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UBC Theses and Dissertations

A study of tetrahedrite in some British Columbia ores Lord, Clifford Symington 1933

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A STUDY OF TEfRAHSDRIfE IN SOKE . B E I 2 I S H COLUMBIA GEES  C l i f f o r d S, LorO.  A I h e s i s S u b m i t t e d f o r t h e Degree o f " MASTER GP A P P i I B B SCISIC® i n t h e Department o f GEOLOGY  The U n i v e r s i t y o f B r i t i s h C o l u m b i a April  1955  CONTENTS page LIST OF ILLUSTRATIONS  INTROKJCTOT Importanee o f Te t r a h e d r i t e O b j e c t and Aims o f P a p e r GrBHO  jT'BiI  i^ClCHOWjL  CHAPTER I .  SllfnmH^r ©d^Hl©33.i> S  -a « © a\a^e~2  .«  o  ©a  oe*  ....o....o«...o..<,oo.o«,  I  e . » « < > . o e . » » » < > « . < > . . < . . . < . • • •  II  o a e ©• a  « o »  o«  e  IIJL  e o • » © © *© o o o » ««  e • © © © •© o * » « •© © o o «  o o  o •© o © o  xlT  a o  METKGDS EMPLOYED.  P r e p a r a t i o n f o r A s s a y ©<,„...  »o«  «e  o- o .© o d  o * o © « o « •«  ©** ©  A s s a y Methods and R e s u l t s ...©.....©........©.....  4  Copper ( a l l samples) < • » «© ©»© © ©«©«««© © ©««© © 3xlirer• ( a l 1 s&ncip 1 e S )  4-  o©©oo©oe©*e©«oo©eo©©«o  l e a d * Zinc„ I n s o l u b l e & I r o n \ Ssunplss 1 j H $ 3 § 5»6)  ©° *  « « « « ©  ^5  a  li€#C&0. e o * « e e -o a « « • • o « « e » w « » « * -or o © © • •<* » © IXI S O l XJifo1 '3 ••••n . • * 6 o « o *• * o » o o -o » c o * c «) « « © •» o -«L X* 021  (-C  /JXJIG  >^  d B st o e a « » o o « » is o o o © o e » o o ©  6  Lead and Z i n c (Samples 4,12,17,18 2Q).© ©«© ©  7  Z i n c ( i n a l l samples) .........©<>»©*<>©©•«©•  7  Sulphur,  8  S  I n s o l u b l e , I r o n ( i n a l l samples)..  6  CONTENTS ( c o n t i n u e d ) (METHODS EMPLOYED Assay Methods and R e s u l t s ) jiiS^S GXXX O  * © © -o 4 © o « & * e a « o « c co  G?GX$.@  «< O o e « ©  Comments on G e n e r a l  e ©o a o o o •  «> o 4 n o o  « a o s o e o •» o « o a o o ©• ©• .& « o •». o e o o -o  Accuracy  E x p l a n a t i o n o f Low T o t a l s  0 0 « <J « O ,» « O •© C O  u a e # o o « o o « see  * « -O 4 0  o « « a a o e o  CHAPTER I I . • THE ORES.- MINERALOGY ArlD PARAGMESIS. Summary o f C h a p t e r  o « a o a •o © « •» © » a » « o e o o * a c  The O r e s i T h e i r M i n e r a l o g y and P a r a g e n e s i s Specimen Ifo» 1, / Treated i n Chapter I I I . Specimen Ho..2; B l a c k B e a r Group, Quesnel M i n i n g D i v i s i o n .».. XiOO EL"t» X 0X1 .© «• « « jDjfl©  i ^ Q p O S X *fe  a »  6  •  « •* .a c o * -o o » e c © « « «  a © ••• * *» o e -« o o  a  Macroscopic D e s c r i p t i o n © & Paragenesis 9 0 » 6 O 9 O »• O O 4 0  « » * as;.® O O O Q A  Specimen l o . J : J o - J o Group, Three F o r k s Slocan Mining D i v i s i o n !I?llS  3)6  S X i>  «- <j « © o « © * e «» o © e o s o  0 0 0 0  M a c r o s c o p i c D e s c r i p t i o n ,.......« M i n e r a l o g y and P a r a g e n e s i s .«. «. Specimen E o , 4; L a n g l e y C o l l e c t i o n , Ainsworth Mining D i v i s i o n . . . jjOcation  o ©  *  o  «  «  The D e p o s i t s «•««•••<>*•«• Macroscopic D e s c r i p t i o n P a r a g e n e s i s «••*•**<.«••*..*«*»• • •  CONTENTS ( c o n t i n u e d ) page  (The Ores: T h e i r M i n e r a l o g y and P a r a g e n e s i s )  Specimen Uo. 3 ; S a d i e C l a i m , Keno H i l l , YulCOn © o © « © © « © © 4 • « © © © » © o © JjQ C  a t X On © © *  The  De  p O S i t  © « © » © « o. © « « o o © © © o © * «  22 22  © © • © © • • © o © o « *©©©©©©©  22  • M a c r o s c o p i c D e s c r i p t i o n »©<,©©© © M i n e r a l o g y and P a r a g e n e s i s «. © ©  2J 2 3  Specimen Ho. 6; Q u e s n e l , C a r i b o o .©©. ©...©.  24  Specimen Ho© 12: I l l e c i l l e w a t  .©...©...©©©.  LiO"3ation © © © * © « © © « * o © © © © « © © . © . © © • The D e p o s i t s ».•••« •«».«••••••« «••••»•• M i n e r a l o g y and P a r a g e n e s i s .... Specimen l\o© 1 7 : Submarine Group, L y t t o n , Asheroft Mining D i v i s i o n o . © . . .  2 3 2 3  2 3 2 6  T  Lo  cat  © © o«•© © © © » © ©. © © © • © © • © • © © © ©  ion  26 2 6  The D e p o s i t s «. •*• © © © © « * » « « © © © © o © © 2 6 F d n e r a l o g y and P a r a g e n e s i s © © ©« 2 7 Specimen Ho© 1 8 ; Snowshoe Group, P r i n c e George, C a r i b o o . © © * © 6 * . © « * © © © ©  ©  at i on © © © © © © © © •© © © ©«©«© © © © © * © The D e p o s i t © © « © © © © « © » © « o © © « © « « Mine r a l o g y © » «««© ©»© •«© * © * ©•».•»•.• «>  sX/OC  XXIO  cl*fj JL  0/1  Star,. •Si'milkame-eri..»  •© a- <a a o o « « 0 9 o o - « 6  , *DC3 T50 B jL ij  e e « o « « « »  o c * c © » «• •» a .o 0 0 0 0 0 ^ 1 1 0 0  M i n e r a l o g y and P a r a g e n e s i s ..©«  CHAPTER I I I .  2 8  \  Specimen Ho* 2 0 ; S i l v e r XJOO  2 8  2 8  29 2 9 ^»  5^  iSy^  2 9  MERCURIAL TSTRAHEDRITE FROM NORTH KOOTEKAY MINES , LTD. , WINDERMERE M I T O G DIYISIOK, Be C«  jintro duet i o n  • •••••••.•.©.•••••©••©•••.©».«..«»««.e,*-,o*.«»«©-o«»  ^2  G01TTMSS ( cont i n u e a) page  (KERGTJRIAL TETRAHEDRITE FROM HORTH KOOTEHAY MIHBS, e t c . ) M e r c u r i a l T e t r a h e d r i t e o f the l i t e r a t u r e IDS ID 0 S X *ti S  o ©« © o « o o  ....... 3 3  ©o a & o 6 o o « o e o e  a <o e -o o  3 ^  D e p o s i t o f S c h w a t z i t e n e a r Sumpter, Oregon  3 6 3 6  G e n e r a l Economic Geology o f Windermere D i s t r i c t .  M i n e r a l o g y and Parage ne s i s ».«•«..•«.....••. «•»«•.«.  41  M a c r o s c o p i c D e s c r i p t i o n o f Specimens . ..<>  41  M i n e r a l o g y and P a r a g e n e s i s  0  0  0  » . o  6  < , « . o .  9  42  o i ,  1. The q u a r t z , p y r i t e , c h a l c o pyrite, tetrahedrite, barite m i n e r a l i s a t i o n • •..««•<>....»•» 2 o The e h a l c o p y r i t e , b o r n i t e , chalcocite, barite mineralX %3>*li X 0 3 X  jllijOll  H C S l C f e X O X l S  « © © e JO o o « o s -e e * o  « « .« ' 6 o e '« -a .o »•« o « a « e *  Physical Properties i \ i x £ i l y s i » 3  43  « ©• « o o o. o  ^ J?  «•.»••©.«*:© .o  4*^3  48  o e o o o o e o . ^ © * * * . * . * . * * *  0x10. ^02^x1111X0. •* *««•*••*«««««* *«»«©»* *««•«-* *  ^X  Comparison w i t h O t h e r D e p o s i t s o f Windermere Dl,  G*SJi @ S X S  S i l 3 ? X CT3.  ••• .JO •«• e •« © * o e « * «  •  o"o * o o o « o o » o « o e o « a o * « * » « «• * « a « « « © o © ® « © « *• o  Sununary' and C o n c l u s i o n s  * o c 0 « o « * c . * o « o o  « * « *  3 ^  .J?^  .57  CONTENTS ( e o n t i n u e d ) CHAPTER I V . ANALYSES & E0R1-TULAE. 3D3**tlSt  9 a # •« « *  0 «  •  « « •» * o «  « o o o e e o * © » o « « *  e o »  Formulae  Formulae and S i l v e r Content .. < >< >  CHAPTER i'r  THE S U f l R C01TTE1T.  L o c a l i t y and S i l v e r Content .«...••.«..  M i n e r a l A s s o c i a t i o n and S i l v e r Content Type o f D e p o s i t and S i l v e r Content .... R e l a t i v e Age o f G a l e n a and T e t r a h e d r i t e S i l v e r Content ... < > P h y s i c a l P r o p e r t i e s and S i l v e r Content E t c h T e s t s and S i l v e r Content .........  CHAPTER Y I .  STMI&RY & C0HCLU5I0HS.  Analyses Accuracy Mercurial  Tetrahedrite  CCKOTTS  (continued) page  .^STTi-Uvl^J^*^*  0OX\'0«iJoSXOX?3^)  ® © « © » o ©  © © ©«©  © « «.© a « - *  © -«© © « ©  © « © © «-.  ^  Argentiferous T e t r a h e d r i t e or F r e i b e r g i t e T e t r a h e d r i t e Low i n S i l v e r Tetrahedrite High i n S i l v e r Galena-Silver  Relations  Type o f D e p o s i t S t r e a k and S i l v e r Content S p e c i f i c G r a v i t y and.) S i l v e r Content F r a c t u r e and L u s t r e  APPE1DIX P o i n t s on Technique employed i n P h o t o m i c r o g r a p h y and P r e p a r a t i o n o f Dammar Gum KEounts ... „, e  • B I B L I O G R A P H Y : ,  77  LIST OF ILLUSTRATIONS  PLATE I ,  O u t l i n e map o f B r i t i s h Columbia showing l o c a l i t i e s f r o m w h i c h t e t r a h e d r i t e was s t u d i e d .........•<>...  PLATE I I .  L a y o u t used i n s e l e c t i n g and c h e c k i n g t e t r a h e d r i t e .................  PLATS III»  C a m e r a - l u e i d a drawing o f s e c t i o n o f ore f r o m Three F o r k s , S I o c a n M i n i n g J D X \T X 2 X 0 2 1  o o o e ••« o> c « a €t .« © o c-  <v o e a » o .a o © a o o o •« ffl  PLATES IV & V.Photomicrographs o f s e c t i o n o f o r e f r o m .••Three ^Soxks-., S l o c a n M i n i n g *0X"V X"3 X 03X  PLATE V I ,  « o o« ©© « « a e «  » a«0ooe « a« a o ©a a * « o  C a m e r a - l u e i d a drawing o f s e c t i o n o f ore from Three F o r k s , S l o c a n M i n i n g •DX"V X  S  X  OSX  © © e .a o « a a o «• © o. o o a e o o a e a o o o o a  o a o •  PLATE V I I .  Photomicrograph o f s e c t i o n o f ore from A i n s w o r t h M i n i n g D i v i s i o n  PLATE V I I I .  Photomicrograph o f s e c t i o n o f ore from Keno H i l l , Yukon D a * * o ©, o. o- o o-ffle ©to0 0  PLATE I X .  «  P h o t o m i c r o g r a p h of, s e c t i o n o f o r e f r o m L y t t o n , , A s h c r o f t M i n i n g D i v i s i o n ......  PLATES X & XI..Camera-lueida d r a w i n g s o f s e c t i o n o f ore from S p a r k l e r Group, S i m i l k a m e e n Mxnxn^ !Dxv xsxo^x « 0 0 » © a © © * a & « * « « « © « © « e © PLATE X I I .  V/inderraere Map A r e a , showing location 0 of P r e t t y G i r l C l a i m O O Q . i . O . . . . . . . . 0 0 .  PLATES X I I I , X I V & XV. P h o t o m i c r o g r a p h s o f s e c t i o n s o f massive ore from P r e t t y G i r l C l a i m PLATES XVI & X V I I . C a m e r a - l u e i d a drawings o f s e c t i o n s o f massive o r e from P r e t t y G i r l C l a i m 0 0 0 0 PLATES X V I I I & X I X . Photomicrographs o f s e c t i o n s o f d i s s e m i n a t e d o r e from P r e t t y G i r l C l a i m •0 0 o a o o v a o a © a a « » a a * « e a a e e A  A  /I A  *  a « « «  LIST OF ILLUSTRATIONS ( c o n t i n u e d ) to f o l l o w page PLATS XX.  P a r a g e n e t i c C h a r t f o r o r e from  PLATE XXI©  Photomiorographic  s e t - u p used ........  76  ^3 IHTR037JCTIOH  l  IMPORTANCE OF TETRAHEDRITE The importance  o f s i l v e r p r o d u c t i o n from t h e p y r i t e -  c h a l c o p y r i t e - s p h a l e r i t e - g a l e n a type o f o r e i s w e l l  recognized.  About t w o - t h i r d s o f t h e e n t i r e p r o d u c t i o n i s o b t a i n e d from a r g e n t i f e r o u s galena© Beyschlag  t  G u i l u appears to have shown t h a t  silver  ¥ogT^ana~iiruscTa; Ore" Del^sTtlTT^'o 1 © 1T"l914 .""p'.Kb"."~"  above .10 p e r c e n t , e x i s t s i n g a l e n a as u n r e p l a c e d s p o t s of" s i l v e r m i n e r a l s , such a s tetrahedrite© GuTId"7Hr©Tf71^ A s s o c i a t e d ^inersU.s, Eo. Geol©, V o l . X I I , p.j^S© He s a y s : "Indeed, much o f the g a l e n a i n t h e s i l v e r d e p o s i t s has r e p l a c e d t e t r a h e d r i t e and i t s s i l v e r c o n t e n t i s thus due t o r e s i d u a l s p o t s o f s i l v e r - b e a r i n g t e t r a h e d r i t e as w e l l as a r g e n t i t e ©" T e t r a h e d r i t e ; , t h e n , i s o f f u n d a m e n t a l importance i n p r i m a r y s i l v e r - l e a d ores© I t i s o f no l e s s importance o f t h e s i l v e r i n secondary thiiTd^ri^  a s the u l t i m a t e source  s i l v e r deposits©  I n G u i l d ' s words,  © "The ruby s i l v e r s rank amongst the most i m p o r t a n t s i l v e r m i n e r a l s i n many o f t h e r i c h d e p o s i t s o f the U n i t e d S t a t e s and elsewhere© AS a l r e a d y p o i n t e d out t h e e a r l y m i n e r a l s o f s i l v e r a r e c o n f i n e d m a i n l y i f not e n t i r e l y t o t e t r a h e d r i t e and argentiferous.galena© They a r e t h e r e f o r e h e l d t o be t h e s o u r c e o f t h e l a t e r e n r i c h e d products© T e t r a h e d r i t e i s p r o b a b l y the most p r o l i f i c source as shown by t h e m i c r o s c o p i c i n v e s t i g a t i o n s , and the f a c t t h a t the l a t e s i l v e r m i n e r a l s a r e most o f t e n a r s e n i c o r antimony compounds©' 5  G u i l d , F.B.: op© c i t . , p.pi^©  The ultimate  above s t a t e m e n t s s h o u l d l e a v e no doubt as t o t h e  economic importance o f t e t r a h e d r i t e . .  Any d a t a on  such a m i n e r a l a r e l i k e l y t o prove t o be o f e v e n t u a l , immediate, v a l u e .  These c o n s i d e r a t i o n s  i f not  c l e a r l y j u s t i f y the  proposed i n v e s t i g a t i o n - a s t u d y o f .the t e t r a h e d r i t e i n a s u i t e o f B r i t i s h Columbia o r e s .  OBJECT AND AIMS OF PAPER •Referring t o the composition of t e t r a h e d r i t e . W i n•e h e l l s a y s ,  \ (  WiltcHe"lT7~A.li.l~limerican li!neralogist'r'^l*«^l"»  192.'W^~§7TET7 ~~ m  "Host o f the s t a n d a r d t e x t books o f m i n e r a l o g y now g i v e t h e f o r m u l a o f t e t r a h e d r i t e as Cug Sb^ S,y w i t h t h e comment t h a t Ag„ 3n„ F e , may ''replace-* p a r t o f the Cu under v a l e n c e control < > That is„ Ag^ 3b^ S^, Zn^ Sb^, Sy, and F e ^ Sb^ a r e supposed t o be p o s s i b l e c o n s t i t u e n t s o f t e t r a h e d r i t e c r y s t a l s t o some extent. I t i s t o o e a r l y as y e t t o c l a i m t h a t the c o n s t i t u t i o n o f t e t r a h e d r i t e can be e x p r e s s e d i n any form t h a t i s c o r r e c t beyond q u e s t i o n but i t i s a t l e a s t p o s s i b l e t o show c o n c l u s i v e l y that the current formula i s i n c o r r e c t j i f t h e b e s t a n a l y s e s now a v a i l a b l e can be t r u s t e d . " and  further,  that  s  " I t i s unfortunately ture that p r a c t i c a l l y a l l a n a l y s e s now a v a i l a b l e were made on samples whose p u r i t y was not t e s t e d by m i c r o s c o p i c methods " Therefore, analyses o f microscopically material  selected  s h o u l d c o n s t i t u t e a d e f i n i t e c o n t r i b u t i o n towards t h e  solution of this  problem.  Ill The s i l v e r c o n t e n t i s o f prime economic i m p o r t a n c e . I t i s hoped t h a t i t may show some d e f i n i t e r e l a t i o n t o lo Geographic d i s t r i b u t i o n of d e p o s i t s 2© M i n e r a l  association  3>o Type o f d e p o s i t 4© R e l a t i v e age o f g a l e n a and t e t r a h e d r i t e J?. P h y s i c a l  properties  L a s t l y , i t may be found p o s s i b l e  to c o r r e l a t e the  r e s u l t s w i t h those o f o t h e r workers i n t h i s  fields  GENERAL SUMMARY A s u i t e o f B r i t i s h Columbia t e t r a h e d r i t e o r e s has been, collected©  Ores from t e i i l o c a l i t i e s were found s u i t a b l e ,  f o r the p r e s e n t investigation©  From t h e s e , pure  tetrahedrite  has been s e l e c t e d , checked w i t h t h e r n e t a l l o g r a p h i e and analysed©  microscope,  An a t t e m p t has been made t o d e v e l o p a s a t i s f a c -  t o r y f o r m u l a , and o t h e r s t u d i e s u n d e r t a k e n , as suggested above ©  IV AGKHOWLEDGHEFTS B e f o r e p r o c e e d i n g , t h e w r i t e r w i s h e s to acknowledge h i s ino.ebtednes3 t o a l l those who i n the p r e p a r a t i o n  o f t h i s paper.  S t a f f o f the U. B. G., s i n c e r e s t thanks. the IJ. 3. G. out.  5  have i n any way a s s i s t e d him To members o f the  the a u t h o r wishes to e x p r e s s h i s  S p e c i a l thanks a r e due  Warren, o f  G a l l o w a y , P r o v i n c i a l M i n e r a l o g i s t , and  Mr. F. v/oodside, B. G. Chamber o f Mines i n d e b t e d f o r comprehensive o f B r i t i s h Columbia.  s  the, w r i t e r i s  s u i t e s of t e t r a h e d r i t e - b e a r i n g o r e s  A l l a n a l y t i c a l work was  under t h e c l o s e s u p e r v i s i o n o f K r . H.F. M i n i n g and M e t a l l u r g y , U. B. C.»  c a r r i e d out  Thomson, Department o f  w i t h o u t whose g u i d a n c e  and  i n t e r e s t the work c o u l d not have been c a r r i e d on.  J-.Ir. I-/.Bo B i s h o p v e r y k i n d l y undertook assaying,  Dr. E.V.  under whose s u p e r v i s i o n t h i s work was c a r r i e d ,  To ! l r . J.D.  sustained  Geological  t o do the r e q u i r e d  fire-  l a s t l y , but none the l e s s s i n c e r e l y , the a u t h o r  w i s h e s to thank h i s c o l l e a g u e s , who  have i n many s m a l l ways  c o l l a b o r a t e d w i t h him d u r i n g the p r e p a r a t i o n  of t h i s paper..  D e s e r v i n g s p e c i a l mention a r e L i e s s r s . J . C u r r i e and A.  Smith.  CHAPTER I  METHODS  mmmv  I  O u t l i n e Map of BRITISH COLUMBIA  SPECIMENS OF TETRAHEDRITE w h i c h a r e s t u d i e d i n t h i s pape are from t h e d e p o s i t s SHOWH IS RED ..• one specimen, n o t shown, came from Keno H i l l , Y. T.  PREPARATION FOR ASSAY Methods employed i n t h e c o l l e c t i o n , s e l e c t i o n and assay o f t h e m a t e r i a l  w i l l be b r i e f l y d e s c r i b e d here©  Through the .kindness o f Mr. J D . G a l l o w a y , e  Department  o f Mines,. V i c t o r i a , and Mr, F© Woodsi&e, BoC. Chamber o f Mines,  Vancouver, a s u i t e o f t e t r a h e d r i t ^ - b e a r i n g  B.C. o r e s was made  a v a i l a b l e f o r study. Of t h e s e , o n l y a few proved  suitable©  S i n c e i t was  n e c e s s a r y t o s e p a r a t e v e r y pure t e t r a h e d r i t e from t h e o r e s o n l y comparatively coarse g r a i n e d m a t e r i a l  c o u l d be u s e d , as  s e l e c t i o n f r o m a f i n e g r a i n e d i n t e r g r o w n o r e would have been i m p r a c t i cable« From each o f t h e s e a p p a r e n t l y s u i t a b l e  specimens,  c h i p s o f t e t r a h e d r i t e were t a k e n , mounted i n dammar gum, and p o l i s h e d , preparatory to microscopic examination.  Examination  showed some o f the t e t r a h e d r i t e t o be so i n t i m a t e l y  intergrown  w i t h o t h e r m i n e r a l s as t o p r e c l u d e any p o s s i b i l i t y o f a s a t i s f a c t o r y separations or of a s a t i s f a c t o r y , corrected, analysis. Specimens which p r o v e d , i n p o l i s h e d s e c t i o n , t o cont a i n pure o r n e a r l y pure t e t r a h e d r i t e , were e i t h e r , 1© i n the case o f t h e l e s s complex o r e s , brokendown w i t h a l i g h t hammer, t h e pure being continuously  selected, or.  2. c r u s h e d t o -10 mesh©  tetrahedrite  where c r u s h i n g was a d o p t e d , a l l ore was passed t h r o u g h a 10 mesh s c r e e n and caught on 14 and dQ mesh s c r e e n s . I t was not found n e c e s s a r y o r p r a c t i c a b l e t o d e a l w i t h m a t e r i a l o f -20 mesh. I t was found most c o n v e n i e n t t o r o u g h l y s e l e c t the m i n e r a l by eye, and t o check t h e s e l e c t i o n w i t h a 10 X b i n o c u l a r microscope. P y r i t e and c h a l e o p y r i t e were common i m p u r i t i e s .  The  l a t t e r was commonly f i n e l y d i s s e m i n a t e d throughout much o f t h e tetrahedrite.  Here, i t was d e c i d e d t o s e l e c t a few hundred  m i l l i g r a m s f r e e from the i m p u r i t y and t o assart t h i s f o r i r o n . T h i s , s u b t r a c t e d from the p e r c e n t a g e o f i r o n i n the main sample, would i n d i c a t e the amount o f i r o n t o be removed as p y r i t e or c h a l e o p y r i t e i m p u r i t y .  