c i t e and carbonate. The dendritic pattern i s most widely developed i n a quartz gangue.  The i n d i v i d u a l dendrites*, one of which i s i l l u s -  trated i n Plate VIII, are up to l/4 inch i n length with a decided branching tendency.  Looally, the dendrites appear to  be oriented i n one of three d i r e c t i o n s , intimating rhombic control;  however when the specimen i s viewed generally the  dendrites have a random orientation and no control i s suggested.  A poor dendritic pattern i s ahown i n Plate IX. The o r i -  gin of the d e n d r i t i c pattern w i l l be discussed f u l l y with the gangue minerals.  S i l v e r i s i n v a r i a b l y associated with t e t r a -  hedrite, argentite and to a minor extent with chalcopyrite, whenever these minerals are present.  These associations have  already been described (see Plates I, II, III, IV and V). Two spectrographic analyses of what was believed to be pure s i l v e r gave the following results: Silver  :  strong  Copper  :  strong  Mercury : weak to moderate Bismuth : weak to moderate  -24Cobalt  : nil  Nickel  :  iiil  Arsenic : n i l Antimony: n i l The oopper oould he due to admixed tetrahedrite or chalcopyrite but since no mercury or bismuth minerals were found in any of the polished sections i t i s only l o g i c a l to assume that these elements are alloyed with the s i l v e r .  It i s i n -  teresting to note that Furnival (1939, p.763) found mercury alloyed with s i l v e r at Contact lake and that Knight (1924» p.35)  reported the same at Cobalt. Native s i l v e r i s the youngest metallic mineral i n the  deposit and with the possible exception of some of the late barren carbonate veins, i s the l a s t mineral to be deposited. Kidd and Haycock (1935, p. 925) state that the s i l v e r i s the l a s t hypogene mineral to form at Labine Point (Eldorado). From the small scope that the specimens o f f e r i t i s r a ther d i f f i o u l t to determine p o s i t i v e l y whether the s i l v e r i s supergene or hypogene;  however, by comparison with other de-  p o s i t s i n the area and considering the negative evidence i t i s concluded that the greater part of the s i l v e r i s hypogene. summary of the points i n favour of hypogene s i l v e r follows: (1) The notable absence of supergene mi nw n l a wnnh =ssgc o v e l l i t e and  chalcocite.  (2) The presence of mercury and bismuth i n the s i l v e r .  A  x  65  Plate IX S i l v e r r e p l a c i n g d e n d r i t e s o f carbonate i n a q u a r t z gangue. i n the csrbonste.  Note the specks o f  x  silver  bo  Plate X  po.\rtly  Q u a r t z , I n a r u d e d e n d r i t i c p a t t e r n , 1»» Inj^ r e p l a c e d b y s i l v e r said c a r b o n a t e . i s mostly  serlcite.  The ====  It i s very u n l i k e l y that these elements would appear . i n supergene s i l v e r , e s p e c i a l l y since no mercury mine r a l i z a t i o n has been noted i n the area. (3) Furnival (1939, p 763) found a homogeneous* coarse, r e c r y s t a l l i z e d structure i n s i l v e r at Contact Laket which, according to Edwards (1947, p.6) i s indicative of hypogene s i l v e r .  . "~ .  (4) Kidd and Haycock (1935, p.926) state that the s i l v e r at Labine Point i s older than ^supergene manganese oxides and after careful study concluded that the greater percentage of the s i l v e r was hypogene. i u r O n e point which makes S.jfpergene o r i g i n f o r the s i l v e r feasible i s the fact that the specimens were taken from within a few feet of the surface. Gangue Minerals:  ^  Quartx- Quartz i s the most abundant gangue mineral.  It  constitutes 90 percent of the gangue i n 60 percent of the specimens and i n the remainder i t i s conspicuous as dendritic inclusions.  The quartz i s a fine to medium grained, white,  c r y s t a l l i n e variety with interlocking, more or less  equidimen-  sional, anhedral grains and displays a vuggy character i n some of the specimens.  The vuggy quartz oontains no s i l v e r miner-  a l i z a t i o n though i t i s immediately adjacent to c r y s t a l l i n e quartz carrying up to 25 percent s i l v e r .  This implies that  the vuggy quartz i s l a t e r than the s i l v e r mineralization and could be a result of secondary deposition by c i r c u l a t i n g ground  -26waters. Bands of " j a s p e r - l i k e " chert, up to l/4 inch wide,-containing cryptocrystalline quartz with f i n e l y disseminated, blotohy hematite, frequently occur at the contact of the quartz veins and the country rock.  