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

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A STUDY OF TEfRAHSDRIfE IN SOKE . BEI2ISH COLUMBIA GEES C l i f f o r d S, LorO. A I h e s i s Submitted f o r the Degree o f " MASTER GP APPiIBB SCISIC® i n the Department o f GEOLOGY The U n i v e r s i t y of B r i t i s h Columbia A p r i l 1955 CONTENTS page LIST OF ILLUSTRATIONS INTROKJCTOT Importanee o f Te t r a h e d r i t e ....o....o«...o..<,oo.o«, I Object and Aims of Paper e . » « < > . o e . » » » < > « . < > . . < . . . < . • • • I I G r B H O jT'BiI SllfnmH^r -a « © a\a^e~2 o a e © • a o « e e o • » © © *© ooo » «« IIJL i ^ C l C H O W j L ©d^Hl©33.i> S .« o © a o e * « o » e • © © © •© o * » « •© © o o « o o o •© o © o a o xlT CHAPTER I . METKGDS EMPLOYED. P r e p a r a t i o n f o r Assay ©<,„... » o « « e o- o .© o d o * o © « o « •« © * * © Assay Methods and Re s u l t s ...©.....©........©..... 4 Copper ( a l l samples) < • » «© ©»© © ©«©«««© © ©««© © 4-3xlirer• ( a l 1 s&ncip 1 eS) o © © o o © o e © * e © « o o © e o © © « 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) © ° * « « « « © a 5^ 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 6 -«L X* 021 (-C / J X J I G d B st o e a « » o o « » is o o o © o e » o o © 6 Lead and Zinc (Samples 4,12,17,18S2Q).© ©«© © 7 Zinc ( i n a l l samples) .........©<>»©*<>©©•«©• 7 Sulphur, I n s o l u b l e , I r o n ( i n a l l samples).. 8 CONTENTS (continued) (METHODS EMPLOYED Assay Methods and R e s u l t s ) j i iS^S G X X X O * © © -o 4 © o « & * e a « o « c co e © o a o o o • « > o 4 n o o G?GX$.@ «< O o e « © « a o s o e o •» o « o a o o ©• ©• .& « o •». o e o o -o Comments on General Accuracy E x p l a n a t i o n of Low T o t a l s 0 0 « <J « O ,» « O •© C O * « -O 4 0 u a e # o o « o o « s e e o « « a a o e o CHAPTER I I . • THE ORES.- MINERALOGY ArlD PARAGMESIS. Summary of Chapter o « a o a •o © « •» © » a » « o e o o * a c The Oresi T h e i r Mineralogy and Paragenesis Specimen Ifo» 1, / Treated i n Chapter I I I . Specimen Ho..2; B l a c k Bear Group, Quesnel Mining D i v i s i o n .».. XiOO EL"t» X 0X1 .© «• « « 6 • « •* .a c o * -o o » e c © « « « jDjfl© i ^ Q p O S X *fe a » a © ••• * *» o e -« o o a Macroscopic D e s c r i p t i o n Paragenesis © & « » * as;.® 9 0 » 6 O 9 O »• O O 4 0 O O O Q A Specimen l o . J : Jo-Jo Group, Three Forks Slocan Mining D i v i s i o n !I?l lS 3)6 S X i> «- <j « © o « © * e «» o © e o s o 0 0 0 0 Macroscopic D e s c r i p t i o n ,.......« Mineralogy and Paragenesis .«. «. Specimen Eo, 4; Langley C o l l e c t i o n , Ainsworth Mining D i v i s i o n . . . j j O c a t i o n o © * o « « The Deposits «•««•••<>*•«• Macroscopic D e s c r i p t i o n Paragenesis «••*•**<.«••*..*«*»• • • CONTENTS (continued) (The Ores: T h e i r Mineralogy and Paragenesis) page Specimen Uo. 3 ; Sadie Claim, Keno H i l l , YulCOn © o © « © © « © © 4 • « © © © » © o © 22 J j Q C a t X On © © * © « © » © « o. © « « o o © © © o © * « 22 The De p O S i t © © • © © • • © o © o « * © © © © © © © 22 • Macroscopic D e s c r i p t i o n »©<,©©© © 2J Mineralogy and Paragenesis «. © © 2 3 Specimen Ho. 6; Quesnel, Cariboo .©©. ©...©. 24 Specimen Ho© 12: I l l e c i l l e w a t .©...©...©©©. 2 3 LiO"3ation © © © * © « © © « * o © © © © « © © . © . © © • 2 3 The Deposits ».•••« •«».«••••••« «••••»•• 2 3 Mineralogy and Paragenesis .... 2 6 Specimen l\To© 1 7 : Submarine Group, L y t t o n , Asheroft Mining D i v i s i o n o . © . . . 26 Lo cat i o n © © o«•© © © © » © ©. ©©©•©©•©• © © © © 2 6 The Deposits «. •*• © © © © « * » « « © © © © o © © 2 6 Fdneralogy and Paragenesis © © ©« 2 7 Specimen Ho© 1 8 ; Snowshoe Group, P r i n c e George, Cariboo . © © * © 6 * . © « * © © © © © 2 8 s X / O C at i on \ © © © © © © © © •© © © ©«©«© © © © © * © 2 8 The Deposit © © « © © © © « © » © « o © © « © « « 2 8 Mine ralogy © » «««© ©»© •«© * © * ©•».•»•.• «> 29 Specimen Ho* 2 0 ; S i l v e r Star,. •Si'milkame-eri..» 2 9 XJOO cl*fj JL 0/1 •© a- <a a o o « « 0 9 o o - « 6 e e « o « « « » ^» 5^  X X I O , *DC3 T50 B jL ij o c * c © » «• •» a .o 0 0 0 0 0 ^ 1 1 0 0 iSy^ Mineralogy and Paragenesis ..©« 2 9 CHAPTER I I I . MERCURIAL TSTRAHEDRITE FROM NORTH KOOTEKAY MINES , LTD. , WINDERMERE MITOG DIYISIOK, Be C« jintro duet i o n • • • • • • • • . • . © . • • • • • © • • © • • • . © » . « . . « » « « . e , * - , o * . « » « © - o « » ^2 G01TTMSS ( cont inue a) (KERGTJRIAL TETRAHEDRITE FROM HORTH KOOTEHAY MIHBS, etc.) page M e r c u r i a l T e t r a h e d r i t e of the l i t e r a t u r e ....... 3 3 IDS ID 0 S X *ti S o © « © o « o o © o a & o 6 o o « o e o e a <o e -o o 3 ^ Deposit of Schwatzite near Sumpter, Oregon 3 6 General Economic Geology of Windermere D i s t r i c t . 3 6 Mineralogy and Parage ne s i s ».«•«..•«.....••. «•»«•.«. 41 Macroscopic D e s c r i p t i o n of Specimens . ..<> 41 Mineralogy and Paragenesis 0 0 0 » . o 6 < , « . o . 9 o i , 42 1. The qu 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 m i n e r a l i s a t i o n • •..««•<>....»•» 43 2 o The e h a l c 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 -X %3>*li X 0 3 X « © © e JO o o « o s -e e * o « ©• « o o o. o ^ J? j l l i j O l l H C S l C f e X O X l S « « .« ' 6 o e '« -a .o »•« o « a « e * «•.»••©.«*:© .o 4*^3 P h y s i c a l P r o p e r t i e s o e o o o o e o . ^ © * * * . * . * . * * * 48 i \ i x £ i l y s i » 3 0x10. ^02^ x1111X0. •* *««•*••*«««««* *«»«©»* *««•«-* * ^X Comparison w i t h Other Deposits of Windermere Dl, S i l 3 ? X C T 3 . ••• .JO •«• e •« © * o e « * « • 3 ^ G*SJi @ S X S o"o * o o o « o o » o « o e o « a o * « * » « «• * « a « « « © o © ® « © « *• o .J?^  Sununary' and Conclusions * o c 0 « o « * c . * o « o o « * « * . 5 7 CONTENTS (eontinued) CHAPTER IV. 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 of Deposit and S i l v e r Content .... R e l a t i v e Age of Galena 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 Tests and S i l v e r Content ......... CHAPTER Y I . STMI&RY & C0HCLU5I0HS. Analyses Accuracy M e r c u r i a l T e t r a h e d r i t e CCKOTTS (continued) page . ^ S T T i - U v l ^ J ^ * ^ * 0 O X \ ' 0 « i J o S X O X ? 3 ^ ) ® © « © » o © © © © « © © « «.© a « - * © -«© © « © © « © © « - . ^ 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 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 T e t r a h e d r i t e High i n S i l v e r G a l e n a - S i l v e r R e l a t i o n s Type of Deposit Streak 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 Photomicrography and P r e p a r a t i o n of Dammar Gum KEounts ... „, e 77 • B I B L I O G R A P H Y : , 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 from which t e t r a h e d r i t e was s t u d i e d .........•<>... PLATE I I . Layout used i n s e l e c t i n g and checking t e t r a h e d r i t e ................. PLATS III» Camera-lueida drawing of s e c t i o n of ore from Three F o r k s , SIocan Mining 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 of s e c t i o n of ore from .••Three ^ Soxks-., Slocan Mining *0X"V X"3 X 03X « o o « © © « « a e « » a « 0 o o e « a « a o © a a * « o PLATE VI, Camera-lueida drawing of s e c t i o n o f ore from Three F o r k s , Slocan Mining •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 of s e c t i o n of ore from Ainsworth Mining D i v i s i o n PLATE V I I I . Photomicrograph of s e c t i o n of ore from Keno H i l l , Yukon D a * * o ©, o. o- o o- ffl e © to 0 0 « PLATE IX. Photomicrograph of, s e c t i o n o f ore from L y t t o n , , A s h c r o f t Mining D i v i s i o n ...... PLATES X & XI..Camera-lueida drawings o f s e c t i o n o f ore from S p a r k l e r Group, Similkameen Mxnxn^ !Dxv xsxo^x «0 0 » © a © © * a & « * « « « © « © « e © PLATE X I I . V/inderraere Map Area, showing l o c a t i o n of P r e t t y G i r l Claim 0 O O Q . i . O . . . . . . . . 0 0 . PLATES X I I I , XIV & XV. Photomicrographs of s e c t i o n s of massive ore from P r e t t y G i r l Claim PLATES XVI & XVII. Camera-lueida drawings of s e c t i o n s of massive ore from P r e t t y G i r l Claim 0 0 0 0 PLATES XVIII & XIX. Photomicrographs of s e c t i o n s of disseminated ore from P r e t t y G i r l Claim •0 0 o a o o v a o a © a a « » a a * « e a a e A e A /I A * a « « « LIST OF ILLUSTRATIONS (continued) to f o l l o w page PLATS XX. Parageneti c Chart f o r ore from PLATE XXI© Photomiorographic set-up used ........ 76 ^3 IHTR037JCTIOH l IMPORTANCE OF TETRAHEDRITE The importance of s i l v e r p r o d u c t i o n from the 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 of ore i s w e l l recognized. About t w o - t h i r d s of the e n t i r e p r o d u c t i o n i s obtained from a r g e n t i f e r o u s galena© G u i l u appears to have shown that s i l v e r Beyschlag t ¥ogT^ana~iiruscTa; Ore" Del^sTtlTT^'o 1 © 1T"l914 .""p'.Kb"."~" above .10 percent, e x i s t s i n galena as unreplaced spots of" s i l v e r m i n e r a l s , such as tetrahedrite© GuTId"7Hr©Tf71^ As s o c i a t e d ^inersU.s, Eo. Geol©, V o l . X I I , p.j^S© He says: "Indeed, much of the galena i n the s i l v e r d e p o s i t s has replaced t e t r a h e d r i t e and i t s s i l v e r content i s thus due to r e s i d u a l spots of 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 ©" Tetrahedrite;, then, i s of fundamental importance i n primary s i l v e r - l e a d ores© I t i s of no l e s s importance as the u l t i m a t e source of the s i l v e r i n secondary s i l v e r deposits© In Gu i l d ' s words, t h i i T d ^ r i ^ © "The ruby s i l v e r s rank amongst the most important s i l v e r minerals i n many of the r i c h d e p o s i t s of the U n i t e d S t a t e s and elsewhere© AS already p o i n t e d out the e a r l y m inerals of s i l v e r are confined mainly i f not e n t i r e l y to t e t r a h e d r i t e and argentiferous.galena© They are the r e f o r e h e l d to be the source o f the l a t e r enriched products© T e t r a h e d r i t e i s probably the most p r o l i f i c source as shown by the microscopic i n v e s t i g a t i o n s , and the f a c t that the l a t e s i l v e r minerals are most o f t e n a r s e n i c or antimony compounds©'5 G u i l d , F.B.: op© c i t . , p.pi^© The above statements should leave no doubt as to the u l t i m a t e economic importance of t e t r a h e d r i t e . . Any data on such a mineral are l i k e l y to prove to be of e v e n t u a l , i f not immediate, va l u e . These c o n s i d e r a t i o n s 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 study of .the t e t r a h e d r i t e i n a s u i t e of B r i t i s h Columbia ores. OBJECT AND AIMS OF PAPER •Referring to the composition of t e t r a h e d r i t e . • \ Winehell says , ( WiltcHe"lT7~A. l i.l~limerican li!neralogist'r'^l*«^l"» 192.'W^~§7TET7m~~ "Host of the standard t e x t books of mineralogy now giv e the formula of t e t r a h e d r i t e as Cug Sb^ S,y w i t h the comment that Ag„ 3n„ Fe, may ''replace-* p a r t of the Cu under valence c o n t r o l <> That is„ Ag^ 3b^ S^, Zn^ Sb^, Sy, and Fe^ Sb^ are supposed t o be p o s s i b l e c o n s t i t u e n t s of t e t r a h e d r i t e c r y s t a l s to some exten t . I t i s too e a r l y as yet to cl a i m that the c o n s t i t u t i o n of t e t r a h e d r i t e can be expressed i n any form th a t i s c o r r e c t beyond question but i t i s at l e a s t p o s s i b l e to 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 the best analyses now a v a i l a b l e can be t r u s t e d . " and f u r t h e r , t h a t s " I t i s u n f o r t u n a t e l y t u r e that p r a c t i c a l l y a l l analyses 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 microscopic methods " Therefore, analyses o f m i c r o s c o p i c a l l y s e l e c t e d m a t e r i a l should 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 the s o l u t i o n o f t h i s problem. I l l The s i l v e r content i s of prime economic importance. I t i s hoped that i t may show some d e f i n i t e r e l a t i o n to -lo Geographic d i s t r i b u t i o n of dep o s i t s 2© M i n e r a l a s s o c i a t i o n 3>o Type of deposit 4© R e l a t i v e age of galena and t e t r a h e d r i t e J?. P h y s i c a l p r o p e r t i e s 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 of o t h e r workers i n t h i s f i e l d s GENERAL SUMMARY A s u i t e of B r i t i s h Columbia t e t r a h e d r i t e ores 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 present investigation© From these, pure t e t r a h e d r i t e has been s e l e c t e d , checked w i t h the rnetallographie microscope, and analysed© An attempt has been made to develop a s a t i s f a c -t o r y formula, and other s t u d i e s undertaken, as suggested above © IV AGKHOWLEDGHEFTS Before proceeding, the w r i t e r wishes to acknowledge h i s ino.ebtednes3 to a l l those who have i n any way a s s i s t e d him i n the p r e p a r a t i o n of t h i s paper. To members of the G e o l o g i c a l S t a f f of the U. B. G., the author wishes to express h i s s i n c e r e s t thanks. S p e c i a l thanks are due Dr. E.V. Warren, of the IJ. 3. G. 5 under whose s u p e r v i s i o n t h i s work was carried, out. To ! l r . J.D. Galloway, 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 of Mines s the, w r i t e r i s indebted f o r comprehensive 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 ores of B r i t i s h Columbia. A l l a n a l y t i c a l work was c a r r i e d out under the c l o s e s u p e r v i s i o n o f K r . H.F. Thomson, Department of Mining and M e t a l l u r g y , U. B. C.» without whose guidance and sustained i n t e r e s t the work could not have been c a r r i e d on. J-.Ir. I-/.Bo Bishop very k i n d l y undertook to do the r e q u i r e d f i r e -a s saying, l a s t l y , but none the l e s s s i n c e r e l y , the author wishes to thank h i s c o l l e a g u e s , who have i n many small ways c o l l a b o r a t e d with him during the p r e p a r a t i o n of t h i s paper.. Deserving s p e c i a l mention are Liessrs. 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 which are s t u d i e d i n t h i s pape are from the deposi t s SHOWH IS RED .• one specimen, not shown, came from Keno H i l l , Y. T. PREPARATION FOR ASSAY Methods employed i n the c o l l e c t i o n , s e l e c t i o n and assay of the 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 of Mr. J eD. Galloway, Department of Mines,. V i c t o r i a , and Mr, F© Woodsi&e, BoC. Chamber of Mines, Vancouver, a s u i t e of t e t r a h e d r i t ^ - b e a r i n g B.C. ores was made a v a i l a b l e f o r study. Of these, only a few proved suitable© Since i t was necessary to separate very pure t e t r a h e d r i t e from the ores only comparatively coarse g r a i n e d m a t e r i a l could be used, as s e l e c t i o n from a f i n e g r a i n e d intergrown ore would have been i m p r a c t i cable« From each of these apparently s u i t a b l e specimens, chips of t e t r a h e d r i t e were taken, mounted i n dammar gum, and p o l i s h e d , p r e p a r a t o r y to microscopic examination. Examination showed some of the t e t r a h e d r i t e to be so i n t i m a t e l y intergrown w i t h other minerals as to preclude any p o s s i b i l i t y of 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 , c o r r e c t e d , a n a l y s i s . Specimens which proved, i n p o l i s h e d s e c t i o n , to con-t a i n pure or 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 of the l e s s complex ores, broken-down wi t h a l i g h t hammer, the pure t e t r a h e d r i t e being c o n t i n u o u s l y s e l e c t e d , or. 2. crushed to -10 mesh© where crushing was adopted, a l l ore was passed through a 10 mesh screen and caught on 14 and dQ mesh screens. I t was not found necessary or p r a c t i c a b l e to deal w i t h m a t e r i a l of -20 mesh. I t was found most convenient to roughly s e l e c t the mineral by eye, and to check the s e l e c t i o n w i t h a 10 X binocu-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 disseminated throughout much of the t e t r a h e d r i t e . Here, i t was decided to 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 to assart t h i s f o r i r o n . This, s u b t r a c t e d from the percentage of i r o n i n the main sample, would i n d i c a t e the amount of i r o n to 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 small percentage of i r o n i n the purer sample would be taken 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 * This method was not found p r a c t i c a b l e f o r two reasons -1. the near i m p o s s i b i l i t y of s e l e c t i n g mineral e n t i r e l y f r e e from the f i n e l y disseminated i m p u r i t i e s , e s p e c i a l l y c h a l e o p y r i t e . 