The s m a l l p e r c e n t a g e o f  i r o n i n the p u r e r sample would be t a k e n as e n t e r i n g i n t o the composition of t e t r a h e d r i t e * T h i s method was not f o u n d p r a c t i c a b l e f o r two reasons 1. t h e n e a r i m p o s s i b i l i t y o f s e l e c t i n g m i n e r a l e n t i r e l y f r e e from t h e f i n e l y d i s s e m i n a t e d impurities, especially  chaleopyrite.  2.. t h e r e l a t i v e l y b r o a d a c c u r a c y l i m i t s o f t h e i r o n a s s a y s when d e a l i n g w i t h s u c h low p e r c e n t age s. E v e n t u a l l y i t was d e c i d e d to remove a l l i r o n as p y r i t e or c h a l e o p y r i t e a c c o r d i n g to the i m p u r i t i e s found. Where no i r o n i m p u r i t i e s were f o u n d , i r o n was assumed t o o c c u r  TlA  S e l e c t i n g a n d " c h e c k i n g pure t e t r a h e d r i t e . ; The' c r u s h e d and s i z e d ore can he seen, s p r e a d out on sheets, o f p a p e r , on e i t h e r s i d e o f the  •  microscope. The g r a i n s a r e p i c k e d out w i t h t w e e z e r s , examined under the b i n o c u l a r , and p l a c e d i n . s u i t a b l y l a b e l l e d p h i a l s s h o w n near the microscope.  as p y r i t e .  Alternatively,  the f o r m u l a ,  enter  with zine.  The  z i n c c o n t e n t was  t h r e e specimens was sphalerite.  more t r o u b l e s o m e .  In only  i t known to be p r e s e n t as an i m p u r i t y - as  I n o t h e r cases i t was  m i n e r a l and y e t o c c u r r e d , i n one  i r o n might have been taken to  not noted i n the  selected  i n q u a n t i t i e s up to s e v e r a l  percent,  ease about b percent's The  possibilities  are  1. t h a t i t i s p r e s e n t as s p h a l e r i t e and d e t e c t i o n under the 2. t h a t z i n c e n t e r s  escaped  microscope.  i n t o the c o m p o s i t i o n of  tetra-  hedrite . J . t h a t i t o c c u r s p a r t l y as an i m p u r i t y and p a r t l y as a m i n e r a l  e n t e r i n g i n t o the c o m p o s i t i o n o f  tetrahedrite* • The  •  p o s s i b i l i t y t h a t z i n c might be present' i n s o l i d  s o l u t i o n has not been Considering  considered* the method o f checking, the p u r i t y o f  the  s e l e c t e d t e t r a h e d r i t e i t is, quite p o s s i b l e that a small percentage o f i m p u r i t y would escape d e t e c t i o n .  It is unlikely,  however, t h a t s e v e r a l p e r c e n t o f s p h a l e r i t e would pass unnoticed. To check t h e s e l e c t e d mineral., a few g r a i n s ( u s u a l l y between 6 and 12) were embedded i n dammar gum, examined under the m e t a l l o g r a p h i c and  oblique  i l l u m i n a t i o n . The  polished  and  m i c r o s c o p e both by r e f l e c t e d  g r a i n s were s e l e c t e d at random  from each sample and. were of such a s i z e as to g i v e an a r e a o f  p o l i s h e d s u r f a c e about e q u i v a l e n t t o a 1/8 i n c h d i s c . The pure m i n e r a l was t h e n g r o u n d , t h o r o u g h l y mixed and was ready f o r a s s a y .  ASSAY METHODS AND RESULTS S t a n d a r d commercial assay methods were employed throughout.  R e s u l t s were r e c o r d e d t o t e n t h s o n l y .  Further  f i g u r e s would have been meaningless.' In a l l cases t h e percentage content o f the f o l l o w i n g elements was d e t e r m i n e d - Copper, S i l v e r , l e a d , Z i n c . I n s o l u b l e , I r o n , Antimony, a r s e n i c and S u l p h u r . a mercury  I n one sample  d e t e r m i n a t i o n was made and checked.. The g e n e r a l methods f o l l o w e d w i l l be o u t l i n e d h e r e .  No attempt w i l l  Copper ( a l l  be made t o g i v e the d e t a i l e d p r o c e d u r e s .  samples).  Copper was determined by t h e F l u o r i d e - I o d i d e method. TlioTnson, K,K.: ~l?0]ypi^^  the~T?ITioTi^  Method... The p r o c e d u r e , as o u t l i n e d by Thomson, was f o l l o w e d c l o s e l y e x c e p t i n g t h a t .5 t o 1 gram o f f e r r o u s ammonium s u l p h a t e was added t o the sample i n each ease.  T h i s was done so as t o have  the assay made i n the presence o f i r o n , a c o n d i t i o n e s s e n t i a l to  accuracy.  The i r o n h y d r o x i d e p r e c i p i t a t e i s a l s o used a s  an i n d i c a t o r o f n e u t r a l i t y . P r e c a u t i o n s t a k e n , when u s i n g t h i s method f o r the d e t e r m i n a t i o n o f copper i n the p r e s e n c e o f mercury, a r e  d e s c r i b e d i n C h a p t e r I I I under. " A n a l y s i s and Formula*'. A l l copper d e t e r m i n a t i o n s Single determinations milligrams of mineral*  were e n t i r e l y s a t i s f a c t o r y < ,  were made on each, u s i n g 2j?0  A l l t i t r a t i o n end p o i n t s were  reason-  a b l y permanent, i n d i c a t i n g s a t i s f a c t o r y c o n d i t i o n s throughout© Samples number 2, 3 , 4 and 6 were r e - a s s a y e d and cheeked closely.  S i l v e r ( a l l samples). Mr© WoB© B i s h o p k i n d l y o f f e r e d to r u n a l l samples f o r silver.  O n e - h a l f t o 1 gram charges were used w i t h  f i r e assay methods©  standard  A- c o r r e c t i o n f o r a b s o r p t i o n o f s i l v e r by  the c u p e l was made where n e c e s s a r y ,  as i n t h e case o f t h e  h i g h - s i l v e r samples© Ho check a s s a y s were made©  Lead, Z i n c , I n s o l u b l e and I r o n (Samples 1, 2 , 3 , 5 & 6 ) . A s s a y s f o r t h i s group o f elements were r u n on 500 m i l l i g r a m s , o f samples 1, 2, j>» > and 6. S t a n d a r d methods ?/ere u s e d , e x c e p t i n g t h e y were m o d i f i e d , t o p e r m i t d e t e r m i n a t i o n s  i n s o f a r as  of the f o u r  elements t o be made on the one weight o f mineral© The m i n e r a l was brought i n t o s o l u t i o n w i t h h y d r o c h l o r i c a c i d and n i t r i c c h l o r a t e m i x t u r e  and t h e n fumed w i t h  s u l p h u r i c acid© Lead was removed a t t h i s p o i n t as i n s o l u b l e l e a d sulphate, together w i t h "Insoluble".  I t was then d i s s o l v e d i n  -6~ ammonium a c e t a t e , s e p a r a t e d  from u n d i s s o l v e d  material includin  " I n s o l u b l e " , and t i t r a t e d w i t h ammonium molybdate.  AS no l e a d  molybdate p r e c i p i t a t e s formed, l e a d was t a k e n as n i l i n a l l cases® I n s o l u b l e - The above r e s i d u e c o n t a i n i n g the "'Insoluble  11  was b o i l e d w i t h h y d r o c h l o r i c a c i d , f i l t e r e d , i g n i t e d and  weighed. I r o n and Z i n c - I r o n and z i n c were c o n t a i n e d i n t h e filtrate  from t h e l e a d  sulphate.  I r o n was s e p a r a t e d alkaline solution.  from z i n c as t h e h y d r o x i d e i n  I t was f i l t e r e d o u t , d i s s o l v e d , and  t i t r a t e d , w i t h p o t a s s i u m dichroraate i n a c i d s o l u t i o n . 21nc d e t e r m i n a t i o n s  were made, on the f i l t r a t e  the i r o n h y d r o x i d e , by t h e F e r r i c y a n i d e Method. to  from  T h i s proved  be q u i t e u n s a t i s f a c t o r y on such l o w p e r c e n t a g e s o f z i n c  w i t h 500 m i l l i g r a m s o f sample. The great accuracy  i r o n determinations  were l a t e r cheeked.  Any  i s n o t t o be e x p e c t e d by v o l u m e t r i c methods,  on such l o w p e r c e n t a g e s ,  where t h e amount o f t h e sample  taken  must be k e p t below 500 m i l l i g r a m s . The  r e s u l t s of the check a s s a y s a r e t a b u l a t e d below.  They g i v e some i d e a o f the o r d e r o f a c c u r a c y these c o n d i t i o n s .  o b t a i n a b l e under  ~7~  Sample number  first  1  »3  2  »3  |  second  assay  - loO  trace  1«  trace  0  1.2  3  .3  assay  •  •  o J?  3*8  ~"  4»-8 1•0  L e a d and Z i n c (Samples 4,12 17,18 and 9  1.4  20).  Heres l e a d and s i n e were r u n on the same sample ( 3 0 0 m i l l i g r a m s ) . the " I n s o l u b l e " and i r o n b e i n g later  9  determined  w i t h the s u l p h u r *  j  F e r r o u s ammonium s u l p h a t e was added to e a c h , t o b r i n g down antimony arid a r s e n i c w i t h i r o n h y d r o x i d e in. a l k a l i n e solution,,  Lead was  i n s o l u b l e l e a d sulphate,, every  t o have been s e p a r a t e d as  Lead r e s u l t s were a g a i n n i l i n  case. Z i n c d e t e r m i n a t i o n s were made by the F e r r i c y a n i d e  Method but p r o v e d t o be u n s a t i s f a c t o r y , as  Zinc  before.  ( i n a l l samples).  !  I t was n e c e s s a r y , t h e n , t o make z i n c a s s a y s on a l l samples by the "Phosphate Z i n c " Method,, !ITeo^T7~~^n771 Te'cluiTcai Melfhoas*"^^  E s s e n t i a l l y , by  \  this ,  I?23 . :  method, t h e z i n c i s s e p a r a t e d as s i n e s u l p h i d e i n weak a c i d s o l u t i o n and p r e c i p i t a t e d as z i n c ammonium phosphate i n a n e u t r a l solution,*  The weight  «3>"64 g i v e s tlie weight  o f the phosphate m u l t i p l i e d by  o f z i n e i n t h e assay,,  There i s good r e a s o n t o b e l i e v e t h a t these  results  are accurate« Only i n one case was an assay d u p l i c a t e d ^  This  checked. 250 m i l l i g r a m s were used f o r a l l a s s a y s .  S u l p h u r , I n s o l u b l e and I r o n ( o n a l l samples)* 230 m i l l i g r a m s and-.* where p o s s i b l e j?O0 m i l l i g r a m s t  were t a k e n o f a l l samples and t h e s e a s s a y e d f o r t h e above t h r e e elements.  " I n s o l u b l e " and i r o n d e t e r m i n a t i o n s served, a s a  check on those a l r e a d y o b t a i n e d . f o r samples 1 , The g e n e r a l procedure  2 , 2, 5 and 6e  i s to convert the sulphides to  s u l p h a t e s and t o p r e c i p i t a t e the s u l p h a t e as b a r i u m s u l p h a t e , to be weighed and c a l c u l a t e d to sulphur* The  s u l p h u r was brought i n t o s o l u t i o n and f i l t e r e d  from t h e " I n s o l u b l e " .  T h i s was b o i l e d w i t h h y d r o c h l o r i c a c i d  and weighed* The  s u l p h u r , i n h y d r o c h l o r i c a c i d s o l u t i o n , was p r e -  c i p i t a t e d as b a r i u m s u l p h a t e by t h e a u d i t i o n o f barium chloride.  T h i s was f i l t e r e d out and weighed* I r o n was p r e c i p i t a t e d from the f i l t r a t e w i t h ammonium  hydroxide  f  r e - d i s s o l v e d i n a c i d , and determined  as b e f o r e *  Antimony© I n e v e r y case„ the--antimony d e t e r m i n a t i o n was made on 2 5 0 milligrams of mineral. The  weighed m i n e r a l was brought i n t o s o l u t i o n w i t h  n i t r i c c h l o r a t e , t h e s o l u t i o n e v a p o r a t e d t o d r y n e s s twice, w i t h hydrochloric a c i d  s  and the r e s i d u e taken i n t o s o l u t i o n w i t h  h y d r o c h l o r i c a c i d and t a r t a r i c acid© added a s a r e d u c i n g  agent©  Sodium s u l p h i t e was  Hydrogen s u l p h i d e gas was b u b b l e d  i n , p r e c i p i t a t i n g a r s e n i c , antimony and c o p p e r .  A r s e n i c and  antimony were d i s s o l v e d from t h i s p r e c i p i t a t e w i t h sodium s u l phide and sodium h y d r o x i d e , acid©  then p r e c i p i t a t e d w i t h s u l p h u r i c  The antimony o f t h e p r e c i p i t a t e was t a l i e n up w i t h h y d r o -  c h l o r i c and t a r t a r i c acid©  Antimony was t i t r a t e d , i n the  presence o f sodium b i c a r b o n a t e , w i t h i o d i n e s o l u t i o n , f r e e i o d i n e a t t h e end p o i n t b e i n g d e t e c t e d w i t h s t a r c h s o l u t i o n * A l l end p o i n t s seemed satisfactory©  However, such a  p r o c e d u r e g i v e s scope f o r a p p r e c i a b l e m a n i p u l a t i o n  errors©  Arsenico I n most c a s e s , 5 0 0 m i l l i g r a m s o f m i n e r a l was assayed f o r arsenico  I n a few e a s e s , o n l y 2 ^ 0 m i l l i g r a m s was available©  The H y d r o z i n e S u l p h a t e Xeffer,  K . J MenHaolIS  D i s t i l l a t i o n Method was  i ^ 1 9 2 8 ,  p.36.  employed, a s o u t l i n e d by K e f f e r . E s s e n t i a l l y , the a r s e n i c i s brought i n t o s o l u t i o n under o x i d i z i n g c o n d i t i o n s and then d i s t i l l e d o f f i n t h e presence o f h y d r o z i n e  s u l p h a t e , h y d r o c h l o r i c a c i d and sodium  - 1 0 -  bromide.  The a r s e n i o u s c h l o r i d e i s condensed, d i s s o l v e d i n  w a t e r , and t i t r a t e d a g a i n s t a n i o d i n e s o l u t i o n i n t h e presence o f sodium b i c a r b o n a t e . These d e t e r m i n a t i o n s appeared to be p e r f e c t l y satisfactory* I t i s worth n o t i n g here t h a t , s h o u l d t i n have been p r e s e n t i n the sample, i t would have been d i s t i l l e d o v e r and t i t r a t e d w i t h the A r s e n i c . percent a r s e n i c .  The r e s u l t s have been r e c o r d e d a s  A c t u a l l y they may be p e r c e n t a r s e n i c p l u s  tin. I n c i d e n t a l l y , the d e t e r m i n a t i o n o f t i n by d i s t i l l a t i o n a p p e a r s t o be a new method.  I n view o f the f a c t that  p r e s e n t methods do n o t appear t o be w h o l l y s a t i s f a c t o r y , i t would appear t o be w e l l w o r t h f u r t h e r i n v e s t i g a t i o n .  General. A s s a y s eoulo. not be r u n i n d u p l i c a t e due t o i n s u f f i cient material.  .For the same r e a s o n , w e i g h t s  o f m i n e r a l were  sometimes used vvhich gave t i t r a t i o n s o f o n l y a few c u b i c centimeters.  Great a c c u r a c y i s n o t t o be e x p e c t e d from  such  titrations.  COMMENTS OF GENERAL ACCURACY  As w i l l be n o t e d i n t h e next c h a p t e r , the t o t a l s i n all  assays f a l l below 100 p e r c e n t , r a n g i n g from 93«2 t o l a c k i n g t h e time and m a t e r i a l r e q u i r e d f o r a check o f  - 1 1 -  a l l a s s a y s j the f o l l o w i n g comments a r e i n order© A l l a s s a y work was c a r r i e d out w i t h c a r e , a s i t was r e a l i z e d from t h e f i r s t t h a t cheek a s s a y s c o u l d n o t be run© F u r t h e r , a l l work was c a r r i e d out under t h e c l o s e s u p e r v i s i o n o f Mr© H©F© Thomson, P r o f e s s o r o f M e t a l l u r g y , U n i v e r s i t y o f B r i t i s h Columbia© A few check a s s a y s have been r u n , as mentioned above© These c h e c k e d t o -within the l i m i t s o f e r r o r o f t h e methods employed and i t i s thought t h a t no major e r r o r s o c c u r i n t h e f i g u r e s given©  "Errors i n t h e o r d e r o f f r a c t i o n s o f a percent  are t o be e x p e c t e d , from the methods employed, but i t i s c l e a r l y n o t i n t h e s e d i s c r e p a n c i e s t h a t we may l o o k f o r t h e missing  percentages© S e v e r a l o t h e r p o i n t s tend t o s u p p o r t t h e b e l i e f i n  the g e n e r a l 1©  accuracy  o f the f i g u r e s g i v e n , a s :  The u n i f o r m l y low r e s u l t s . The  maximum d i v e r g e n c e  o f t o t a l s i s j>«2 p e r c e n t , and  the average v a r i a t i o n much l e s s .  The f a c t t h a t t h e s e a r e  u n i f o r m l y l o w s u g g e s t s one o f two a l t e r n a t i v e s . E i t h e r the methods employed g i v e c o n s i s t e n t l y l o w r e s u l t s o r i m p u r i t i e s , not a s s a y e d f o r , a r e p r e s e n t  throughout.  A combination of  t h e s e two p o s s i b l e causes i s a l s o t o be considered© As more o r l e s s s t a n d a r d  a s s a y methods have been  used t h r o u g h o u t , t h e second a l t e r n a t i v e appears to be t h e more probable© Had  t h e t o t a l s been e r r a t i c - some below and o t h e r s  above 1 0 0 p e r c e n t  - t h e f a u l t would o b v i o u s l y have been w i t h  -12the a s s a y i n g  0  2« A tendency towards c o n s t a n c y i n the summation o f the a t o m i c p r o p o r t i o n s o f copper and s i l v e r . • T h i s w i l l be seen f r o m the t a b l e on Page 7« E x c l u d i n g Samples 1 and 5 (by r e a s o n of t h e i r l i a r c o m p o s i t i o n ) the r e m a i n d e r f a l l are.  Samples 2 ,  into  6 ; Samples 3 , 1 7 , 2 0 ;  pecu-  t h r e e groups.  These  Samples 4 ( ? ) , 12, 18.  3 . A p a r a l l e l tendency i n the case o f a r s e n i c and  antimony.  Here we have e x a c t l y the same groups as b e f o r e : Samples 2 and 6;  3> 17  and 20;  and 4, 12  and  18.  Such c l o s e , p a r a l l e l g r o u p i n g must be more t h a n a coincidence*  EXPLANATION OF LOW  TOTALS  The f o l l o w i n g c o n s i d e r a t i o n s a c c o u n t , i n p a r t a t l e a s t , f o r the l o w  totals.  1. The p r o b a b l e presence o f some s o l u b l e o r p a r t i a l l y s o l u b l e gangue  s  g i v i n g a low r e s u l t  f o r "Insoluble",  w h i c h i s assumed to i n c l u d e a l l gangue, as q u a r t z . 2.  The presence o f minor amounts o f copper c a r b o n a t e s and silicate  3.  ( c r y s o c o l l a ) i n the s e l e c t e d  material.  The p r o b a b l e presence of o t h e r elements not a s s a y e d f o r .  4. The  p e r s i s t e n t presence of a d u l l brownish black to  b l a c k c o a t i n g on the .selected g r a i n s . 5*  The p e r s i s t e n t presence of t h i s same n o n - m e t a l l i c m a t e r i a l i n prominent p a r t s t h r o u g h o u t many o f t h e  - 1 3 "  sections  examined.  O t h e r e l e m e n t s not a s s a y e d f o r and l i k e l y to o c c u r are  5  as s u g g e s t e d by Dana, n i c k e l , c o b a l t , mercury, manganese  DanaT^^  ' ' "~*"'""  b i s m u t h and t i n .  The t i n c o n t e n t , i f any, has p r o b a b l y been  i n c l u d e d i n the a r s e n i c r e s u l t s , as e x p l a i n e d above. V a r i o u s elements might be p r e s e n t i n a s o l u b l e gangue  such as l i m e and magnesia., b a r i u m , s u l p h a t e , a l u m i n a ,  5  etc.  "*>  CHAPTER I I THE ORES - MIIERALGCST AHD PARAGEHESIS.  SuTM&EY OF CHAPTER The adequately  t r e a t e d i n Chapter I I I o The  with  m e r c u r i a l o r e , from t h e Windermere, has been  o r e s from the o t h e r n i n e l o c a l i t i e s w i l l be d e a l t  here,. Each d e p o s i t w i l l be d i s c u s s e d b r i e f l y , i n s o f a r as  p u b l i s h e d data a r e a v a i l a b l e .  I n some cases a p e r u s a l o f t h e  l i t e r a t u r e has r e v e a l e d no r e f e r e n c e s t o the d e p o s i t s .  I n such  e a s e s , a g e n e r a l d i s t r i c t d e s c r i p t i o n i s a l l t h a t has been possible. The  specimens f r o m t h e d e p o s i t s w i l l t h e n be d e a l t  w i t h , each i n t u r n , f i r s t m a c r o s c o p i c a l l y and then m i c r o s c o p i c a l l y , g i v i n g the mineralogy under the m e t a l l o g r a p h i c  and p a r a g e n e s i s  microscope.  