They carry l i t t l e or no s i l v e r mineral-  i z a t i o n and are considered to be l a t e r than the s i l v e r .  It i s  thought that the chert bands, because of t h e i r very fine grained .character, were deposited from c o l l o i d a l suspension near the close of the s i l v e r mineralization.  On the basis that the  hematite i n the deposit i s of hypogene o r i g i n and that i t i s not uncommon to get' c o l l o i d a l s i l i c a deposited i n the late stages of mineralization, i t i s assumed that the chert i s of hypogene o r i g i n . The quartz bodies have sharp, frozen contacts.  ¥o one  specimen showed both walls but from descriptions by Kidd (1932P, (1) p.27c),. Lord (1941, p.49) and Dr. 0. R i l e y the quartz appears as lenses up to eight inches by 30 inches i n brecciated and sheared zones.  In thin section the quartz frequently contains  i n t e r s t i t i a l f i n e grained s e r i o i t e indicating that at least some of i t i s replacement  of the s e r i c i t i c rock i n or near the  shear zone. Two &ges of quartz are evident i n the s e r i c i t i c gangue. One appears as altered i r r e g u l a r remnants, that have been extensively replaced by s e r i o i t e ;  the other i s a fresh euhedral  (l) Riley, 0.: Oral Communication, 1948.  -27-  quartz displaying a poor dendritic pattern, with minor replacement by carbonate. by the s i l v e r .  The dendritic pattern i s largely inherited  (See Plate X).  In a quartz gangue the s i l v e r has a strong tendency to be i n t e r s t i t i a l to the quartz grains and to replace carbonate (Plates IX and XI).  ICven i n eases where no carbonate appears  to be present, s l i g h t effervescence  can frequently be observed  along the margins of s i l v e r grains when a drop of dilute hydrochloric acid i s applied to the area, suggesting that the s i l v e r may  have replaced carbonate,  In thin section s i l v e r  dendrites are often surrounded by a narrow rim, less than 1 mm.  wide, of c r y p t o c r y s t a l l i n e quartz that i s much f i n e r than  the fine to medium-grained groundmass.  This could be due to,  either excessive quartz entering solution at the time of s i l v e r replacement and being redeposited  i n s i t u as a d r y p t o c r y s t a l - \  l i n e rim around the s i l v e r , or to an introduction of cherty quartz with the s i l v e r .  Of the two proposals the f i r s t  one  seems to be more plausible as i t does not involve introduction of s i l i c e o u s material and as the c r y p t o c r y s t a l l i n e quartz a tendency to grade into the quartz gangue.  has  The fact that  some of the rims have a s l i g h t l y cloudy appearance somewhat resembling  some of the chert bands may  support  the l a t t e r  proposal. A l l the quartz i s d e f i n i t e l y older than the s i l v e r minera l i z a t i o n , excepting possibly of course, the chert bandstand the rims around the s i l v e r dendrites.  -28S e r i c i t i c Gangue - S e r i e i t e i s next i n abundance to quartz as a gangue mineral i n the specimens studied.  It i s  composed of a mass of small f i b r e s or flakes of s e r i e i t e less than 0.3 mm.  i n length, with minor amounts of carbonates, and  a few remnant grains of quartz that have been l a r g e l y replaced^ by the s e r i e i t e .  Euhedral grains of quartz i n a poor dendrit-  ic pattern, some carbonate and the metallic ore minerals are a l l younger than the gangue. means of immersion  The s e r i e i t e , as determined by  o i l s , has a mean index of about 1,572, thus  indicating that i t i s close to pure muscovite i n composition (Wlnchell, 1946,  p.268).  Carbonate Gangue - Most of the carbonate i n the specimens i s present i n barren c a l e i t e stringers up to l/4 inch wide, that cut indiscriminately through the altered rock.  These  stringers commonly have narrow seams of chert along t h e i r contacts^and are usually devoid of any mineralization.  The only  carbonate which i s consistently related to the s i l v e r i s that replaced by the s i l v e r and associated with quartz (Plates X ana XI). Kiaa (1932P, p.27c) ana Lora (1941, p.49) give the impression that most of the s i l v e r i s i n carbonate veins or lenses rather than quartz;  thus, i t appears that carbonate i s con-  siderably more important as a gangue i n the aeposit than the available specimens inaicate.  