2.. the r e l a t i v e l y broad accuracy l i m i t s of the i r o n assays when d e a l i n g w i t h such low percent-age s. E v e n t u a l l y i t was decided 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 according 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 found, i r o n was assumed to occur TlA S e l e c t i n g and"checking pure t e t r a h e d r i t e . ; The' crushed and s i z e d ore can he seen, spread out on sheets, of paper, on e i t h e r side o f the • microscope. The g r a i n s are p i c k e d out with tweezers, examined under the b i n o c u l a r , and placed 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 . A l t e r n a t i v e l y , i r o n might have been taken to enter the formula, with z i n e . The z i n c content was more troublesome. In only three specimens was i t known to be present as an i m p u r i t y - as s p h a l e r i t e . In other cases i t was not noted i n the s e l e c t e d m i n e r a l and yet occurred, i n q u a n t i t i e s up to s e v e r a l percent, i n one ease about b percent's The p o s s i b i l i t i e s are 1. t h a t i t i s present as s p h a l e r i t e and escaped d e t e c t i o n under the microscope. 2. that z i n c enters i n t o the composition of t e t r a -h e d r i t e . J . that i t occurs 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 composition of t e t r a h e d r i t e * • • The p o s s i b i l i t y that 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 considered* Considering the method of checking, the p u r i t y of the s e l e c t e d t e t r a h e d r i t e i t is, q u i t e p o s s i b l e that a small per-centage of i m p u r i t y would escape d e t e c t i o n . I t i s u n l i k e l y , however, that s e v e r a l percent of s p h a l e r i t e would pass unnoticed. To check the 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, p o l i s h e d and examined under the m e t a l l o g r a p h i c microscope both by r e f l e c t e d and oblique i l l u m i n a t i o n . The g r a i n s were se l e c t e d at random from each sample and. were of such a s i z e as to give an area of p o l i s h e d surface about equivalent to a 1/8 i n c h d i s c . The pure m i n e r al was then ground, thoroughly mixed and was ready f o r assay. ASSAY METHODS AND RESULTS Standard commercial assay methods were employed throughout. R e s u l t s were recorded to tenths only. Further f i g u r e s would have been meaningless.' In a l l cases the percentage content of the f o l l o w i n g elements was determined - Copper, S i l v e r , l e a d , Z inc. I n s o l u b l e , I r o n , Antimony, a r s e n i c and Sulphur. In one sample a mercury determination was made and checked.. The general methods f o l l o w e d w i l l be o u t l i n e d here. No attempt w i l l be made to giv e the d e t a i l e d procedures. Copper ( a l l samples). Copper was determined by the 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 procedure, 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 excepting t h a t .5 t o 1 gram of f e r r o u s ammonium sulphate was added to the sample i n each ease. This was done so as to have the assay made i n the presence of 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 hydroxide p r e c i p i t a t e i s a l s o used as an i n d i c a t o r of n e u t r a l i t y . P r ecautions taken, when using t h i s method f o r the determination of copper i n the presence of mercury, are d e s c r i b e d i n Chapter I I I under. " A n a l y s i s and Formula*'. A l l copper determinations were e n t i r e l y satisfactory<, S i n g l e determinations were made on each, us i n g 2j?0 m i l l i g r a m s of min e r a l * A l l t i t r a t i o n end p o i n t s were reason-ably 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 re-assayed and cheeked c l o s e l y . S i l v e r ( a l l samples). Mr© WoB© Bishop k i n d l y o f f e r e d to run a l l samples f o r s i l v e r . One-half to 1 gram charges were used with standard f i r e assay methods© A- c o r r e c t i o n f o r a b s o r p t i o n of s i l v e r by the cupel was made where necessary, as i n the case of the h i g h - s i l v e r samples© Ho check assays 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 ) . Assays f o r t h i s group of elements were run on 500 m i l l i g r a m s , o f samples 1, 2, j>» > and 6. Standard methods ?/ere used, excepting i n s o f a r as they were mo d i f i e d , to permit determinations of the fo u r elements to be made on the one weight of mineral© The mineral was brought i n t o s o l u t i o n with hydro-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 mixture and then fumed wi t h s u l p h u r i c acid© Lead was removed at t h i s point as i n s o l u b l e l e a d sulphate, together w i t h " I n s o l u b l e " . I t was then d i s s o l v e d i n -6~ ammonium a c e t a t e , separated from undissolved m a t e r i a l i n c l u d i n " 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 taken as n i l i n a l l cases® In s o l u b l e - The above residue c o n t a i n i n g the "'Insol-uble 1 1 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 Zinc - Iro n and z i n c were contained i n the f i l t r a t e from the l e a d sulphate. I r o n was separated from z i n c as the hydroxide i n a l k a l i n e s o l u t i o n . I t was f i l t e r e d out, d i s s o l v e d , and t i t r a t e d , w i t h potassium dichroraate i n a c i d s o l u t i o n . 21nc determinations were made, on the f i l t r a t e from the i r o n hydroxide, by the F e r r i c y a n i d e Method. This proved to be quite u n s a t i s f a c t o r y on such low percentages of z i n c w i t h 500 m i l l i g r a m s of sample. The i r o n determinations were l a t e r cheeked. Any great accuracy i s not to be expected by vol u m e t r i c methods, on such low percentages, where the amount of the sample taken must be kept below 500 m i l l i g r a m s . The r e s u l t s of the check assays are t a b u l a t e d below. They give some idea of the order of accuracy o b t a i n a b l e under these c o n d i t i o n s . ~7~ Sample number f i r s t assay | second assay 1 » 3 - loO t r a c e 2 » 3 1« 0 t r a c e 3 1.2 . 3 • • 3 * 8 4»-8 o J? ~" 1 • 0 1.4 Lead and Zinc (Samples 4,12 917,18 and 20). Heres l e a d and s i n e were run 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 being determined l a t e r 9 w i t h the sulphur* j Ferrous ammonium sulphate was added to each, to b r i n g down antimony arid a r s e n i c w i t h i r o n hydroxide in. a l k a l i n e solution,, Lead was to have been separated as i n s o l u b l e l e a d sulphate,, Lead r e s u l t s were again n i l i n every case. Zinc determinations were made by the F e r r i c y a n i d e Method but proved to be u n s a t i s f a c t o r y , as before. Zinc ( i n a l l samples). ! I t was necessary, then, to make z i n c assays on a l l \ samples by the "Phosphate Z i n c " Method,, E s s e n t i a l l y , by t h i s !ITeo^T7~~^n771 Te'cluiTcai Melfhoas*"^^ , I ? 2 3 : . method, the z i n c i s separated as s i n e sulphide 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 of the phosphate m u l t i p l i e d by «3>"64 g i v e s tlie weight of zi n e i n the assay,, There i s good reason to b e l i e v e that these r e s u l t s 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 assays. Sulphur, I n s o l u b l e and I r o n (on 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 t j?O0 m i l l i g r a m s were taken of a l l samples and these assayed f o r the above three elements. " I n s o l u b l e " and i r o n determinations served, as a check on those a l r e a d y obtained .for samples 1 , 2 , 2, 5 and 6e The general procedure i s to convert the sulphides to sulphates and to p r e c i p i t a t e the sulphate as barium sulphate, to be weighed and c a l c u l a t e d to sulphur* The sulphur was brought i n t o s o l u t i o n and f i l t e r e d from the " I n s o l u b l e " . This 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 pre-c i p i t a t e d as barium sulphate by the a u d i t i o n of barium c h l o r i d e . This 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 before* Antimony© In every case„ the--antimony determination was made on 2 5 0 m i l l i g r a m s o f m i n e r a l . The weighed mineral 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 , the s o l u t i o n evaporated to dryness twice, w i t h h y d r o c h l o r i c a c i d s and the residue taken i n t o s o l u t i o n with 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© Sodium s u l p h i t e was added as a reducing agent© Hydrogen sulphide gas was bubbled i n , p r e c i p i t a t i n g a r s e n i c , antimony and copper. 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 with sodium s u l -phide and sodium hydroxide, 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 acid© The antimony of the p r e c i p i t a t e was talien up w i t h hydro-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 of sodium bicar 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 at the end point being detected 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 procedure g i v e s scope f o r appreciable manipulation errors© Arsenico I n most cases, 5 0 0 m i l l i g r a m s of mineral was assayed f o r arsenico In a few eases, only 2 ^ 0 m i l l i g r a m s was available© The Hydrozine Sulphate D i s t i l l a t i o n Method was X e f f e r , K . J MenHaolIS i ^ 1 9 2 8 , p . 3 6 . employed, as 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 the presence of hydrozine sulphate, h y d r o c h l o r i c a c i d and sodium - 1 0 -bromide. The arsenious c h l o r i d e i s condensed, d i s s o l v e d i n water, and t i t r a t e d against an i o d i n e s o l u t i o n i n the presence of sodium bicarbonate. These determinations appeared to be p e r f e c t l y s a t i s f a c t o r y * I t i s worth n o t i n g here t h a t , should t i n have been present i n the sample, i t would have been d i s t i l l e d over and t i t r a t e d w ith the A r s e n i c . The r e s u l t s have been recorded as percent a r s e n i c . A c t u a l l y they may be percent a r s e n i c plus t i n . I n c i d e n t a l l y , the determination of t i n by d i s t i l l a -t i o n appears to be a new method. In view of the f a c t that present methods do not appear to be wholly s a t i s f a c t o r y , it-would appear to be w e l l worth f u r t h e r i n v e s t i g a t i o n . General. Assays eoulo. not be run i n d u p l i c a t e due to i n s u f f i -c i e n t m a t e r i a l . .For the same reason, weights of mineral were sometimes used vvhich gave t i t r a t i o n s o f only a few cubic centimeters. Great accuracy i s not to be expected from such t i t r a t i o n s . COMMENTS OF GENERAL ACCURACY As w i l l be noted i n the next chapter, the t o t a l s i n a l l assays f a l l below 100 percent, ranging from 93«2 to l a c k i n g the time and m a t e r i a l r e q u i r e d f o r a check of - 1 1 -a l l a s s a y s j the f o l l o w i n g comments are i n order© A l l assay work was c a r r i e d out w i t h care, as i t was r e a l i z e d from the f i r s t that cheek assays could not be run© F u r t h e r , a l l work was c a r r i e d out under the clo s e s u p e r v i s i o n of Mr© H©F© Thomson, P r o f e s s o r of M e t a l l u r g y , U n i v e r s i t y of B r i t i s h Columbia© A few check assays have been run, as mentioned above© These checked to -within the l i m i t s of e r r o r of the methods employed and i t i s thought t h a t no major e r r o r s occur i n the f i g u r e s given© "Errors i n the order of f r a c t i o n s of a percent are to be expected, from the methods employed, but i t i s c l e a r l y not i n these d i s c r e p a n c i e s that we may look f o r the missing percentages© Several other p o i n t s tend to support the b e l i e f i n the general accuracy of the f i g u r e s g i v e n , as: 1 © The u n i f o r m l y low r e s u l t s . The maximum divergence o f t o t a l s i s j>«2 percent, and the average v a r i a t i o n much l e s s . The f a c t that these are u n i f o r m l y low suggests one of 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 low r e s u l t s or i m p u r i t i e s , not assayed f o r , are present throughout. A combination of these two p o s s i b l e causes i s a l s o to be considered© As more or l e s s standard assay methods have been used throughout, the second a l t e r n a t i v e appears to be the more probable© Had the t o t a l s been e r r a t i c - some below and others above 1 0 0 percent - the f a u l t would obviously have been w i t h -12-the a s s a y i n g 0 2« A tendency towards constancy i n the summation of the atomic p r o p o r t i o n s of copper and s i l v e r . • This w i l l be seen from the t a b l e on Page 7« E x c l u d i n g Samples 1 and 5 (by reason of t h e i r pecu-l i a r composition) the remainder f a l l i n t o three groups. These are. Samples 2 , 6 ; Samples 3 , 1 7 , 2 0 ; Samples 4(?) , 12, 18. 3 . A p a r a l l e l tendency i n the case of a r s e n i c and antimony. Here we have e x a c t l y the same groups as before: 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 grouping must be more than a coincidence* EXPLANATION OF LOW TOTALS The following c o n s i d e r a t i o n s account, i n part at l e a s t , f o r the low t o t a l s . 1. The probable presence of some s o l u b l e or 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 " I n s o l u b l e " , which i s assumed to i n c l u d e a l l gangue, as quartz. 2. The presence of minor amounts of copper carbonates and s i l i c a t e ( c r y s o c o l l a ) i n the s e l e c t e d m a t e r i a l . 3 . The probable presence of other elements not assayed 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 black 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 non-metallic m a t e r i a l i n prominent p a r t s throughout many of the - 1 3 " s e c t i o n s examined. Other elements not assayed f o r and l i k e l y to occur a r e 5 as suggested by Dana, n i c k e l , c o b a l t , mercury, manganese DanaT^^ ' ' "~*"'"" bismuth and t i n . The t i n content, i f any, has probably 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 explained above. Various elements might be present i n a s o l u b l e gangue 5 such as lime and magnesia., barium, s u l p h a t e , alumina, e t c . "*> CHAPTER I I THE ORES - MIIERALGCST AHD PARAGEHESIS. SuTM&EY OF CHAPTER The m e r c u r i a l ore, from the Windermere, has been adequately t r e a t e d i n Chapter I I I o The ores from the other nine l o c a l i t i e s w i l l be dea l t w i t h here,. Each deposit w i l l be discussed b r i e f l y , i n s o f a r as pub l i s h e d data are a v a i l a b l e . I n some cases a per u s a l of the l i t e r a t u r e has r e v e a l e d no ref e r e n c e s to the d e p o s i t s . In such eases, a general d i s t r i c t d e s c r i p t i o n i s a l l that has been p o s s i b l e . The specimens from the d e p o s i t s w i l l then be dealt with, 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 and paragenesis as determined under the metall o g r a p h i c microscope. Studies of mineralogy and paragenesis were undertaken f o r s e v e r a l reasons. l o An accurate i d e a of the mineral a s s o c i a t i o n i s e s s e n t i a l i n view of the i m p r a c t i c a b i l i t y of s e l e c t i n g abso-l u t e l y pure t e t r a h e d r i t e f o r assay. 