Studies of mineralogy for  several  as d e t e r m i n e d  and p a r a g e n e s i s  were u n d e r t a k e n  reasons.  l o An a c c u r a t e i d e a o f t h e m i n e r a l a s s o c i a t i o n i s e s s e n t i a l i n v i e w o f t h e i m p r a c t i c a b i l i t y o f s e l e c t i n g absol u t e l y pure t e t r a h e d r i t e f o r a s s a y . 2. I n d e t e r m i n i n g  t h e o r d e r o f d e p o s i t i o n o f the  m i n e r a l s , s p e c i a l a t t e n t i o n was g i v e n to g a l e n a - t e t r a h e d r i t e relations.  As suggested  by Warren, t h e o r d e r o f d e p o s i t i o n o f  W a C T e ^ T ^ ^ y ^ X ^ ^ ^ ^ ^ ^ooi^anicat ion. these m i n e r a l s may b e a r some r e l a t i o n to t h e d i s t r i b u t i o n o f s i l v e r between t e t r a h e d r i t e and g a l e n a  i n t h e same o r e .  Early  g a l e n a might be shown to be t h e s i l v e r b e a r i n g m i n e r a l o r , s h o u l d t e t r a h e d r i t e be the e a r l i e r o f t h e two, i t may be t h e  - 1 5 -  silver carrier.  This p o s s i b i l i t y will  i n s o f a r as p o s s i b l e  be d i s c u s s e d  later,  w i t h o u t a s s a y s o f the g a l e n a .  3 « F u r t h e r work w i l l be n e c e s s a r y , i n v o l v i n g a s s a y s o f the accompanying g a l e n a , to complete t h i s phase o f t h e i n v e s tigation.  The p a r a g e n e t i c d e t e r m i n a t i o n s , a l r e a d y made, w i l l  be e s s e n t i a l . 4. I t may be p o s s i b l e  t o show some r e l a t i o n between  a n a l y s e s and m i n e r a l a s s o c i a t i o n . u s e f u l i n t h e case o f t h e s i l v e r  T h i s would be e s p e c i a l l y content.  THE DEES: THEIR MINERALOGY AND PARAGENESIS A z u r i t e , m a l a c h i t e and c r y s o c o l l a have been r e c o g n i z e d i n many specimens and p r o b a b l y o c c u r to some e x t e n t i n o. JL «L & In the d e s c r i p t i o n o f m i n e r a l o g y but l i t t l e  a t t e n t i o n has been p a i d t o these  minerals.  At the time, i t was not thought  o f any p a r t i c u l a r importance  and p a r a g e n e s i s , supergene that  they would be  i n t h i s study.  A z u r i t e , a s s u g g e s t e d by DoImage, may be the more l)oTimge^~Y7: ^ l * r ^ r ^ common carbonate  *"" ~  with t e t r a h e d r i t e , a t l e a s t under  o f a l t e r a t i o n as found i n B r i t i s h  conditions  Columbia.  Specimen No. 1. T h i s has been a d e q u a t e l y  t r e a t e d i n Chapter I I I .  Specimen No. 2. B l a c k B e a r Group, (-.uesnel M i n i n g D i v i s i o n .  -16L o c a t i o n - The  c l a i m s are s i t u a t e d about JO m i l e s  e a s t o f C u e s n e l j n e a r the n o r t h e a s t They a r e r e a c h e d by a road and The to  bank of Cuesnel  trail  river.  from the town.  - T h i s group i s d e s c r i b e d i n the 1?21  deposit  south-  report  the B r i t i s h C o l u m b i a M i n i s t e r o f Mines as the Copper Cueen  Group. B7oT"Tfi1^ The  1928  d e s c r i p t i o n i s f o u n d under the h e a d i n g o f  B l a c k B e a r Group. F.irr^TnT^ M i n e r a l i z a t i o n accompanies a q u a r t z v e i n o c c u r r i n g in  a s h e a r zone i n what has  been c l a s s i f i e d as an a u g i t e  p h y r i t e by the P r o v i n c i a l M i n e r a l o g i s t . f e e t , and  the s h e a r zone about 15  a z u r i t e and a l i t t l e  The  per-  v e i n i s 2 to 2-g-  feet, i n width.  c h a l e o p y r i t e are noted.  The  Tetrahedrite, v e i n trends  0  n o r t h and  s o u t h and d i p s 27  q u a r t z v e i n i s r e p o r t e d to be  east«  The  s c h i s t e n c l o s i n g the  barren.  M a c r o s c o p i c d e s c r i p t i o n - I n the m a t e r i a l i n v e s t i g a t e d t e t r a h e d r i t e was ted  masses t h r o u g h a medium-grained, g r a n u l a r ,  q u a r t z gangue. The  s c a t t e r e d as h i g h l y i r r e g u l a r and  A little  interrupted fracture.  conchoidal Paragenesis  present.  so shows a much-  I n d e t a i l , as under a hand l e n s ,  i n d i v i d u a l g r a i n s o f t e t r a h e d r i t e seem to have the istic  interconnec-  milk-white  l i m o n i t e and a z u r i t e are  t e t r a h e d r i t e i s f i n e l y g r a n u l a r and  t  f r a c t u r e and  character-  lustre.  - T e t r a h e d r i t e , q u a r t z and  a s i n g l e g r a i n of  a g r e e n i s h c a r b o n a t e gangue were the o n l y m i n e r a l s  recognized.  - 1 7 -  Specimen Ho. J»  J o - J o Group. Three F o r k s , S l o c a n Mining Division© Location  - The c l a i m s  a r e s i t u a t e d about 7 m i l e s from t h e  town o f Three F o r k s ( o n t h e C . K . R ) 0  The  0  D e p o s i t - I n the 1904 A n n u a l Report o f the B. G©  M i n i s t e r o f M i n e s t h i s group i s s t a t e d to be o f "about the same c h a r a c t e r " as the M c A l l i s t e r g r o u p , which i t n e a r l y adjoins© BToVTJinT^  ReptT7~I904, 'p'nH2'»  On t h i s p r o p e r t y , a m i n e r a l i z e d  quartz v e i n , l y i n g  between  s c h i s t and a r g i l l i t e , t r e n d s n o r t h e a s t - s o u t h w e s t , and d i p s j>0° southeast© carry  The v e i n i s 3 t o 4 f e e t wide and i s r e p o r t e d t o  " g a l e n a , g r a y c o p p e r , and s i l v e r s u l p h i d e s ,  shipped, r u n n i n g o v e r 2.50 oz© t o the t o n .  f!  Macroscopic d e s c r i p t i o n - Tetrahedrite and  o c c u r s i n bunches  i r r e g u l a r s t r i n g e r s between w e l l rounded a r e a s o f b l u i s h  white milky  quartz©  M i n o r amounts o f t h e m i n e r a l have good  eonchoidal f r a c t u r e and b r i l l i a n t has  the o r e as  a less regular  lustre©  Most o f t h e m i n e r a l  f r a c t u r e and somewhat l o w e r l u s t r e .  M i n e r a l o g y and P a r a g e n e s i s - I n p o l i s h e d  section, tetra-  h e d r i t e , g a l e n a and s p h a l e r i t e ( ? ) were r e c o g n i z e d .  The gangue  i s quartz© Tetrahedrite metallies©  c o n s t i t u t e s t h e main b u l k o f t h e  Galena o c c u r s i n m i n o r quantities©  Sphalerite (?)  i s rare© The  o r d e r o f m i n e r a l d e p o s i t i o n has been d e t e r m i n e d  • s a t i s f a c t o r i l y ; a t l e a s t f o r the s e c t ions .examined© The  s p h a l e r i t e was not i d e n t i f i e d w i t h  certainty.  By  .' -SPECIMEN"  3  T e t r a h e d r i t e and s p h a l e r i t e .  Tetrahedrit  h e r e , i s u n q u e s t i o n a b l y the younger m i n e r a l , embays  9  v e i n s , and i n c l u d e s , the s p h a l e r i t e .  • Camera l u c i d a drawing  X 273 .  SPECIMEN  3  A v e i n l e t ' o f -tetrahedrite-..ana- g a l e n a i n . quartz. T e t r a h e d r i t e f i r s t v e i n e d the. q u a r t z . Galena has now l a r g e l y r e p l a c e d t h i s v e i n , l e a v i n g a few u n r e p l a c e d " i s l a n d s " and specks of tetrahedrite©. Galena e t c h e d w i t h n i t r i c - a c i d Panchromatic  plate  second exposure  .' .  PLATE  SPECIMEN Etched galena replacing  3 tetrahedrite  and q u a r t z .  The w e l l rounded o u t l i n e s of u n r e p l a c e d ''islands•' o f t e t r a h e d r i t e and q u a r t z show c l e a r l y . seem to be l i t t l e  There would  doubt as t o the l a t e age o f the  galena. Panchromatic l/^O  plate  second exposure  '.  X 85  r  ^  L  A  PLATE 6  : SPECIMEN  y  /: ' G a i e n a , q u a r t z and t e t r a h e d r i t e .  The g a l e n a .  v e i n s •••the • t e t r a h e d r i t e .  t h i s - evidence  Contradicting  we have the t e t r a h e d r i t e embaying, and i n c l u d i n g "islands'  11  o f , the g a l e n a .  inconclusive. :of c h a l e o p y r i t e  D i r e c t e v i d e n c e ,- t h e n  s  is  I n d i r e c t e v i d e n c e , as the o c c u r r e n c e typically within tetrahedrite  than within.galena,  rather  s u g g e s t s t h a t t e t r a h e d r i t e was.  i n t r o d u c e d b e f o r e the g a l e n a . . C a m e r a - l u e i d a drawing  X 8j? .  s u n l i g h t t h e powder was a l i g h t y e l l o w - somewhat l i g h t e r t h a n i s t y p i c a l f o r blende.  C o l o u r , e t c h t e s t s , and h a r d n e s s  cheek  with those g i v e n f o r blende. Sphalerite i n t h e accompanying  i s r e p l a c e d by t e t r a h e d r i t e as i l l u s t r a t e c a m e r a - l u e i d a drawing.  sphalerite i s obvious.  The v e i n i n g  o f the  Unreplaeed " i s l a n d s " o f s p h a l e r i t e are  s u r r o u n d e d by t h e t e t r a h e d r i t e . o f t h e r e p l a c i n g v e i n l e t .  The  s p h a l e r i t e b o u n d a r i e s t e n d t o be concave towards the r e p l a c i n g tet'rahe d r i t e . G-alena c l e a r l y r e p l a c e s t e t r a h e d r i t e as shown i n t h e accompanying the  photomicrograph ( P l a t e V  ).  I n the p h o t o g r a p h ,  g a l e n a has been e t c h e d w i t h n i t r i c a c i d t o g i v e  contrast.  The w e l l rounded u n r e p l a c e d a r e a s o f t e t r a h e d r i t e c o m p l e t e l y s u r r o u n d e d by the g a l e n a a r e e x c e l l e n t e v i d e n c e o f replacement I t i s n o t e w o r t h y t h a t no specks o f t e t r a h e d r i t e , o r o t h e r unetched m i n e r a l , were observed w i t h i n t h e e t c h e d g a l e n a areas.  • .  •  Replacement  • '  by g a l e n a shows a tendency t o commence  along the s p h a l e r i t e - t e t r a h e d r i t e The sequence  contacts.  of deposition,  youngest  i  |  as e s t a b l i s h e d  above, i s :  galena  i  —  r i  tetrahedrite  |  sphalerite  i  oldest  T h i s i s the normal sequence  f o r these m i n e r a l s .  G u i l d , F.IJ.'; A M i c r o s c o p i c Study o f 'the S i l v e r Ores and t h e i r asso elated, Minerals» E e . G e o l . , Vol.XII., 1917 , . pp. 3QQ & 506.  Specimen Eo,  4=  langley C o l l e c t i o n s Ainsworth Mining L o c a t i o n . - T h i s ore was  Division.  s u p p l i e d by the B. C. Chamber o f  Mines from the L a n g l e y C o l l e c t i o n from the A i n s w o r t h Division.,  The  p r e c i s e l o c a l i t y from w h i c h i t was  Mining  t a k e n i s not  knowno The  D e p o s i t s - Most o f -the A i n s w o r t h l e a d - s i l v e r d e p o s i t s  o c c u r a s s o c i a t e d w i t h the l i m e s t o n e bands o f the SIocan A i n s w o r t h s e r i e s , a l t h o u g h some are i n q u a r t z i t e s . are o f b o t h the t r u e f i s s u r e and replacement a r e p r o b a b l y contemporaneous* f o l l o w master j o i n t  and  Deposits  t y p e s , and  The main f i s s u r e v e i n s  these may  planes.  G a l e n a and s p h a l e r i t e o c c u r i n a gangue o f s i d e r i t e , q u a r t z and f l u o r i t e .  The g a l e n a i s s i l v e r b e a r i n g ,  u s u a l l y c a r r y i n g about 20 ounces per t o n . i t o c c u r s , i s a l w a y s secondary.  calcite,  I'-Iative s i l v e r , where  S i l v e r , where i t o c c u r s i n the  p r i m a r y m i n e r a l i z a t i o n , i s i n t i m a t e l y mixed w i t h t h e g a l e n a invisible.  Uo mention o f t e t r a h e d r i t e ( o r f r e i b e r g i t e )  and  was  found* I t i s i n t e r e s t i n g t o n o t e t h a t "The  replacement  veins,  i n c o n t r a s t t o the f i s s u r e v e i n s , c a r r y low v a l u e s i n s i l v e r and l e a d and h i g h v a l u e s i n z i n c . " pTFysdale, cTW.y" G e ^ . S u r ^ Macroscopic  191^7 V»5b * :  d e s c r i p t i o n - Masses o f t e t r a h e d r i t e and  a  l i t t l e g a l e n a o c c u r i n a gangue o f coarse m i l k y xvhite q u a r t z . The  t e t r a h e d r i t e v a r i e s from t h a t w i t h a h i g h l u s t r e  and  smoothly c u r v i n g u n i n t e r r u p t e d f r a c t u r e to t h a t w i t h an  -20i r r e g u l a r f r a c t u r e and  steely  lustre.  M i n e r a l o g y and P a r a g e n e s i s - The  following  metallic  m i n e r a l s were r e c o g n i z e d ; t e t r a h e d r i t e , g a l e n a , a supergene ( ? ) m i n e r a l and c h a l e o p y r i t e .  They o c c u r q u a n t i t a t i v e l y i n about  the o r d e r m e n t i o n e d , t e t r a h e d r i t e b e i n g the most abundant. others are r e l a t i v e l y  The  unimportant.  The  gangue i s qua acta.  The  o r d e r o f d e p o s i t i o n of the ore m i n e r a l s c o u l d not  be d e t e r m i n e d  w i t h any degree o f c e r t a i n t y . .  M i n e r a l s , other  Ithan t e t r a h e d r i t e , o c c u r i n such s m a l l q u a n t i t i e s t h a t but c o n t a c t a r e a s c o u l d be found The  few  i n polished sections.  i n t e r - r e l a t i o n s oi* the supergene ( ? ) m i n e r a l , the  g a l e n a and the t e t r a h e d r i t e are shown i n the accompanying photomicrograph The t h a n , the  (Plate  Til).  supergene m i n e r a l v e i n s , and i s c l e a r l y younger  tetrahedrite. I t s u r r o u n d s , and makes a f e a t h e r y c o n t a c t w i t h , the  galena.  I t i s p r o b a b l y younger t h a n the  galena.  Hear the c e n t r e o f the photomicrograph  i s an a r e a o f  t e t r a h e d r i t e w h i c h has a p p a r e n t l y been v e i n e d and n e a r l y surrounded  by g a l e n a .  The  supergene m i n e r a l has  r e p l a c e d the g a l e n a so t h a t now broken.  selectively  the g a l e n a v e i n l e t i s somewhat  Former c o n t i n u i t y o f the v e i n l e t i s f u r t h e r suggested  by the p a r a l l e l o r i e n t a t i o n o f the c l e a v a g e p i t s i n the a t e i t h e r end The  galena  o f the r e p l a c e d v e i n l e t . evidence  f o r t h i s p r o c e s s o f the s e l e c t i v e r e -  placement o f the g a l e n a i s c o n f i r m e d on o t h e r c o n t a c t s ' i n the  -21same s e c t i o n .  The c o n t a c t between t h e supergene  u s u a l l y a s e r i e s o f smooth c u r v e s .  mineral i s  But the same  supergene  m i n e r a l has r e p l a c e d the g a l e n a i n such a way as t o l e a v e a highly i r r e g u l a r contact.  This.seems  t o t h e w r i t e r t o suggest  a more r a p i d replacement o f t h e g a l e n a .  I t might., however, be  e x p l a i n e d by some r e f e r e n c e t o the p r o p e r t i e s  which r e s u l t i n  c l e a v a g e and l a c k o f c l e a v a g e i n g a l e n a and t e t r a h e d r i t e respectively^ Chaleopyrite occurs i n e n t i r e l y i n s i g n i f i c a n t  quan-  tities. The m i n e r a l above d e s c r i b e d a s supergene was n o t identified..  The f o l l o w i n g p r o p e r t i e s s l i g h t l y harder than  were d e t e r m i n e d : tetrahedrite  powder w h i t e very  brittle  c o l o u r d a r k e r and g r a y e r t h a n t e t r a h e d r i t e o r galena non-metallic s t a i n s dark brown w i t h n i t r i c  acid  the v e i n l e t s a r e banded p a r a l l e l t o the w a l l s . P a r a g e n e t i c e v i d e n c e brought o u t here i s i n c o n c l u sive..  The f o l l o w i n g t e n t a t i v e sequence i s s u g g e s t e d . youngest j ----— •oldest  t  u n i d e n t i f i e d supergene  \~ g a l e n a i ! tetrahedrite  (  mineral  PLATE  SPECIMEN  4  I n d i c a t i n g replacement  of g a l e n a and t e t r a h e d r i t e .  The r e p l a c i n g m i n e r a l ("Sup") has n o t been i d e n t i f i e d . I t i s p r o b a b l y supergene.  " I s l a n d " and " d e l t a " .  s t r u c t u r e o f the r e p l a c e d m i n e r a l s , e s p e c i a l l y t h e t e t r a h e d r i t e , show c l e a r l y .  The f e a t h e r y b o r d e r s o f  the g a l e n a c o n t r a s t w i t h the c o m p a r a t i v e l y r e g u l a r t e t r a h e d r i t e boundaries. p r e f e r e n t i a l replacement Panchromatic  This i s taken to i n d i c a t e o f the g a l e n a .  plate  l/j?0 second exposure • natural colors  ,  :  •" , X 8,5  Specimen K o . 3« S a d i e C l a i m , Keno H i l l , Yukon© L o c a t i o n - Keno H i l l  l i e s about 40 m i l e s 'northeast o f t h e  town o f Mayo, Yukon Territory© The  Deposit - I n r e v i e w i n g the mining  i n d u s t r y i n the  Yukon f o r 1530, C o c k f i e l d s t a t e s "The S a d i e ore shoot proved t o be t h e l a r g e s t found t o date and f u r n i s h e d 100,000 t o n s o f ore© 7  GockfieI'd", WTIi ©; Ge oTTSu^  5 0 , PtTF,~~pT4.©.""*~  T h i s p r o p e r t y was worked by T r e a d w e l l - Y u k o n Go©, L t d . , under l e a s e from Keno H i l l , Ltd©, d u r i n g 1 9 2 9 , and was e x h a u s t e d e a r l y i n 1930* T h i s d e p o s i t l i e s a t the s o u t h e a s t Vein i n greenstone - the Sadie-Treadwell  end o f a f a u l t e d  vein.  The v e i n has  been t r a c e d f o r n e a r l y 3000 f e e t w i t h an average w i d t h o f 7 t o C o c k f i e l d , W E ; G e q l . S u r v , 0 a n . , Summ.Eept. 1923, Pt«A, p.14. s  a  8 f e e t and a maximum w i d t h o f 70 f e e t . did  n o t extend below the 400 f o o t l e v e l .  On the S a d i e , t h e ore T h i s s h a l l o w depth  seems t o be c h a r a c t e r i s t i c o f the o r e s h o o t s o f the camp. A n o t h e r g e n e r a l f e a t u r e o f t h e carap i s t h e e x i s t e n c e o f a numb e r o f n o r t h e a s t t r e n d i n g f a u l t s w h i l e the general, t r e n d o f t h e m i n e r a l i z e d v e i n s i s to the northeast.  Ore s h o o t s g e n e r a l l y  o c c u r a t o r n e a r t h e i n t e r s e c t i o n o f t h e two t y p e s o f f i s s u r e s . This suggests  that either:  1. f i s s u r e i n t e r s e c t i o n s have l o c a l i z e d the m i n e r a l i z a tion,  or  2. m i n e r a l i z a t i o n h a s l o c a l i z e d the y o u n g e r , northwest trending f a u l t s .  I n h i s I93O r e p o r t , C o c k f i e l d l e a v e s t h i s p r o b l e m  unsettled.  . C o o k f i e l d , W71".;' opr~c*iT*. , Su^7Re^t7~1930~7~p74T  ""  "  The v e i n i s one o f the main l o n g i t u d i n a l f r a c t u r e s o f the a r e a , and  i s c u t by a f a u l t a l o n g i t s l e n g t h .  I t i s o f f s e t by  numerous c r o s s - f r a c t u r e s , and one l a r g e c r o s s - f a u l t on t h e Sadie property. G a l e n a , f r e i b e r g i t e and s p h a l e r i t e have been n o t e d as t h e i m p o r t a n t o r e m i n e r a l s , s i l v e r , p y r a r g y r i t e , quartz,  w i t h a s i d e r i t e gangue.  arsenopyrite  s  Native  p y r i t e and c h a l e o -  p y r i t e occur.  •  ClTeT£fTeTd7~WTE^  , Pt .A, pp.4-J7  H a c r o s c e p i c d e s c r i p t i o n - I r r e g u l a r masses o f t e t r a h e d r i t e o c c u r i n a l i g h t b r o w n i s h s i d e r i t e gangue.  The few specks o f  g a l e n a a r e u s u a l l y s e p a r a t e d by gangue from t h e t e t r a h e d r i t e . The s i d e r i t e i s c o a r s e g r a i n e d and shows t h e c h a r a c t e r i s t i c curving  cleavage  faces.  M i n e r a l o g y and P a r a g e n e s i s - I n p o l i s h e d hedrite, chaleopyrite, recognized.  section, tetra-  and s p e c k s o f a s i l v e r y m i n e r a l were  The gangue i s s i d e r i t e .  