"Science, Faculty of"@en . "Earth, Ocean and Atmospheric Sciences, Department of"@en . "DSpace"@en . "UBCV"@en . "Young, John W."@en . "2012-03-20T20:46:53Z"@en . "1948"@en . "Master of Applied Science - MASc"@en . "University of British Columbia"@en . "Some conceptions by Bowen regarding the processes apparently involved in the formation of ultra-basic lamprophyres have been applied to observations made on reaction-rims in the rocks of this thesis. An attempt has been made to find, in the reaction-rims surrounding basic minerals, phenomena that might indicate that reactions took place, during the time the rock was forming, between the basic minerals and an alkaline liquid. No conclusive evidence of such reactions was found but the suggestion is made that there is an unusually great development of reaction rims, especially in the more basic lamprophyres, that may be due to the effect of an alkaline liquid. Another theory by Bowen, dealing with the possible origin of ore-bearing solutions, has been amplified to present possible reasons for a close relation between lamprophyres and ore.\r\nOn the more practical side, a petrographic study of lamprophyres and associated ore has revealed an intra-mineralization age for lamprophyres whose field relations do not conclusively indicate contemporaneity with ore.\r\nA compilation from the literature, of facts pertaining to most of the lamprophyre occurrences in British Columbia, has provided interesting statistics on the geographical and geological distribution of lamprophyres, and on their relations to different types of ore. The majority of lamprophyres occur in the Rossland-Ymir-Nelson-Slocan belt, near the eastern contact of the Nelson series of batholiths, while most of the remainder are confined to the eastern contact of the Coast Range batholith. The lamprophyres of the Nelson batholith region are associated with ores which, in the Rossland, Salmo, Ymir and Nelson areas are almost half of the Pb, Zn, Ag type and in the Ainsworth-Slocan districts, entirely of the Pb, Zn, Ag type. It is in the Ainsworth-Slocan districts furthermore, that lamprophyres are perhaps most densely concentrated and show the closest time relation to ore. The lamprophyres along the east-side of the Coast Range batholith provide most of the evidence indicating that post-ore lamprophyres are predominantly associated with ores containing Au and Cu.\r\nThe conclusion seems inescapable that lamprophyres are concentrated in the two most intensely mineralized zones of the province. Furthermore, a marked affinity is shown by lamprophyres for those areas in which Pb, Zn, Ag mineralization either is prominent or, at least, is present along with other metals. These statistical facts suggest that the relation between ore and lamprophyres is not purely one of chance and they arouse our curiosity as to what reasons may exist for such a relationship."@en . "https://circle.library.ubc.ca/rest/handle/2429/41598?expand=metadata"@en . "rib Cop, J THE RELATIONSHIP BETWEEN LAMPROPHYRE PYXES AND ORE DEPOSITS WITH SPECIAL REFERENCE TO BRITISH COLUMBIA A t h e s i s submitted i n p a r t i a l f u l f i l l m e n t of the requirements f o r the degree of MASTER OF APPLIED SCIENCE In the Department of GEOLOGY AND GEOGRAPHY 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 , 1948. by JOHN W. YOUNG ACKNOWLEDGMENTS The w r i t e r wishes to acknowledge the a s s i t a n o e rendered by the f o l l o w i n g : Dr. K. DeP. Watson, Dr. W.H. 'White, Mr. W.M. Sharp, Mr. J.A. Donnan, the s t a f f s of the Pioneer and B r a l o r n e mines and the v a r i o u s f e l l o w students who communicated t o the w r i t e r any r e f e r e n c e s to lamprophyres encountered by them i n t h e i r r e a d i n g . S p e c i a l thanks are owing Dr. H. C. Gunning under whose d i r e c t i o n the work was c a r r i e d out. TABLE OP CONTENTS ABSTRACT INTRODUCTION , 1 DEFINITION AND CLASSIFICATION OF LAMPROPHYRE DYKES... 