2. In determining the order of 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 r e l a t i o n s . As suggested by Warren, the order of d e p o s i t i o n of W a C T e ^ T ^ ^ y ^ X ^ ^ ^ ^ ^ ^ooi^anicat i o n . these minerals may bear some r e l a t i o n to the d i s t r i b u t i o n of s i l v e r between t e t r a h e d r i t e and galena i n the same ore. E a r l y galena might be shown to be the s i l v e r bearing mineral o r , should t e t r a h e d r i t e be the e a r l i e r of the two, i t may be the - 1 5 -s i l v e r c a r r i e r . This p o s s i b i l i t y w i l l be discussed l a t e r , i n s o f a r as p o s s i b l e without assays of the galena. 3 « F u r t h e r work w i l l be necessary, i n v o l v i n g assays o f the accompanying galena, to complete t h i s phase of the i n v e s -t i g a t i o n . The paragenetic d e t e r m i n a t i o n s , already 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 to show some r e l a t i o n between analyses and mineral a s s o c i a t i o n . This would be e s p e c i a l l y u s e f u l i n the case of the s i l v e r content. THE DEES: THEIR MINERALOGY AND PARAGENESIS A z u r i t e , malachite and c r y s o c o l l a have been recog-n i z e d i n many specimens and probably occur to some extent i n o. JL «L & In the d e s c r i p t i o n of mineralogy and paragenesis, but l i t t l e a t t e n t i o n has been paid to these supergene mi n e r a l s . At the time, i t was not thought that they would be of any p a r t i c u l a r importance i n t h i s study. A z u r i t e , as suggested 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 , at l e a s t under c o n d i t i o n s of a l t e r a t i o n as found i n B r i t i s h Columbia. Specimen No. 1. This has been adequately treated i n Chapter I I I . Specimen No. 2. Black Bear Group, (-.uesnel Mining D i v i s i o n . -16-L o c a t i o n - The claims are s i t u a t e d about JO m i l e s south-east of Cuesnelj near the northeast bank of Cuesnel r i v e r . They are reached by a road and t r a i l from the town. The deposit - This group i s described i n the 1?21 report to the B r i t i s h Columbia M i n i s t e r of Mines as the Copper Cueen Group. B7oT"Tfi1^ The 1928 d e s c r i p t i o n i s found under the heading of Black Bear Group. F . i r r ^ T n T ^ M i n e r a l i z a t i o n accompanies a quartz v e i n o c c u r r i n g i n a shear zone i n what has been c l a s s i f i e d as an augite per-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 . The v e i n i s 2 to 2-g-f e e t , and the shear zone about 15 f e e t , i n width. T e t r a h e d r i t e , a z u r i t e and a l i t t l e c h a l e o p y r i t e are noted. The v e i n trends 0 n o r t h and south and d i p s 27 east« The s c h i s t e n c l o s i n g the quartz v e i n i s r e p o r t e d to be barren. Macroscopic 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 t e t r a h e d r i t e was 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 interconnec-ted masses through a medium-grained, g r a n u l a r , milk-white quartz gangue. A l i t t l e l i m o n i t e and a z u r i t e are present. The 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 so shows a much-i n t e r r u p t e d f r a c t u r e . In 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 of t e t r a h e d r i t e seem to have the character-i s t i c conchoidal f r a c t u r e and l u s t r e . Paragenesis - T e t r a h e d r i t e , quartz and a s i n g l e g r a i n of a g r e e n i s h carbonate gangue were the only minerals recognized. - 1 7 -Specimen Ho. J» Jo-Jo Group. Three Forks, Slocan Mining Division© L o c a t i o n - The claims are s i t u a t e d about 7 miles from the town o f Three Forks (on the C.K.R 0) 0 The Deposit - In the 1904 Annual Report of the B. G© M i n i s t e r of Mines t h i s group i s s t a t e d to be of "about the same character" as the M c A l l i s t e r group, 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 , trends northeast-southwest, and dips j>0° southeast© The v e i n i s 3 to 4 fee t wide and i s reported to ca r r y "galena, gray copper, and s i l v e r s u l p h i d e s , the ore as shipped, running over 2.50 oz© to the t o n . f ! Macroscopic d e s c r i p t i o n - T e t r a h e d r i t e occurs i n bunches and i r r e g u l a r s t r i n g e r s between w e l l rounded areas of b l u i s h white milky quartz© Minor amounts o f the mineral have good eonchoidal f r a c t u r e and b r i l l i a n t lustre© Most of the mineral has a l e s s r e g u l a r f r a c t u r e and somewhat lower l u s t r e . Mineralogy and Paragenesis - In p o l i s h e d s e c t i o n , t e t r a -h e d r i t e , galena and s p h a l e r i t e (?) were recognized. The gangue i s quartz© T e t r a h e d r i t e c o n s t i t u t e s the main bulk of the metallies© Galena occurs i n minor quantities© S p h a l e r i t e (?) i s rare© The order of mineral d e p o s i t i o n has been determined • s a t i s f a c t o r i l y ; at l e a s t f o r the sect 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 c e r t a i n t y . 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 . T e t r a h e d r i t here, i s unquestionably 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 ' of -tetrahedrite-..ana- galena i n . quartz. T e t r a h e d r i t e f i r s t veined the. quartz. 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 unreplaced " i s l a n d s " and specks of tetrahedrite©. Galena etched w i t h n i t r i c - a c i d Panchromatic p l a t e . ' . second exposure PLATE SPECIMEN 3 Etched galena r e p l a c i n g t e t r a h e d r i t e and quartz. The w e l l rounded o u t l i n e s of unreplaced ''islands•' of t e t r a h e d r i t e and quartz show c l e a r l y . There would seem to be l i t t l e doubt as to the l a t e age of the galena. Panchromatic p l a t e l/^O second exposure '. X 85 r ^ L A PLATE 6 : SPECIMEN y /: ' Gaiena, quartz and t e t r a h e d r i t e . The galena . veins •••the • t e t r a h e d r i t e . C o n t r a d i c t i n g t h i s - evidence 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' 1 1 of, the galena. D i r e c t evidence ,- t h e n s i s i n c o n c l u s i v e . I n d i r e c t evidence, as the occurrence :of c h a l e o p y r i t e t y p i c a l l y w i t h i n t e t r a h e d r i t e r a t h e r than w i t h i n . g a l e n a , suggests that t e t r a h e d r i t e was. intro d u c e d before the galena. . Camera-lueida drawing X 8j? . s u n l i g h t the powder was a l i g h t y e l l o w - somewhat l i g h t e r than i s t y p i c a l f o r blende. Colour, etch t e s t s , and hardness cheek with those g i v e n f o r blende. S p h a l e r i t e i s replaced by t e t r a h e d r i t e as i l l u s t r a t e i n the accompanying camera-lueida drawing. The v e i n i n g of the s p h a l e r i t e i s obvious. Unreplaeed " i s l a n d s " of s p h a l e r i t e are surrounded by the t e t r a h e d r i t e . of the 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 boundaries tend to 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 the accompanying photomicrograph ( P l a t e V ). In the photograph, the galena has been etched with n i t r i c a c i d to give c o n t r a s t . The w e l l rounded unreplaced areas of t e t r a h e d r i t e completely surrounded by the galena are e x c e l l e n t evidence of replacement I t i s noteworthy that no specks of t e t r a h e d r i t e , or other unetched m i n e r a l , were observed w i t h i n the etched galena areas. • . • • ' Replacement by galena shows a tendency to 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 c o n t a c t s . The sequence of d e p o s i t i o n , as e s t a b l i s h e d above, i s : i youngest | galena i — r t e t r a h e d r i t e i i o l d e s t | s p h a l e r i t e This i s the normal sequence f o r these minerals. G u i l d , F.IJ.'; A Microscopic Study of 'the S i l v e r Ores and t h e i r asso elated, Minerals» Ee.Geol., Vol.XII., 1917 , . pp. 3QQ & 506. Specimen Eo, 4= l a n g l e y C o l l e c t i o n s Ainsworth Mining D i v i s i o n . L o c a t i o n . - This ore was s u p p l i e d by the B. C. Chamber of Mines from the Langley C o l l e c t i o n from the Ainsworth Mining Division., The p r e c i s e l o c a l i t y from which i t was taken i s not knowno The Deposits - Most of -the A i n s worth l e a d - s i l v e r deposits occur a s s o c i a t e d with the limestone bands of the SIocan and Ainsworth s e r i e s , although some are i n q u a r t z i t e s . Deposits are of both the t r u e f i s s u r e and replacement t y p e s , and these are probably contemporaneous* The main f i s s u r e veins may f o l l o w master j o i n t planes. Galena and s p h a l e r i t e occur i n a gangue of c a l c i t e , s i d e r i t e , quartz and f l u o r i t e . The galena 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 ton. I'-Iative s i l v e r , where i t o c c u r s , i s always secondary. S i l v e r , where i t occurs i n the primary 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 the galena and i n v i s i b l e . Uo mention of 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 ) was found* I t i s i n t e r e s t i n g to note that "The replacement v e i n s , i n c o n t r a s t to the f i s s u r e v e i n s , carry low values i n s i l v e r and l e a d and h i g h values i n z i n c . " pTFysdale, cTW.y" G e ^ . S u r ^ 191^7 V»5b:* Macroscopic d e s c r i p t i o n - Masses of t e t r a h e d r i t e and a l i t t l e galena occur i n a gangue of coarse milky xvhite quartz. The t e t r a h e d r i t e v a r i e s from that w i t h a high l u s t r e and smoothly curving u n i n t e r r u p t e d f r a c t u r e to that w i t h an -20-i r r e g u l a r f r a c t u r e and s t e e l y l u s t r e . Mineralogy and Paragenesis - The f o l l o w i n g m e t a l l i c m i n e r a l s were recognized; t e t r a h e d r i t e , g alena, a supergene (?) mineral and c h a l e o p y r i t e . They occur q u a n t i t a t i v e l y i n about the order mentioned, t e t r a h e d r i t e being the most abundant. The others are r e l a t i v e l y unimportant. The gangue i s qua acta. The order of d e p o s i t i o n of the ore minerals could not be determined w i t h any degree of certainty.. M i n e r a l s , other Ithan t e t r a h e d r i t e , occur i n such small q u a n t i t i e s that but few contact areas could be found i n p o l i s h e d s e c t i o n s . The 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 galena and the t e t r a h e d r i t e are shown i n the accompanying photomicrograph ( P l a t e T i l ) . The supergene mineral v e i n s , and i s c l e a r l y younger than, the t e t r a h e d r i t e . I t surrounds, and makes a f e a t h e r y contact w i t h , the galena. I t i s probably younger than the galena. Hear the centre of the photomicrograph i s an area of t e t r a h e d r i t e which has apparently been veined and n e a r l y surrounded by galena. The supergene mineral has s e l e c t i v e l y r e p l a c e d the galena so t h a t now the galena v e i n l e t i s somewhat broken. Former c o n t i n u i t y of 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 of the cleavage p i t s i n the galena at e i t h e r end of the replaced v e i n l e t . The evidence f o r t h i s process of the s e l e c t i v e r e -placement of the galena i s confirmed on other c o n t a c t s ' i n the -21-same s e c t i o n . The contact between the supergene mineral i s u s u a l l y a s e r i e s of smooth curves. But the same supergene mineral has r e p l a c e d the galena i n such a way as to leave a h i g h l y i r r e g u l a r c o ntact. This.seems to the w r i t e r to suggest a more r a p i d replacement of the galena. I t might., however, be expla i n e d by some reference to the p r o p e r t i e s which r e s u l t i n cleavage and l a c k of cleavage i n galena and t e t r a h e d r i t e r e s p e c t i v e l y ^ C h a l e o p y r i t e 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-t i t i e s . The m i n e r a l above described as supergene was not i d e n t i f i e d . . The f o l l o w i n g p r o p e r t i e s were determined: s l i g h t l y harder than t e t r a h e d r i t e powder white very b r i t t l e c o l o u r darker and grayer than t e t r a h e d r i t e or galena n o n - m e t a l l i c s t a i n s dark brown with n i t r i c a c i d the v e i n l e t s are banded p a r a l l e l to the w a l l s . Paragenetic evidence brought out 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 suggested. youngest j u n i d e n t i f i e d supergene m i neral t ----— \~ galena i • o l d e s t ! t e t r a h e d r i t e ( PLATE SPECIMEN 4 I n d i c a t i n g replacement of galena and t e t r a h e d r i t e . The r e p l a c i n g mineral ("Sup") has not been i d e n t i f i e d . I t i s probably supergene. " I s l a n d " and " d e l t a " . s t r u c t u r e of the re p l a c e d m i n e r a l s , e s p e c i a l l y the 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 borders of the galena c o n t r a s t w i t h the comparatively r e g u l a r t e t r a h e d r i t e boundaries. This i s taken to i n d i c a t e p r e f e r e n t i a l replacement of the galena. Panchromatic p l a t e l/j?0 second exposure , : • n a t u r a l c o l o r s •" , X 8,5 Specimen K o . 3« Sadie Claim, 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 mil e s 'northeast of the town of Mayo, Yukon Territory© The Deposit - In reviewing 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 Sadie ore shoot proved to be the l a r g e s t found t o date and f u r n i s h e d 100,000 tons of ore© 7 GockfieI'd", WTIi ©; Ge oTTSu^ 5 0 , PtTF,~~pT4.©.""*~ This property was worked by Treadwell-Yukon Go©, L t d . , under lease from Keno H i l l , Ltd©, during 1 9 2 9 , and was exhausted e a r l y i n 1930* This deposit l i e s at the southeast end of a f a u l t e d Vein i n greenstone - the Sadie-Treadwell v e i n . The v e i n has been traced f o r n e a r l y 3000 f e e t w i t h an average width of 7 to C o c k f i e l d , W sE a; Geql.Surv , 0 a n ., Summ.Eept. 1923, Pt«A, p.14. 8 f e e t and a maximum width of 70 f e e t . On the Sadie, the ore did not extend below the 400 foot l e v e l . This shallow depth seems to be c h a r a c t e r i s t i c of the ore shoots of the camp. Another general f e a t u r e of the carap i s the ex i s t e n c e of a num-ber o f northeast t r e n d i n g f a u l t s while the general, t r e n d of the m i n e r a l i z e d v e i n s i s to the no r t h e a s t . Ore shoots g e n e r a l l y occur at or near the i n t e r s e c t i o n of the two types of f i s s u r e s . This suggests that e i t h e r : 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 -t i o n , o r 2. m i n e r a l i z a t i o n has l o c a l i z e d the younger, northwest t r e n d i n g 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 leaves t h i s problem u n s e t t l e d . .Cookfield, W71".;' opr~c*iT*. , Su^7Re^t7~1930~7~p74T "" " The v e i n i s one of the main l o n g i t u d i n a l f r a c t u r e s of the area, and i s cut by a f a u l t along 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 the Sadie property. Galena, f r e i b e r g i t e and s p h a l e r i t e have been noted as the important ore m i n e r a l s , w i t h a s i d e r i t e gangue. Native s i l v e r , p y r a r g y r i t e , quartz, a r s e n o p y r i t e s p y r i t e and chaleo-p y r i t e occur. • ClTeT£fTeTd7~WTE^ , Pt .A, pp.4-J7 Hacroscepic d e s c r i p t i o n - I r r e g u l a r masses of t e t r a h e d r i t e occur i n a l i g h t brownish s i d e r i t e gangue. The few specks of galena are u s u a l l y separated by gangue from the t e t r a h e d r i t e . The s i d e r i t e i s coarse g r a i n e d and shows the c h a r a c t e r i s t i c c u r v i n g cleavage fa c e s . Mineralogy and Paragenesis - I n p o l i s h e d s e c t i o n , t e t r a -h e d r i t e , c h a l e o p y r i t e , and specks of a s i l v e r y mineral were recognized. The gangue i s s i d e r i t e . There i s very l i t t l e q uartz. I t was not p o s s i b l e to cut a s e c t i o n showing t e t r a -h e d r i t e and galena i n co n t a c t , as these two minerals were everywhere separated by gangue. T e t r a h e d r i t e and galena are the only m e t a l l i c s present i n ap p r e c i a b l e q u a n t i t i e s . C h a l e o p y r i t e cuts 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 and i s c l e a r l y the younger. PLATE 8 SPECIMEN 5 Te 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 veins s i d e r i t e along the cleavage. One edge of the v e i n l e t of t e t r a h e d r i t e (dark) f o l l o w s cleavage i n the s i d e r i t e throughout i t s l e n g t h . I r r e g u l a r replacement i s more common on the other boundary. Such a v e i n l e t would 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 f i l l i n g , , and to a l e s s extent from-subsequent replacement of the- host. Panchromatic P l a t e l/j50 second exposure Galena veins s i d e r i t e , guided by cleavage d i r e c t i o n s as shown i n the accompanying photomicrograph ( P l a t e V I I I ) . 