There i s v e r y  little  quartz. I t was n o t p o s s i b l e  t o c u t a s e c t i o n showing t e t r a -  h e d r i t e and g a l e n a i n c o n t a c t ,  as these two m i n e r a l s were  everywhere s e p a r a t e d by gangue. Tetrahedrite present i n appreciable Chaleopyrite and  and g a l e n a a r e t h e o n l y  metallics  quantities. c u t s the t e t r a h e d r i t e i n f i n e v e i n l e t s  i s c l e a r l y the younger.  PLATE 8  SPECIMEN  5  T e t r a h e d r i t e -arid . s i d e r i t e . ' T e t r a h e d r i t e v e i n s s i d e r i t e a l o n g the c l e a v a g e . of t e t r a h e d r i t e  (dark) follows  throughout i t s length.  One edge o f t h e v e i n l e t c l e a v a g e i n the s i d e r i t e  I r r e g u l a r replacement i s more  common on the o t h e r boundary.  Such a v e i n l e t  seem to have r e s u l t e d p r i m a r i l y from f i s s u r e and t o a l e s s e x t e n t from-subsequent the- h o s t . Panchromatic l/j50 second  Plate exposure  would filling,,  replacement o f  Galena v e i n s s i d e r i t e , g u i d e d by c l e a v a g e as shown i n t h e accompanying p h o t o m i c r o g r a p h ( P l a t e  directions VIII).  An u n i d e n t i f i e d s i l v e r m i n e r a l o c c u r s i n v e r y q u a n t i t i e s as blebs with the t e t r a h e d r i t e .  rounded t o s u b - a n g u l a r o u t l i n e s i n  I t s colour  than the t e t r a h e d r i t e .  i s a l i g h t e r shade o f s i l v e r gra;  Absence o f r e l i e f would I n d i c a t e  i t s hardness i s about t h a t o f t e t r a h e d r i t e . t e s t s could  not be made on such s m a l l  i s not n a t i v e  small  that  Hardness and e t c h  species o f m a t e r i a l .  It  s i l v e r and seems to be t o o h a r d f o r the u s u a l  s i l v e r and l e a d s u l p h a r s e n i d e s and s u l p h a n t i m o n i d e s . The o r d e r o f d e p o s i t i o n youngest  J »  i s probably as f o l l o w s : chaleopyrite  i  -i i oldest  -  9  I •• »  tetrahedrite siderite  T h i s replacement o f t e t r a h e d r i t e by c h a l e o p y r i t e i s as would be e x p e c t e d . Qui 1 d~FTirrr~JIi^roi"e'bpTo™Stu7Ly~of~SiTver OrosZ V o l . X I I , " 1 ? 1 7 , p.334. The t e t r a h e d r i t e  Ec.Geol. ,  ~*  i n t h i s o r e a s s a y e d 25«2 p e r c e n t  s i l v e r , thus p l a c i n g i t i n the c l a s s o f F r e i b e r g i t e .  Specimen Ho. 6. I t i s n o t known from what p r o p e r t y t h i s o r e was taken. I t was c o l l e c t e d by Mr. A. H u t c h i n s o n , o f ( l u e s n e l , Cariboo M i n i n g D i v i s i o n . Group, P r i n c e  Specimen No. 18 i s from t h e Snowshoe  George, C a r i b o o , o f w h i c h Mr. H u t c h i n s o n i s p a r t  owner*, I t seems p r o b a b l e the  t h a t Specimens fa and 18 a r e from  same p r o p e r t y , e s p e c i a l l y a s t h e o r e s t h e m s e l v e s a r e  macroscopically  identical.  Mineralogy purity.  and P a r a g e n e s i s  - T h i s o r e was o f e x c e p t i o n a l  O n l y t e t r a h e d r i t e and q u a r t z were found i n t h e  p o l i s h e d sections.. The s u r f a c e o f the t e t r a h e d r i t e was somewhat more p i t t e d than i s usual f o r t h i s mineral*  Specimen II o. 12. l o c a t i o n - The l o c a t i o n o f the d e p o s i t from which t h i s sample was t a k e n i s not known. "Illecillewat  1 1  The l o c a l i t y was given, as  w h i c h would p l a c e the d e p o s i t so me where i n the  Revelstoke-Glacier The D e p o s i t s  district. - Gunning, i n h i s r e p o r t on the B i g Bend map  a r e a , d i v i d e s the m i n e r a l d e p o s i t s i n t o f o u r c l a s s e s , namely 1. G o l d - Q u a r t z v e i n s . 2.  Copper d e p o s i t s .  J . Lead Zinc d e p o s i t s . 4. Q u a r t z - T e t r a h e d r i t e  veins.  ^aSoingT"' H.C. y.'O'eolbSaryTCanr. ''Sdmm»K'ept» 192"87"P%«A, p» 1.5,5» T h i s specimen c l e a r l y b e l o n g s to t h e f o u r t h c l a s s . The o n l y quart z - t e t r a h e d r i t e v e i n s d e s c r i b e d i n the I l l e c i l l e w a t d i s t r i c t a r e t h o s e o f t h e O l d George group. ^onnlngV 'ttT8Tr~oj?*^iX»,' 'p*^IT"~ ~ " * These v e i n s a r e s t a k e d on a s e r i e s o f s m a l l  irregular.  - 2 6 -  l e n t i c u l a r , guartz veins i n c r y s t a l l i n e limestone.  Ore  m i n e r a l s a r e p y r i t e , s p h a l e r i t e , g a l e n a , b o u l a n g e r i t e and probably t e t r a h e d r i t e .  Values are p r i n c i p a l l y i n s i l v e r .  The  gangue i s q u a r t z w i t h some c a l c i t e . O t h e r s i m i l a r o c c u r r e n c e s i n t h e B i g Bend a r e a c a r r y t e t r a h e d r i t e , b o u r n o n i t e and b o u l a n g e r i t e ( ? ) . M i n e r a l o g y and P a r a g e n e s i s - P o l i s h e d s u r f a c e s showed o n l y v e r y pure t e t r a h e d r i t e and q u a r t z . E x a m i n a t i o n , under b i n o c u l a r s , o f the c r u s h e d o r e showed a v e r y few g r a i n s o f p y r i t e , c h a l e o p y r i t e ( ? ) , g a l e n a and s p h a l e r i t e ( ? ) . These c o u l d n o t be found i n the p o l i s h e d s e c t i o n s and no d e p o s i t i o n a l sequence was worked o u t .  Specimen Fo. 1 7 . Submarine Group, L y t t o n , A s h e r o f t H i n i n g D i v i s i o n . L o c a t i o n - llo r e f e r e n c e to t h i s p r o p e r t y was found i n the B.C. M i n i s t e r o f Mines o r G e o l o g i c a l Survey o f Canada r e p o r t s . The  D e p o s i t s ~ Lode d e p o s i t s i n the A s h e r o f t  District  have been summarized a s f o l l o w s : B.C.^ l A n J i a T e ^ "Lode m i n i n g i n t h i s d i v i s i o n has been i d e n t i f i e d c h i e f l y w i t h low grade copper i m p r e g n a t i o n s  o f zones o f s h e a r -  i n g and f r a c t u r i n g i n a complex s e r i e s o f r o c k s o f p l u t o n i c , v o l c a n i c and sedimentary  origin.  This m i n e r a l i z a t i o n i s of a  p o s s i b l y more r e c e n t o r i g i n t h a n i s the ease w i t h the ore b o d i e s i n c l o s e r r e l a t i o n s h i p t o the s e a t o f the main w e s t e r n  - 2 7 -  bathclithic intrusion. " Ore m i n e r a l s a r e b o r n i t e and c h a l c o p y r i t e , c a r r y i n g v a l u e s i n g o l d and s i l v e r .  usually  Bo mention o f the o c c u r -  rence o f t e t r a h e d r i t e was found. M i n e r a l o g y and P a r a g e n e s i s - T e t r a h e d r i t e , p y r i t e a r e recognized© greenish,  The gangue i s q u a r t z .  supergene m i n e r a l v e i n s  g a l e n a and • An u n i d e n t i f i e d ,  the t e t r a h e d r i t e .  Galena and p y r i t e r e p r e s e n t o n l y a s m a l l o f the m e t a l l i e s .  percentage  P y r i t e a p p e a r s as a few s m a l l rounded  blebs. The p a r a g e n e s i s , i n t h i s c a s e , c o u l d n o t be determined very  satisfactorily.  P y r i t e , i n deposits early-formed mineral. g r a i n s , suggests e a r l y  of t h i s t y p e , i s u s u a l l y an  I t s o c c u r r e n c e h e r e , a s i s o l a t e d rounded deposition.  Galena d o u b t f u l l y v e i n s  tetrahedrite.  P y r i t e , taken  to be the f i r s t - f o r m e d m i n e r a l , was n o t e d i n t e t r a h e d r i t e  only.  T h i s i s c o n f i r m a t o r y e v i d e n c e o f the l a t e age o f t h e g a l e n a , a s , i f g a l e n a had r e p l a c e d  p y r i t e p r i o r t o the i n t r o d u c t i o n o f  t e t r a h e d r i t e , i t might now be e x p e c t e d t o i n c l u d e However, due t o t h e r e l a t i v e l y g r e a t e r  some p y r i t e . .  abundance o f t e t r a -  h e d r i t e , t h e v a l u e o f t h i s i n d i r e c t e v i d e n c e i s questionable. Contradicting  t h e above e v i d e n c e as t o t h e l a t e age  of the g a l e n a we have the f a c t t h a t t h e t e t r a h e d r i t e shows a tendency to embay t h e g a l e n a . has l i t t l e d i a g n o s t i c  However, t h i s f a c t , i n i t s e l f ,  value.  The o r d e r o f d e p o s i t i o n , t h e n , i s d o u b t f u l l y  PLATE 9  SPECIMEN  17  An e n l a r g e d photograph o f fragments o f c r y s t a l s o f t e t r a h e d r i t e from Ore Specimen 17• The g e n e r a l t e t r a h e d r a l form shows c l e a r l y , w i t h "o", "n" and "d" f a c e s as marked. X  8  d e t e r m i n e d as f o l l o w s : youngest . .  j i i „„ „ j i J ra  oldest  ra  galena tetrahedrite pyrite  T h i s i s t h e normal sequence. The  d i f f i c u l t y experienced i n accurately  determining  t h i s sequence was due t o t h e i m p o s s i b i l i t y o f o b t a i n i n g more t h a n a v e r y few g a l e n a - t e t r a h e d r i t e  contacts.  Specimen i?o. 18. Snowshoe Group , P r i n c e George, Location - This property  Cariboo.  i s mentioned i n the 1918 Annual  Report o f t h e B.C. M i n i s t e r o f Mines.  I t i s s i t u a t e d lj? m i l e s  ^3T5THS!fn^  T9T87~p7l2Tr~^  northeast The  o f P r i n c e George. Deposit - According  t o t h e 1922 r e p o r t , m i n e r a l i z a t i o n  IfTS^^  _ '__""*  accompanies a c l i o r i t e dyke, up t o 300 f e e t i n w i d t h , shale. and  "*"""  cutting  The v e r y s l i g h t m i n e r a l i z a t i o n o f 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 i s found i n the d i o r i t e and a l o n g the d i o r i t e -  s l a t e contact  zone.  I t i s f u r t h e r s t a t e d t h a t "assays show  t h a t t h e m i n e r a l i z e d r o c k does n o t c a r r y a p p r e c i a b l e  values I n  g o l d and s i l v e r , and t h a t the average samples have t o o l o w a copper c o n t e n t t o be o f commercial i m p o r t a n c e . " I n the  I 9 2 3  report, according  to i n f o r m a t i o n  supplied  by one of the s h a r e h o l d e r s ,  "We  went down on t h i s ( s h a f t )  17  f e e t , to a depth o f 27 f e e t , ana ore taken out at t h i s depth assayed $23 i n g o l d , s i l v e r and copper, and had widened out from a s t r i n g e r to 5 f e e t wide, with evidence o f s t i l l widening... "  Unfortunately,  metals a r e grouped t o g e t h e r . information  further-  the assay r e s u l t s f o r the three I t should  be emphasized that  this  i s s u p p l i e d by one of the owners.  M i n e r a l o g y ~ Only t e t r a h e d r i t e and quartz were noted i n the p o l i s h e d  sections.  Specimen Uo. 2 0 . S i l v e r S t a r , Similkameen. Location  - T h i s i s one o f the claims  o f the S p a r k l e r  Group, s i t u a t e d on Gambia Greek, a t r i b u t a r y o f Similkameen r i v e r w i t h i n about b m i l e s o f the headwaters. The  Deposit  - Tetrahedrite  i s not mentioned i n the descrip-  t i o n s o f t h i s group i n the Annual Reports o f the E.G. M i n i s t e r o f Liines.  I t i s s t a t e d that  "The copper contents were not  assayed." •  The  pyrite-arsenopyrite-sphalerite-chaloopyrite  m i n e r a l i z a t i o n seems to be g e n e t i c a l l y r e l a t e d to an i n t r u s i o n of gabbro i n t o the s e d i n i e n t a r i e s . o f v e i n s and lens-shaped b o d i e s , other  The ore occurs i n a s e r i e s  l o c a l i z e d by j o i n t  planes and  f r a c t u r e s i n the rock. M i n e r a l o g y and Paragenesis - The minerals  arsenopyrite,  occurring are:  s p h a l e r i t e ( ? ) , galena, t e t r a h e d r i t e , chalco-  •.-30p y r i t e , hypogene (?) v e i n l e t s and The  Quartz.  o r d e r o f abundance of the ore m i n e r a l s i s about  as f o l l o w s , b e g i n n i n g with the most p l e n t i f u l : chaleopyrite,  g a l e n a , ( s p h a l e r i t e (?) and  tetrahedrite,  arsenopyrite).  l a r g e a r e a s of t e t r a h e d r i t e are- r e l a t i v e l y except  for irregularly  d i s t r i b u t e d b l e b s of  pure  chaleopyrite*  These v a r y from the merest specks to f a i r s i z e d masses, a l though i t i s r a r e l y so p l e n t i f u l as to be v i s i b l e without microscope.  These seem to be r e s i d u a l areas i n the  tetrahedrite.  The  chaleopyrite  towards the t e t r a h e d r i t e .  we  as shown i n P l a t e X I , where c h a l e o p y r i t e tetrahedrite. h e d r i t e has  Age  the c h a l e o p y r i t e  concave  have the r e l a t i o n s  seems to v e i n the  r e l a t i o n s are i n d e t e r m i n a t e .  replaced  replacing  boundaries are u s u a l l y  Occasionally  the  That  tetra-  seems the. more, l i k e l y  interpretation* The r e l a t i v e ages of g a l e n a and t e t r a h e d r i t e not be proved c o n c l u s i v e l y . character  No  evidence o t h e r than the  of the c o n t a c t s could be  found.  P l a t e X i s taken to i n d i c a t e t h a t has  replaced  the g a l e n a f o r the f o l l o w i n g  1. smoothly  could  the t e t r a h e d r i t e  reasons:  curved c o n t a c t s are convex towards t e t r a -  hedrite. 2.  residual "outliers'  1  of galena occur i n the t e t r a h e d r i t e .  C e r t a i n r e l a t i o n s , seen i n other s e c t i o n s , equally well  be i n t e r p r e t e d as g a l e n a v e i n i n g  as g a l e n a p a r t i a l l y  replaced  however, i s r a r e l y surrounded  by t e t r a h e d r i t e .  can  tetrahedrite  or  Chaleopyrite,  by galena w h i l e i t s occurrence  as b l e b s w i t h i n  tetrahedrite i s c h a r a c t e r i s t i c  that galena has r e p l a c e d  both t e t r a h e d r i t e and  The above evidence i s a d m i t t e d l y A tentative  This  suggest  chalcopyrite.  inconclusive.  sequence i s ;  youngest  galena tetrahedrite chalcopyrite  oldest  arsenopyrite  The ores having been d e s c r i b e d next be c o n s i d e r e d .  9  the a n a l y s e s w i l l  PLATE 10  SPECIMEN  20  G a l e n a , t e t r a h e d r i t e , c h a l c o p y r i t e and  quartz.  T e t r a h e d r i t e appears t o " b i t e i n t o " g a l e n a , and therefore doubtfully replaces i t . Camera-lucida  drawing  X  275  PLATE 11  SPECIMEN  20  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 q u a r t z . The c h a l c o p y r i t e , unquestionably  i n t h i s s e c t i o n at l e a s t , i s  the younger.  I t a l s o occurs as  i r r e g u l a r rounded b l e b s throughout Such an o c c u r r e n c e , i n i t s e l f , Camera l u c i d a drawing  the t e t r a h e d r i t e .  i s non-diagnostic. X 8.5  CHAPTER I I I MERCURIAL TETRAHEDRITE FROM NORTH KOOTEETAY MUTES, L f B . , OTBERMBRE MIMING DIVISION, B.C.  INTRODUCTION I7h.ile making p r e l i m i n a r y blowpipe a suite of t e t r a h e d r i t e noted,  ores o f B.C.,  determinations  a mercurial variety  l a t e r work showed the s e l e c t e d m i n e r a l to be  on was  carrying  about 6 f » mercury. -4s s c h w a t z i t e ( m e r c u r i a l t e t r a h e d r i t e ) was . l y unknown i n B.C.,  and  i s o f r a r e occurrence throughout  world, a s e p a r a t e c h a p t e r has been devoted Six  previousthe  to t h i s occurrenceo  o c c u r r e n c e s o f s c h w a t z i t e are l i s t e d by Dana  Dana ; A System o f M i n e r a l o g y ,  S i x t h E d i t i o n , lBfb~~T^"ip?".  "~  The,mercury content v a r i e s from 2 . 7 0 t o 1 7 . 3 2 .  with analyses.  Mercury content of the o r i g i n a l  occurrence a t Schwaz, i n the  T y r o l , i s g i v e n as 15«j?£° In North America, Sumpter, Oregon. LTndgrerr,  VU  No  mercurial t e t r a h e d r i t e occurs  o t h e r o c c u r r e n c e o f the m i n e r a l on  ; 22nd Ann. Re*p*tT7 U« 3.0. S.', Pt" TJd^LffiL''  near  this  'lpTbb'4".' "*"  c o n t i n e n t i s known t o the w r i t e r . Proposed O u t l i n e . Occurrences  of m e r c u r i a l t e t r a h e d r i t e , as d e s c r i b e d  i n the l i t e r a t u r e , w i l l be b r i e f l y attention w i l l est  discussed.  be g i v e n t o an occurrence  Special  i n Oregon, the  known d e p o s i t to that of the Windermere D i s t r i c t .  Economic Geology o f the Windermere w i l l be b r i e f l y  The  r e s u l t s of a d e t a i l e d study o f the  be g i v e n and d i s c u s s e d .  The  described,  and p u b l i s h e d data on the occurrence to be studied, w i l l summarized.  near-  be  ore-will  -33 MERCURIAL TETRAHEDRITE OF THE  LITERATURE  G e n e r a l l y speaking, mercury o c c u r s i n two deposits.  By f a r the most important  types of  are those i n which the  metal occurs i n the form of c i n n a b a r .  In o t h e r d e p o s i t s i t  occurs as.an e s s e n t i a l c o n s t i t u e n t i n t e t r a h e d r i t e , as  first  d e s c r i b e d from Sehwaz, T y r o l . 'Beyscnlag, Yogt '& Krusch, 0r^'De^sit"'s"7~v'oTT!l,' p.~4~j7T Cinnabar  sometimes occurs i n the o x i d a t i o n zone  through the decomposition  of tetrahedrite.  z a t i o n at the s u r f a c e may  persist  be taken by mercury-bearing  occurrence  or non-occurrence  tetrahedrite.  of o t h e r heavy metal  w i t h the cinnabar o f s u r f a c e showings may  •  The  compounds  give a c l u e as to i t s  - a p o i n t of economic  importance.  Other q u i c k s i l v e r m i n e r a l s are o f secondary ance e  minerali-  to depth or I t s p l a c e , In  depth, may  primary or secondary nature  Cinnabar  import-  .  M e r c u r i a l t e t r a h e d r i t e might be s a i d to form a c o n n e c t i n g l i n k between t y p i c a l mercury d e p o s i t s ( c i n n a b a r ) on the one hand and  s i l v e r - l e a d - z i n c deposits (galena, sphalerite  and t e t r a h e d r i t e ) on the o t h e r . under "Mineralogy and  T h i s w i l l be f u r t h e r d i s c u s s e d  Paragenesis."  Known D e p o s i t s . The  accompanying t a b l e o f a n t i m o n i a l q u i c k s i l v e r  d e p o s i t s i s taken from Becker.  1  The data  2  from d e p o s i t s i n  1 Ber. Vogt & Krush', Ore D e p o s i t s , V o i . l , p.4i?b". 2 L i n d g r e n , W.; U.S.G.S. 22nd Ann.Rept., P t . 2 , 1901, p.664.  -33af  i  03 a +>  14 05  « a  i 1  •H - H  • H  a += GS  o  o  o s!  - H  4=  54  •-CJ  ! 05 14  54 4 * CiJ - H  o pq  .43  4= •H 54  SI  1  S4 c  14  i  +=> •H O rH  rH  £>; CD  •H 4^  •H  H  V>  0)  a 0> •1-1  •rt  54  o  1 I  PI  4=  ca $4  o  ret  54  r-i  54  i4  14  0) o  4=  45  S3  0)  s  H  14  O  ?d r-i  ©  U  PQ  J4  m  « O  a  • H  4=  I o  14 O  -H  a  o rH •H - H O s5 e-t a  &  54 03 d O  o  rH &  i-i  o  o o  O  • H  G3  r-3  +3  $4 +»  « o  54  pq  %4  60 ! S3  4=  a +=> a  a*  s  14  in -r-!  o  o  •H O N  .o o  O K fe5 - H  s  35  •H  4=  »H  « © t p IH  rH  ©.  I  •I  O  4 C3 4= S  H  as  O a  C3 S4 - H • H 4»  a  • O •,  CD  o  t»  • H  81 CSS «H  54  I ta £ o o 54  rQ  43  si <&  &  54 <M  O  o  • H  O  O  J4  <J>  ^  >  M ».H O CO {25 4=>  Cd r H  > >  J4  CO  a «8  CD C3 - H 4= O 54 CS ^> r H ffl  54  GO  flS - H Ja{ • H  ft  1 -fl  -H  54 54  0) o ElO P-i a > a J4 d o  4=>  to  rH * O 54 <D.O © .54 « f d <D 4= i  SH - H  S  - H  54  4=  Oregon and B r i t i s h Columbia are  added*  With the e x c e p t i o n o f the B o s n i a o c c u r r e n c e , a l l are pre K e s o z o i c . Galena  Quartz, p y r i t e and c a l c i t e are u s u a l l y present.  and s p h a l e r i t e and b a r i t e may o c c u r . Becker,  le'ckerT^G'g*;~  summarizing h i s monograph  UTSTG.S.  ,^onVxITr7~ToW7  d e p o s i t s o f the P a c i f i c "The with  on the mercury  p°4537~""  slope, says: "  m i n e r a l s which occur i n c o n s i d e r a b l y q u a n t i t i e s  q u i c k s i l v e r ores are few i n number.  i s n e a r l y always p r e s e n t , a r s e n i c or many l o c a l i t i e s and copper  P y r i t e o r marcasite  antimony i s found at  ores sometimes accompany cinnabar.  Other m e t a l l i f e r o u s m i n e r a l s are comparatively  rare.  The  p r i n c i p a l gangue seems to be i n v a r i a b l y e i t h e r s i l i c a , times hydrous,  or carbonates, c h i e f l y  As t o the temperature  some-  calcite."  o f f o r m a t i o n o f mercury  deposits, lindgren states:  XinSgren, W ~T~Mineral Deposits,"T92B',' a  "The  p.559«  •  ~"  occurrence o f q u i c k s i l v e r m i n e r a l s i s by no  means c o n f i n e d to any c e r t a i n k i n d o f d e p o s i t s or to any g i v e n age  o r epoch o f m e t a l l i z a t i o n .  However such minerals are not  known to occur i n d e p o s i t s o f d i s t i n c t l y igneous pegmatite  d i k e s , nor i n v e i n s of the deepest  o r i g i n nor i n  zone.  High temp-  e r a t u r e i s e v i d e n t l y u n f a v o r a b l e f o r t h e i r development." As the m i n e r a l a s s o c i a t i o n of E p i t h e r m a l mercury d e p o s i t s , he g i v e s cinnabar, p y r i t e , marcasite, s t i b n i t e  common  c h a l c o p y r i t e and m i l l e r i t e  rare  -35o p a l , chalcedony, b a r i t e and  q u a r t z , c a l c i t e , dolomite  alunite  common gangue r a r e gangue  As a Hesothermal a s s o c i a t i o n he &ive3 bindgren, K.;  op. e i t . , p.b2?7  p y r i t e , a r s e n o p y r i t e , c h a l c o p y r i t e , g a l e n a , blende, t e t r a h e d r i t e and  cinnabar l e s s  gangue o f quartz and  with  conspicuous,  calcite.  A r s e n o p y r i t e here i n d i c a t e s d e p o s i t i o n under c o n d i t i o n s of temperature  and  pressure at l e a s t above those u s u a l l y  r e s p o n s i b l e f o r Epithermal d e p o s i t i o n . T h i s m i n e r a l i s a p p a r e n t l y absent and  i s not mentioned i n Becker's  from the Windermere  table.  A l l these d e p o s i t s , with the e x c e p t i o n of t h a t i n Oregon, seem to be o f r a t h e r low temperature  d e p o s i t i o n , agree-  i n g more n e a r l y with E p i t h e r m a l than with Me so thermal mineral associations. The m e r c u r i a l v a r i e t i e s of t e t r a h e d r i t e g i v e n i n Dana show a h i g h e r average s p e c i f i c g r a v i t y than the normal variety.  V a r i a t i o n i n the s p e c i f i c g r a v i t y does not  correspond  with the v a r i a t i o n s i n mercury c o n t e n t . The  appearance of a r s e n o p y r i t e i n the Sumpter,  Oregon, d e p o s i t makes the m i n e r a l assemblage of t h i s g o l d d e p o s i t agree more c l o s e l y with t h a t c i t e d from Lindgren as a Mesothermal  occurrence.  Deposit  o f Schwatzite  near Sumpter, Oregon.  T h i s b e i n g the n e a r e s t known occurrence  of mercurial  t e t r a h e d r i t e , i t seems worthy o f a short d e s c r i p t i o n . LTndgren, VI.; U.S.G.s7^1nT7^nn.ReptTr3?t»2, l ^ Q l T p.bb4. . The d e p o s i t was worked by the Columbia Gold Co.  s  as a g o l d d e p o s i t .  M i n e r a l i z a t i o n i s found along a  f r a c t u r e zone i n b r i t t l e , b l a c k s i l i c e o u s a r g i l l i t e s , showing s t r a t i f i c a t i o n or s c h i s t o s i t y . o east and d i p s 60  Mining  southwest.  rarely  The zone t r e n d s n o r t h -  This f r a c t u r e zone , about 40  f e e t wide, c o n s i s t s o f abundant b l a c k a r g i l l i t e fragments and b l o c k s i n a m a t r i x o f white q u a r t z . shows drusy comb s t r u c t u r e .  The q u a r t z sometimes  P y r i t e . s e r i c i t e , and sometimes  . c a l c i t e have r e s u l t e d from the a l t e r a t i o n o f the w a l l rock. M e t a l l i c m i n e r a l s are c h i e f l y p y r i t e and arseno^ pyrite.  Other m i n e r a l s found are n a t i v e copper, g o l d ,  s p h a l e r i t e , p y r a r g y r i t e , cinnabar, antimonite, c h a l e o p y r i t e , s t i b n i t e , a t e l l u r i d e and s c h w a t z i t e . quartz.  The gangue i s c h i e f l y  Other gangue minerals are s e r i c i t e , f u c h s i t e , and  calcite. The pay occurs i n s t r e a k s , f o l l o w i n g e i t h e r w a l l , or c r o s s i n g from one w a l l to another.  GENERAL ECONOMIC GEOLOGY OF WINDERMERE DISTRICT A g e n e r a l o u t l i n e o f the Economic Geology o f t h i s d i s t r i c t w i l l be g i v e n here. occurrence  The r e l a t i o n o f the m e r c u r i a l  to type occurrences o f the d i s t r i c t  can then be  -37discussed, below.  I t w i l l be seen t h a t the mineral a s s o c i a t i o n  o f the m e r c u r i a l d e p o s i t The been covered  General  i s e x c e p t i o n a l f o r the Windermere.  and Economic Geology o f the area  by Walker i n h i s r e p o r t on the  Mineral Deposits  o f Windermere Map  Area,  "Geology  has  and  B.C."  WalkerT"?". 1 .; ' G^l".l^urvTGan. t"l!iem7T4W7~WZbT  ~  ?  ~ '  The N o r t h Kootenay Mines d e p o s i t l i e s w e l l w i t h i n t h i s map  a r e a , and The  on the  e a s t e r n s l o p e o f the P u r c e l l  exposures are o f Devonian and  i n t r u d e d by J u r a s s i c g r a n i t e The  these are  sills.  sedimentary formations  Upper Devonian i n age.  o l d e r sediments  stocks.  Pre-Cambrian P u r c e l l and  cut by greenstone dykes and  Windermere S e r i e s are  Unconformably o v e r l y i n g  ranging  from Upper Cambrian to  These are a l l i n t r u d e d by Mesozoic  ( p r o b a b l y J u r a s s i c ) g r a n i t e stocks and  apophyses.  unconformable" o v e r l a i n , w i t h i n the map  a r e a , by  P l e i s t o c e n e and  This i s  unconsolidated  Recent d e p o s i t s .  L e a d - s i l v e r and l e a d - s i l v e r - z i n c are the Important m e t a l l i c d e p o s i t s of the  area.  d e p o s i t s o f v a l u e have been found. gypsum d e p o s i t s of any op.  range.  economically  I'o copper or g o l d  E o r are the b a r i t e and  importance at  present.  c i t . , p.4 L e a d - s i l v e r and  l e a d - s i l v e r - z i n e d e p o s i t s occur  as  f i s s u r e and bed v e i n s , a s s o c i a t e d w i t h minor a n t i c l i n a l f o l d s on the l i m b s o f the l a r g e r f o l d s . with  The  v e i n s tend to  the f o l d i n g - about n o r t h JO degrees west.  commonly the rocks o f the P u r c e l l  series.  strike  They are  -38M e t a l l i c m i n e r a l s noted a r e ; galena sphalerite pyrite chaleopyrite freibergite some c o v e l l i t e Oxidized minerals are; chiefly  cerussite  Gangue m i n e r a l s a r e ; quartz (two  generations)  c a l c i t e (white to p a l e cream) barite  (dense and massive to c r y s t a l l i n e and white to pale green)  siderite (alteration of pyrite) She  order o f d e p o s i t i o n i s g i v e n as y o ung e s t  \ «  g ale na  i  tetrahedrite  §  s i ,—i—.—..j !  \ i i  oldest  sphalerite pyrite gangue  As quartz i s the c h i e f gangue mineral,, the o f b a r i t e and determined pyrite  s  calcite  i n the sequence has  accurately.  position  probably not been  S i d e r i t e gangue i s younger than the  from which, a c c o r d i n g to Walker, i t lias been formed.  op. e i t . , p.43' I f he i n t e n d s to imply that the b a r i t e i s one  of the  first  formed m i n e r a l s , t h i s c o n c l u s i o n does not  check w i t h that  a r r i v e d a t "by the present w r i t e r . Ee mentions s e v e r a l n o t a b l e to  t e t r a h e d r i t e he  features.  With r e f e r e n c e  says;  " dp'. ciTr7~p744T  '  *"* ' ' ~" '  -—  -  " F r e i b e r g i t e or 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 Is the p r i n c i p a l silver-bearing mineral. in  i t s microchemical  silver  content.  r e a c t i o n s a p p a r e n t l y due  to the v a r y i n g  11  T h i s statement of  I t shows marked v a r i a t i o n s  may  be found  the p o s s i b l e mercury content  to be s i g n i f i c a n t  i n view  o f o t h e r t e t r a h e d r i t e ores o f  Windermere-. F u r t h e r , i n accordance the  with general observations i n  C o r d i l l e r a , he f i n d s t h a t  ""op. .-cTF^''.,"".pT4^T~  ~ "~*~~' „ "  M  r  "  r7  "  f  !  "  ~  "the p r o p e r t i e s s i t u a t e d at the h i g h e r e l e v a t i o n s are on the whole e s s e n t i a l l y l e a d - s i l v e r b e a r i n g and  practically  f r e e from z i n c , whereas the p r o p e r t i e s l o c a t e d a t lower tudes  c a r r y c o n s i d e r a b l y more s i n e , and  t i e s that the replacement  o f z i n c blende  i t i s i n these  altiproper-  by galena Is n o t i c e -  able . * The  p r o p e r t y o f the P e r t h Kootenay Mines l t d . ,  at an  e l e v a t i o n of 92J50 f e e t j u d g i n g by the ore examined, c a r r i e s no s  z i n c and  so f i t s  into t h i s general  rule.  F u r t h e r , there are no contact metamorphic d e p o s i t s , nor are c o n t a c t phenomena w e l l developed.  To quote Walker,  WINDERMERE MAP AREA showing l o c a t i o n o f PRETTY GIRL CLAIM, NORTH KOOTENAY MINES, LTD.  -40"There i s no evidence o f m i n e r a l i z a t i o n being centrated  i n the neighborhood o f g r a n i t e He  period  con-  bodies."  b e l i e v e s that the d e p o s i t s are connected w i t h the  of J u r a s s i c mountain b u i l d i n g and igneous i n t r u s i o n .  THE  DEPOSIT  P r e t t y G i r l C l a i m , N o r t h ICootenay Mines, l t d . T h i s deposit  i s f i r s t mentioned, i n the 18?8 Annual  Report o f the B.C. M i n i s t e r of Mines, as one o f six l o c a t i o n s , viz.,  the Yenus, Hew Chum, P r e t t y G i r l , Mimaiehaha, O l d Chum,  and Beauty, h e l d by the Hew Golden B. 0 . Company, o f London, England, r e p r e s e n t e d  by W.G. M i t c h e l l - I n n e s ,  o f Golden.  Of  the group, o n l y the P r e t t y G i r l has been worked. c l a i m i s s i t u a t e d about 1 8 m i l e s west o f the town  The o f Windermere.  I t l i e s on the summit o f the d i v i d e between the  headwaters of B o u l d e r and Law's Creek, at an e l e v a t i o n of f e e t , on the east  slope  92j?0  of the P u r c e l l Range.  Walker, i n h i s s e c t i o n on Economic Geology, makes no  pp. c i t . , p.43. mention o f the P r e t t y G i r l  c l a i m and has not v i s i t e d  that  ridge. Pe r so 11a 1 coramuni e a t i 0 11.  '  For data on t h i s p r o p e r t y ,  ~  "  reference  "  must be made to  r e p o r t s o f trie B.C. M i n i s t e r o f Mines. The  mineralized  zone, some 6 - 8  f e e t wide, occurs i n  steeply dipping  s o f t shales  t r e n d i n g I 25  0  W.  The  gray copper  ore , w i t h accompanying carbonates , l i e s between the l a y e r s o f the  shales  or s l a t e s .  The  statement i s made that  "There seems to be no v e i n i n the u s u a l o f the  term,- but  A representative  acceptance  a zone i n the bedding of the shales-  !l  sample i s s t a t e d to c o n t a i n 26.68% copper  55«»5 oz. o f s i l v e r per t o n . In the 1915  . .  r e p o r t mention i s made of a v e i n "which to 10  v a r i e s from a seam up  inches  i n width, c o n s i s t i n g of  quartz somewhat s t a i n e d w i t h m a l a c h i t e (copper  carbonate)."  B. br~f!it5Tilie^  ~  Assays o f grab samples gave 20.8/. copper and s i l v e r per  BTG.  '  58 ounces of  ton. I n the '1928  as  and  r e p o r t the p r o p e r t y  i s again  r e f e r r e d to  follows; ~  M i n i s t e r ' ^ ? Mines, Ann.F^pTr"l9.2d7~P^2To^ "The  P r e t t y G i r l , s i t u a t e d on the  r i d g e between Slade and  Law  Creeks, was  ICootenay Mines, L t d . , of which J.A. No  further information  MINERALOGY AND  summit o f  the  operated by the North  Lundy i s p r e s i d e n t . "  i s g i v e n i n these  reports.  PARAGENESIS  Macroscopic D e s c r i p t i o n of Specimen In a l l , s e v e r a l pounds o f ore from the North ICootenay Mines was  obtained  o f Mines, Vancouver.  through the  courtesy  o f the B.C.  Chamber  It  showed hut  have come from the  little  v a r i a t i o n and  same lump of  ore.  In a l l p r o b a b i l i t y i t i s not but,  might w e l l a l l  representative  i n the absence o f a more complete s u i t e , w i l l  material  be  described. One It  piece  i s a greyish  of ore  green i n d u r a t e d  somewhat s c a l y t a l c o s e tact.  was  vein  M a l a c h i t e ana the  ore  ore  con-  tetrahedrite. study of  a s s o c i a t i o n o f the more  wall.  a z u r i t e with a l i t t l e  i r o n oxide  are  tends to occur i n bands - a band of massive  c o m p a r a t i v e l y pure t e t r a h e d r i t e a g a i n s t  mineralization The  wall.  conspicuous a l t e r a t i o n p r o d u c t s . The  and  at the  at hand to permit of the of the  vein  i n p a r t a l t e r e d to a  w i t h massive m e r c u r i a l  s i g n i f i c a n c e , I f any,  massive ore w i t h the  shale  o f the  or c h l o r i t i c m a t e r i a l  I t i s i n contact  .Insufficient material the  c a r r i e s a piece  t h i s b a r i t i c ore.  p y r i t e and In the  resultant  seen i n  absence o f a s y s t e m a t i c s u i t e  of  r e l a t i o n of  walls.  M i n e r a l o g y and  tetrahedrite  i r o n oxide are  o b s e r v a t i o n s can be made on the  banding to v e i n  The  sparser  i n a f i n e l y c r y s t a l l i n e - white b a r i t i c gangue.  chaleopyrite,  specimens, no  a band of  following  Paragenesis  m i n e r a l s have been r e c o g n i z e d :  (mercurial),  pyrite, chaleopyrite,  c h a l e o c i t e , a z u r i t e , m a l a c h i t e , b a r i t e ana  bornite,  quartz.  T h i s appears to be an unusual a s s o c i a t i o n f o r  the  PLATE 13  SPECIMEN  1  B a r i t e , t e t r a h e d r i t e , p y r i t e and  chaleopyrite»  Taken to show the t y p i c a l mode o f : o c c u r r e n c e c h a l e o p y r i t e w i t h i n t e t r a h e d r i t e - as  of  irregular  v e i n l e t s and i s o l a t e x l bleihsi throughout»  The  dark  border around the gangue i s ' merely. a d e p r e s s i o n . dark areas w i t h i n the t e t r a h e d r i t e are pits., originally  containing earthy black non-metallic  material. Panchromatic p l a t e Kodak C o l o r f i l t e r .(X 3) 1/23  second exposure  • X  83  The  PLATE'14  SPECIMEN Tetrahedrite, chaleopyrite bordering  1  c h a l e o p y r i t e and p y r i t e .  The  occurs as v e i n l e t s and as areas  pyrite residuals.  This  close  a s s o c i a t i o n of p y r i t e and c h a l e o p y r i t e i s typical  i n t h i s ore.  containing believed  The b l a c k areas are p i t s ,  s o f t non m e t a l l i c m a t e r i a l .  This i s  to account, i n p a r t , f o r the low assay  totals. Panchromatic p l a t e Kodak C o l o r f i l t e r l/10 second  (X 3)  exposure  X  273  PLATE  SPECIMEN Tetrahedrite pyrite.  1  ana c h a l e o p y r i t e r e p l a c i n g •  The p y r i t e shows as w e l l rounded  of h i g h r e l i e f .  Tetrahedrite  are not d i f f e r e n t i a t e d of the s m a l l e r Tetrahedrite,  grains  and c h a l e o p y r i t e  i n the photograph.  Many-  v a i n l e t s are of c h a l e o p y r i t e . intimately associated  (as u s u a l )  w i t h c h a l e o p y r i t e , and r e p l a c i n g p y r i t e i n t h i s way, i s undoubtedly primary. Panchromatic Kodak C o l o r  •.  Plate filter  (X 3)  I/25 second.exposure  X 85  '  PLATE 16  SPECIMEN Chalcopyrite, The  veinlet  pyrite and•tetrahedrite.  i s a supergene m i n e r a l .  This association is typical.  1  Pyrite  g r a i n s arranged  o f p y r i t e ana  chalcopyrite  occurs as i s o l a t e d rounded  i n l i n e s , forming  "veinlets".  C h a l c o p y r i t e occupies these same l i n e s , surroundi n g or b o r d e r i n g the p y r i t e .  Such p y r i t e  "veinlets"  may or may not be accompanied by c h a l c o p y r i t e p y r i t e seems to be e s s e n t i a l to c h a l c o p y r i t e Oamera-lucida  drawing  but areas.  X 85  PLATE 17  SPECIMEN Chalcopyrite,  1  p y r i t e , t e t r a h e d r i t e and  bariteo . Chalcopyrite  shown r e p l a c i n g pyrite„  Tetrahedrite-chalcopyrite minate. Camera-lucida drawing  r e l a t i o n s Indeter-  -43" •'Windermere D i s t r i c t . I n the ore examined, the a s s o c i a t i o n o f t e t r a h e d r i t e , p y r i t e and c h a l c o p y r i t e i n a gangue of quarts and b a r i t e i s by f a r the most common.  She  age  r e l a t i o n s f o r t h i s group o f  m i n e r a l s have been f a i r l y s a t i s f a c t o r i l y determined discussed f i r s t .  and w i l l  be  T h i s i s the m i n e r a l a s s o c i a t i o n found In the  massive ore. A somewhat d i f f e r e n t and l e s s s a t i s f a c t o r i l y termined a s s o c i a t i o n i s found t i o n i n the gangue a r e a s .  de-  i n the disseminated m i n e r a l i z a -  The m i n e r a l s here are too  fine-  g r a i n e d and too I n t i m a t e l y i n t e r g r o w n to permit o f s a t i s f a c t o r y determination.  F u r t h e r , they occur i n such small q u a n t i t i e s as  to be of minor importance  only.  The  d i s c u s s i o n of the  para-  g e n e s i s o f t h i s group, arid of i t s r e l a t i o n to the f i r s t w i l l be l e f t u n t i l  later.  M a l a c h i t e , a z u r i t e and alteration 1.  group,  limonitic  i r o n oxide occur as  products.  The q u a r t z , p y r 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 , b a r i t e mineru  alization. These m i n e r a l s were d e p o s i t e d i n the order mentioned. O v e r l a p p i n g and contemporaneous d e p o s i t i o n o c c u r r e d i n the ease of c h a l c o p y r i t e and The  tetrahedrite.  r e l a t i o n s w i l l be d i s c u s s e d , as f a r as p o s s i b l e ,  i n the order of d e p o s i t i o n . Quartz occurs as a few i s o l a t e d rounded g r a i n s i n the b a r i t e and  i s probably one  o f the f i r s t  P y r i t e i s undoubtedly  formed m i n e r a l s .  an e a r l y mineral o c c u r r i n g  ~44-  . .  c h a r a c t e r i s t i c a l l y as groups and i n c l u d e d i n , and  veined  by,  t e t r a h e d r i t e and  T h i s i s c l e a r l y shown i n P l a t e Chaleopyrite i s i n c l u d e d and  chaleopyrite,,  XV.  v e i n s t e t r a h e d r i t e and,  embayed by i t . Therefore  deposited  b e f o r e , a f t e r , and  hedrite.  P l a t e s XIV  this  masses of w e l l rounded g r a i n s  i n other  1  i t must have been  contemporaneously w i t h ,  and XVI  places  , taken t o g e t h e r ,  tetra-  illustrate  overlap. Chaleopyrite  t e t r a h e d r i t e , and  i s u s u a l l y seen as patches and  accompanying p y r i t e .  v e i n i n g t e t r a h e d r i t e are not v e r y as i s o l a t e d b l e b s  and  blebs  in  Good examples o f i t s  common.  I t sometimes occurs  specks i n t e t r a h e d r i t e , but  p a r t i s found as i l l u s t r a t e d  i n Plates  a s s o c i a t e d with p y r i t e .  