2 THEORIES AS TO THE ORIGIN OF LAMPROPHYRE ROCKS 4 Theories by Niggli 4 Theories by Grout and Reynolds 5 Theories by Spurr and Comments based on the Findings of this Thesis..... 6 Theories by Bowen 7 A POSSIBLE CONNECTION BETWEEN ORE-FORMING SOLUTIONS AND THE ALKALINE SOLUTIONS BELIEVED TO BE IMPORTANT IN THE ORIGIN OF LAMPROPHYRES.. 11 AN ATTEMPTED APPLICATION OF BOWEN'S ALKALINE SOLUTION REACTION THEORY TO THE PRESENT WORK... 16 The Evidence of Phenocrysts and Groundmass Minerals 16 Conclusions , 20 LAMPROPHYRE OCCURRENCES IN BRITISH COLUMBIA AND THEIR RELATIONS TO ORE DEPOSITS..... 21 TABLE I - THE MORE IMPORTANT FEATURES OF LAMPROPHYRE OCCURRENCES IN MINERALIZED AREAS OF B.C. 24 COMMENTARY ON THE COMPILED DATA PERTAINING TO LAMPROPHYRE OCCURRENCES IN B.C 31 The Ore-lamprophyre Relationship in Relation to the Metals Content of the Associated Ores.. 32 Geographical Distribution of Lamprophyres in B.C. and the General Character of Associated Ores 34 g&BLB Off O O B f M f S ( 8 o W \u00C2\u00A7 } A B R I E F S U M M A R Y O F T H E L A B O R A T O R Y ,WORK U N D E R T A K E N . A N D - T H E R E S U L T S O B T A I N E D 3 9 A P P E N D I X A - C O M P I L A T I O N . . 1 A B I B L I O G R A P H Y 6 2 A A P P E N D I X B - M E G A S C O P I C , P E T R O G R A P H I C A N D F I E L D - R E L A T I O N D E S C R I P T I O N S I B P H O T O M I C R O G R A P H S 66B (i) ABSTRACT Some conceptions by Bowen regarding the processes appar-ently involved in the formation of ultra-basio lamprophyres have been applied to observations made on reaction-rims in the rocks of this thesis. An attempt has been made to find, in the reaction-rims surrounding basic minerals, phenomena that might indicate that reactions took place, during the time the rock was forming, between the basic minerals and an alkaline liquid. No conclusive evidence of such reactions was found but the sug-gestion is made that there is an unusually great development of reaction rims, especially in the more basic lamprophyres* that may be due to the effect of an alkaline liquid. Another theory by Bowen, dealing with the possible origin of ore-bearing solu-tions, has been amplified to present possible reasons for a close relation between lamprophyres and ore. On the more practical side, a petrographic study of lampro phyres and associated ore has revealed an intra-mineralization age for lamprophyres whose f i e l d relations do not conclusively indicate contemporaneity with ore. A compilation from the literature, of facts pertaining to most of the lamprophyre occurrences in British Columbia, has provided interesting statistics on the geographical and geo-logical distribution of lamprophyres, and on their relations to different types of ore. The majority of lamprophyres ocour in the Rossland-Ymir^Nelson-Slooan belt, near the eastern con-( i i ) tact of the Nelson series of batholiths, while most of the re-mainder are confined to the eastern contact of the Coast Range batholith. The lamprophyres of the Nelson batholith region are associated with ores which, in the Rossland, Salmo, Ymir and Nelson areas are almost half of the Pb, Zn, Ag type and in the Ainsworth-Slocan districts, entirely of the Pb, Zn, Ag type. It is in the Ainsworth-Slocan d i s t r i c t s furthermore, that lamprophyres are perhaps most densely concentrated and show the closest time relation to ore. The lamprophyres along the east-side of the Coast Range batholith provide most of the evidence for bolieving that post-ore lamprophyres are predominantly as-sociated with ores containing Au and Cu. The conclusion seems