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 occurs i n very small q u a n t i t i e s as blebs w i t h rounded to sub-angular o u t l i n e s i n the t e t r a h e d r i t e . I t s c o l o u r i s a l i g h t e r shade o f s i l v e r gra; than the t e t r a h e d r i t e . Absence of r e l i e f would I n d i c a t e that i t s hardness i s about that of t e t r a h e d r i t e . Hardness and etch t e s t s could not be made on such small species of m a t e r i a l . I t i s not n a t i v e s i l v e r and seems to be too hard f o r the usual s i l v e r and l e a d sulpharsenides and sulphantimonides. The order of d e p o s i t i o n i s probably as f o l l o w s : youngest J c h a l e o p y r i t e » i - i t e t r a h e d r i t e i 9 o l d e s t I s i d e r i t e - • » This replacement of 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 expected. Qui 1 d~FTirrr~JIi^roi"e'bpTo™Stu7Ly~of~SiTver OrosZ Ec.Geol. , ~* V o l . X I I , " 1 ? 1 7 , p.334. The t e t r a h e d r i t e i n t h i s ore assayed 25«2 percent s i l v e r , thus p l a c i n g i t i n the c l a s s of F r e i b e r g i t e . Specimen Ho. 6. I t i s not known from what property t h i s ore was taken. I t was c o l l e c t e d by Mr. A. Hutchinson, of (luesnel, Cariboo Mining D i v i s i o n . Specimen No. 18 i s from the Snowshoe Group, P r i n c e George, Cariboo, of which Mr. Hutchinson i s part owner*, I t seems probable that Specimens fa and 18 are from the same prop e r t y , e s p e c i a l l y as the ores themselves are ma c r o s c o p i c a l l y i d e n t i c a l . Mineralogy and Paragenesis - This ore was of e x c e p t i o n a l p u r i t y . Only t e t r a h e d r i t e and quartz were found i n the p o l i s h e d sections.. The surface of 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 us u a l f o r t h i s m i n e r a l * Specimen II o. 12. l o c a t i o n - The l o c a t i o n of the deposit from which t h i s sample was taken i s not known. The l o c a l i t y was given, as " I l l e c i l l e w a t 1 1 which would place the deposit so me where i n the R e v e l s t o k e - G l a c i e r d i s t r i c t . The Deposits - Gunning, i n h i s r e p o r t on the B i g Bend map area, d i v i d e s the mineral 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. Gold-Quartz 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. Quartz-Tetrahedrite v e i n s . ^aSoingT"' H.C. y.'O'eolbSaryTCanr. ''Sdmm»K'ept» 192"87"P%«A, p» 1.5,5» This specimen c l e a r l y belongs to the f o u r t h c l a s s . The only quart z - t e t r a h e d r i t e veins described i n the I l l e c i l l e w a t d i s t r i c t are those of the Old George group. ^onnlngV 'ttT8Tr~oj?*^iX»,' 'p*^IT"~ ~ " * These veins are staked on a s e r i e s of small i r r e g u l a r . - 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 minerals are p y r i t e , s p h a l e r i t e , g a l e n a , boulangerite 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 quartz w i t h some c a l c i t e . Other s i m i l a r occurrences i n the B i g Bend area c a r r y t e t r a h e d r i t e , bournonite and bo u l a n g e r i t e ( ? ) . Mineralogy and Paragenesis - P o l i s h e d surfaces showed only very pure t e t r a h e d r i t e and quartz. Examination, under b i n o c u l a r s , of the crushed ore showed a very few g r a i n s of p y r i t e , c h a l e o p y r i t e ( ? ) , galena and s p h a l e r i t e ( ? ) . These could not 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 out. Specimen Fo. 1 7 . Submarine Group, L y t t o n , Asheroft Hining D i v i s i o n . L o c a t i o n - llo reference to t h i s property was found i n the B.C. M i n i s t e r of Mines or G e o l o g i c a l Survey of Canada r e p o r t s . The Deposits ~ Lode depos i t s i n the Asheroft D i s t r i c t have been summarized as f o l l o w s : B.C.^ lAnJiaTe^ "Lode mining 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 impregnations of zones o f shear-ing and f r a c t u r i n g i n a complex s e r i e s of rocks of p l u t o n i c , v o l c a n i c and sedimentary o r i g i n . 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 recent o r i g i n than i s the ease w i t h the ore bodies i n c l o s e r r e l a t i o n s h i p to the seat of the main western - 2 7 -b a t h c l i t h i c i n t r u s i o n . " Ore minerals are b o r n i t e and c h a l c o p y r i t e , u s u a l l y c a r r y i n g values i n gold and s i l v e r . Bo mention of the occur-rence of t e t r a h e d r i t e was found. Mineralogy and Paragenesis - T e t r a h e d r i t e , galena and • p y r i t e are recognized© The gangue i s quartz. An u n i d e n t i f i e d , g r e e n i s h , supergene mineral ve i n s the t e t r a h e d r i t e . Galena and p y r i t e represent only a small percentage of the m e t a l l i e s . P y r i t e appears as a few small rounded bl e b s . The paragenesis, i n t h i s case, could not be determined very s a t i s f a c t o r i l y . P y r i t e , i n de p o s i t s of t h i s type, i s u s u a l l y an early-formed m i n e r a l . I t s occurrence here, as i s o l a t e d rounded g r a i n s , suggests e a r l y d e p o s i t i o n . Galena d o u b t f u l l y v e i n s t e t r a h e d r i t e . 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 noted i n t e t r a h e d r i t e only. T h i s i s confirmatory evidence of the l a t e age of the galena, as, i f galena had re p l a c e d p y r i t e p r i o r to the i n t r o d u c t i o n of t e t r a h e d r i t e , i t might now be expected to i n c l u d e some pyrite.. However, due to the r e l a t i v e l y g r e a t e r abundance of t e t r a -h e d r i t e , the value of t h i s i n d i r e c t evidence i s questionable. C o n t r a d i c t i n g the above evidence as to the l a t e age of the galena we have the f a c t that the t e t r a h e d r i t e shows a tendency to embay the galena. However, t h i s f a c t , i n i t s e l f , has l i t t l e d i a g n o s t i c v a l u e . The order of d e p o s i t i o n , then, i s d o u b t f u l l y PLATE 9 SPECIMEN 1 7 An enlarged photograph of fragments of c r y s t a l s of t e t r a h e d r i t e from Ore Specimen 17• The general 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" faces as marked. X 8 determined as f o l l o w s : youngest j galena i . . i „„ra„raj t e t r a h e d r i t e i o l d e s t J p y r i t e T h i s i s the normal sequence. The d i f f i c u l t y experienced i n a c c u r a t e l y determining t h i s sequence was due t o the i m p o s s i b i l i t y of o b t a i n i n g more than a very few g a l e n a - t e t r a h e d r i t e c o n t a c t s . Specimen i?o. 18. Snowshoe Group , P r i n c e George, Cariboo. L o c a t i o n - This property i s mentioned i n the 1918 Annual Report o f the B.C. M i n i s t e r of Mines. I t i s s i t u a t e d lj? miles ^3T5THS!fn^ T9T87~p7l2Tr~^ northeast o f P r i n c e George. The Deposit - According to the 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 to 300 feet i n wi d t h , c u t t i n g shale. The very s l i g h t m i n e r a l i z a t i o n of p y r i t e , p y r r h o t i t e , and 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 along 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 that "assays show that the m i n e r a l i z e d rock does not carry appreciable values I n gold and s i l v e r , and that the average samples have too low a copper content to be of commercial importance." In the I 9 2 3 r e p o r t , according to i n f o r m a t i o n s u p p l i e d by one of the shareholders, "We went down on t h i s (shaft) 17 f e e t , to a depth of 27 f e e t , ana ore taken out at this depth assayed $23 i n gold, s i l v e r and copper, and had widened out from a stringer to 5 feet wide, with evidence of s t i l l further-widening... " Unfortunately, the assay r e s u l t s f o r the three metals are grouped together. It should be emphasized that t h i s information i s supplied by one of the owners. Mineralogy ~ Only tetrahedrite and quartz were noted i n the polished sections. Specimen Uo. 2 0 . S i l v e r Star, Similkameen. Location - This i s one of the claims of the Sparkler Group, situa t e d on Gambia Greek, a t r i b u t a r y of Similkameen r i v e r within about b miles of the headwaters. The Deposit - Tetrahedrite i s not mentioned i n the descrip-tions of t h i s group i n the Annual Reports of the E.G. Minister of Liines. It i s stated that "The copper contents were not assayed." • The pyrite-arsenopyrite-sphalerite-chaloopyrite mineralization seems to be g e n e t i c a l l y r e l a t e d to an in t r u s i o n of gabbro into the sedinientaries. The ore occurs i n a series of veins and lens-shaped bodies, l o c a l i z e d by joint planes and other fractures i n the rock. Mineralogy and Paragenesis - The minerals occurring are: arsenopyrite, sphalerite ( ? ) , galena, tetrahedrite, chalco-•.-30-p y r i t e , hypogene (?) v e i n l e t s and Q u a r t z . The order of abundance of the ore minerals i s about as follows, beginning with the most p l e n t i f u l : t e t r a h e d r i t e , chaleopyrite, galena, (sp h a l e r i t e (?) and arsenopyrite). large areas of tetrahedrite are- r e l a t i v e l y pure except for i r r e g u l a r l y d i s t r i b u t e d blebs of chaleopyrite* These vary from the merest specks to f a i r sized 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 the microscope. These seem to be residual areas i n the replacing t e t r a h e d r i t e . The chaleopyrite boundaries are usually concave towards the t e t r a h e d r i t e . Occasionally we have the r e l a t i o n s as shown i n Plate XI, where chaleopyrite seems to vein the te t r a h e d r i t e . Age r e l a t i o n s are indeterminate. That t e t r a -hedrite has replaced the chaleopyrite seems the. more, l i k e l y i n t e r p r e t a t i o n * The r e l a t i v e ages of galena and tetrahedrite could not be proved conclusively. No evidence other than the character of the contacts could be found. Plate X i s taken to indicate that the tetrahedrite has replaced the galena f o r the following reasons: 1. smoothly curved contacts are convex towards t e t r a -hedrite. 2. residual "outliers' 1 of galena occur i n the tetrahedrite. Certain r e l a t i o n s , seen i n other sections, can equally well be interpreted as galena veining tetrahedrite or as galena p a r t i a l l y replaced by tetrahedrite. Chaleopyrite, however, i s r a r e l y surrounded by galena while i t s occurrence as blebs within tetrahedrite i s c h a r a c t e r i s t i c This suggest that galena has replaced both tetrahedrite and chalcopyrite. The above evidence i s admittedly inconclusive. A tentative sequence i s ; youngest oldest galena tetrahedrite chalcopyrite a r s e n o p y r i t e The ores having been described 9 the analyses w i l l next be considered. PLATE 10 SPECIMEN 20 Galena, t e t r a h e d r i t e , c h a l c o p y r i t e and quartz. T e t r a h e d r i t e appears to " b i t e i n t o " galena, and t h e r e f o r e d o u b t f u l l y replaces i t . Camera-lucida drawing X 275 PLATE 11 SPECIMEN 20 Chalcopyrite, tetrahedrite and quartz. The chalcopyrite, i n t h i s section at l e a s t , i s unquestionably the younger. It also occurs as i r r e g u l a r rounded blebs throughout the tetrahedrite. Such an occurrence, i n i t s e l f , i s non-diagnostic. Camera lucida drawing 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 preliminary blowpipe determinations on a suite of tetrahedrite ores of B.C., a mercurial variety was noted, l a t e r work showed the selected mineral to be carrying about 6 f » mercury. -4s schwatzite (mercurial tetrahedrite) was previous-. l y unknown i n B.C., and i s of rare occurrence throughout the world, a separate chapter has been devoted to t h i s occurrenceo Six occurrences of schwatzite are l i s t e d by Dana Dana ; A System of Mineralogy, Sixth E d i t i o n , lBfb~~T^"ip?". "~ with analyses. The,mercury content varies from 2 . 7 0 to 1 7 . 3 2 . Mercury content of the o r i g i n a l occurrence at Schwaz, i n the T y r o l , i s given as 15«j?£° In North America, mercurial tetrahedrite occurs near Sumpter, Oregon. No other occurrence of the mineral on t h i s LTndgrerr, VU ; 22nd Ann. Re*p*tT7 U« 3.0. S.', Pt" TJd^LffiL'' 'lpTbb'4".' "*" continent i s known to the writer. Proposed Outline. Occurrences of mercurial tetrahedrite, as described 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 discussed. Special attention w i l l be given to an occurrence i n Oregon, the near-est known deposit to that of the Windermere D i s t r i c t . The Economic Geology of the Windermere w i l l be b r i e f l y described, and published data on the occurrence to be studied, w i l l be summarized. The r e s u l t s of a detailed study of the o r e - w i l l be given and discussed. -33 MERCURIAL TETRAHEDRITE OF THE LITERATURE Generally speaking, mercury occurs i n two types of deposits. By f a r the most important are those i n which the metal occurs i n the form of cinnabar. In other deposits i t occurs as.an e s s e n t i a l constituent i n tetrahedrite, as f i r s t described from Sehwaz, Tyr o l . 'Beyscnlag, Yogt '& Krusch, 0r^'De^sit"'s"7~v'oTT!l,' p.~4~j7T Cinnabar sometimes occurs i n the oxidation zone through the decomposition of t e t r a h e d r i t e . Cinnabar minerali-zation at the surface may p e r s i s t to depth or I t s place, In depth, may be taken by mercury-bearing tetrahedrite. The occurrence or non-occurrence of other heavy metal compounds with the cinnabar of surface showings may give a clue as to i t s primary or secondary nature - a point of economic importance. Other q u i c k s i l v e r minerals are of secondary import-ance e • . Mercurial tetrahedrite might be said to form a connecting l i n k between t y p i c a l mercury deposits (cinnabar) on the one hand and s i l v e r - l e a d - z i n c deposits (galena, sphalerite and tetrahedrite) on the other. This w i l l be further discussed under "Mineralogy and Paragenesis." Known Deposits. The accompanying table of antimonial q u i c k s i l v e r 1 2 deposits i s taken from Becker. The data from deposits i n 1 Ber. Vogt & Krush', Ore Deposits, V o i . l , p.4i?b". 2 Lindgren, W.; U.S.G.S. 22nd Ann.Rept., Pt.2, 1901, p.664. -33a-14 05 o s! 54 4 * CiJ - H o pq •H 54 +=> •H O r H 0> •1-1 ca $4 « © tp IH r H 35 •H 14 PQ « O a o • H 14 4= O r H . o o •H - H O s5 e-t a O 54 03 d • H i - i G3 o o r-3 4= SI S4 c •H 4^ a o 1 I f 03 a +> o i £>; •H V> 4= 54 4= S3 0) H © U I - H a o +3 o •H O N o & rH & o 54 O pq $4 +» « o o • H t» 81 CSS «H 54 • H o ! 