presence of p y r i t e would appear to  The  have been e s p e c i a l l y f a v o r a b l e rite. and  concentrated.  XIV  - closely  to the d e p o s i t i o n o f chaleopy-  these same l i n e s that we Tetrahedrite  •.be, comparatively It  The barium and  areas on  to  chaleopyrite  and  contemporaneous.  a sodium b i c a r b o n a t e  gangue i s u n a f f e c t e d  XIX  determined by a flame t e s t f o r f u s i o n t e s t f o r sulphate.  by a c i d , c o l o r l e s s , and  It c l e a r l y r e p l a c e s  c h a l e o p y r i t e and  chaleopyrite  pure.  b a r i t e gangue was  Plate  find  e i t h e r side are l i k e l y  i s probable that most of the  t e t r a h e d r i t e are  quartz.  and  P y r i t e o c c u r s as l i n e s or " v e I n l e t s " o f i s o l a t e d g r a i n s  i t i s along  cite.  XVI  f o r the most  harder than c a l -  a l l o t h e r hypogene m e t a l l i e s  and  shows replacement remnants o f p y r i t e ,  tetrahedrite i n barite.  The  PLATS 18  SPECIMEN  1  B o r n i t e i n dark "barite gangue. determinations magnification.  were i m p r a c t i c a b l e  Accurate under t h i s  The dark gangue d i s t i n c t l y  embays, and i s t h e r e f o r e younger than, the metallics.  The main b o r n i t e mass  contains  l a t h s and v e i n l e t s of c h a l c o p y r i t e , best at the top of the s e c t i o n .  seen  The p a t c h y areas  w i t h i n the b o r n i t e may i n d i c a t e replacement by c h a l c o c i t e or c o v e l l i t e and l i m o n i t e . Panchromatic p l a t e Kodak Color f i l t e r  (X 3)  l/10 second exposure  X 275  PLATS 19  SPECIMEN  1  P y r i t e and t e t r a h e d r i t e . i n b a r i t e gangue. Relations  here are taken to i n d i c a t e replacement  o f the s u l p h i d e s  by the gangue.  They appear as  embayed, and i n c o m p l e t e l y r e p l a c e d , scattered  through the r e p l a c i n g  Panchromatic no  filter  remnants  gangue.  plate X  85  CHART showing RELATIVE AGES OF MINERALS i n ore from PRETTY GIRL CLAIM WINDERMERE M.D.  I*]  5 0)  0  10  i c u CD 0 a  O  o  I  • •-§1 id f)  E to  s 0  M  t 0 O y t  2.The c h a l e o p y r i t e , b o r n i t e , c h a l c o c i t e , b a r i t e m i n e r a l i z a t i o n . The ization  s m a l l amounts i n which t h i s disseminated  occurs p r e c l u d e s  mineral-  the p o s s i b i l i t y of p o s i t i v e i d e n t i f i -  cation. Chaleopyrite  was s a t i s f a c t o r i l y  identified.  A p i n k i s h brown m i n e r a l may be b o r n i t e although the colour i s a l i t t l e  too d e c i d e d .  The p o s s i b i l i t y o f i t s being  b o r n i t e i s supported by the occurrences w i t h i n i t , o f l a t h s or n e e d l e s o f c h a l e o p y r i t e , o r i e n t e d i n three that these are f o l l o w i n g o c t o h e d r a l A b l u i s h mineral  groups.  I t may be  cleavage.  has about the c o l o u r o f c o v e l l i t e .  I r r e g u l a r feathery-edged areas o f a s l i g h t l y darker, brownish m i n e r a l oblique  a r e developed I n the c o v e l l i t e  (?).  By  i l l u m i n a t i o n i t seems to show a f a i n t brownish r e d  internal reflection.  I t s c o l o u r , by r e f l e c t e d l i g h t , however,  does not seem t o q u i t e cheek with that o f l i m o n i t e . IIo p a r t i c u l a r mineral relief  o f t h i s group shows any marked  so a l l must be of the same order  of hardness.  These m i n e r a l s are shown on P l a t e Bornite  (?) was the f i r s t  to be  XVIII.  deposited.  T h i s i s cut by d i s t i n c t v e i n l e t s of c h a l e o p y r i t e . Chaleopyrite ite (?).  a l s o occurs as l a t h s or needles w i t h i n the born-  T h i s mode o f occurrence may i n d i c a t e , a c c o r d i n g to  l i n d g r e n , e i t h e r replacement o r unmixing. "'Lindg'r'en', TTIneral  Deposits,  I n the present younger than the b o r n i t e  1JZti'^fTdlJl  case, then, c h a l e o p y r i t e  i s i n part  (?) and i n part e i t h e r younger o r  conteraporaneous. The  c o v e l l i t e replaces bornite  phery o f the grains©  (?) about the p e r i -  Replacement v e i n l e t s from the c o v e l l i t e -  b o r d e r may i s o l a t e a r e a s o f b o r n i t e ana f i n a l l y leave a few i r r e g u l a r l y rounded remnants o f b o r n i t e i n covellite© C h a l c o p y r i t e needles r a r e l y cut the covellite© project due  A few  i n t o i t from the b o r n i t e but t h i s r e l a t i o n i s probably  to delayed  replacement o f c h a l c o p y r i t e by covellite©  b o r n i t e has been p r e f e r e n t i a l l y replaced©  •  A r e a s o f a somewhat darker grayish-brown r e p l a c e the c o v e l l i t e with  The  mineral  a f e a t h e r y embaying border.  A l l are r e p l a c e d by b a r i t e gangue except the supergene c o v e l l i t e  ( ? ) and i t s r e p l a c i n g  Chalcopyrite mineralization©  mineral.  i s common to the: above two types o f  In the absence o f evidence to the c o n t r a r y i t  must be assumed t h a t we have but one g e n e r a t i o n  of chalcopyrite.  C o r r e l a t i n g , we see t h a t b o r n i t e ( ? ) was d e p o s i t e d a f t e r (probably)  p y r i t e and before  barite..  I f the remaining  minerals  (covellite  (?) and l i m o n i t e ( ? ) ) are supergene, and have  metasoraatically r e p l a c e d the b o r n i t e , they are probably  younger  than the b a r i t e , r  fhe time r e l a t i o n s o f these minerals  are shown  g r a p h i c a l l y i n P l a t e XX.  Etch  Reactions  E t c h t e s t s were made on g r a i n s o f pure s e l e c t e d mineral  and a r e compared w i t h  etch t e s t s g i v e n f o r t e t r a h e d r i t e  -47i n standard works on the s u b j e c t . The m a t e r i a l used than the S c h w a t z i t e .  showed no m e t a l l i c m i n e r a l s other  I r r e g u l a r cracks and p i t s were common on  the p o l i s h e d s u r f a c e s .  As the reagents were a p p l i e d only to  the m i n e r a l under examination;,  r e s u l t s were not i n f l u e n c e d by  galvanic action.  ,  C o n s i s t e n t technique was employed throughout. specimen was p o l i s h e d on the rouge b l o c k immediately a p p l y i n g the reagent..  The reagent was l e f t  The  before  i n contact with  the m i n e r a l f o r one minute, then washed o f f with a stream o f water from:the t a p . f a c e allowed to d r y .  S u r p l u s water was blown away and the s u r The e f f e c t  o f t h e r e a c t i o n was then  observed. The specimen was then .-re-poll shed, on the rouge b l o c k p r e p a r a t o r y to the next  test.  A l l r e a c t i o n s were checked  by r e p e t i t i o n , u s i n g o t h e r  grains. The schwatzite.  f o l l o w i n g t e s t s , then, were obtained f o r They check v e r y c l o s e l y w i t h those p u b l i s h e d f o r  t e t r a h e d r i t e , and, i n themselves variety of tetrahedrite.  w i l l not determine  this  -48As determined f o r schwatzite  as g i v e n f o r T e t r a h e d r i t e , in Farnham |  HNCL cone.  >  ESO.  •. •.:  .  1:1  KC!f  2 0 %  HgClg  sat.?  Aqua Fcegia  somet imes stains faint  neg.  neg.  neg.  • neg.  neg.  neg.  neg.  neg.  •  JHunt  i neg*.  neg. to v e r y • s l i g h t brown stain  Short  neg.- fumes fume s tarnish tarnish  neg.  F e C l , 2 0 f.  'J  slowly stains brown  very s l i g h t brown s t a i n  1 : 1  HOI  irridescence to brovm stain fumes t a r n i s h  Davy & Farnham  neg.  • neg.  neg. fumes may t a r n i s h slightly  The m e r c u r i a l m i n e r a l appears to show a more d e f i n i t e r e a c t i o n to n i t r i c  a c i d than the o r d i n a r y  varieties.  Physical Properties The p h y s i c a l p r o p e r t i e s of t h i s t e t r a h e d r i t e show a d i s t i n c t v a r i a t i o n from those  o f the normal m i n e r a l -  -49presumably due  to the mercury content.,  T y p i c a l t e t r a h e d r i t e shows a smooth conchoidal f r a c t u r e and a h i g h , almost  splendent, l u s t r e .  t i e s the f r a c t u r e i s somewhat uneven - almost very high .lustre not apparent. mineral i t i s at once apparent o f the normal m a t e r i a l .  In o t h e r varis hackly and  the  On examining the m e r c u r i a l t h a t i t has not the appearance  I t has a s i l v e r y white c o l o u r and a  d i s t i n c t l y uneven f r a c t u r e .  Under the hand l e n s there i s seei  to be a d e c i d e d tendency towards conchoidal f r a c t u r e i n individual grains. In the accompanying t a b l e , the p h y s i c a l p r o p e r t i e s o f t h i s m i n e r a l are t a b u l a t e d against those g i v e n i n Dana. 'pan&J~^ET§,T^^S^a%^' b'f~B^^  "~~~~  r  Dana l i s t s an a n a l y s i s of s c h w a t z i t e c a r r y i n g 5°57  percent mercury with a s p e c i f i c g r a v i t y of 4 . 7 3 3 * present m a t e r i a l we of 4 . 8 3 .  ;  I&  the  have 6 . i f . mercury and a s p e c i f i c g r a v i t y  """37"!  - 5 0 -  Comparison o f P h y s i c a l P r o p e r t i e s of T e t r a h e d r i t e and Schwatzite AS  i n Jana  .  Schwatzite Windermere, B.C.  i  isometric  tetrahedral  a l s o massive; g r a n u l a r , f i n e ; compact»  coarse o r  ma s s i ve  granular  cleavage none  cleavage none  f r a c t u r e subconehoidal to uneven  uneven, subconchoidal in detail  rather  l e s s b r i t t l e than m a t e r i a l with smooth fracture.  brittle  l u s t r e m e t a l l i c , o f t e n splendent, c o l o u r f l i n t gray to i r o n b l a c k ,  m e t a l l i c , not s p l e n dent  s t r e a k l i k e c o l o u r , sometimes i n c l i n i n g to brown and c h e r r y red  powder dark r e d d i s h brown  H  a  3-4  G  -  4.4-3«l  medium hardness  Schwatzite G s  4 . 7 3 3 - 5 . 3 . 5 6  (average 5 ° 0 8 l )  G  =  4.83  -51AMALYSIS AID FORMULA Analyses/ of course  s  had. to he made i n presence o f  mercury. To check the e f f e c t  o f mercury on copper assays by  the F l u o r i d e - I o d i d e method, a s e r i e s o f s y n t h e t i c samples were made up with known amounts o f copper, and assayed. foil  Pure  copper  i n the presence o f f e r r o u s ammonium sulphate was used to  standardize the standard s o l u t i o n o f thiosulphate.  Synthetic  samples o f ore were made up with copper and antimony present i n the p r o p o r t i o n s found i n the p r e l i m i n a r y a s s a y s . mercury was added.  To one s e t  I n another i t was added i n the p r o p o r t i o n  found i n the n a t u r a l ore and i n o t h e r assays i t was added i n two,  t h r e e and f o u r times t h e n a t u r a l The  percentage.  r e s u l t s o f assays on these show a p r o g r e s s i v e  small i n t e r f e r e n c e o f mercury on the copper d e t e r m i n a t i o n s . The e f f e c t , however, o f b percent mercury i s but s l i g h t .  In  t h i s ease the value o f the t h i o s u l p h a t e s o l u t i o n i n terms o f copper was.obtained  by t i t r a t i o n o f the s y n t h e t i c sample  con-  t a i n i n g b p e r c e n t E g , and the e f f e c t o f the i n t e r f e r e n c e  thus  compensated f o r . The A n a l y s i s gave Copper  53» 8  Silver  .2  Lead Zinc  4.0  Insol.  4.9  -521,0  Iron  . 23.4  antimony Arsenic  1.4  Sulphur  22.1  Mercury  6.1  Taking out the i n s o l u b l e and  c o r r e c t i n g to 100  p e r c e n t , we  have • -. Copper  36.8  Silver  .  Zinc  .2 4.3  Iron Antimony  25.4  Arseni c  1.5  Sulphur-  24.0  Mercury  6.6 100.0  I n s u f f i c i e n t m a t e r i a l was The  a v a i l a b l e f o r check a n a l y s e s .  low t o t a l i s probable to be accounted f o r as  follows 1.  fhe presence of copper carbonates, conspicuous i the o r e .  2. B a r i t e gangue e n t e r i n g i n t o the assayed The gangue i s dominantly b a r i t e . SO^  material  N e i t h e r Ba nor  were assayed f o r .  3» The probable presence of other elements, not  ~33~ • assayed f o r , i n t h i s somewhat unusual ore. D i v i d i n g by atomic weights, we  get  the atomic proper-  tions Copper  .373  Silver  a002  Zinc  .066  Iron  .021  Ant imony  .211  Arsenic  .020  Sulphur  »750  Mercury.  .ojo  I r o n was o f corresponding  deducted as c h a l e o p y r i t e i m p u r i t y .  valence  Copper  )  Silver  )  Zinc  ^  Mercury  j  were grouped.  We  Elements  have -  ,10  Ant iraony )  ,23  Arsenic  .71  Sulphur These p r o p o r t i o n s 3  (Cu,Ag)  2  correspond to the S,  formula,  (Hg.Zn)S . ( A s , S b )  2  S^  T h i s i s the u s u a l formula f o r the other samples of tetrahedrite indefinite  studied.  proportions.  Here, however, mercury r e p l a c e s z i n c i n  -54GOMPARISOlf WITS OTHER DEPOSITS OF WIFDERMERE DISTRICT Mercury i n t e t r a h e d r i t e has not p r e v i o u s l y "been recognized i n t h i s d i s t r i c t t e r i s t i c mineral.  a l t h o u g h t e t r a h e d r i t e i s a charac-  'When the presence o f mercury was d e t e c t e d i n  the  m i n e r a l i t was hoped that i t might prove to be g e n e r a l i n  the  gray copper ores o f the district© Specimens from s e v e r a l p r o s p e c t s i n the d i s t r i c t were  made a v a i l a b l e through the k i n d n e s s o f Dr. J.F. Walker, G e o l o g i c a l Survey Canada. I t was hoped mercury would be i d e n t i f i e d i n some o f these p r o s p e c t s , g i v i n g a d i s t r i c t  of mercurial  tetrahedrite.  Several methods suggested themselves f o r the detect i o n o f mercury. The most'obvious method was t o use the o r d i n a r y commercial assay methods on s e l e c t e d t e t r a h e d r i t e . of  Specimens  ore from two p r o s p e c t s were l a r g e enough to permit o f the  use o f t h i s method.  Assays on t e t r a h e d r i t e from the Hot Punch  group, and from the S i l v e r Spray p r o p e r t y , gave mercury n i l . These p r o p e r t i e s are l o c a t e d about 5 and 11 m i l e s , to  the south of the P r e t t y G i r l  Walker,  respectively,  claim.  J,FT; op. citVV_PP_«4F-49. Specimens from o t h e r p r o p e r t i e s c o n s i s t e d only o f  p o l i s h e d s e c t i o n s so t h a t assay and blowpipe methods were excluded. I t was hoped that the presence of mercury would g i v e the  m i n e r a l some c h a r a c t e r i s t i c etch t e s t .  A careful series of  e t c h t e s t s , run on the known m e r c u r i a l t e t r a h e d r i t e , gave the  -55r e s u l t s t a b u l a t e d on page 48. tic.  E t c h t e s t s , then,  the other  These proved to be non-diagnos-  could not be used to detect mercury i n  specimens. Hierocheraical t e s t s were hot  used.  Galena, s p h a l e r i t e , p y r i t e , a l i t t l e and  t e t r a h e d r i t e , i n a quartz gangue i s the  mineral  assemblage o f the d i s t r i c t .  chaleopyrite,  characteristic  In the deposit under d i s -  c u s s i o n -we have m e r c u r i a l t e t r a h e d r i t e , p y r i t e , and c h a l e o p y r i t e , i n a b a r i t e gangue. i t e was  little  ITeither galena nor  sphaler-  noted. A comparison of the m i n e r a l  a s s o c i a t i o n shows the  m e r c u r i a l d e p o s i t to be unusual i n the d i s t r i c t creases  a  the l i k e l i h o o d of mercury being  and  so  found i n the  de-  tetra-  h e d r i t e o f the other d e p o s i t s - d e p o s i t s of a d i f f e r e n t  type.  T h i s b r i n g s us to the q u e s t i o n of g e n e s i s .  GE1ES1S But l i t t l e  can be s a i d here, due  d e t a i l e d p u b l i s h e d i n f o r m a t i o n on the  to the l a c k of  property.  M i n e r a l i z a t i o n occurs as a zone, between the o f the B.C.  W.  T h i s corresponds w i t h  M i n i s t e r of Mines" ; Ann.Kept. 1898,  general Walker, The  s h a l e s , t r e n d i n g If Z$°  bedding  PP»1042  & 1Q54.  trend of l e a d - S i l v e r - Z i n c deposit s as a l r e a d y  the '  described.  J.F.; op. c i t . • P«43.  deposit  i s r e f e r r e d to as a "zone", f o l l o w i n g the  o f the s h a l e s .  bedding  T h i s would suggest replacement, e i t h e r s e l e c t i v e  •-56-. replacement wards from  o f f a v o u r a b l e beds or replacement some permeable channel.  by s o l u t i o n s out'  Lacking d e t a i l e d  informa-  t i o n , i t i s u s e l e s s to s p e c u l a t e on the o r i g i n of t h i s  bedding  channel. A s m a l l p i e c e o f the v e i n w a l l on one mens was  of the  speci-  s u g g e s t i v e o f f i l l i n g , w i t h p o s s i b l e subordinate  replacements 'The d e p o s i t w i l l be compared w i t h l i n d g r e n * s Mesothermal  and E p i t h e r m a l  intermediate  deposits... I t w i l l  be seen to occupy an  position.  Of E p i t h e r m a l d e p o s i t s l i n d g r e n says;  ^ j M r e n , W..; M i n e r a l P ^ r o s T E F r T Q ^ I ^ " A r s e n i c and arrtimony, bismuth the t y p i c a l  q u i c k s i l v e r d e p o s i t s belong  ti—complex  silver  to t h i s  sulphantimonides  i d e s are a l s o c h a r a c t e r i s t i c ; - - — A m o n g pyrargyrite, miargyrite,  are common class. and  them are  sulpharsen-  proustite,  stephanite, polybasite, tetrahedrite  and more r a r e l y e n a r g i t e . "Of the gangue m i n e r a l s quartz i s the most abundant, —  O a l c i t e , dolomite, b a r i t e , and f l u o r i t e are l o c a l l y  dominant gangue m i n e r a l s . "  ,  Of Mesothermal d e p o s i t s , he L i n d g r e n , tf.; op. "The copper,  .  says:  c i t . , p.599'  p r i n c i p a l metals  l e a d and  the  zinc.  The  a r s e n i d e s , sulphantimonides  c o n t a i n e d are g o l d ,  silver,  ore m i n e r a l s are s u l p h i d e s ,  and  sulpharsenides.  c o p y r i t e , a r s e n o p y r i t e , g a l e n a , z i n c blende,  Pyrite.  chal-  tetrahedrite,  tennantite  and n a t i v e g o l d are the most common  predominating gangue mineral  . —  The  i s q u a r t z , hut carbonates are  a l s o common, such as c a l c i t e , dolomite and a n k e r i t e , — - — ; f l u o r i t e and b a r i t e are o c c a s i o n a l l y o f importance; —  if  In t h i s ease we have prominent b a r i t e , the presence o f mercury and the absence o f g a l e n a against The  i n c l u d i n g the deposit  and s p h a l e r i t e ; a l l  i n the t y p i c a l Lie so thermal  class.  mercury and b a r i t e would suggest a somewhat lower tempera-  ture o f deposition. not very  diagnostic. The  should  P y r i t e , c h a l e o p y r i t e and t e t r a h e d r i t e are  ore has not t y p i c a l B p i t h e r m a l . s t r u c t u r e .  probably  It  be c l a s s e d as a low temperature Mesothermal  deposit. Deposits a connecting with  cinnabar  deposits.  o f t h i s type might be c o n s i d e r e d  l i n k between normal E p i t hernial mercury and the t y p i c a l  In t h i s connection  Be3rsinn!aliT  as forming deposits  s i l v e r - l e a d - z i n c Mesothermal B e y s c h l a g , Vogt, and Erusch say;  «" 0~re~DepcTsTts, 1916, p«b57« "Such occurrences  (mercurial tetrahedrite) i n  g e n e r a l , however, are r a r e ana of l i t t l e may be s a i d t h a t a sharp l i n e  importance, so that i t  e x i s t s between the l e a d - s i l v e r - "  z i n c l o d e s and the q u i c k s i l v e r lodes  proper."  