inescapable that lamprophyres are con-centrated in the two most intensely mineralized zones of the province. Furthermore, a marked a f f i n i t y is shown by lampro-phyres for those areas in which Pb, Zn, Ag mineralization either is prominent or, at least, is present along with other metals. These s t a t i s t i c a l facts suggest that the relation between ore and lamprophyres is not purely one of chance and they arouse our curiosity as to what reasons may exist for such a relation-ship. 139\u00C2\u00B0 138\u00C2\u00B0 137\u00C2\u00B0 136\u00C2\u00B0 135\u00C2\u00B0 134\u00C2\u00B0 133\u00C2\u00B0 132\u00C2\u00B0 131 130\u00C2\u00B0 1 2 9 s 1 2 8 \u00C2\u00B0 1 2 7 \u00C2\u00B0 1 2 6 \u00C2\u00B0 1 2 5 \u00C2\u00B0 1 2 4 \u00C2\u00B0 1 2 3 \u00C2\u00B0 1 2 2 \u00C2\u00B0 1 2 1 \u00C2\u00B0 1 2 Q \u00C2\u00B0 1 1 9 \u00C2\u00B0 1 1 8 \u00C2\u00B0 117 c 1 1 6 \u00C2\u00B0 1 1 5 \u00C2\u00B0 1 1 4 \u00C2\u00B0 113 112^ 111\u00C2\u00B0 110\u00C2\u00B0 GENERALIZED GEOLOGY LEGEND Volcanic and sedimentary rocks, coal. Mainly sedimentary rocks, coal. Scale %r_ 1944 LEGEND M i n i n g R e c o r d e r ' s O f f i c e s *fr I M i n i n g D i v i s i o n B o u n d a r i e s S u b \" (\u00E2\u0080\u00A2) I R a l v v a y s ~ 136\u00C2\u00B0 135\u00C2\u00B0 134 133' 132 131 13 O c 129\u00C2\u00B0Lo ' 'g\u00C2\u00BBt -udel28 0 West 1 2 7 \u00C2\u00B0 from 1 2 6 \u00C2\u00B0 G r e e n w i c h l 2 5 c 1 2 4 1 2 3 \u00C2\u00B0 1 2 2 121 1 2 0 119 118 117 116 115 G e o g r d p n * O iv . Oept of U n a s , B C INTRODUCTION The purpose of t h i s t h e s i s i s to i n v e s t i g a t e lamprophyre dykes i n B r i t i s h Columbia f o r evidence that may help to de-termine whether they are connected w i t h ore d e p o s i t s i n t h e i r o r i g i n . The method of a t t a c k has i n v o l v e d f i r s t , a study of the t h e o r i e s , put forward by v a r i o u s a u t h o r i t i e s , t h at d e a l w i t h the o r i g i n o f lamprophyres i n the e x p e c t a t i o n t h a t some might suggest reasons f o r a c l o s e time and space r e l a t i o n s h i p be-tween lamprophyres and ore. A l a b o r a t o r y study has been made of lamprophyres and ore from s e v e r a l mines and a s e a r c h of the l i t e r a t u r e was undertaken to o b t a i n a r e c o r d of a l l the r e -ported lamprophyres i n B r i t i s h Columbia t o g e t h e r w i t h t h e i r a s s o c i a t e d ores. DEFINITION AND CLASSIFICATION OF LAMPROPHYRE DYKES. The term \"lamprophyre\" covers a large and ill-defined group of rocks which typically occur as dykes or small i n -trusives. In their chemical composition, lamprophyres are characterized by a medium to low s i l i c a percentage and a con-siderable relative quantity of sodium and potassium, the a l -kali metals. In addition, oxides of calcium, magnesium and iron are abundant so that the rocks are rich in ferromagnes-ian minerals. The textural c r i t e r i a that may assist in determining whether or not a rock is a lamprophyre are the prevalence of a porphyritic texture, the phenocrysts being most commonly the ferromagnesian minerals or, in the absence of a porphy-r i t i c texture, the panidiomorphic texture, in which the rock is holocrystalline and commonly equigranular with the compon-ent minerals a l l tending to form euhedral crystals. The classification of the different lamprophyric types is (1) (2) dealt with by Harker and Johannsen. The more commonly occur-ring types are summarized in the following table after Johannsen. (See next page.) (1) Harker, A.: \"Petrology for Students\". Page 134. Ii9\") D i s t r i c t P r o p e r t y Lamprophyre \u00E2\u0080\u00A2Pre- \u00E2\u0080\u00A2Post-'unoer-' Type 'Ch i e f ' Ore Ore t a i n of Ore Metals Remarks. Br i d g e R i v e r D i s t r i c t Terrace Area Usk t o Cedarvale H a z e l t o n -Smithers D i s t r i c t B r a l o r n e P i o n e e r La L i b e r t a d S t . P a u l and X-claims Kalum Lake Mines, L t d . Golden Crown Group & K l e -anza Company Ter r a c e C l a i m Rosie Group Columario C o n s o l i d a t e d G.M.