Kiaa (1936, p.40) reportea the  following analysis of white carbonate with s i l v e r from the Bonanza aeposit:  Percent Insoluble  -  Metals  -  2°3 Alg0  " -  FeO  -  0.29  MnO  -  3.18  OaO  -  41.50  MgO  -  0.56  C0„  -  35.38  F e  3  10.96 1.14 3  ,  0  6  8.76  98.83 Equivalent to FeCOg  -  0.61  Mn00  -  5.51  -  74.11  -  1.18  3  OaOO, o MgG0 3  A l l the carbonate effervesces r e a d i l y with cold dilute hydrochloric acid i n d i c a t i n g that i t i s largely c a l c i t e . Origin of the Dendritic Form of S i l v e r : There i s l i t t l e doubt that the dendritic form of the s i l v e r has been inherited from either the quartz or carbonate. Plate X shows p a r t i a l replacement of dendritic quartz by carbonate and s i l v e r and though i t i s not i l l u s t r a t e d the dendrite of s i l v e r i n Plate VIII changes abruptly to carbonate outside the f i e l d of the photomicrograph.  The problem then i s :  "the o r i g i n of the dendrites of carbonate and quartz".  -30-  In the ease of the carbonate dendrites i n the quartz gangue (Plates IX and XI) the carbonate i s mainly i n t e r s t i t i a l to  the grains of quartz with the s i l v e r following the pattern  of  the carbonate when i t i s present.  Thin section study of  this material was rather disheartening i n that very l i t t l e carbonate was seen i n the sections;  nevertheless, i t i s ap-  parent that the s i l v e r dendrites have replaced a dendritic structure i n the quartz gangue caused by a special arrangement of  certain quartz grains.  For example, i n one thin section"  several doubly terminated quartz prisms l i e side by side i n a row with t h e i r ends terminating i n rude pyramids.  Silver  has replaced these prism? r e s u l t i n g i n the dendritic pattern. In Plate VIII the arms of the s i l v e r dendrite could e a s i l y represent replacement of rude prisms of quartz l y i n g side by side;  as a matter of f a c t , under the e x i s t i n g circumstances  i t i s d i f f i c u l t to explain them by any other means.  In p o l -  ished section, s i l v e r i s seen to have frequently replaced dendrites of carbonate i n a quartz matrix.  In this case the  carbonate evidently has replaced the d e n d r i t i c a l l y arranged quartz a n d i n t u r n i s replaced by s i l v e r . J  >  The doubly terminated quartz prisms must have formed i n a medium that did not seriously obstruct t h e i r growth and, i n addition, permitted them to grow i n two directions.  This  type of medium might be provided by: (1)  replacement of a gangue, such as a carbonate, which  offers l i t t l e resistance to the replacing solutions and the  -31growth of c r y s t a l s .  The growth of the doubly terminated quartz  prisms could have started along minute fractures or joints i n the carbonate.  This would explain the random orientation of  the dendrites and i n addition would help to explain the rhombic control which i s suggested by some of the dendritic patterns.  The objection to t h i s theory i s that there i s no  evidence that the quartz i s a replacement  of carbonate.  (2) the quartz c r y s t a l l i z i n g i n an open f i s s u r e .  Al-  though i t might be possible to have doubly terminated quartz prisms developed i n open f i s s u r e s , i t i s d i f f i c u l t to v i s u a l ize how the decided random orientation of the dendrites could be produced by t h i s means.  In addition, there i s no evidence  in the deposit of fissure f i l l i n g . In summary, no d e f i n i t e conclusion has been arrived at as to the o r i g i n of the rows of doubly terminated quartz prisms, Two theories have been suggested but both of these lack sube s t a n t i a t i n g evidence.  The o r i g i n of the dendritic structure  c e r t a i n l y warrants further study and as an approach to this the writer suggests the study of thin sections cut to give various orientations of the quartz prisms. lem of the selective replacement  At the same time the prob-  of the rows of quartz prisms  by the s i l v e r , or carbonate,in preference to the unoriented quartz gangue might be investigated,In the s e r i c i t i c gangue the s i l v e r i n h e r i t s i t s dendritic fomm from fresh euhedral quartz arranged i n a dendritic pattern (Plate ,'Xi).  