SUMMARY AID COHCLtTSlOHS A deposit  of m e r c u r i a l  t e t r a h e d r i t e occurs  m i l e s west o f the town o f Windermere, B.0.  about 18  -58The  mercurial  content o f the  ore has  not  previously  been r e c o g n i z e d . lundy, J .A. , P r e s . HorTE^Co~o"te"hay~Sines l t d . ' ^ p e r s o n a l 'eVramuhi. cation. l  1  :  Mercurial P y r i t e and  tetrahedrite  chalcopyrite  are  the  i s . the dominant m e t a l l i c . o t h e r important s u l p h i d e s .  The  gangue i s b a r i t e . T h i s m i n e r a l a s s o c i a t i o n i s unusual I n the Windermere district. It  probably i n d i c a t e s d e p o s i t i o n  below that o f the  at a temperature  normal s i l v e r - l e a d - z i n c d e p o s i t s  of  the  district. The  s e l e c t e d m i n e r a l was  a n a l y s e d and  the  following  formula suggested.  3 [(Cu,Ag) •  The  physical  2  S , (Kg , Z n ) s ] . properties  (As,Sb)  g  S  d i f f e r somewhat from those  o f t y p i c a l t e t r a h e d r i t e , n o t a b l y those of f r a c t u r e , b r i t t l e n e s s , colour,  l u s t r e and The  those o f the The  etch r e a c t i o n s normal  and  do not  differ materially  from  tetrahedrite.  economic importance of the  i n t h i s deposit at hand.  streak.  discovery  cannot•be e s t i m a t e d from the  meagre  o f mercury information  A c c e s s i b i l i t y , tonnage, average mercury content,  treatment, are  f a c t o r s to be  considered.  CHAPTER I f  ANALYSES & FORlB-lAl.  ~59~ DATA Assays were made o f pure t e t r a h e d r i t e from each specimen, as d e s c r i b e d above* The dumber  1  Cu  uncorrected  Ag  Pb  Zn  Insole  53.8 —  2  assay r e s u l t s a r e shown below.  ••5  35-7  3  «  4  °  °  5o4  4.9  1.0  5.3  V  11.0  4.8  12.5  .4  4.3  2.4  2.1  4  32.8  4.8  5  3.^ «  25.2  6  36.5  12 .  35*7  2.9  4.8  17  29.8  7.8  4.8  18  37.4  20  31*2  • ^ 4.8 -  3*4  3«7  .4  6.3  _  S  Eg  Total  23.4 1.4  22.1  6.1  96.9  21.0  3.7  23.6  OR R  20.4 1.3  20.6  93 = 5  2.0  22.5  95.1  22. 5  93.2  24.2 If .8  As  •&  y-eO  22.5 * A  24.9  98.5  2.2  18.6  6.0  24.9  96.3  2.8  3.7  I8.5  4,6  23.5  95.5  1.6  1.2  23o3 3.8  24.5  97.6  1.0  23.9  23.7  96.6  show an a p p r e c i a b l e  F u r t h e r , the t o t a l s f a l l  1.4  "Insoluble"  short o f 100 percent.  F o r the purposes o f c a l c u l a t i o n s , the " I n s o l u b l e " was removed and the percentages a d j u s t e d to g i v e a t o t a l o f 100 p e r c e n t , as shown below.  /  1.4  12.8  6.3  These analyses content.  Sb  -6oBum™ ber  Cu  1  36.8  »2  4 . 3 6,6  2  3?0  *6  3  27.8  13.6  4  35*4  5c  20.6  27.1  6  38 «4  Zn  ?e  Sb  As  S  1.2  25.4  1.5  24.0  92.0  100.0  6.0  .6  23. 2  26.0  90.5  100.0  5«9  •5  25.2  1.6  25.4  81.0  100.0  4.6  2.5  26.1  2.1  24.3  92.7  100.0  1.5  5*1  21» 3  .2  24.2  93.0  100.0  .•5  6.0  1.5  23«7  3c7  '26.2  95.1  100.0  2.5  19-6  6.3  26.2  95*1  100.0  5.9  20*0  5.0  •25.3  92.'7  100.0  '24.3  4.0  25.5  96.O  100.0  25., < >" 1.5  '25.5  93.8  100.0  Ag  2  Eg  Uncorrected total less Insol.  12  37.5  3»0  5«1  17  32.2  8*4  5.2  18  38.9  .'5  5.6  1.2  20  3>«3  6.7  6.7  1.0  •  *•»  ^  A tomic p r o p o r t i o n s were c a l e u l ated i n each case dividing  by the  atomic weight- s. Copper  64  Silver  108  Mercury Iron Antimony  All  calculations  5  Atomic weights used were is  0  Zinc  Total  65.^1. 201 56  126  Arsenic  75  Sulphur  32  have been made on a t e n i n c h s l i d e r u l e ,  g r e a t e r a c c u r a c y being meaningless. The atomic p r o p o r t i o n s are shown below, t o g e t h e r  by  -61w  i  t  h  t h e  number  i  r  o  minerals  n  known to be present  Cu  Ag  Zn  1  .575  ,002  .0.66  .030 .021  2  .617  .006  .092  .011  3  .434  • 12 6  «090  4  .553  .048  Hg  Fe  Sb  as  Impurities,  Iron Impurities  As  s  .020  .750  ..193  .054  , .812  .009  .210  , .021  .070  .041  .217  .028  «759 c h a l e o p y r i t e  . 251  .023  .091  .177  .003  .755  *600  .005  .092  .027  .197  .049 . .818  12  .586  .028  .078  .041  .163  .084 , .818  17  .503  .084  .079  .070  -167 . .067  = 791 p y r i t e  18  .608  .005  .086  .021  .202  .053  .797  20  .521  • 062  .102  .018  .213  .020  . 7/1 c h a l e o p y r i t e  5 6  I r o n was Where I r o n m i n e r a l s the  i r o n was  t a k e n to be present were not  assumed to be  T h i s assumption was and  18j  respectively. low  The  only as an  chaleopyrite pyrite & chaleopyrite  impurity* sections,  as p y r i t e .  n e c e s s a r y f o r specimens 2,  (uncorrected) . 6 ,  assaying  «793  noted i n the p o l i s h e d  present  Chaleopyrite  .4,  1.4  and  assumption i s j u s t i f i a b l e ,  1.2  3*  percent  i n view o f  6 iron  the  percentages. The  being  atomic p r o p o r t i o n s  taken out  with the f o r the  were then c o r r e c t e d , i r o n  as p y r i t e or c h a l e o p y r i t e  combined copper and  sulphur.  i m p u r i t i e s , are g i v e n below.  The  impurities,  together  f i g u r e s , corrected  -62Humb  e  r  . ^u  Zn  Hg  Fe  Sb  As  s  .211  .020  .708  i  = 554  .002  ,066  2  o6l7  .006  .092  = 193  .054  »790  3  .434  .126  .090  .210  .021  *775  4 •  ,512  .048  .070  .217  .028  .677  5  . 231  .231  .023  -177  .003  «573  6  06OO  .005  .092  .197  .049  . 7 64  12  .566  .028  .078  .163  .084  .736  17  .503  .084  .079  .167  .067  . 651  18  .608  .005  .086  .202  .053  .755  20  «503  .062  . 10 2  .213  .020  .755  030  FORMULAE Formulae, f i t t e d to these atomic p r o p o r t i o n s i n t o t h r e e groups.  S i l v e r , mercury and z i n c are assumed to  " r e p l a c e " copper under valence c o n t r o l . replacing  fall  A r s e n i c i s taken as  antimony.  Below are shown the atomic p r o p o r t i o n s , c o r r e c t e d f o r i m p u r i t i e s , grouped, and g i v e n to two f i g u r e s , and the c o r r e s p o n d i n g approximate formulae.  -63-  3[( Cu,Ag) S ,(Hg, Zn) s j . (As,Sb) S 2  2  o 62 .56  •09 .09  25  •79  lo[(Gu Ag) S,Zns1  . 3(As Sb),  •23  *77  l0L(0u Ag) S Zns]  .  >  2  t  2  2^  5  ?  5(As,3b)^ approx  ,56 ,48  . 61  • 07 .02  22  .76  8[(Cu Ag) S Zns]. y  P  3(As,Sb)  t  2 3 S  approx .18  = 57  lo[(Cu Ag) S,Zns| . 3(As Sb) S^ 2  t  8  £  ,09  25  -76  3 [(Cu,Ag) S , Z n s ] .  (As,Sb) S  • 59  .08  .25  • 74  3 (Cu,Ag) S ,Zns] .  (As,Sb) S^  17  59  .08  .23  .65  3 (Ca,Ag) S,ZnS * ( A s , S b ) S ^  18  61  ,09  -2.5  75  23  *75  o  12  20  56  10  2  £  2  2  very approx.  £  3 ( C u A g ) S , Z n s ] .(As, i b ) 8  2  10 [(Cu Ag) s  >] .  2 3 S  3(As,Sb) S  .  ?  A l l a n a l y s e s , with the e x c e p t i o n o f numbers 4 ana fit  fairly  c l o s e l y one o r the o t h e r o f the two formulae: 1) 2)  lo[(Cu,Ag) S,Zns] . 3(As,Sb) S  5  3(As,Sb) S  3  2  9[( C u , A g ) S , Z n s j . £  2  2  or ^[(Cu.Ag) S . Z n s ] .  (AS.SD)  23  ?rom these a n a l y s e s , t e t r a h e d r i t e would appear to  7  3  17,  form an isomorphous series© The  a n a l y s i s o f sample 4 f i t s approximately the  8 [( Cu,Ag)' S , Z n s J © ^ U s . S b ) ^  formula  w h i c h again f i t s  2  the isomorphous  series.  . Copper and s i l v e r r e p l a c e one another t i o n s from 3 7 - 4 percent percent  into  copper and ©4 percent  copper and 25©2 percent  i n a l l propor-  s i l v e r to 1?.2  silver©  Z i n c , as z i n c s u l p h i d e , r e p l a c e s the ( C u , A g ) m o l e c u l e i n v a r i a b l e p r o p o r t i o n s , the z i n c forming up t o 6.5 percent o f the m i n e r a l , by weight. In a l l a n a l y s e s , except 4 percent  or over.  one, z i n c was present as  As no z i n c was found  i n the p o l i s h e d  s e c t i o n s o f the m a t e r i a l s t u d i e d under the microscope,  it is  l o g i c a l to assume t h a t i t should be i n c l u d e d In the formula© In the m e r c u r i a l t e t r a h e d r i t e (Specimen Ho. 1) mercury and z i n c , h a v i n g the same v a l e n c e , have been w r i t t e n a r e p l a c i n g each other i n i n d e f i n i t e p r o p o r t i o n s . molecule the  T h i s (Hg,Zn)S  i n turn replaces, again i n i n d e f i n i t e proportions,  (Cu,Ag) S molecule © 2  Specimen 5 i s remarkable f o r i t s h i g h s i l v e r of  25©2 p e r c e n t .  general  It f i t s ,  content  q u i t e c l o s e l y , one o f the same two  formulae.  Formulae and S i l v e r I f we study these formulae c o n t e n t , and omit approximations,  Content i n r e l a t i o n to s i l v e r  those o f D u m b e r s 4 and 17,  both o f which are  we see t h a t the f o l l o w i n g r e l a t i o n h o l d s :  l o w - s i l v e r t e t r a h e d r i t e , formula: 3[(Cu Ag) f  2  S,Zns] . ( A S S D ) S  2  h i g h - s i l v e r t e t r a h e d r i t e , formula; 10 [ ( C u A g ) $  dumber 2 appears neralization»  '  2  S,Zns] . 3(As,So)  to he an e x c e p t i o n t o  this  (  CmPTIR  T  S H I S1I.V33B. C G N O T T ,  -b6~ OUTXIHE OF CHAPTER The  s i l v e r content o f t e t r a h e d r i t e i s c l e a r l y o f  major importance.  I n t h i s Chapter i t w i l l be c o n s i d e r e d i n  connection with; I- geographical l o c a t i o n o f deposits s t u d i e d . 2. t h e m i n e r a l a s s o c i a t i o n o f t h e s e d e p o s i t s . 5« t h e type o f d e p o s i t , i . e . t r u e . f i s s u r e o r replacement. 4.. the. age o f t h e a s s o c i a t e d m i n e r a l s , p a r t i c u l a r l y the g a l e n a . 5» p h y s i c a l p r o p e r t i e s . 6. e t c h t e s t s .  LOCALITY Specimens 2, 6 and 18 a r e from a d j a c e n t areas i n C a r i b o o and Quesnel M i n i n g D i v i s i o n s ( P l a t e  ).  I t i s p o s s i b l e t h a t Specimens b and 18 a r e from the same d e p o s i t . U n c o r r e c t e d a s s a y s o f t h e t e t r a h e d r i t e from these d e p o s i t s g i v e a s i l v e r content o f . 5 5 , . 5 and . 4 5 p e r c e n t , respectively. These d e p o s i t s w i l l be c o n s i d e r e d f u r t h e r , under the heading  of "Mineral A s s o c i a t i o n " .  MINERAL ASSOCIATION above t h r e e specimens ( 2 , 6 and 18) w i t h v e r y low  s i l v e r a r e o f s i m p l e m i n e r a l a s s o c i a t i o n - q u a r t s and t e t r a drite only.  The next l o w e s t s i l v e r assay was from Specimen  Ho* 12 - a l s o a simple ore o f q u a r t z and t e t r a h e d r i t e .  Here,  however, v e r y minor q u a n t i t i e s o f o t h e r m i n e r a l s , i n c l u d i n g g a l e n a , appeared. With t h e e x c e p t i o n o f Specimen Ko. 1, a l l o t h e r ores c a r r y a t l e a s t 4.8 p e r c e n t s i l v e r , and w i t h t h i s marked i n crease  i n s i l v e r c o n t e n t , we have a p a r a l l e l marked i n c r e a s e ixi  the p r o p o r t i o n o f a s s o c i a t e d m i n e r a l s .  The o n l y o t h e r m e t a l l i c  m i n e r a l - common t o a l l t h e s e i s g a l e n a . T h e r e f o r e , i t might be c o n c l u d e d t h a t these q u a r t z t e t r a h e d r i t e o r e s , when f r e e f r o m g a l e n a , a r e v e r y p o o r i n s i l v e r and, f u r t h e r , t h a t t h e appearance o f g a l e n a for, the  accounts  o r i s i n some way connected w i t h , the s i l v e r content o f tetrahedrite. .Further work,on the s i l v e r c o n t e n t o f t h e g a l e n a o f  t h e s e o r e s , would be o f i n t e r e s t . A s s a y s on o t h e r o r e s , a l o n g s i m i l a r l i n e s , w i l l be needed t o e s t a b l i s h t h i s r e l a t i o n . i t would be o f t h e utmost p r a c t i c a l The  Should i t be e s t a b l i s h e d , importance.  p o s s i b i l i t y o f e s t a b l i s h i n g some such  s h i p f o r the g o l d c o n t e n t a t once suggests  itself.  relationGold  d e t e r m i n a t i o n s were not made i n the course o f t h i s work. However, i n c o n n e c t i o n w i t h Specimen JTo. .18, i t has been s t a t e d t h a t "the a s s a y s show t h a t t h e m i n e r a l i z e d rock does not c a r r y a p p r e c i a b l e v a l u e s i n g o l d and s i l v e r . "  This  s u g g e s t s t h a t these s i m p l e t e t r a h e d r i t e - q u a r t a v e i n s are poor i n b o t h g o l d and s i l v e r .  I f t h i s i s tore, they can he o f  l i t t l e economic i m p o r t a n c e .  TYPE OF DEPOSIT Generally, t e t r a h e d r i t e of f i s s u r e veins c a r r i e s a h i g h e r p e r c e n t a g e of s i l v e r t h a n t h a t o f replacement warren, I I . ? . ; p e r s o n a l c o ^ u n T c a t i nr)7~  ~—'  deposits,  -  A l l d e p o s i t s c o n s i d e r e d here p r o b a b l y b e l o n g to the true f i s s u r e type. The g e n e r a l i z a t i o n does not h o l d i n t h i s case. o f the t e n samples a s s a y e d c a r r i e d One  Four  percent s i l v e r or l e s s .  of t h e s e , the m e r c u r i a l m i n e r a l d i s c u s s e d i n  C h a p t e r 111, i s u n u s u a l and i t s f a i l u r e to f i t the g e n e r a l i z a t i o n i s not  surprising.  The. o t h e r s , Specimens 2, 6 and 18, are the s i m p l e t e t r a h e d r i t e - q u a r t z o r e s mentioned under KIFSRAL ASSOCIATION. They a r e low i n s i l v e r and y e t are undoubtedly from f i s s u r e veins.  RELATIVE AGE OF GALSTTA AI?D TETRAHEDRITE Here, a g a i n , f u r t h e r work must be done on the c o n t e n t o f the a s s o c i a t e d g a l e n a .  silver  I t might t h e n be p o s s i b l e to  show some r e l a t i o n between the r e l a t i v e ages of these m i n e r a l s and the d i s t r i b u t i o n o f the s i l v e r . The g a l e n a - t e t r a h e d r i t e o r e s i n t h i s group a r e those  -69o f Kmttbers 3 ,  4, 5  17  3  and  c o u l d not be d e t e r m i n e d .  20.  -The age  5  of the g a l e n a i n Ho.  I n the r e m a i n i n g  f o u r , g a l e n a was,  as  n e a r l y as c o u l d be d e t e r m i n e d , l a t e r than the t e t r a h e d r i t e . I n a l l t h e s e we have 4.8  percent  s i l v e r , or  over.  As p o i n t e d out above, i t a p p e a r s , from a  general  s u r v e y o f the a n a l y s e s , t h a t t h e r e i s some c l o s e c o n n e c t i o n tween t h e p r e s e n c e o f g a l e n a and tetrahedrite.  the s i l v e r content  be-  o f the  And  y e t g a l e n a seems to have formed l a t e r t h a n  the t e t r a h e d r i t e .  This point requires f u r t h e r i n v e s t i g a t i o n .  l a c k i n g galena assays,  f u r t h e r s p e c u l a t i o n here i s  meaningless.  PHYSICAL PROPERTIES The  p h y s i c a l p r o p e r t i e s to be  t o s i l v e r content l) • 2) 3)  considered  in relation  are: streak specific gravity f r a c t u r e and. l u s t r e .  Streak. All  specimens gave a b l a c k o r v e r y dark brown s t r e a k  on the s t r e a k p l a t e . I t i s o n l y under s p e c i a l c o n d i t i o n s t h a t the browni s h and  r e d d i s h shades can be o b s e r v e d to advantage. Two  methods were used ixi comparing the s t r e a k s  and  i n each case the samples were a r r a n g e d i n o r d e r , a c c o r d i n g the s t r e a k , from r e d d i s h brown to d u l l b l a c k , and numbered  to  -70eonsecutively.  Thus the powder a t the r e d d i s h end o f the  s c a l e was g i v e n the number 1, number  and t h a t a t the b l a c k end, the  10. The f i r s t method c o n s i s t e d i n comparing the shade o f  the  v e r y f i n e powder w h i c h a d h e r e d to the g l a s s w a l l s o f the  v i a l s i n which the p u r e , powdered m i n e r a l was k e p t p r i o r t o assay.  The second method was to s p r e a d a u n i f o r m l y t h i n l a y e r  o f each powdered specimen on a sheet o f w h i t e paper,  i n each  case t h e y were a r r a n g e d i n o r d e r a c c o r d i n g to shade, and numbered 1 to  10..  The r e s u l t s a r e g i v e n below: j  Specimen number  Stream number (on g l a s s ) 6  •• • .,„ 2  «. •  j  S t r e a k number ( o n paper) 1 ( d a r k choeol a t e brnwn'l  1  3  4  8  6  4  9  7  5  10  3  6  J  (dull black)  4  [ '  10 ( d u l l brownis black) j • 94-  12  5  2  17  7  8  18  2  20  1  (reddish brown)  :  1  '  J  3  As comparison was made by eye o n l y , these r e s u l t s p r o b a b l y would not be d u p l i c a t e d i n a n o t h e r t r i a l .  J  The above t a b l e w i l l be r e a r r a n g e d t o p e r m i t a more ready comparison  o f s i l v e r c o n t e n t and s t r e a k number.  The  s i l v e r c o n t e n t w i l l be i n c l u d e d i n t h e t a b l e and specimens a r r a n g e d i n o r d e r o f s i l v e r c o n t e n t , b e g i n n i n g w i t h the lowest,  Specimen number  Silver content  Streak Streak• number number ( o n g l a s s ) 1 ( on pape r )  1  6  18  1  1  .45  b 2 •  .'  2.9  4  •4.8  20 • ~ —  :  1  —  ~  17  _  j  3 7  3 ® —>  —  I  9 3  I  8  2 : —  8 10  I  "Z  •8  •  6  I t i s t o be o b s e r v e d 1.  ^  6.35  11.0  5  ?  '-'  7 /  „  . : 4  _ 3 |  3  ••it'-1  9  3  7.8  3  5  10  |-  7 7 10  that;  The f i v e specimens showing a s i l v e r c o n t e n t o f 2.9  per-  cent or under have, w i t h one e x c e p t i o n , an average s t r e a k number o f 3« 2 . The f o u r specimens showing a s i l v e r content o f from 4 . 8 to 11.0  p e r c e n t have, w i t h one e x c e p t i o n , an average  s t r e a k number o f 7 o r 8 . 3.  The r e m a i n i n g specimen, w i t h a s i l v e r content o f 25»2 p e r c e n t , has a n average s t r e a k number o f 1 0 .  1 |  ~  1  4  -55  12  i  2  *5  Average streak numhe r *-*• *•» x 3  T h e r e f o r e , we may c o n c l u d e ,  t h a t , the da rice r the  s t r e a k the g r e a t e r the s i l v e r c o n t e n t .  This conclusion i s i n  d i r e c t c o n t r a d i c t i o n t o Dana, who, under " F r e i b e r g i t e " s t a t e s "streak often reddish". Dana,' E.S.: "The" System' of" 1-lineral"ogy /""fath^'Edit'i^^nro 9~b7 p.I38, r  T h i s c o n c l u s i o n i s p r o b a b l y .of l i t t l e  practical  i m p o r t a n c e as the d i f f e r e n c e s i n t h e s t r e a k a r e much t o o s l i g h t to p e r m i t o f more t h a n a d o u b t f u l comparison w i t h specimens o f known s i l v e r c o n t e n t .  S t i l l , at t i m e s , i n f i e l d  work, such a method o f e s t i m a t i n g the s i l v e r content  might be  useful. Specific Gravity. S p e c i f i c g r a v i t y determinations specimens. as  were made f o r s i x  They were c o r r e c t e d f o r " I n s o l u b l e " c o n t e n t ,  taken  silica. The c o r r e c t e d r e s u l t s , a r r a n g e d i n o r d e r o f t h e i r  s i l v e r c o n t e n t , a r e g i v e n below; Specimen number 1  percent silver• . 2 ( 6 . 1 mercury)  6  •  4  specific gravity •  •  4.83  4.43 4.8  4.57  20  6.3  4.67  5  25.2  4.71  F o r numbers 6 , 4, 2 0 and 5 the s p e c i f i c g r a v i t y  i4  •73v a r i e s d i r e c t l y as the s i l v e r c o n t e n t .  The mercury content o:  number 1 a c c o u n t s f o r i t s h i g h s p e c i f i c g r a v i t y . F r a c t u r e and L u s t r e . Specimens were a r r a n g e d s i d e by s i d e , i n o r d e r o f t h e i r s i l v e r content.  