05 14 i « a1 •H - H a += o i • H - H S 4= G •-CJ 60 ! S3 a +=> a o CD H 0) 54 s o ret r-i s O ?d r-i m I ta £ o o 54 r Q & 54 <M O flS - H Ja{ • H ^ > M ».H O CO {25 4=> 4= a * 14 CD 4 3 si <& ft <J> GO Cd rH > > J4 CO r H •rt 54 14 •I I O 4S s in -r-! O as a C3 4= H - H O O J4 54 54 0) o 4=> ElO P-i a> a J4 d o to 54 .43 1 © . 14 PI »H 4= O K fe5 - H i4 4= 0) o 45 J4 % 4 C3 S4 - H •H 4» a • O •, 1 -fl a «8 CD C3 - H 4= O 54 CS ^> rH ffl 54 r H * O <D.O .54 « f d <D 4= SH S - H - H 54 i 54 © Oregon and B r i t i s h Columbia are added* With the exception of the Bosnia occurrence, a l l are pre Kesozoic. Quartz, pyrite and c a l c i t e are usually present. Galena and sphalerite and barite may occur. Becker, summarizing h i s monograph on the mercury le'ckerT^G'g*;~ U T S T G . S . ,^onVxITr7~ToW7 p ° 4 5 3 7 ~ " " deposits of the P a c i f i c slope, says: " "The minerals which occur i n considerably quantities with q u i c k s i l v e r ores are few i n number. Py r i t e or marcasite i s nearly always present, arsenic or antimony i s found at many l o c a l i t i e s and copper ores sometimes accompany cinnabar. Other metalliferous minerals 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 , some-times hydrous, or carbonates, c h i e f l y c a l c i t e . " As to the temperature of formation of mercury deposits, lindgren states: XinSgren, Wa~T~Mineral Deposits,"T92B',' p . 5 5 9 « • ~ " "The occurrence of q u i c k s i l v e r minerals i s by no means confined to any c e r t a i n kind of deposits or to any given age or epoch of m e t a l l i z a t i o n . However such minerals are not known to occur i n deposits of d i s t i n c t l y igneous o r i g i n nor i n pegmatite dikes, nor i n veins of the deepest zone. High temp-erature i s evidently unfavorable f o r t h e i r development." As the mineral association of Epithermal mercury deposits, he gives cinnabar, p y r i t e , marcasite, s t i b n i t e common chalcopyrite and m i l l e r i t e rare -35-opal, chalcedony, quartz, c a l c i t e , dolomite barite and alunite As a Hesothermal as s o c i a t i o n he &ive3 common gangue rare gangue bindgren, K.; op. e i t . , p.b2?7 p y r i t e , arsenopyrite, chalcopyrite, galena, blende, with tetrahedrite and cinnabar l e s s conspicuous, gangue of quartz and c a l c i t e . Arsenopyrite here indicates deposition under condi-tions of temperature and pressure at least above those usually responsible f o r Epithermal deposition. This mineral i s apparently absent from the Windermere and i s not mentioned i n Becker's t a b l e . A l l these deposits, with the exception of that i n Oregon, seem to be of rather low temperature deposition, agree-ing more nearly with Epithermal than with Me so thermal mineral associations. The mercurial v a r i e t i e s of tetrahedrite given i n Dana show a higher average s p e c i f i c gravity than the normal v a r i e t y . V a r i a t i o n i n the s p e c i f i c gravity does not correspond with the v a r i a t i o n s i n mercury content. The appearance of arsenopyrite i n the Sumpter, Oregon, deposit makes the mineral assemblage of t h i s gold deposit agree more clos e l y with that c i t e d from Lindgren as a Mesothermal occurrence. Deposit of Schwatzite near Sumpter, Oregon. This being the nearest known occurrence of mercurial te t r a h e d r i t e , i t seems worthy of a short description. LTndgren, VI.; U.S.G.s7^1nT7^nn.ReptTr3?t»2, l^QlT p.bb4. . The deposit was worked by the Columbia Gold Mining Co. s as a gold deposit. M i n e r a l i z a t i o n i s found along a fracture zone i n b r i t t l e , black s i l i c e o u s a r g i l l i t e s , r a r e l y 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 . The zone trends north-o east and dips 60 southwest. This fracture zone , about 40 feet wide, consists of abundant black a r g i l l i t e fragments and blocks i n a matrix of white quartz. The quartz sometimes shows drusy comb structure. P y r i t e . s e r i c i t e , and sometimes .calcite have resulted from the a l t e r a t i o n of the wa l l rock. M e t a l l i c minerals are c h i e f l y p y rite and arseno^ p y r i t e . Other minerals found are native copper, gold, sphalerite , pyrargyrite, cinnabar, antimonite, chaleopyrite, s t i b n i t e , a t e l l u r i d e and schwatzite. The gangue i s c h i e f l y quartz. Other gangue minerals are s e r i c i t e , fuchsite , and c a l c i t e . The pay occurs i n streaks, following either wall, or crossing from one wall to another. GENERAL ECONOMIC GEOLOGY OF WINDERMERE DISTRICT A general outline of the Economic Geology of t h i s d i s t r i c t w i l l be given here. The r e l a t i o n of the mercurial occurrence to type occurrences of the d i s t r i c t can then be - 3 7 -discussed, below. It w i l l be seen that the mineral association of the mercurial deposit i s exceptional f o r the Windermere. The General and Economic Geology of the area has been covered by Walker i n h i s report on the "Geology and Mineral Deposits of Windermere Map Area, B.C." WalkerT"?". 1?.; ' G^l".l^urvTGan. t"l!iem7T4W7~WZbT ~ ~ ' The North Kootenay Mines deposit l i e s well within t h i s map area, and on the eastern slope of the P u r c e l l range. The exposures are of Devonian and older sediments intruded by Jurassic granite stocks. The Pre-Cambrian P u r c e l l and Windermere Series are cut by greenstone dykes and s i l l s . Unconformably overlying these are sedimentary formations ranging from Upper Cambrian to Upper Devonian i n age. These are a l l intruded by Mesozoic (probably Jurassic) granite stocks and apophyses. This i s unconformable" o v e r l a i n , within the map area, by unconsolidated Pleistocene and Recent deposits. Lead-silver and l e a d - s i l v e r - z i n c are the economically Important m e t a l l i c deposits of the area. I'o copper or gold deposits of value have been found. Eor are the barite and gypsum deposits of any importance at present. op. c i t . , p.4 Lead-silver and l e a d - s i l v e r - z i n e deposits occur as f i s s u r e and bed veins, associated with minor a n t i c l i n a l folds on the limbs of the l a r g e r f o l d s . The veins tend to s t r i k e with the f o l d i n g - about north JO degrees west. They are commonly the rocks of the P u r c e l l s e r i e s . -38-M e t a l l i c minerals noted are; galena sphalerite p y r i t e chaleopyrite f r e i b e r g i t e some c o v e l l i t e Oxidized minerals are; c h i e f l y cerussite Gangue minerals are; quartz (two generations) c a l c i t e (white to pale cream) bari t e (dense and massive to c r y s t a l l i n e and white to pale green) s i d e r i t e ( a l t e r a t i o n of pyrite) She order of deposition i s given as y o ung est \ g ale na « § i t e t rahedrite s i , — i — . — . . j sphalerite ! \ pyrite i oldest i gangue As quartz i s the chief gangue mineral,, the p o s i t i o n of b a r i t e and c a l c i t e i n the sequence has probably not been determined accurately. S i d e r i t e gangue i s younger than the pyrite s from which, according to Walker, i t lias been formed. op. e i t . , p.43' I f he intends to imply that the barite i s one of the f i r s t formed minerals, t h i s conclusion does not check with that a r r i v e d at "by the present writer. Ee mentions several notable features. With reference to tetrahedrite he says; " dp'. ciTr7~p744T ' *"* ' ' ~" ' -— -"Freibergite or argentiferous tetrahedrite Is the p r i n c i p a l s i l v e r - b e a r i n g mineral. It shows marked variations i n i t s microchemical reactions apparently due to the varying s i l v e r content. 1 1 This statement may be found to be s i g n i f i c a n t i n view of the possible mercury content of other tetrahedrite ores of Windermere-. Further, i n accordance with general observations i n the C o r d i l l e r a , he finds that ""op. .-cTF^ ''.,"".pT4^ TM~ r~r7"~*~~' „ " " " f ! " ~ "the properties situated at the higher elevations 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 bearing and p r a c t i c a l l y free from z i n c , whereas the properties located at lower a l t i -tudes carry considerably more sine, and i t i s i n these proper-t i e s that the replacement of zinc blende by galena Is notice-able . * The property of the Perth Kootenay Mines l t d . , at an elevation of 92J50 feet s judging by the ore examined, carries no zinc and so f i t s into t h i s general r u l e . Further, there are no contact metamorphic deposits, nor are contact phenomena w e l l developed. To quote Walker, WINDERMERE MAP AREA showing l o c a t i o n of PRETTY GIRL CLAIM, NORTH KOOTENAY MINES, LTD. -40-"There i s no evidence of mineralization being con-centrated i n the neighborhood of granite bodies." He believes that the deposits are connected with the period of Jurassic mountain bu i l d i n g and igneous intr u s i o n . THE DEPOSIT Pretty G i r l Claim, North ICootenay Mines, l t d . This deposit i s f i r s t mentioned, i n the 18?8 Annual Report of the B.C. Minister of Mines, as one of six l o c a t i o n s , v i z . , the Yenus, Hew Chum, Pretty G i r l , Mimaiehaha, Old Chum, and Beauty, held by the Hew Golden B. 0. Company, of London, England, represented by W.G. Mitchell-Innes, of Golden. Of the group, only the Pretty G i r l has been worked. The claim i s situated about 1 8 miles west of the town of Windermere. It l i e s on the summit of the divide between the headwaters of Boulder and Law's Creek, at an elevation of 92j?0 feet, on the east slope of the P u r c e l l Range. Walker, i n h i s section on Economic Geology, makes no pp. c i t . , p.43. mention o f the Pretty G i r l claim and has not v i s i t e d that ridge. Pe r so 11a 1 co ramun i e a t i 0 11. ' ~ " " For data on t h i s property, reference must be made to reports of trie B.C. Minister of Mines. The mineralized zone, some 6 - 8 feet wide, occurs i n 0 steeply dipping so f t shales trending I 25 W. The gray copper ore , with accompanying carbonates , l i e s between the layers of 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 usual acceptance of the term,- but a zone i n the bedding of the shales- !l A representative sample i s stated to contain 26.68% copper and 55«»5 oz. of s i l v e r per ton. . . In the 1915 report mention i s made of a vein "which varies from a seam up to 10 inches i n width, consisting of quartz somewhat stained with malachite (copper carbonate)." B. br~f!it5Tilie^ ~ ' Assays of grab samples gave 20.8/. copper and 58 ounces of s i l v e r per ton. In the '1928 report the property i s again referred to as follows; BTG. M i n i s t e r ' ^ ? Mines, Ann.F^pTr"l9.2d7~P^2To^ ~ "The Pretty G i r l , situated on the summit of the ridge between Slade and Law Creeks, was operated by the North ICootenay Mines, Ltd., of which J.A. Lundy i s president." No further information i s given i n these reports. MINERALOGY AND PARAGENESIS Macroscopic Description of Specimen In a l l , several pounds of ore from the North ICooten-ay Mines was obtained through the courtesy of the B.C. Chamber of Mines, Vancouver. It showed hut l i t t l e v a r i a t i o n and might well a l l have come from the same lump of ore. In a l l p r o b a b i l i t y i t i s not representative material but, i n the absence of a more complete sui t e , w i l l be described. One piece of ore c a r r i e s a piece of the vein wall. It i s a greyish green indurated shale i n part altered to a somewhat scaly talcose or c h l o r i t i c material at the ore con-t a c t . It i s i n contact with massive mercurial t e t r a h e d r i t e . .Insufficient material was at hand to permit of the study of the s i g n i f i c a n c e , I f any, of the association of the more massive ore with the vein wall. Malachite ana azurite with a l i t t l e i r o n oxide are the conspicuous a l t e r a t i o n products. The ore tends to occur i n bands - a band of massive and comparatively pure tetrahedrite against a band of sparser mineralization i n a f i n e l y crystalline- white b a r i t i c gangue. The chaleopyrite, pyrite and resultant i r o n oxide are seen i n t h i s b a r i t i c ore. In the absence of a systematic suite of specimens, no observations can be made on the r e l a t i o n of banding to vein walls. Mineralogy and Paragenesis The following minerals have been recognized: tetrahedrite (mercurial), p y r i t e , chaleopyrite, bornite, chaleocite, a z u r i t e , malachite, barite ana quartz. This appears to be an unusual association for the PLATE 13 SPECIMEN 1 B a r i t e , t e t r a h e d r i t e , pyrite and chaleopyrite» Taken to show the t y p i c a l mode of:occurrence of chaleopyrite within tetrahedrite - as i r r e g u l a r v e i n l e t s and isolatexl bleihsi throughout» The dark border around the gangue is' merely. a depression. The dark areas within the tetrahedrite are pits., o r i g i n a l l y containing earthy black non-metallic material. Panchromatic plate Kodak Color f i l t e r .(X 3) • 1/23 second exposure X 83 PLATE'14 SPECIMEN 1 Tetrahedrite, chaleopyrite and p y r i t e . The chaleopyrite occurs as v e i n l e t s and as areas bordering p y r i t e r e s i d u a l s . This close association of pyrite and chaleopyrite i s t y p i c a l i n t h i s ore. The black areas are p i t s , containing soft non met a l l i c material. This i s believed to account, i n part, for the low assay t o t a l s . Panchromatic plate Kodak Color f i l t e r (X 3) l/10 second exposure X 273 PLATE SPECIMEN 1 Tetrahedrite ana chaleopyrite replacing • p y r i t e . The pyrite shows as well rounded grains of high r e l i e f . Tetrahedrite and chaleopyrite are not d i f f e r e n t i a t e d i n the photograph. Many-of the smaller vainlets are of chaleopyrite. Tetrahedrite, intimately associated (as usual) with chaleopyrite, and replacing pyrite i n this way, i s undoubtedly primary. •. ' Panchromatic Plate Kodak Color f i l t e r (X 3) I/25 second.exposure X 85 PLATE 16 SPECIMEN 1 Chalcopyrite, p y r i t e and•tetrahedrite. The veinlet i s a supergene mineral. This association of p y r i t e ana chalcopyrite i s t y p i c a l . Pyrite occurs as isola t e d rounded grains arranged i n l i n e s , forming " v e i n l e t s " . Chalcopyrite occupies these same l i n e s , surround-i n g or bordering the p y r i t e . Such py r i t e " v e i n l e t s " may or may not be accompanied by chalcopyrite but pyr i t e seems to be e s s e n t i a l to chalcopyrite areas. Oamera-lucida drawing X 85 PLATE 17 SPECIMEN 1 Chalcopyrite, p y r i t e , tetrahedrite and ba r i t e o . Chalcopyrite shown replacing pyrite„ Tetrahedrite-chalcopyrite r e l a t i o n s Indeter-minate. Camera-lucida drawing -43" •'Windermere D i s t r i c t . In the ore examined, the association of tetrahedrite, p y r i t e and chalcopyrite i n a gangue of quarts and barite 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 of minerals have been f a i r l y s a t i s f a c t o r i l y determined and w i l l be discussed f i r s t . This i s the mineral association 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 de-termined a s s o c i a t i o n i s found i n the disseminated mineraliza-t i o n i n the gangue areas. The minerals here are too f i n e -grained and too Intimately intergrown to permit of s a t i s f a c t o r y determination. Further, they occur i n such small quantities as to be of minor importance only. The discussion of the para-genesis of 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 group, w i l l be l e f t u n t i l l a t e r . Malachite, azurite and l i m o n i t i c iron oxide occur as a l t e r a t i o n products. 