The explanation here i s not so d i f f i c u l t .  -32The quartz i n an i n d i v i d u a l dendrite a l l has the same orientation and from i t s fresh appearance, as compared to the corroded remnants of older quartz i n the same gangue, and i t s strongl y euhedral shape i t i s believed that i t has replaced the s e r i c i t i c gangue.  Here again there i s discordance  polished and t h i n sections. the; impression  between the  In the polished sections one gets  that s i l v e r i n v a r i a b l y replaced carbonate a f t e r  quartz, while i n thin section carbonate i s less abundant and the majority of the s i l v e r replaced quartz d i r e c t l y , i n the absence of carbonate.  In view of the fact that approximately  twice as many polished sections were studied containing dendriti c s i l v e r as thin sections, the writer concludes that the majority of the s i l v e r i s a replacement' of carbonate a f t e r quartz,but  that direct replacement of quartz by s i l v e r i s more  prevalent than indicated by polished section.  There i s l i t t l e  doubt that the s i l v e r prefers carbonate to quartz as indicated by the conspicuous specks of s i l v e r i n the carbonate and the equally noticeable absence of s i l v e r i n the quartz i n Plates IX,  £ n d a n X /XII.  Ho detailed study was made of dendritic s i l v e r i n a carbonate gangue but one instance was noted of a^dendritic structure i n carbonate due to d i f f e r e n t i a l polishing (Plate ill)'.' s i m i l a r to that reported by Kidd and Haycock (1935, p.956). Kldd and Haycock interpreted this as being two carbonates of d i f f e r e n t hardness with the s i l v e r p r e f e r r i n g the softer.  x  204  ' Plate XI Carbonate b e i n g r e p l a c e d by s i l v e r i n a q u a r t z gangue.  x 204v Plate XII D i f f e r e n t i a l p o l i s h i n g i n a carbonate gangue.  -33Summary of Mineralogy: The mineralogy of Bonanza i s very s i m i l a r to that described by ICidd and Haycock (1935) and Furnival (1939) at Labine Point and Contact Lake, except that f a r fewer minerals were i d e n t i f i e d at Bonanza;  however, i t must be kept i n mind  that no more than 15 specimens were examined by the writer compared to the hundreds examined by Kidd, Haycock, and Furnival.. It i s i n t e r e s t i n g to note that Kidd and Haycock (1935, p.888) i d e n t i f i e d chalcopyrite, bornite, sphalerite, tetrahedrite, c o v e l l i t e , and e r y t h r i t e on the Bonanza claims, (1) and R.B. Scott found several radioactive specimens Bonanza dump i n 1945*  (1) Scott, R.B.: Oral Communication.  i n the  -34PABA GENESIS  Kidd and Haycock (1935, p. 931) have divided the mineralization of the Echo Bay d i s t r i c t into three main stages: (1) pyrometasomatic stage (2) hydrothermal  stage  (3) supergene stage. This same c l a s s i f i c a t i o n i s well suited f o r the Bonanza deposit. The pyrometasomatic stage, at Dowdell Point, i s connected with the granodiorite intrusion, and i s concerned  primarily'  with the introduction of magnetite and the a l t e r a t i o n of the handed sedimentary rocks, characterized by widespread ment of c h l o r i t e , s e r i e i t e and carbonate.  develop-  I t i s the e a r l i e s t  of the three stages. The hydrothermal stage i s the most important as f a r as the economic aspects of the deposit are concerned.  The quartz  and carbonate gangues and a l l the m e t a l l i c minerals, excepting magnetite, are confined to the hydrothermal period. l i t t l e information was obtained concerning the r e l a t i v e age of the hematite;  i t i s undoubtedly  part of the brecciated zone.  early, as i t cements  On the other hand, i t occurs i n  minor amounts i n the chert bands which are regarded as being late.  Murphy '(1946, p.432) t i e s the major part of the hematite  i n with the quartz and i t i s reasonable to assume that the same relationship holds at Dowdell Point, with minor surges  -35 of hematite following l a t e r . Where carbonate i s present i n direct association with s i l v e r i t i s unquestionably the older of the two, but i n the case of the barren carbonate stringers some uncertainty arises. These stringers contain no mineralization and are often associated with chert bands.  