There was no c l e a r r e l a t i o n between  v a r i a t i o n s i n f r a c t u r e and l u s t r e , and s i l v e r  content.  ETCH TESTS A s y s t e m a t i c s e r i e s o f e t c h t e s t s were made on pure tetrahedrite  from each specimen.  As the s i l v e r c o n t e n t  varied  up t o 25.2 p e r c e n t i t was hoped t h a t t h e s i l v e r content would i n some way be r e f l e c t e d i n the e t c h  reactions.  A s t a n d a r d i z e d technique, was employed these t e s t s .  throughout  The same g r a i n of. pure t e t r a h e d r i t e was used f o r  the s e r i e s o f r e a g e n t s . tween each t e s t .  I t was p o l i s h e d on rouged chamois be-  Reagents were a l l o w e d t o remain on the s p e c i -  men f o r one minute and. t h e n washed w i t h a, g e n t l e stream o f water.  S u r p l u s w a t e r was blown away, and the specimen d r i e d  and examined.  For f a i n t r e a c t i o n s ,  e t c h e d and unetehed p o r -  t i o n s i n c o n t a c t were examined. R e s u l t s were checked and t a b u l a t e d .  Ho s i g n i f i c a n t  v a r i a t i o n s i n the e t c h t e a t s , from those g i v e n i n s t a n d a r d w o r k s , were n o t e d .  Concentrated  l i g h t brown s t a i n .  R e a c t i o n s t o o t h e r r e a g e n t s were p r a c t i -  c a l l y negative.  n i t r i c acid normally l e f t a  CHAPTER V I  smsimr  ked  ooifoiusiGis  -74The  r e s u l t s o f t h i s paper a r e summarized below.  All  a n a l y s e s f a l l a p p r e c i a b l y below 100 p e r c e n t .  The  percentages  ANALYSES.  ACCURACY. g i v e n are probably c o r r e c t .  t o t a l s are s a t i s f a c t o r i l y explained.  The l o w  S u f f i c i e n t c h e c k i n g has  been done t o j u s t i f y c o n f i d e n c e i n t h e r e s u l t s .  HERCURIAX TETRAHHDRITB. T e t r a h e d r i t e from N o r t h Kootenay Mines , l t d . , dermere, a s s a y e d  6.1  p e r c e n t mercury.  Win-  Mercurial tetrahedrite,  o r s c h w a t z i t e , has not p r e v i o u s l y been r e c o g n i z e d I n B r i t i s h Columbia.  Etch r e a c t i o n s are not d i a g n o s t i c .  The f r a c t u r e and  the l u s t r e a r e not those o f normal t e t r a h e d r i t e . The  f o r m u l a may be w r i t t e n  3[(0u.,Afi) S 2  f  (Hg,Zn)s], ( A s , S b ) S, 2  ARGENTIFEROUS TETRA1U3DRITE OR FREIBERGITE. T e t r a h e d r i t e from Keno H i l l , Yukon, assayed 2J5.2 percent s i l v e r .  This i s remarkably  h i g h , as ©ana  (unabridged)  l i s t s o n l y two examples o f f r e i b e r g i t e c a r r y i n g over 25 percent silver. E t c h r e a c t i o n s a r e n o t d i a g n o s t i c . Nor can f r a c t u r e o r l u s t r e be c o r r e l a t e d w i t h t h e . h i g h s i l v e r The f o r m u l a may be w r i t t e n  content.  "75lo[(Cu Ag) t  2  3,Zns]. 3 ( A s , S b )  2  3^  An a n a l y s i s o f the a s s o c i a t e d g a l e n a would be interesting.  TETRAHEDRITE LOW IK SILVER. Where t e t r a h e d r i t e i s low i n s i l v e r i t i s u n a s s o e l a ted  w i t h o t h e r m i n e r a l s and we f i n d a simple t e t r a h e d r i t e -  q u a r t z o r e . Three such samples came from the Cariboo  and one  from the I l l e c i l l e w a t .  TISTRAHEDRITE HIGH I F SILVER. • As the s i l v e r c o n t e n t the o r e s become more complex. r e l a t e d to t h e g a l e n a  of t h e t e t r a h e d r i t e i n c r e a s e s , The i n c r e a s e i s c l o s e l y  content.  GALENA-SILVER RELATIONS. F u r t h e r work i s r e q u i r e d t o show whether o r n o t t h e r e i s any p a r a l l e l  r e l a t i o n i n t h e s i l v e r content  o f the  g a l e n a , or. ordex'ly d i s t r i b u t i o n o f the s i l v e r between g a l e n a and t e t r a h e d r i t e .  TYPE OF DEPOSIT.. A l l o r e s examined a r e from f i s s u r e v e i n s , as cont r a s t e d t o true replacement d e p o s i t s .  The s i l v e r c o n t e n t o f  the t e t r a h e d r i t e o f t h e s e v e i n d e p o s i t s v a r i e s w i d e l y , up t o 25 p e r c e n t .  The a s s o c i a t i o n o f t e t r a h e d r i t e w i t h g a l e n a , and  other m i n e r a l s , i n quartz v e i n s , favours the formation of  -76highly argentiferous tetrahedrite.  STREAK AND SILVER  The  CONTENT.  s t r e a k s v a r y from dark r e d d i s h brown t o d u l l  black,  l o w s i l v e r content  gives a reddish streak; high  content  r e s u l t s i n a d u l l black  silver  streak.  SPECIFIC GRAVITY AND SILVER CONTENT. The  s p e c i f i c g r a v i t y o f t e t r a h e d r i t e tends to i n -  c r e a s e a s the s i l v e r c o n t e n t .  The presence o f mercury i s a l s o  i n d i c a t e d by an i n c r e a s e d s p e c i f i c g r a v i t y .  FRACTURE AND LUSTRE. F r a c t u r e and l u s t r e v a r y w i t h t h e source o f t h e tetrahedrite.  No r e l a t i o n between the v a r i a t i o n o f t h e s e  p h y s i c a l p r o p e r t i e s and t h e s i l v e r content was n o t e d . FORMULAE  T e t r a h e d r i t e , a s s t u d i e d , appears t o vary i n composition,  forming  an isomorphous s e r i e s .  The  formulae are;  The  composition  o f the h i g h l y a r g e n t i f e r o u s v a r i e -  t i e s c o r r e s p o n d s t o t h a t o f the f i r s t  formula.  PLATE 21  5>  PEOTOMIOROGRAPHIC SET UP  - 7 7 -  A few d e t a i l s o f t e c h n i q u e a r e appended.  This i s  j u s t i f i e d o n l y i n s o f a r as d e t a i l s o f method d i f f e r from those of standard p r a c t i c e . A v a i l a b l e a p p a r a t u s , not always the most s u i t a b l e , has had t o be u s e d .  The a c t u a l t e c h n i q u e e v o l v e d f o r t h i s  a p p a r a t u s may be o f i n t e r e s t to those w o r k i n g a l o n g s i m i l a r l i n e s i n the f u t u r e . , T e c h n i q u e , j u s t i f y i n g mention h e r e , i s t h a t  developed  for: 1. P r e p a r a t i o n o f dammar gum and mounting m i n e r a l s p e c i mens t h e r e i n . 2.o P h o t o m i c r o g r a p h y .  •  . MWim  SECTIONS  Where i t was n e c e s s a r y to p o l i s h s m a l l p i e c e s o f o r e , o r where i t was d e s i r a b l e , because o f t h e s a v i n g o f time i n g r i n d i n g , t o p r e p a r e s e c t i o n s under one h a l f i n c h i n d i a m e t e r , i t was f o u n d c o n v e n i e n t to use a gum mount o f the f o l l o w i n g composition. Composition Dammar Gum ~ — ~ - 3 p a r t s —»—-•- 150 grams S h e l l a c (lemon)- Z p a r t s — - — — Turpentine (pure) 1 p a r t P r e p a r a t i o n o f Stock  —  5  100 grams 0  grams  Gum.  The gum i s p r e p a r e d , as d e s c r i b e d b e l c w , poured and c o o l e d , b r o k e n t o a c o n v e n i e n t s i z e , and k e p t t o be r e m e l t e d  -78and u s e d as required©  I n t h i s work, about 300 grams was  p r e p a r e d a t a time© The  dammar gum i s t h o r o u g h l y m e l t e d i n an aluminum  o r enameled saucepan©  S h e l l a c f l a k e s a r e added g r a d u a l l y w i t h  c o n t i n u a l stirring© T u r p e n t i n e i s added as r a p i d l y as possible©  The  m i x t u r e I s s t i r r e d a s v i g o r o u s l y as p o s s i b l e , care b e i n g n e c e s s a r y t o prevent t h e t u r p e n t i n e t a k i n g f i r e . must be kept q u i t e h o t d u r i n g t h i s  The m i x t u r e  addition.  When a l l t h e t u r p e n t i n e has been s t i r r e d i n , t h e gum i s q u i c k l y poured o n a w e l l o i l e d sheet o f t i n and a l l o w e d t o cool.  I t w i l l be r a t h e r b r i t t l e  when c o l d .  I t i s now r e a d y to be r e m e l t e d and used i n t h e mounting  o f specimens as r e q u i r e d *  Mounting  t h e Specimen. B r a s s r i n g s , s e c t i o n s c u t from b r a s s t u b i n g j were  used a s moulds.  Dimensions  o f the moulds may v a r y from f- x is  i n c h t o Ig- x •§• i n c h * In use» t h e s e a r e o i l e d w i t h heavy machine o i l , and set  on an o i l e d t i n plate©  quite f l u i d .  The gum i s m e l t e d , and heated  A t h i n l a y e r o f gum i s q u i c k l y poured i n t o  till each  mould, the m i n e r a l specimen o r specimens q u i c k l y p r e s s e d i n t o t h i s , and the mould then f i l l e d w i t h t h e hot gum.  With r a p i d  and a c c u r a t e m a n i p u l a t i o n , s i x o r e i g h t s e c t i o n s can r e a d i l y be mounted a t one t i m e . Any m e l t e d gum, not poured, s h o u l d be d i s c a r d e d . I t cannot be r e m e l t e d and used.  Where s m a l l fragments o f m i n e r a l had t o be mounted, t h e s e were a r r a n g e d a s r e q u i r e d i n t h e bottom o f t h e mould, on the o i l e d t i n , and v e r y hot gum poured i n t o f i l l  t h e mould©  S h i s procedure was f o u n d more s a t i s f a c t o r y , f o r s m a l l g r a i n s , t h a n t h a t d e s c r i b e d above. O i l e d paper i n the moulds was found u n n e c e s s a r y . G r i n d i n g and P o l i s h i n g . The mounted specimens  a r e removed from t h e b r a s s  moulds and ground and p o l i s h e d a s u s u a l . The mounts, a f t e r s t a n d i n g s e v e r a l months, t e n d t o warp and oracle.  PHGT0MIOROG-RAPHT General.  i Photography ..of p o l i s h e d s e c t i o n s o f o r e s t h r o u g h the  m e t a l l o g r a p h i c m i c r o s c o p e i s i d e n t i c a l i n p r i n c i p l e -with the b e t t e r known p h o t o g r a p h i c p r o c e s s e s . E s s e n t i a l l y , the r e q u i r e d s e c t i o n i s brought i n t o the f i e l d o f v i e w o f t h e m i c r o s c o p e , a camera b e l l o w s superimposed on the e y e p i e c e , and t h e r e s u l t a n t image s h a r p l y f o c u s s e d by means o f the micrometer f o c u s s i n g screw o f t h e m i c r o s c o p e .  A  p h o t o g r a p h i c p l a t e i s s u b s t i t u t e d f o r the f o c u s s i n g s c r e e n , g i v e n a p r e d e t e r m i n e d e x p o s u r e , and developed and p r i n t e d as usual. Apparatus. The p h o t o g r a p h i c s e t - u p , u s i n g equipment a v a i l a b l e a t  t h e . U n i v e r s i t y o f B r i t i s h Columbia, i s shown i n the accompanying  i l l u s t r a t i o n ( P l a t e X O ). The r e g u l a r s h u t t e r , w i t h l e n s e s , i s removed from the  camera,,  The a d o p t e r , o f c o n c e n t r i c m e t a l r i n g s , i s s l i p p e d  o v e r t h e e y e p i e c e o f t h e microscope and the camera b e l l o w s l o w e r t o f i t I n t o t h i s adopter*. The a r e lamp i l l u s t r a t e d , w i t h i t s accompanying r e s i s t a n c e , i s used as a s o u r c e o f i l l u m i n a t i o n .  I t i s s e t up  so a s t o p r o j e c t a h o r i z o n t a l beam i n t o t h e v e r t i c a l tor  o f the m i c r o s c o p e .  illumina-  The a r e was found t o be q u i t e s t a b l e  f o r t h e s h o r t exposure t i m e s r e q u i r e d . For a c c u r a t e t i m i n g o f exposures, the s h u t t e r o f the c o p y i n g camera, minus l e n s e s , i s f i x e d i n t h e beam o f t h e lamp as shown. l i g h t f i l t e r s , when u s e d , a r e p l a c e d o v e r t h e m i c r o s c o p e e y e p i e c e , w i t h i n t h e camera b e l l o w s . Bausch and Lomb  m i c r o s c o p e 1J2416 was used.  Photographic M a t e r i a l . W r a t t e n and Wainwright P a n c h r o m a t i c p l a t e s , 3i- x 4ii n c h e s , were used e x c l u s i v e l y . F i l t e r s , from a s e t o f Wratten "M" f i l t e r s , were u s e d , a s r e q u i r e d , t o i n c r e a s e t h e c o n t r a s t between the important minerals.  These f i l t e r s  n e c e s s i t a t e t h e use o f panchro-  m a t i c p l a t e s , a s above. P r e p a r a t i o n f o r Exposure. I n g e n e r a l , when a c l e a r , s h a r p , image appears on  the f o c u s s i n g s c r e e n , the a p p a r a t u s i s i n adjustment© t h e n s i m p l y a m a t t e r of c o r r e c t exposure and The  It i s  development.  a r e a t o be photographed must f i r s t be l o c a t e d ,  u s i n g the microscope as u s u a l .  Some source o f i l l u m i n a t i o n  o t h e r t h a n the a r e lamp must be used.  When t h i s has been done,  and s u i t a b l e m a g n i f i c a t i o n u s e d , t h e a r c lamp, s h u t t e r camera b e l l o w s are s e t up as shown, i n P l a t e are now at  r,  XXI  «  and  Adjustments  made w i t h the s h u t t e r mechanism i n the l i g h t beam, set  T , and  s h u t t e r and diaphragm wide open.  ,s  The  v e r t i c a l i l l u m i n a t o r w i l l probably  require  ad-  j u s t m e n t , on b o t h ' t h e h o r i z o n t a l and v e r t i c a l a x i s , so as t o give a b r i g h t , uniform  f i e l d on the ground g l a s s .  The  camera  b e l l o w s are a d j u s t e d so as t o g i v e the r e q u i r e d s i z e of image. T h i s i s b e s t made somewhat l a r g e r t h a n r e q u i r e d i n the p r i n t , and masked t o the r e q u i r e d s i z e i n the The focus being  image i s s h a r p l y f o c u s s e d ,  d e t e r m i n e d w i t h the  final  printing.  the p o i n t o f p e r f e c t  a i d of a l e n s .  V/ith the m i c r o s c o p e and  o b j e c t i v e s a v a i l a b l e , when  u s i n g the h i g h e r m a g n i f i c a t i o n s , i t i s i m p o s s i b l e to o b t a i n sharp f o c u s over the f u l l  field.  I n such eases the area  g r e a t e s t importance i s p l a c e d i n the c e n t r e o f the f i e l d u s i n g c r o s s m o t i o n screws on the microscope s t a g e ) and sharply.  Excessive  (by focussed  r e l i e f i n the s e c t i o n w i l l r e n d e r sharp  f o c u s on a l l m i n e r a l s Care and  of  impossible  of  attainment.  judgment are r e q u i r e d he r e ,  as the  result-  ant photograph can be no more d i s t i n e t than the image which appears on the s c r e e n .  Contrast  can be m o d i f i e d by the use  of  f i l t e r s , but d e f i n i t i o n i s c o n t r o l l e d a t t h i s p o i n t by correcti l l u m i n a t i o n and f o c u s s i n g . N e g l e c t i n g , f o r t h e p r e s e n t , t h e use o f l i g h t  fil-  t e r s ( t o be d i s c u s s e d l a t e r ) , we a r e now ready t o make the expo s u r e . The  Exposure. The s h u t t e r i s c l o s e d , c u t t i n g o f f a l l l i g h t  from  the s e c t i o n * A p l a t e h o l d e r w i t h p l a t e i s i n s e r t e d I n place of the ground g l a s s , l o c k e d , and t h e dark s l i d e drawn o u t . One f i f t i e t h o f a second was found t o be a s u i t a b l e exposure f o r average s e c t i o n s .  T h i s exposure i s a c c u r a t e l y  made w i t h t h e s h u t t e r mechanism i n t h e l i g h t beam. The p l a t e i s t h e n ready f o r development. Development. • Development o f the panchromatic p l a t e s must be done by the a i d o f a g r e e n s a f e l i g h t .  They s h o u l d not be exposed,  even t o t h i s l i g h t , l o n g e r t h a n a b s o l u t e l y n e c e s s a r y , n o r should  t h e y be h e l d c l o s e t o i t . Kodak ITetol Q u i n o l d e v e l o p e r powders were used.  C o m p l e t i o n o f development was d e t e r m i n e d by i n s p e c t i o n under the g r e e n s a f e l i g h t . Development i s complete when: 1) h i g h l i g h t s o f s u b j e c t a r e j u s t v i s i b l e t h r o u g h t h e back of the p l a t e ; 2 ) when t h e image ceases t o develop f u r t h e r ;  3) when, the p r o p e r l y exposed p l a t e reaches the c o r r e c t density. These presuppose  a f a i r l y c o r r e c t l y exposed  plate.  I t would he more s a t i s f a c t o r y t o d e v e l o p these p l a t e s by the "Time and Temperature Method".  T h i s ivould i n v o l v e the  d e t e r m i n a t i o n o f the c o r r e c t time o f development w i t h i n a range of probable temperatures, i n a developer of f i x e d composition and c o n c e n t r a t i o n . Once these f a c t o r s were d e t e r m i n e d d e v e l o p ment c o u l d be done i n t o t a l  darkness.  O t h e r d e t a i l s o f developments  e t c . , have been t a b u -  l a t e d and f i l e d w i t h t h e Department o f Geology.  They r e f e r  p a r t i c u l a r l y to Copying and the P r e p a r a t i o n o f L a n t e r n S l i d e s  s  but c o n t a i n many p o i n t s o f use h e r e . Printing. S a t i s f a c t o r y p r i n t s were o b t a i n e d from Photo is,rts Supply,  Vancouver.  Use o f C o n t r a s t F i l t e r s . L i g h t f i l t e r s may  have t o be used t o g i v e the  r e q u i r e d c o n t r a s t i n the p h o t o m i c r o g r a p h .  I n the s e l e c t i o n o f  the best f i l t e r o r f i l t e r s , v i s u a l i n s p e c t i o n i s p r o b a b l y the best guide.  F i l t e r s wi 11 r e q u i r e i n c r e a s e d exposure.  Eastman Kodak Co.:  "Photomicrography" and "Wratten L i g h t Filters'*.  F o r d i s c u s s i o n o f the use of f i l t e r s , the r e a d e r i s r e f e r r e d t o the above pamphlets.  Both are r e a d i l y o b t a i n a b l e  b r i e f , and i n s t r u c t i v e , and, such b e i n g the ease, no d i s c u s s i o n i s required here.  further  ~~  Other g e n e r a l  t e x t s a r e l i s t e d I n the  Bibliography.  A n d e r s o n , A.L.  N o t e s on o x i d a t i o n o f J a m e s o n i t e , S p h a l ~ e r i t e , and T e t r a h e d r i t e . E c . G e o l . , V o l . X X Y I I , p.687.  Bancroft,  S l o c a n Map A r e a . G e o l . S u r v . C a n * , Summ.Rept«, 1919K P t . B .  Bate man,  M.F. A.M.  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Fairbanks,  Farnham, Guild,  E.E<  C.M.  F.H.  Gunning,  E.G.  The Enrichment o f S u l p h i d e Ores. U n i t e d States Geol. Surv., B u l l . 5 2 9 ,  1913.  The l a b o r a t o r y I n v e s t i g a t i o n o f Ore Minerals. McGraw-Hill, 1 9 2 8 . D e t e r m i n a t i o n o f the Opaque M i n e r a l s . MeGraw-Hill, 1931. The M i c r o s c o p i c Study o f S i l v e r Ores and Associated Minerals. Ee. G e o l . , V o l . X I I , 1 9 1 7 , p.297. A S i l v e r T i n V e i n a t Snowflake Mine, Sc. G e o l . , V o l . X X V I , p . 2 1 5 .  B.0.  Geology and M i n e r a l D e p o s i t s o f the "Big Bend. G e o l . Surv. Can., Summ.Rept., 1 9 2 8 , Pt.A. Xardeau Map A r e a . G e o l . Surv. Can., Memoir 161. Hynes,  D.P.  Geology o f Mina Mexico V e i n s . Ec. G e o l . , V o l . V I I , 1912, p.280,  I r v i n g , J i D . , and B a n c r o f t , H Geology and Ore D e p o s i t s near l a k e C i t y , Colorado. U n i t e d S t a t e s Geol. Surv., B u l l . 4 7 8 , p . 5 2 . 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M i n i n g E n g i n e e r s , V o l . 3 0 1901, p.424.  Whitehead, V/,I«  Technique o f M i n e r a l o g r a p h y . Ec. G e o l . , V o l . X I I , 1917, p.697=  Wine h e l l ,  Chemical C o n s t i t u t i o n o f T e t r a h e d r i t e T e n n a n t i t e System. American M i n e r a l o g i s t , V o l i l l . 1926, p.181.  A.K.  

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