1 . Theu quartz, p y r i t e , chalcopyrite, tetrahedrite, barite miner-a l i z a t i o n . These minerals were deposited i n the order mentioned. Overlapping and contemporaneous deposition occurred i n the ease of chalcopyrite and tetrahedrite. The r e l a t i o n s w i l l be discussed, as f a r as possible, i n the order of deposition. Quartz occurs as a few i s o l a t e d rounded grains i n the bar i t e and i s probably one of the f i r s t formed minerals. Pyr i t e i s undoubtedly an early mineral occurring ~44- . . c h a r a c t e r i s t i c a l l y as groups and masses of well rounded grains included i n , and veined by, tetrahedrite and chaleopyrite,, This i s c l e a r l y shown i n Plate XV. Chaleopyrite veins tetrahedrite and, i n other places 1 i s included and embayed by i t . Therefore i t must have been deposited before, a f t e r , and contemporaneously with, t e t r a -hedrite. Plates XIV and XVI , taken together, i l l u s t r a t e t h i s overlap. Chaleopyrite i s usually seen as patches and blebs i n t e t r a h e d r i t e , and accompanying p y r i t e . Good examples of i t s veining tetrahedrite are not very common. It sometimes occurs as i s o l a t e d blebs and specks i n tetrahedri t e , but f o r the most part i s found as i l l u s t r a t e d i n Plates XVI and XIV - c l o s e l y associated with p y r i t e . The presence of pyrite would appear to have been e s p e c i a l l y favorable to the deposition of chaleopy-r i t e . P y r i t e occurs as l i n e s or "veInlets" of i s o l a t e d grains and i t i s along these same l i n e s that we f i n d chaleopyrite concentrated. Tetrahedrite areas on either side are l i k e l y to •.be, comparatively pure. It is probable that most of the chaleopyrite and t e t r a h e d r i t e are contemporaneous. The barite gangue was determined by a flame test f o r barium and a sodium bicarbonate fusion test f o r sulphate. The gangue i s unaffected by a c i d , c o l o r l e s s , and harder than c a l -c i t e . It c l e a r l y replaces a l l other hypogene metallies and quartz. Plate XIX shows replacement remnants of p y r i t e , chaleopyrite and tetrahedrite i n b a r i t e . PLATS 18 SPECIMEN 1 Bornite i n dark "barite gangue. Accurate determinations were impracticable under t h i s magnification. The dark gangue d i s t i n c t l y embays, and i s therefore younger than, the m e t a l l i c s . The main bornite mass contains laths and veinlets of chalcopyrite, best seen at the top of the section. The patchy areas within the bornite may indicate replacement by chalcocite or c o v e l l i t e and limonite. Panchromatic plate 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 tetrahedrite. i n barite gangue. Relations here are taken to indicate replacement of the sulphides by the gangue. They appear as embayed, and incompletely replaced, remnants scattered through the replacing gangue. Panchromatic plate no f i l t e r X 85 CHART showing RELATIVE AGES OF MINERALS i n ore from PRETTY GIRL CLAIM WINDERMERE M.D. I*] 5 0) c u CD 0 a 0 i • •-§1 O id f) s 0 I M t 0 O 10 o E to y t 2.The chaleopyrite, bornite, chalcocite, barite mineralization. The small amounts i n which t h i s disseminated mineral-i z a t i o n occurs precludes the p o s s i b i l i t y of posit 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 i d e n t i f i e d . A pinkish brown mineral may be bornite although the colour i s a l i t t l e too decided. The p o s s i b i l i t y of i t s being bornite i s supported by the occurrences within i t , of laths or needles of chaleopyrite, oriented i n three groups. It may be that these are following octohedral cleavage. A b l u i s h mineral has about the colour o f c o v e l l i t e . Irregular feathery-edged areas of a s l i g h t l y darker, brownish mineral are developed In the c o v e l l i t e ( ? ) . By oblique i l l u m i n a t i o n i t seems to show a f a i n t brownish red i n t e r n a l r e f l e c t i o n . Its colour, by r e f l e c t e d l i g h t , however, does not seem to quite cheek with that of limonite. IIo p a r t i c u l a r mineral of t h i s group shows any marked r e l i e f so a l l must be of the same order of hardness. These minerals are shown on Plate XVIII. Bornite (?) was the f i r s t to be deposited. This i s cut by d i s t i n c t v e i n l e t s of chaleopyrite. Chaleopyrite also occurs as laths or needles within the born-i t e ( ? ) . This mode of occurrence may indicate, according to lindgren, e i t h e r replacement or unmixing. "'Lindg'r'en', TTIneral Deposits, 1JZti'^fTdlJl In the present case, then, chaleopyrite i s i n part younger than the bornite (?) and i n part either younger or conteraporaneous. The c o v e l l i t e replaces bornite (?) about the p e r i -phery of the grains© Replacement v e i n l e t s from the c o v e l l i t e -border may i s o l a t e areas of bornite ana f i n a l l y leave a few i r r e g u l a r l y rounded remnants of bornite i n covellite© Chalcopyrite needles r a r e l y cut the covellite© A few project into i t from the bornite but t h i s r e l a t i o n i s probably due to delayed replacement of chalcopyrite by covellite© The bornite has been p r e f e r e n t i a l l y replaced© • Areas of a somewhat darker grayish-brown mineral replace the c o v e l l i t e with a feathery embaying border. A l l are replaced by barite gangue except the super-gene c o v e l l i t e (?) and i t s replacing mineral. Chalcopyrite i s common to the: above two types of mineralization© In the absence of evidence to the contrary i t must be assumed that we have but one generation of chalcopyrite. Correlating, we see that bornite (?) was deposited a f t e r (probably) pyrite and before barite.. I f the remaining minerals ( c o v e l l i t e (?) and limonite (?)) are supergene, and have metasoraatically replaced the bornite, they are probably younger than the b a r i t e , rfhe time relations of these minerals are shown grap h i c a l l y i n Plate XX. Etch Reactions Etch tests were made on grains of pure selected mineral and are compared with etch t e s t s given for tetrahedrite -47-i n standard works on the subject. The material used showed no metallic minerals other than the Schwatzite. Irregular cracks and p i t s were common on the polished surfaces. As the reagents were applied only to the mineral under examination;, r e s u l t s were not influenced by galvanic action. , Consistent technique was employed throughout. The specimen was polished on the rouge block immediately before applying the reagent.. The reagent was l e f t i n contact with the mineral f o r one minute, then washed o f f with a stream of water from:the tap. Surplus water was blown away and the sur-face allowed to dry. The e f f e c t of the reaction was then observed. The specimen was then .-re-poll shed, on the rouge block preparatory to the next t e s t . A l l reactions were checked by r e p e t i t i o n , using other grains. The following t e s t s , then, were obtained f o r schwatzite. They check very c l o s e l y with those published f o r tet r a h e d r i t e , and, i n themselves w i l l not determine t h i s v a r i e t y of tetrahedrite. -48-As determined f o r schwatzite as given f o r Tetrahedrite, i n Farnham | Davy & Farnham Short J-Hunt HNCL cone. > •. •.: . irridescence to brovm s t a i n fumes t a r n i s h slowly stains brown neg.- fumes tarnish fume s t a r -nish ESO. 1 : 1 very s l i g h t brown s t a i n i HOI 1 : 1 neg. neg*. • neg. KC!f 2 0 % neg. to very •sli g h t brown s t a i n some-t imes stains f a i n t neg. F e C l , 2 0 f. 'J • neg. neg. neg. • neg. neg. HgClg sat.? neg. neg. neg. Aqua Fcegia neg. fumes may tarni s h s l i g h t l y The mercurial mineral appears to show a more def i n i t e reaction to n i t r i c acid than the ordinary v a r i e t i e s . Physical Properties The physical properties of t h i s tetrahedrite show a d i s t i n c t v a r i a t i o n from those of the normal mineral --49-presumably due to the mercury content., Typical tetrahedrite shows a smooth conchoidal fracture and a high, almost splendent, l u s t r e . In other varis t i e s the fracture i s somewhat uneven - almost hackly and the very high .lustre not apparent. On examining the mercurial mineral i t i s at once apparent that i t has not the appearance of the normal material. It has a s i l v e r y white colour and a d i s t i n c t l y uneven frac t u r e . Under the hand lens there i s seei to be a decided tendency towards conchoidal fracture i n i n d i v i d u a l grains. In the accompanying table, the physical properties of t h i s mineral are tabulated against those given i n Dana. 'pan&J~^ET§,T^^S^a%^' b'f~B^^ "~~~~r """37"! Dana l i s t s an analysis of schwatzite carrying 5°57 percent mercury with a s p e c i f i c gravity of 4 . 7 3 3 * I& the present material we have 6 . i f . mercury and a s p e c i f i c gravity of 4 . 8 3 . ; - 5 0 -Comparison of Physical Properties of Tetrahedrite and Schwatzite AS i n Jana Schwatzite . i Windermere, B.C. isometric tetrahedral also massive; granular, coarse or f i n e ; compact» ma s s i ve granular cleavage none cleavage none fracture subconehoidal to uneven uneven, subconchoidal i n d e t a i l rather b r i t t l e l e s s b r i t t l e than material with smooth fracture. l u s t r e m e t a l l i c , often splendent, colour f l i n t gray to iron black, m e t a l l i c , not splen-dent streak l i k e colour, sometimes i n c l i n i n g to brown and cherry-red powder dark reddish brown H a 3 - 4 medium hardness G - 4 . 4-3«l Schwatzite G s 4 . 7 3 3 - 5 . 3 . 5 6 (average 5°08l) G = 4 . 8 3 - 5 1 -AMALYSIS AID FORMULA Analyses/ of course s had. to he made i n presence of mercury. To check the eff e c t of mercury on copper assays by the Fluoride-Iodide method, a series of synthetic samples were made up with known amounts of copper, and assayed. Pure copper f o i l i n the presence of ferrous ammonium sulphate was used to standardize the standard solu t i o n of thiosulphate. Synthetic samples of ore were made up with copper and antimony present i n the proportions found i n the preliminary assays. To one set mercury was added. In another i t was added i n the proportion found i n the natural ore and i n other assays i t was added i n two, three and four times the natural percentage. The r e s u l t s of assays on these show a progressive small interference of mercury on the copper determinations. The e f f e c t , however, of b percent mercury i s but s l i g h t . In th i s ease the value of the thiosulphate solution i n terms of copper was.obtained by t i t r a t i o n o f the synthetic sample con-t a i n i n g b percent Eg, and the e f f e c t of the interference thus compensated f o r . The Analysis gave -Copper 53» 8 S i l v e r .2 Lead Zinc 4.0 Insol. 4.9 - 5 2 -Iron 1,0 antimony . 23.4 Arsenic 1.4 Sulphur 22.1 Mercury 6.1 Taking out the insoluble and correcting to 100 percent, we have • -. Copper 36.8 S i l v e r . . 2 Zinc 4 . 3 Iron Antimony 2 5 . 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 material was available f o r check analyses. The low t o t a l i s probable to be accounted for as follows -1. fhe presence of copper carbonates, conspicuous i the ore. 2. Barite gangue entering into the assayed material The gangue i s dominantly b a r i t e . Neither Ba nor SO^ 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. Dividing by atomic weights, we get the atomic proper-tions -Copper .373 S i l v e r a002 Zinc .066 Iron .021 Ant imony .211 Arsenic .020 Sulphur »750 Mercury. .ojo Iron was deducted as chaleopyrite impurity. Elements of corresponding valence were grouped. We have -Copper ) S i l v e r ) Zinc ^ Mercury j Ant iraony ) ,10 ,23 Arsenic Sulphur .71 These proportions correspond to the formula, 3 (Cu,Ag) 2 S, (Hg.Zn)S . (As,Sb) 2 S^ This i s the usual formula f o r the other samples of tetrahedrite studied. Here, however, mercury replaces zinc i n i n d e f i n i t e proportions. -54-GOMPARISOlf WITS OTHER DEPOSITS OF WIFDERMERE DISTRICT Mercury i n tetrahedrite has not previously "been recognized i n t h i s d i s t r i c t although tetrahedrite i s a charac-t e r i s t i c mineral. 'When the presence of mercury was detected i n the mineral i t was hoped that i t might prove to be general i n the gray copper ores of the district© Specimens from several prospects i n the d i s t r i c t were made av a i l a b l e through the kindness of Dr. J.F. Walker, Geological Survey Canada. It was hoped mercury would be i d e n t i f i e d i n some of these prospects, giving a d i s t r i c t of mercurial tetrahedrite. Several methods suggested themselves for the detec-t i o n of mercury. The most'obvious method was to use the ordinary commercial assay methods on selected tetrahedrite. Specimens of ore from two prospects were large enough to permit of the use of t h i s method. Assays on tetrahedrite from the Hot Punch group, and from the S i l v e r Spray property, gave mercury n i l . These properties are located about 5 and 11 miles, respectively, to the south of the Pretty G i r l claim. Walker, J,FT; op. citVV_PP_«4F-49. Specimens from other properties consisted only of polished sections so that assay and blowpipe methods were excluded. It was hoped that the presence of mercury would give the mineral some c h a r a c t e r i s t i c etch t e s t . A careful series of etch t e s t s , run on the known mercurial tetrahedrite, gave the - 5 5 -r e s u l t s tabulated on page 48. These proved to be non-diagnos-t i c . Etch t e s t s , then, could not be used to detect mercury i n the other specimens. Hierocheraical tests 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 chaleopyrite, and t e t r a h e d r i t e , i n a quartz gangue i s the c h a r a c t e r i s t i c mineral assemblage of the d i s t r i c t . In the deposit under d i s -cussion -we have mercurial t e t r a h e d r i t e , p y r i t e , and a l i t t l e chaleopyrite, i n a barite gangue. ITeither galena nor sphaler-i t e was noted. A comparison of the mineral association shows the mercurial deposit to be unusual i n the d i s t r i c t and so de-creases the l i k e l i h o o d of mercury being found i n the t e t r a -hedrite of the other deposits - deposits of a di f f e r e n t type. This brings us to the question of genesis. GE1ES1S But l i t t l e can be said here, due to the lack of d e t a i l e d published information on the property. M i n e r a l i z a t i o n occurs as a zone, between the bedding of the shales, trending If Z$° W. This corresponds with the B.C. M i n i s t e r of Mines" ; Ann.Kept. 1898, PP» 1042 & 1Q54. ' general trend of lead-S i l v e r - Z i n c deposit s as already described. Walker, J.F.; op. c i t . • P«43. The deposit i s referred to as a "zone", following the bedding of the shales. This would suggest replacement, either selective •-56-. replacement of favourable beds or replacement by solutions out' wards from some permeable channel. Lacking detailed informa-t i o n , i t i s useless to speculate on the o r i g i n of t h i s bedding channel. A small piece of the vein wall on one of the speci-mens was suggestive of f i l l i n g , with possible subordinate replacements 'The deposit w i l l be compared with lindgren*s Meso-thermal and Epithermal deposits... It w i l l be seen to occupy an intermediate p o s i t i o n . Of Epithermal deposits lindgren 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 ^ "Arsenic and arrtimony, bismuth are common the t y p i c a l q u i c k s i l v e r deposits belong to t h i s c l a s s . t i — c o m p l e x s i l v e r sulphantimonides and sulpharsen-ides are also c h a r a c t e r i s t i c ; - - — A m o n g them are proustite, pyrargyrite, miargyrite, stephanite, polybasite, tetrahedrite and more r a r e l y enargite. "Of the gangue minerals quartz i s the most abundant, — Oalcite , dolomite, b a r i t e , and f l u o r i t e are l o c a l l y the dominant gangue minerals." , . Of Mesothermal deposits, he says: Lindgren, tf.; op. c i t . , p.599' "The p r i n c i p a l metals contained are gold, s i l v e r , copper, lead and zinc. The ore minerals are sulphides, arsenides, sulphantimonides and sulpharsenides. P y r i t e . chal-copyrite, arsenopyrite, galena, zinc blende, tetrahedrite, tennantite and native gold are the most common . — The predominating gangue mineral i s quartz, hut carbonates are also 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 barite are occasionally of importance; — if In t h i s ease we have prominent b a r i t e , the presence of mercury and the absence of galena and sphalerite; a l l against including the deposit i n the t y p i c a l Lie so thermal class. The mercury and bari t e would suggest a somewhat lower tempera-ture of deposition. P y r i t e , chaleopyrite and tetrahedrite are not very diagnostic. The ore has not t y p i c a l Bpithermal.structure. It should probably be classed as a low temperature Mesothermal deposit. Deposits of thi s type might be considered as forming a connecting l i n k between normal Epit hernial mercury deposits with cinnabar and the t y p i c a l s i l v e r - l e a d - z i n c Mesothermal deposits. In t h i s connection Beyschlag, Vogt, and Erusch say; Be3rsinn!aliT «" 0~re~DepcTsTts, 1916, p«b57« "Such occurrences (mercurial tetrahedrite) i n general, however, are rare ana of l i t t l e importance, so that i t may be said that a sharp l i n e exists between the lead-silver-" zinc lodes and the qu i c k s i l v e r lodes proper." SUMMARY AID COHCLtTSlOHS A deposit of mercurial tetrahedrite occurs about 18 miles west of the town of Windermere, B.0. -58-The mercurial content of the ore has not previously been recognized. lundy, J .A. , Pres. lHorTE^Co~o"te"hay~Sines ltd.'