The fact that the stringers are i n a  mineralized zone and are barren and, i n addition, are associated with late chert bands suggests that they are l a t e . Purnival (1939, p.768) recognized much the same phenomena at Contact Lake but in his case the carbonate was mineralized. Though the-sulphide mineralization does follow a d e f i n i t e sequence i t i s very sparse.  In no instance was  enough to be seen with the nakea eye.  i t abundant  These sulphides appear  to be the forerunners of the s i l v e r mineralization with the early t r i c k l i n g s being copper-iron sulphides, followed by copper, and antimony or arsenic sulphides, then by the s i l v e r sulphide and f i n a l l y by the great surge of s i l v e r mineralization. At the Bonanza property the supergene stage i s n e g l i g i b l e in that no supergene minerals were i d e n t i f i e d . Table I gives the suggested paragenesis f o r the minerali z a t i o n at Bonanza.  -36TABLE I . Magnetite • Hematite Quartz  -^^m^P^-  Carbonate  <t^l-  >  Chalcopyrite Tetrahedrite Argentite  —  Silver  <^kfm\\\+ 7  Unknown  < 0  TEMPERATURE OF FORMATION No d e f i n i t e c r i t e r i o n could be found i n the suite of specimens studied that might be used as a geological thermometer. The occurrence of chert bands might indicate' epithermal tures, but i s not conclusive.  tempera-  The vuggy quartz suggests low  pressure but, as was mentioned, i t could be supergene.  None of  the other minerals, textures or structures can be considered diagnostic of any p a r t i c u l a r temperature. At other deposits i n the Eoho Bay d i s t r i c t however, more d e f i n i t e evidence of the temperature of deposition of the s i l ver has been found.  Furnival (1939, p.770) found a coarse,  homogeneous, r e c r y s t a l l i z e d texture i n the s i l v e r i n d i c a t i n g i t had been deposited above i t s r e c r y s t a l l i z a t i o n temperature of 200°C;  Furnival (1939) and Zidd and Haycock (1935) i d e n t i -  f i e d native bismuth, which i s e a r l i e r than the s i l v e r , suggest-  -37ing a temperature of s i l v e r deposition of less than 271°C, Kidd and Haycock (1935, p.932) remark that f i e l d  evidence  indicates a low pressure "but give no further explanation. Although d i r e c t supporting evidence i s lacking, the Bonanza deposit i s p r o v i s i o n a l l y placed i n the epithermal to mesothermal group i n view of the following points: (1) The investigations of Furnival, Kidd and Haycock at Contact Lake and Labine Point (Eldorado) suggest a s i l v e r deposition temperature of between 200 and 271°C  possibly  accompanied by a low pressure. (2) S i l v e r i s a mineral t y p i c a l l y deposited under e p i thermal to mesothermal conditions.  OBI SIN OF THE SOLUTIONS Much has been written on the o r i g i n of the s i l v e r bearing solutions i n the Echo Bay d i s t r i c t , with the result that two d i f f e r e n t hypotheses have developed  regarding t h e i r o r i g i n .  Kidd and Hayoook (1935), a f t e r t h e i r detailed work on the E l dorado Ores, prefer the granite as the o r i g i n f o r the s i l v e r , while Furnival (1939) and Murphy (1946) show preference f o r the diabase  sill.  A b r i e f summary of the evidence supporting both hypotheses is made below.  -38 I.  Evidence favouring the granite as the o r i g i n of the s i l ver mineralization. (1) The areal d i s t r i b u t i o n of the known s i l v e r  deposits  i s adjacent to the Dowdell Point granite or i t s equivalent. (2) The close association of the pitchblende mineralization, with the pitchblende  and s i l v e r  believed to be  genetically related to the granite. (3) The presence of a l i t t l e f l u o r i t e i n both the Bonanza deposit and the Dowdell Point granite.  None of the  other intrusives i n the area have been found to contain f l u o r i t e . II.  Evidence supporting  the diabase s i l l as the o r i g i n of the  s i l v e r mineralization. (1)  S i l v e r has been found i n the s i l l .  (2) The s i l v e r i s l a t e r than the youngest acid i n t r u s i v e . (3) The close areal association of diabase s i l l s or dykes and the s i l v e r deposits. , (4) The s i l v e r veins at Oobalt, Ontario, both above and below the M p i s s i n g diabase s i l l , are generally r e garded as being genetically related to the parent magma of the s i l l . As can be seen, the evidence on both sides i s rather flimsy and c e r t a i n l y f a r from conclusive.  