^personal 1 'eVramuhi-. : cation. Mercurial tetrahedrite is. the dominant me t a l l i c . P y r i t e and chalcopyrite are the other important sulphides. The gangue i s b a r i t e . This mineral association i s unusual In the Windermere d i s t r i c t . It probably indicates deposition at a temperature below that of the normal s i l v e r - l e a d - z i n c deposits of the d i s t r i c t . The selected mineral was analysed and the following formula suggested. 3 [(Cu,Ag) 2 S , (Kg , Z n ) s ] . (As,Sb) g S • The physical properties d i f f e r somewhat from those of t y p i c a l t e t r a h e d r i t e , notably those of fracture, b r i t t l e n e s s , colour, l u s t r e and streak. The etch reactions do not d i f f e r materially from those of the normal tetr a h e d r i t e . The economic importance of the discovery of mercury i n t h i s deposit cannot•be estimated from the meagre information at hand. A c c e s s i b i l i t y , tonnage, average mercury content, and treatment, are factors to be considered. CHAPTER I f ANALYSES & FORlB-lAl. ~59~ DATA Assays were made of pure tetrahedrite from each specimen, as described above* The uncorrected assay results are shown below. dum-ber Cu Ag Pb Zn Insole Sb As S Eg Total 1 53.8 — 4 ° ° 4.9 1.0 23.4 1 .4 22.1 6.1 96.9 2 35-7 ••5 « 5o4 5.3 V 21.0 3 . 7 23.6 OR R / y-eO 3 11.0 4 . 8 12 .5 .4 20.4 1.3 20.6 93 = 5 4 32.8 4 . 8 4 . 3 2.4 2.1 24 .2 2.0 22.5 95.1 5 3.^  « 2 5 . 2 • ^  4.8 I f .8 •& 22. 5 93.2 6 3 6 . 5 - 3«7 3*4 1.4 22 .5 * A 24 .9 98.5 12 . 35*7 2.9 4.8 2 .2 18.6 6.0 24.9 96.3 17 29.8 7 . 8 4 . 8 2.8 3 . 7 I 8 . 5 4 , 6 23.5 95.5 18 3 7 . 4 .4 1.6 1.2 23o3 3.8 24 .5 97.6 20 31*2 6.3 _ 6.3 12.8 1.0 23.9 1.4 2 3 . 7 96.6 These analyses show an appreciable "Insoluble" content. Further, the t o t a l s f a l l short of 100 percent. For the purposes of ca l c u l a t i o n s , the "Insoluble" was removed and the percentages adjusted to give a t o t a l of 100 percent, as shown below. - 6 o -Bum™ ber Cu Ag Zn Eg ?e Sb As Uncor-rected S t o t a l l e s s Insol. Total 1 36.8 » 2 4 . 3 6,6 1.2 25.4 1.5 24 .0 92.0 100.0 2 3 ? 0 *6 6.0 . 6 23. 2 26.0 90.5 100.0 3 27.8 13.6 5«9 •5 25.2 1.6 25.4 81.0 100.0 4 35*4 5c 2 4 . 6 2.5 26.1 2.1 24 .3 92.7 100.0 20.6 27.1 1.5 5*1 21» 3 . 2 24.2 93.0 100.0 6 38 «4 .•5 6 .0 1.5 23«7 3c7 '26.2 95.1 100.0 12 37.5 3»0 5«1 2.5 19-6 6.3 26.2 95*1 100.0 17 3 2 . 2 8*4 5.2 • 5.9 20*0 5.0 •25.3 92.'7 100.0 18 38.9 .'5 5 .6 1.2 '24.3 4 . 0 2 5 . 5 96.O 100.0 20 3>«3 6.7 6.7 1.0 25., <> *•» ^ " 1.5 '25.5 93.8 100.0 A tomic proportions were caleul ated i n each case 5 by div i d i n g by the atomic weight-s.0 Atomic weights used were is Copper 64 S i l v e r 108 Zinc 65.^ 1. Mercury 201 Iron 56 Antimony 126 Arsenic 75 Sulphur 32 A l l c a l c u l a t i o n s have been made on a ten inch slide r u l e , greater accuracy being meaningless. The atomic proportions are shown below, together - 6 1 -w i t h t h e i r o n minerals known to be present as Impurities, num-ber Cu Ag Zn Hg Fe Sb As s Iron Impurities 1 .575 ,002 .0.66 .030 .021 .020 .750 Chaleopyrite 2 .617 .006 .092 .011 ..193 .054 , .812 3 .434 • 12 6 «090 .009 .210 , .021 «793 4 .553 .048 .070 .041 .217 .028 «759 chaleopyrite 5 . 251 .023 .091 .177 .003 .755 chaleopyrite 6 *600 .005 .092 .027 .197 .049 . .818 12 .586 .028 .078 .041 .163 .084 , .818 pyrite & chaleopyrite 17 . 5 0 3 .084 .079 .070 -167 . .067 = 791 pyrite 18 .608 .005 . 0 8 6 .021 .202 .053 .797 20 .521 • 062 .102 .018 .213 .020 . 7/1 chaleopyrite Iron was taken to be present only as an impurity* Where Iron minerals were not noted i n the polished sections, the i r o n was assumed to be present as p y r i t e . This assumption was necessary f o r specimens 2, 3* 6 and 18j assaying (uncorrected) . 6 , .4, 1.4 and 1.2 percent iron respectively. The assumption i s j u s t i f i a b l e , i n view of the low percentages. The atomic proportions were then corrected, i r o n being taken out as p y r i t e or chaleopyrite impurities, together with the combined copper and sulphur. The f i g u r e s , corrected for the impurities, are given below. -62-Hum-b e r . ^u Zn Hg Fe 030 i = 554 .002 ,066 2 o6l7 .006 .092 3 .434 .126 .090 4 • ,512 .048 .070 5 . 231 .231 .023 6 0 6 O O .005 .092 12 .566 .028 .078 17 .503 .084 .079 18 .608 .005 .086 20 «503 .062 . 10 2 Sb As s .211 .020 .708 = 193 .054 »790 .210 .021 *775 .217 .028 .677 -177 .003 «573 .197 .049 . 7 64 .163 .084 .736 .167 .067 . 651 .202 .053 .755 .213 .020 .755 FORMULAE Formulae, f i t t e d to these atomic proportions f a l l into three groups. S i l v e r , mercury and zinc are assumed to "replace" copper under valence control. Arsenic i s taken as replacing antimony. Below are shown the atomic proportions, corrected f o r impurities, grouped, and given to two figures, and the corresponding approximate formulae. - 6 3 -o 12 17 18 o 62 .56 ,56 ,48 . 61 • 59 59 61 •09 .09 • 07 .02 ,09 .08 .08 ,09 25 •23 22 .18 25 .25 . 2 3 -2.5 •79 *77 .76 = 57 -76 • 74 .65 75 3[( Cu,Ag) 2S ,(Hg, Zn) sj. (As,Sb) 2 S lo[(Gu >Ag) 2S,Zns1 . 3(As 5Sb), 2 ^ l 0 L ( 0 u t A g ) 2 S ? Z n s ] . 5 ( A s , 3 b ) ^ 8 [ ( C u y A g ) P S t Z n s ] . 3 ( A s , S b ) approx 2 S 3 approx l o [ ( C u t A g ) 2 S , Z n s | . 3 ( A s 8 S b ) £ S ^ 3 [(Cu,Ag) 2 S , Z n s ] . ( A s , S b ) £ S 3 ( C u , A g ) 2 S , Z n s ] . ( A s , S b ) 2 S ^ 3 ( C a , A g ) S , Z n S * ( A s , S b ) £ S ^ v e r y 3 (Cu 8Ag) 2S, Z n s ] .(As, i b ) approx. 2 S 3 20 56 10 23 *75 10 [(Cu sAg) >] . 3(As,Sb) ?S 7 . 3 A l l analyses, with the exception of numbers 4 ana 17, f i t f a i r l y c l o s e l y one or the other of the two formulae: 1) lo[(Cu,Ag) 2S,Zns] . 3(As,Sb) 2S 5 2) 9[( Cu,Ag) £S,Znsj. 3(As,Sb) 2S 3 or ^[(Cu.Ag) S.Zns]. ( A S . S D ) 2 3 ?rom these analyses, tetrahedrite would appear to form an isomorphous series© The analysis of sample 4 f i t s approximately the formula 8 [( Cu,Ag)'2S , Z n s J © ^ U s . S b ) ^ w h i c h again f i t s into the isomorphous se r i e s . . Copper and s i l v e r replace one another i n a l l propor-tions from 37-4 percent copper and ©4 percent s i l v e r to 1?.2 percent copper and 25©2 percent silver© Zinc, as zinc sulphide, replaces the ( C u , A g ) m o l e -cule i n variable proportions, the zinc forming up to 6.5 percent of the mineral, by weight. In a l l analyses, except one, zinc was present as 4 percent or over. As no zinc was found i n the polished sections of the material studied under the microscope, i t i s l o g i c a l to assume that i t should be included In the formula© In the mercurial tetrahedrite (Specimen Ho. 1) mercury and zinc, having the same valence, have been written a replacing each other i n i n d e f i n i t e proportions. This (Hg,Zn)S molecule i n turn replaces, again i n i n d e f i n i t e proportions, the (Cu,Ag) 2S molecule © Specimen 5 i s remarkable for i t s high s i l v e r content of 25©2 percent. It f i t s , quite clo s e l y , one of the same two general formulae. Formulae and S i l v e r Content I f we study these formulae i n r e l a t i o n to s i l v e r content, and omit those of D u m b e rs 4 and 17, both of which are approximations, we see that the following r e l a t i o n holds: l o w - s i l v e r tetrahedrite, formula: 3 [ ( C u f A g ) 2 S,Zns] . ( A S S S D ) 2 h i g h - s i l v e r tetrahedrite, formula; 10 [(Cu $Ag) 2 S,Zns] . 3(As,So) ( dumber 2 appears to he an exception to t h i s neralization» ' C m P T I R T SHI S1I.V33B. C G N O T T , -b6~ OUTXIHE OF CHAPTER The s i l v e r content of t e t r a h e d r i t e i s c l e a r l y of major importance. In t h i s Chapter i t w i l l be considered i n connection w i t h ; I- geographical l o c a t i o n o f deposits s t u d i e d . 2. the mineral a s s o c i a t i o n of these d e p o s i t s . 5« the type of d e p o s i t , i . e . t r u e . f i s s u r e or replace-ment. 4.. the. age of the 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 galena. 5» p h y s i c a l p r o p e r t i e s . 6. etch t e s t s . LOCALITY Specimens 2, 6 and 18 are from adjacent areas i n Cariboo and Quesnel Mining 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 are from the same d e p o s i t . Uncorrected assays of the t e t r a h e d r i t e from these de p o s i t s g i v e a s i l v e r content of . 5 5 , . 5 and .45 percent, r e s p e c t i v e l y . These depo s i t s w i l l be considered 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 three specimens ( 2 , 6 and 18) with very low s i l v e r are of simple mineral a s s o c i a t i o n - quarts and t e t r a -d r i t e o n l y . The next lowest s i l v e r assay was from Specimen Ho* 12 - al s o a simple ore of quartz and t e t r a h e d r i t e . Here, however, very minor q u a n t i t i e s of other m i n e r a l s , including galena, appeared. With the exc e p t i o n of Specimen Ko. 1, a l l other ores c a r r y at l e a s t 4.8 percent s i l v e r , and with t h i s marked i n -crease i n s i l v e r content, we have a p a r a l l e l marked increase 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 only other m e t a l l i c mineral - common to a l l these i s galena. Therefore, i t might be concluded that these quartz-t e t r a h e d r i t e o r e s , when f r e e from galena, are very poor i n s i l v e r and, f u r t h e r , that the appearance of galena accounts f o r , or i s i n some way connected w i t h , the s i l v e r content of the t e t r a h e d r i t e . .Further work,on the s i l v e r content of the galena of these ores, would be of i n t e r e s t . Assays on other ores, along s i m i l a r l i n e s , w i l l be needed to e s t a b l i s h t h i s r e l a t i o n . Should i t be e s t a b l i s h e d , i t would be of the utmost p r a c t i c a l importance. The p o s s i b i l i t y of e s t a b l i s h i n g some such r e l a t i o n -s h i p f o r the g o l d content at once suggests i t s e l f . Gold determinations were not made i n the course of t h i s work. However, i n connection w i t h Specimen JTo. .18, i t has been s t a t e d that "the assays show that the m i n e r a l i z e d rock does not ca r r y appreciable values i n gold and s i l v e r . " This suggests that these simple 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 both gold and s i l v e r . I f t h i s i s tore, they can he of l i t t l e economic importance. TYPE OF DEPOSIT G e n e r a l l y , 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 percentage of s i l v e r than that o f replacement deposits, warren, II.?.; personal c o ^ u n T c a t i nr)7~ ~—' -A l l d e p o s i t s considered here probably belong 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 hold i n t h i s case. Four of the t e n samples assayed c a r r i e d percent s i l v e r or l e s s . One of these, the m e r c u r i a l mineral discussed i n Chapter 111, i s unusual 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 s u r p r i s i n g . The. o t h e r s , Specimens 2, 6 and 18, are the simple t e t r a h e d r i t e - q u a r t z ores mentioned under KIFSRAL ASSOCIATION. They are low i n s i l v e r and yet are undoubtedly from f i s s u r e v e i n s . RELATIVE AGE OF GALSTTA AI?D TETRAHEDRITE Here, again, f u r t h e r work must be done on the s i l v e r content of the a s s o c i a t e d galena. I t might then 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 minerals and the d i s t r i b u t i o n of 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 ores i n t h i s group are those -69-of Kmttbers 3 , 4, 5 3 17 and 20. -The age of the galena i n Ho. 5 could not be determined. In the remaining f o u r , galena was, as n e a r l y as could be determined, l a t e r than the t e t r a h e d r i t e . In a l l these we have 4 . 8 percent s i l v e r , or over. As pointed out above, i t appears, from a general survey of the a n a l y s e s , that there i s some close connection be-tween the presence of galena and the s i l v e r content of the t e t r a h e d r i t e . And yet galena seems to have formed l a t e r than the t e t r a h e d r i t e . This point r e q u i r e s 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 considered i n r e l a t i o n t o s i l v e r content are: l ) streak • 2) s p e c i f i c g r a v i t y 3) f r a c t u r e and. l u s t r e . Streak. A l l specimens gave a black or very dark brown streak on the streak 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 brown-i s h and r e d d i s h shades can be observed to advantage. Two methods were used ixi comparing the streaks and i n each case the samples were arranged i n order, according to the s t r e a k , from reddish brown to d u l l b l a c k , and numbered - 7 0 -e o n s e c u t i v e l y . Thus the powder at the r e d d i s h end of the s c a l e was g i v e n the number 1, and that at the black end, the number 10. The f i r s t method c o n s i s t e d i n comparing the shade of the very f i n e powder which adhered to the g l a s s w a l l s of the v i a l s i n which the pure, powdered mineral was kept p r i o r to assay. The second method was to spread a uni f o r m l y t h i n l a y e r of each powdered specimen on a sheet of white paper, i n each case they were arranged i n order according to shade, and numbered 1 to 1 0 . . The r e s u l t s are g i v e n below: j Specimen number Stream number j Streak number (on g l a s s ) (on paper) 6 1 (dark choeo-•• • .,„ 1 l a t e brnwn'l 2 « . • 3 4 3 8 6 4 9 7 5 10 ( d u l l black) [ 10 ( d u l l brownis ' black) j 6 J 4 9 12 5 • 4- : 1 2 ' J 17 7 8 18 2 20 1 ( r e d d i s h brown) 3 J As comparison was made by eye onl y , these r e s u l t s probably would not be d u p l i c a t e d i n another t r i a l . The above t a b l e w i l l be rearranged to permit a more ready comparison of s i l v e r content and streak number. The s i l v e r content w i l l be i n c l u d e d i n the ta b l e and specimens arranged i n order of s i l v e r content, beginning w i t h the lowest, Specimen number S i l v e r content Streak • number (on g l a s s ) Streak-number 1 ( on pape r) Average streak numhe r 1 1 6 i *-*• *•» x | 3 18 1 .45 2 5 1 ~ 3 1 b *5 4 9 ••it'-1 '-' 7 2 • .' -55 3 . : 4 „ / I "Z I 9 I 12 2.9 _ 3 ^ 3 4 •4.8 | _ ? • •8 20 • ~ — : — ~ 6.35 3 2 1 17 7.8 7 8 7 3 11.0 8 — : — |-6 7 5 j 3 ® —> 10 10 10 I t i s to be observed t h a t ; 1. The f i v e specimens showing a s i l v e r content of 2.9 per-cent or under have, w i t h one exception, an average streak number of 3« 2 . The four specimens showing a s i l v e r content of from 4 .8 to 11.0 percent have, w i t h one exception, an average str e a k number of 7 or 8 . 