Associations are  strongly emphasized, but i n no single case i s anything approaching  p o s i t i v e evidence c i t e d .  The writer f e e l s he i s i n no  -39-  ppsition to choose either hypothesis and i s of the opinion that the s i l v e r may he genetically related to e i t h e r the d i a base s i l l or the granite.  COMPARISON OF THE BONANZA DEPOSIT WITH OTHER DEPOSITS GENERAL In the comparison of the Bonanza deposit with other deposits, i t should be kept i n mind that only a limited number of specimens were examined, and thus i t i s possible that the complete picture of the mineralization of the Bonanza property has not been determined.  In order to make the comparison more  complete the writer has f i r s t compared the Bonanza- deposit with the other deposits i n the Echo Bay d i s t r i c t and has then compared these as a unit with s i m i l a r deposits throughout the world. The major discrepancies between the Bonanza mineralization and  the Echo Bay d i s t r i c t as a unit are: (1) The pitchblende at Bonanza.  and cobalt-nickel minerals are absent  In addition, other minerals such as  native bismuth, bornite, molybdenite, and  stromeyerite  j a l p a i t e , which are common In the d i s t r i c t , have  not been i d e n t i f i e d i n the specimens examined. (2) Dendritic s i l v e r i s more abundant at Bonanza and the dendritic structure i s inherited from the quartz, whereas at the other properties the dendritic structure  -40  of the s i l v e r i s .commonly inherited from dendritic pitchblende or dendritic cobalt-nickel minerals. In summary, the Bonanza deposit  i s s i m i l a r to the other  deposits of the Echo Bay d i s t r i c t only i n the s i l v e r minerali z a t i o n , wall rock a l t e r a t i o n , and relationship to intrusive ' bodies.  The absence of pitchblende and cobalt-nickel miner-  als make the deposit  unique i n the area.  A summarization of the main c h a r a c t e r i s t i c s of the Echo Bay  d i s t r i c t i s as follows: The mineralization  consists primarily of early pitchblende,  followed by cobalt-nickel minerals, some sulphides, a l l y native s i l v e r . dant.  and f i n -  Oopper minerals are widespread and abun-  Characteristic minerals found are magnetite, hematite,  pitchblende, cobalt-nickel arsenides and sulpharsenides, native bismuth, chalcopyrite, galena, sphalerite,  argentite,  native s i l v e r , and mercury alloyed with the s i l v e r .  Gangue  minerals comprise quartz, c a l c i t e , manganiferous carbonate, and  barite. The pitchblende i s thought to be genetically related to  a granite  intrusive while the s i l v e r i s believed  either to the granite or to a diabase s i l l .  related  The deposits are  c l a s s i f i e d as lower epithermal to upper mesothermal and are believed  to be of Pre-Cambrian age.  COMPARISON WITH THE SILVER DEPOSITS AT COBALT, ONTARIO "is  The assemblage of minerals at Cobalt, Ontario sass very  -41s i m i l a r to those of the Eoho Bay d i s t r i c t .  The cobalt-nickel  arsenides and sulpharsenides, the character and manner of replacement of the s i l v e r , the gangues, and the presence of mercury i n the s i l v e r are p r a c t i c a l l y i d e n t i c a l with the Great Bear Lake deposits.  On the other hand, no pitchblende, hema-  t i t e , or magnetite has been reported at Gobalt and i n addition, chalcopyrite i s not so widespread nor so abundant at the Ontario locality.  At Cobalt the deposits are generally accepted  as being genetically related to a diabase dyke whereas i n the Echo Bay d i s t r i c t there i s some doubt whether the s i l v e r mine r a l i z a t i o n i s related to a diabase.  Both deposits are  thought to be late Pre-Cambrian age. COMPARISON WITH THE ERZGEBIRGE DEPOSITS OP SAXONY AND  CZECHOSLOVAKIA IN CENTRAL EUROPE  The deposits of pitchblende, c o b a l t - n i c k e l / m i n e r a l s , and s i l v e r i n the Erzgebirge area most, c l o s e l y resemble those of the Eoho Bay d i s t r i c t .  