3 . The remaining specimen, with a s i l v e r content of 25»2 percent, has an average s t r e a k number of 10. Therefore, we may conclude, t h a t , the da rice r the streak the g r e a t e r the s i l v e r content. This c o n c l u s i o n i s i n d i r e c t c o n t r a d i c t i o n to Dana, who, under " F r e i b e r g i t e " s t a t e s "streak o f t e n r e d d i s h " . Dana,' E.S.: "The" System' of" 1-lineral"ogy /""fath^'Edit'i^^nror9~b7 p.I38, T h i s c o n c l u s i o n i s probably .of l i t t l e p r a c t i c a l importance as the d i f f e r e n c e s i n the streak are much too s l i g h t to permit of more than a doubtful comparison w i t h specimens of known s i l v e r content. S t i l l , at times, i n f i e l d work, such a method of e s t i m a t i n g the s i l v e r content might be u s e f u l . S p e c i f i c G r a v i t y . S p e c i f i c g r a v i t y determinations were made f o r s i x specimens. They were c o r r e c t e d f o r " I n s o l u b l e " content, taken as s i l i c a . The c o r r e c t e d r e s u l t s , arranged i n order of t h e i r s i l v e r content, are g i v e n below; Specimen number percent s i l v e r • s p e c i f i c g r a v i t y 1 . 2 ( 6 . 1 mer-cury) • • 4 . 8 3 6 4.43 • 4 4 . 8 4 . 5 7 2 0 6 . 3 4 . 6 7 5 2 5 . 2 4 . 7 1 For numbers 6 , 4, 2 0 and 5 the s p e c i f i c g r a v i t y •73- i4 v a r i e s d i r e c t l y as the s i l v e r content. The mercury content o: number 1 accounts f o r i t s high s p e c i f i c g r a v i t y . F r a cture and L u s t r e . Specimens were arranged side by s i d e , i n order of 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 systematic s e r i e s of etch t e s t s were made on pure t e t r a h e d r i t e from each specimen. As the s i l v e r content v a r i e d up to 25.2 percent i t was hoped that the 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 etch r e a c t i o n s . A s t a n d a r d i z e d technique, was employed throughout these t e s t s . 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 of reagents. I t was p o l i s h e d on rouged chamois be-tween each t e s t . Reagents were allowed to remain on the s p e c i -men f o r one minute and. then washed with a, ge n t l e stream of water. Surplus water 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 , etched and unetehed por-t i o n s i n contact 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 etch t e a t s , from those g i v e n i n standard works, were noted. Concentrated n i t r i c a c i d normally l e f t a l i g h t brown s t a i n . Reactions to other reagents were p r a c t i -c a l l y negative. CHAPTER VI smsimr ked o o i f o i u s i G i s - 7 4 -The r e s u l t s of t h i s paper are summarized below. ANALYSES. A l l analyses f a l l a p p r e c i a b l y below 100 percent. ACCURACY. The percentages g i v e n are probably c o r r e c t . The low t o t a l s are s a t i s f a c t o r i l y e x plained. S u f f i c i e n t checking has been done to j u s t i f y confidence i n the r e s u l t s . HERCURIAX TETRAHHDRITB. T e t r a h e d r i t e from North Kootenay Mines , l t d . , Win-dermere, assayed 6.1 percent mercury. M e r c u r i a l t e t r a h e d r i t e , or s c h w a t z i t e , has not p r e v i o u s l y been recognized In 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 are not those of normal t e t r a h e d r i t e . The formula may be w r i t t e n 3[(0u.,Afi) 2 S f (Hg,Zn)s], ( A s , S b ) 2 S, 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 of f r e i b e r g i t e c a r r y i n g over 25 percent s i l v e r . Etch r e a c t i o n s are not d i a g n o s t i c . Nor can f r a c t u r e or l u s t r e be c o r r e l a t e d with the.high s i l v e r content. The formula may be w r i t t e n " 7 5 -l o [ ( C u t A g ) 2 3,Zns]. 3 ( A s , S b ) 2 3^ An a n a l y s i s of the a s s o c i a t e d galena would be i n t e r e s t i n g . 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 unassoela-ted with other minerals and we f i n d a simple t e t r a h e d r i t e -quartz ore. 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 IF SILVER. • As the s i l v e r content of the t e t r a h e d r i t e i n c r e a s e s , the ores become more complex. The increase i s c l o s e l y r e l a t e d to the galena content. GALENA-SILVER RELATIONS. F u r t h e r work i s required to show whether or not there i s any p a r a l l e l r e l a t i o n i n the s i l v e r content of the gale n a , or. ordex'ly d i s t r i b u t i o n of the s i l v e r between galena and t e t r a h e d r i t e . TYPE OF DEPOSIT.. A l l ores examined are from f i s s u r e v e i n s , as con-t r a s t e d to true replacement d e p o s i t s . The s i l v e r content of the t e t r a h e d r i t e of these v e i n deposits v a r i e s w i d e l y , up to 25 percent. The a s s o c i a t i o n of t e t r a h e d r i t e with galena, and other m i n e r a l s , i n quartz v e i n s , favours the formation of - 7 6 -h i g h l y 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 . STREAK AND SILVER CONTENT. The s t r e a k s vary from dark r e d d i s h brown to d u l l b l a c k , low s i l v e r content g i v e s a r e d d i s h streak; high s i l v e r content r e s u l t s i n a d u l l black streak. SPECIFIC GRAVITY AND SILVER CONTENT. The s p e c i f i c g r a v i t y of t e t r a h e d r i t e tends to i n -crease as the s i l v e r content. 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. Frac t u r e and l u s t r e vary w i t h the source of the t e t r a h e d r i t e . No r e l a t i o n between the v a r i a t i o n of these p h y s i c a l p r o p e r t i e s and the s i l v e r content was noted. FORMULAE T e t r a h e d r i t e , as s t u d i e d , appears to vary i n composition, forming an isomorphous s e r i e s . The formulae are; The composition of 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 corresponds t o that of the f i r s t formula. PLATE 21 5> PEOTOMIOROGRAPHIC SET UP - 7 7 -A few d e t a i l s of technique are appended. This i s j u s t i f i e d only i n s o f a r as d e t a i l s of 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 apparatus , not always the most s u i t a b l e , has had to be used. The a c t u a l technique evolved f o r t h i s apparatus may be of i n t e r e s t to those working along s i m i l a r l i n e s i n the f u t u r e . , Technique, j u s t i f y i n g mention here, i s that developed f o r : 1. P r e p a r a t i o n of dammar gum and mounting mineral s p e c i -mens t h e r e i n . 2.o Photomicrography. • . MWim SECTIONS Where i t was necessary to p o l i s h small pieces of ore, or where i t was d e s i r a b l e , because of the saving of time i n g r i n d i n g , to prepare s e c t i o n s under one h a l f inch i n diameter, i t was found convenient to use a gum mount of the f o l l o w i n g composition. Composition Dammar Gum ~—~- 3 parts —»—-•- 150 grams S h e l l a c (lemon)- Z p a r t s — - — — 100 grams Turpentine (pure) 1 part — 5 0 grams P r e p a r a t i o n of Stock Gum. The gum i s prepared, as described belcw, poured and cooled, broken to a convenient s i z e , and kept to be remelted - 7 8 -and used as required© In t h i s work, about 300 grams was prepared at a time© The dammar gum i s thoroughly melted i n an aluminum or enameled saucepan© S h e l l a c f l a k e s are added g r a d u a l l y with c o n t i n u a l stirring© Turpentine i s added as r a p i d l y as possible© The mixture I s s t i r r e d as v i g o r o u s l y as p o s s i b l e , care being necessary to prevent the turpentine t a k i n g f i r e . The mixture must be kept q u i t e hot during t h i s a d d i t i o n . When a l l the turpentine has been s t i r r e d i n , the gum i s q u i c k l y poured on a w e l l o i l e d sheet o f t i n and allowed to c o o l . 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 ready to be remelted and used i n the mount-ing of specimens as re q u i r e d * Mounting the Specimen. Brass r i n g s , s e c t i o n s cut from brass t u b i n g j were used as moulds. Dimensions of the moulds may vary from f- x is i n c h to Ig- x •§• i n c h * In use» these are 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© The gum i s melted, and heated t i l l q u i t e f l u i d . A t h i n l a y e r of gum i s q u i c k l y poured i n t o each mould, the mineral specimen or specimens q u i c k l y pressed i n t o t h i s , and the mould then f i l l e d w i t h the hot gum. With r a p i d and accurate m a n i p u l a t i o n , s i x or eig h t s e c t i o n s can r e a d i l y be mounted at one time. Any melted gum, not poured, should be discarded. I t cannot be remelted and used. Where small fragments of mineral had to be mounted, these were arranged as r e q u i r e d i n the bottom o f the mould, on the o i l e d t i n , and very hot gum poured i n to f i l l the mould© Shis procedure was found more s a t i s f a c t o r y , f o r small g r a i n s , than that described above. O i l e d paper i n the moulds was found unnecessary. G r i n d i n g and P o l i s h i n g . The mounted specimens are removed from the brass moulds and ground and p o l i s h e d as u s u a l . The mounts, a f t e r standing s e v e r a l months, tend to 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 of ores through the meta l l o g r a p h i c microscope 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 photographic processes. 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 of view of the microscope, a camera bellows superimposed on the eyepiece, and the r e s u l t a n t image sharply focussed by means of the micrometer f o c u s s i n g screw of the microscope. A photographic p l a t e i s s u b s t i t u t e d f o r the fo c u s s i n g screen, g i v e n a predetermined exposure, and developed and p r i n t e d as u s u a l . Apparatus. The photographic set-up, using equipment a v a i l a b l e at 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 accompany-in g 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 adopter, of c o n c e n t r i c metal r i n g s , i s s l i p p e d over the eyepiece of the microscope and the camera bellows lower to f i t Into t h i s adopter*. The are 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 source of i l l u m i n a t i o n . I t i s set up so as to p r o j e c t a h o r i z o n t a l beam i n t o the v e r t i c a l i l l u m i n a -t o r of the microscope. The are was found to be quite s t a b l e f o r the short exposure times r e q u i r e d . For accurate t i m i n g of exposures, the s h u t t e r of the copying camera, minus l e n s e s , i s f i x e d i n the beam of the lamp as shown. l i g h t f i l t e r s , when used, are placed over the microscope eyepiece, w i t h i n the camera bellows. Bausch and Lomb microscope 1J2416 was used. Photographic M a t e r i a l . Wratten and Wainwright Panchromatic p l a t e s , 3i- x 4i-inch e s , were used e x c l u s i v e l y . F i l t e r s , from a set of Wratten "M" f i l t e r s , were used, as r e q u i r e d , to inc r e a s e the contrast between the impor-tant m i n e r a l s . These f i l t e r s n e c e s s i t a t e the use of panchro-matic p l a t e s , as above. P r e p a r a t i o n f o r Exposure. In g e n e r a l , when a c l e a r , sharp, image appears on the f o c u s s i n g screen, the apparatus i s i n adjustment© I t i s then simply a matter of c o r r e c t exposure and development. The area to be photographed must f i r s t be l o c a t e d , using the microscope as u s u a l . Some source of i l l u m i n a t i o n other than the are 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 used, the arc lamp, s h u t t e r and camera bellows are set up as shown, i n P l a t e XXI « Adjustments are now made with the s h u t t e r mechanism i n the l i g h t beam, set at r,T,s, and s h u t t e r and diaphragm wide open. 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-justment, on both'the 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 to g i v e a b r i g h t , uniform f i e l d on the ground g l a s s . The camera bel l o w s are a d j u s t e d so as to g i v e the r e q u i r e d s i z e of image. This i s best made somewhat l a r g e r than r e q u i r e d i n the f i n a l p r i n t , and masked to the r e q u i r e d s i z e i n the p r i n t i n g . The image i s s h a r p l y focussed, the point of p e r f e c t focus being determined w i t h the a i d of a l e n s . V/ith the microscope and o b j e c t i v e s a v a i l a b l e , when using 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 impossible to o b t a i n sharp focus over the f u l l f i e l d . I n such eases the area of g r e a t e s t importance i s placed i n the centre of the f i e l d (by u s i n g cross motion screws on the microscope stage) and focussed s h a r p l y . Excessive r e l i e f i n the s e c t i o n w i l l render sharp focus on a l l minerals impossible of attainment. Care and judgment are r e q u i r e d he r e , as the r e s u l t -ant photograph can be no more d i s t i n e t than the image which appears on the screen. Contrast can be modified by the use o f 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 at t h i s point by correct-i 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 the present, the use of l i g h t f i l -t e r s ( t o be discussed l a t e r ) , we are now ready to make the expo sure. 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 In place of the ground g l a s s , l o c k e d , and the dark s l i d e drawn out. One f i f t i e t h of a second was found to be a s u i t a b l e exposure f o r average s e c t i o n s . This exposure i s a c c u r a t e l y made w i t h the s h u t t e r mechanism i n the l i g h t beam. The p l a t e i s then ready f o r development. Development. • Development of the panchromatic p l a t e s must be done by the a i d of a green safe l i g h t . They should not be exposed, even to t h i s l i g h t , l o n g e r than a b s o l u t e l y necessary, nor should they be h e l d c l o s e to i t . Kodak ITetol Quinol developer powders were used. Completion of development was determined by i n s p e c t i o n under the green 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 of subject are j u s t v i s i b l e through the back of the p l a t e ; 2 ) when the image ceases to 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 d e n s i t y . These presuppose a f a i r l y c o r r e c t l y exposed p l a t e . I t would he more s a t i s f a c t o r y to develop these p l a t e s by the "Time and Temperature Method". This ivould i n v o l v e the d e t e r m i n a t i o n of the c o r r e c t time of development w i t h i n a range o f 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 determined develop-ment could be done i n t o t a l darkness. Other d e t a i l s of developments e t c . , have been tabu-l a t e d and f i l e d w i t h the Department of 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 of Lantern S l i d e s s but c o n t a i n many p o i n t s of use here. P r i n t i n g . S a t i s f a c t o r y p r i n t s were obtained from Photo is,rts Supply, Vancouver. Use of Contrast F i l t e r s . L i g h t f i l t e r s may have to be used to give the r e q u i r e d c o n t r a s t i n the photomicrograph. In the s e l e c t i o n of the best f i l t e r or 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 probably 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 ~~ F i l t e r s ' * . For d i s c u s s i o n of the use of f i l t e r s , the reader i s r e f e r r e d t o the above pamphlets. Both are r e a d i l y obtainable b r i e f , and i n s t r u c t i v e , and, such being the ease, no f u r t h e r d i s c u s s i o n i s r e q u i r e d here. Other general t e x t s are l i s t e d I n the Bibliography. Anderson, A.L. B a n c r o f t , M.F. Bate man, A.M. Barnard, J.E. & Welch, F.V. Becker, G.F. Notes on o x i d a t i o n of Jamesonite, Sphal~ e r i t e , and T e t r a h e d r i t e . Ec. Geol., Vol.XXYII, p.687. Slocan Map Area. Geol.Surv.Can*, Summ.Rept«, 1919K Pt.B. Notes on S i l v e r Lead Deposits of Slocan. Ec. Geol., Vol.XX, p.554. P r a c t i c a l Photomicrography. 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