Bastin (1917,pp.121-122) has summar-  ized these deposits from the o r i g i n a l works of Milller (1860); Step, Josef and F.Becke (1904), and Viebig (1905). The Erzgebirge deposits occur as veins i n and near i n trusive masses of late Palaeozoic granite, with which the deposits may  be genetically connected.  Milller (1860) has c l a s s i - ^  f i e d the deposits as follows: A.  Older ore forming period. 1. Veins of t i n type 2. Veins of p y r i t i c lead-zinc type  -42-  B.  Younger ore forming period. 3. Veins of the Gobalt-rSilver type with pitchblende 4. Veins of the iron and manganese type.  It i s with the deposits of type B3 that we are p a r t i c u l a r l y concerned.  Notable deposits of this type occur at Jaachims-  thal i n Bohemia, and at Schneeberg, Annaberg, and iiohanngeorgenstadt i n Saxony. cribed the mineralogy  Held (1932, p 65) has competently desi n the following quotation:  "Veins of  type 3 vary somewhat i n different l o c a l i t i e s , but i n general carry the following minerals: pitchblende, s i l v e r , both native and as sulphosalts, arsenides and sulpharsenides of cobalt, n i c k e l and iron, native bismuth, antimonial minerals, i n c l u d ing tetrahedrite, s t i b n i t e , and b e r t h i e r i t e , sulphides, p y r i t e , chalcopyrite and sphalerite. s i d e r i t e , manganosiderite, fluorite.  Gangue minerals comprise quartz,  c a l c i t e , dolomite, barite, and  Pitchblende i s l a t e r than the cobalt-nickel miner-  als but e a r l i e r than the s i l v e r ores.  In the Annaberg d i s t r i c t  of the Saxon Erzgebirge, the c o b a l t - s i l v e r veins i n many places cut and displace the e a r l i e r t i n , copper and p y r i t i c lead-zinc veins."  In addition to Reid's summary i t i s worth  noting that at Schneeberg bismuth i s prevalent enough to become the major ore mineral. From the above description, i t i s evident that the Erzgebirge deposits and those of the Echo Bay d i s t r i c t , i f considered c o l l e c t i v e l y , are s i m i l a r both geologically and minerailogically.  The major discrepancies are:  -43(1) The association of the Erzgebirge deposits with t i n minerals. (2) At Erzgebirge the cobalt-nickel minerals are considered to be older than the pitchblende while at Great Bear Lake the pitchblende i s considered the older. COMPARISON WITH MISCELLANEOUS DEPOSITS There are other deposits that deserve b r i e f mention i n this comparison.  These are:  (1) Ten deposits of Cornwall (Pearce, 1875). (2) S i l v e r I s l e t property near Port Arthur, G n t . d n g a l l , 1887). (3) Native S i l v e r Ores near Wickenburg, Arizona (Bastin, 1922). (4) S i l v e r deposits at Sabinal, Mexico (Krieger, 1935). (5) S i l v e r deposits at KtJnigsberg, Norway (Beyschlag, Vogt and Krusch, 1915). 'The deposits of Cornwall are notably t i n and copper lodes a associated with g r a n i t i c intrusives.  Pitchblende has been  fecund at several l o c a l i t i e s associated with copper, cobalt, n i c k e l , bismuth, and lead ores; ver found.  at only one l o c a l i t y was s i l -  According to Pearce (1875), the pitchblende and  associated minerals, commonly occur as small veins crossing the t i n lodes. The deposits at S i l v e r I s l e t , Ontario, Sabinal, Mexioo, and Wickenburg, Arizona are s i m i l a r enough to the cobalt de-  -44-  posits to warrant no further comparison. The deposits at Konigsherg, Norway are mainly s i l v e r , believed to be supergene, and contain no pitchblende niokel minerals. Bay  or cobalt-  They can hardly be compared with the Echo  deposits, CONCLUSIONS  The  suite of specimens studied i s rather, a limited c o l l e c -  t i o n and may deposit;  not be a genuine representation of the Bonanza  therefore, i n evaluating the following conclusions  t h i s point should be borne i n mind. 1.  The magnetite i s of pyrometasomatic o r i g i n and i s related  to the granodiorite intrusion, while a l l the other m e t a l l i c and gangue minerals, excepting s e r i e i t e , are of hydrothermal origin. S.  The order of deposition of the minerals  i s believed to be  magnetite, quartz, hematite, carbonate, chalcopyrite, t e t r a hedrite, argentite, and native s i l v e r . bonate may  also be present  Late hematite, and car-  i n minor amounts. The exact  rela-  tive age of the unknown mineral could not be determined. 3.  Evidence suggests that the native s i l v e r i s of hypogene  origin.  It occurs primarily as dendrites, but occasionally  core replacements, by s i l v e r , of tetrahedrite, argentite, and chalcopyrite are also well developed. 4.  The dendritic structure of the s i l v e r i s inherited from  rows of doubly terminated  quartz prisms i n a quartz gangue^or  -45from a rude dendritic pattern of euhedral quarta grains i n a s e r i c i t i o gangue.  Two hypotheses have been advanced for the  o r i g i n of the doubly terminated quartz prisms but both lack sustaining evidence.  The rude dendritic pattern of euhedral e  quartz grains i s thought to be replacment  of the s e r i c i t i o  gangue. 5.  The Bonanza deposit i s s i m i l a r to other deposits i n the  Echo Bay d i s t r i c t only i n the s i l v e r mineralization, wall rock a l t e r a t i o n and relationship to intrusive bodies.  The absence  of pitchblende and cobalt-nickel minerals d i f f e r e n t i a t e s i t from other deposits i n the area.  -46" BIBLIOGRAPHY 1.  Bastin,E.S.(1932): Contributions to Economic Geology. U.S. Geol. Surv. B u l l . 735, pp. 131-155. 2. Bastin.E.S. and'Hill, J.M.(1917): Economic Geology of G i l p i n County and Adjacent Parts of Clear Creek and Boulder Counties, Colorado. U.S. Geol. Surv., Professional Paper, 94. 3. Beyschlag, Vogt and Krusch (1916): Ore Deposits, Vol,II, translated by S.J. Truscott. Maomillan and Co. l t d . , london. 4. Edwards, A.B.(l947): Textures of Ore Minerals, Aust. I, M.M, 5. : • F u r n i v a l , G.M.(1934): S i l v e r Mineralization at Great Bear lake, C.M.J., Vol. 55, No. 1, pp. 5-8. 6 (1939): A iilver-Pitohblende Deposit at Contact lake.. Econ. Geol., V o l . 34, No. 7, pp. 739-776. 7. Kidd, £.]?. (1931): Great Bear lake - Coppermine River Area, Mackenzie D i s t r i o t , N.W.T., Geol. Surv. Canada, Summ. Rept., Part C., pp. 47-69. 8. (1932 A): The Great Bear lake - Coppermine River D i s t r i c t , C.M.J. V o l . 53, No.l, pp.5-12, 9. (1932 B): A Pitchblende-Silver Deposit, Great Bear Lake, Canada, Econ. Geol. Vol. 27, No. 2, • p p . . 145-159. 10. (1932 C): Geology and Mineral Deposits of Great Bear Lake - Coppermine D i s t r i c t , C.I.M.M., B u l l . 245, pp. 512-523. 11. (1932 D): Great Bear Lake Are'a, N.W.T., Geol. Surv. Canada, Summ. Rept., P a r f 0. pp. 1-36. 12. .......... (1936): Rae to Great Bear Lake, Mackenzie D i s t r i c t , N.W.T., Geol. Surv. Canada, Mem. 187. 13. Kidd, D.P. and Haycock, M.H. (1935): Minerography of the Ores of Great Bear Lake. G.S.A. Vol. 46, pp. 879-960. 14. Knight, C.W. (1922):: Geology and the Mine Workings of Cobalt and South Lorraine Silver Areas. Ont. Dept. Mines, Vol. 31, Part I I . 15 (1930): Pitchblende at Great Bear Lake, C.M.J. Vol, 51, No, 41, pp, 962-965. 16. Erieger, P. (1935): Primary Silver Mineralization at Sabinal, Chihuahua, Mexico. Econ. Geol. V o l . 30, No, 3, pp. 242-259. 17. Lindgren, W. (1933): Mineral Deposits. McGraw-Hill Book Co. New York, N.Y. . 18. Lord, C.3.(1941): Mineral Industry of the Northwest Territories. Geol. Surv. Canada, Mem. 230. 19. Mtlller, H. (1860): Der E r z d i s t r i k t von Schneeberg i n Erzgebirge, i n B. von Cotta's Gangstudien, Vol. 3, pp. 129-138.  -47BIBLIOGRAPHY (cont'd) 20. 21. 22. 23. 24. 25. 26.  27 28. 29.  Murphy, 2. (1946): Geology and Mineralogy at Eldorado. G.I.M.M. B u l l . 413, pp. 426-435. Pearce, R. (1875): Notes on Pitchblende i n Cornwall. Roy. Geol. Soc. Cornwall Trans. Vol. 9, pp. 103-104. Reid, J.A. (1932): The Minerals of Great Bear Lake, C.M.J. V o l . 53, No. 2, pp. 61-66. Riley, C. (1933): Some Mineral Relationships i n the Great Bear Lake Area. C.M.J. Vol. 54, No.4, pp. 137-141. Robinson, H.S. (1933): Notes on the Echo Bay D i s t r i c t , N.W.T. C.I.M.M. B u l l . 258, pp.609-628. Step, Josef and Becke (1904): Das Vorkommen des Uranpecherzes zu St. Joachimsthal. X. Akad, Wiss. Wien S i t z u n g l i e r . Vol. 113, pp. 585-618. Spenoe, H.S. (1931): The Pitchblende and Silver Discoveries at Great Bear Lake, N.W.T. Can. Dept. Mines, Mines Branch, Invest. Min. Res. and Min. Ind. No. 3, pp. 55-92. (1932): Radium and S i l v e r at Great Bear Lake, Min. Met. , Vol. 13, No. 303, pp. 147-151. Viebeg, W. (1905); Die Silber-Wismutgfinge von Johanngeorgenstadt i n Erzgebirge. Zeitschr. prakt. Geologie Vol. 13, pp. 89-115. Winohell, A.1*. (1946): Elements of Optical Mineralogy, Part I I , Third Edition. John Wiley & Sons, • New York. -  

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