\u00C2\u00BB L t d . C o r d i l l e r a Mine Lorna May Claim Grotbto group S i l v e r B a s i n group Great Ohio ' x x x X X X X X M M (?) M M M(?) (?) H Au Au n i l Au, Ag Au, Ag(Cu) Au( Cu) (Pb,Zn (Au) Au, (Cu,Pb Cu Cu,Pb, Zn (?) (?) Zn,Pb Quartz i s b a r r e n . Deposit c o n s i s t s o f py-r i t i z e d c o u n t r y r o c k as-s a y i n g t r a o e i n g o l d . Sparse b o r n i t e and o h a l -e b p y r i t e i n q u a r t z v e i n s . V e i n s o f t e n f o l l o w s m a l l oamptonite dykes and cut through them. The dykes themselves a r e m i n e r a l i s -ed. TABLE. I. (COMT'D) D i s t r i c t P r o p e r t y Lamprophyre 'Pre- 'Post-'Uncer-* Type 1 C h i e f Ore ! Ore ! t a i n .'of Ore .'Metals Remarks A l i c e Arm D i s t r i c t P o r t l a n d Canal Area Taku R i v e r Area Duthie mine Rocher De-houle mine S i l v e r Creek group G l a c i e r Gulch Gold Group Wolf Mine Esperanza Mine La Rose 2 p r o p e r t i e s N o r t h S t a r group D o l l y V ardeni. Premier m i n e ~ M a n n v i l l e Ore Body x x X X X M-H M E<* M -M(?) M (?) E-M E-M E-M Ag, Pb Zn Au,Ag, Cu Zn A u , ( B i F r a c t u r e s i n the lampro-phyre dykes a r e mineral-i z e d . Limestone replacement type ore. Ag,Cu ,2n Ag,Cu, Zn,Pb Ag,Cu,Zn Ag Ag,Au, Pb,Zn) Zn,Cu Lamprophyres are m o s t l y l a t e r than ore but some are v e r y n e a r l y contem-poraneous. - 3 I -COMMENTARY O H THE COMPILED DATA PERTAINING TO LAMPROPHYRE OCCURRENCES IN B.C. Of the 84 occurrences of lamprophyre l i s t e d i n Table I, \Z 29 35 are p o s t - o r e , 1\u00C2\u00A3 are pre-ore, -85- are u n c e r t a i n due l a r g e l y to the absence of i n t e r s e c t i o n s with the ore, and e i g h t are v e r y n e a r l y contemporaneous w i t h the ore, though tending u s u a l l y to a s l i g h t l y post-ore age. In a d d i t i o n , the lamprophyres of Rossland, not t a b u l a t e d i n d e t a i l , are p o s t - , pre-and i n t r a -ore w i t h the post-ore r e p r e s e n t a t i v e s predominating. The lamprophyres f o r which a very n e a r l y contemporaneous, or \"intraHnineralization 1 , r e l a t i o n to the ore i s p o s t u l a t e d are i n the Rossland mining camp, Reeves-McDonald Mine, S u l l i v a n mine, Slocan mining camp, Ainsworth mining camp and Premier mine. At Rossland, S u l l i v a n and Premier, t h i s r e l a t i o n i s de-duoed f o r only that s m a l l p r o p o r t i o n of the t o t a l number of lamprophyre dykes present whioh cut the ore but e i t h e r are m i n e r a l i z e d by o r e - s o l u t i o n s or d e l i m i t the l a t e r , p r e o i o u s -metal m i n e r a l i z a t i o n of the ore. In the Slocan and Ainsworth camps, the dykes are l a r g e l y p r e - o r e , but o r e - f i l l e d f r a c t u r e s are i n t i m a t e l y a s s o c i a t e d w i t h the dykes and show phenomena whioh i n d i c a t e t h a t the f r a c t u r i n g and ore f o r m a t i o n took p l a c e almost contemporaneously w i t h the emplacement of the dyke. Before going on to c o n s i d e r the compiled data i n g r e a t e r d e t a i l i t w i l l be a d v i s a b l e to emphasize that evidence of con-temporaneity or pre-ore age i s not always e a s i l y observed i n - 3 2 -the f i e l d . A d e f i n i t e c o n c l u s i o n that the lamprophyres a t the S u l l i v a n and Mayflower mines h e r e i n d e s o r i b e d are e a r l i e r than some of the m i n e r a l i z a t i o n would be almost impossible without a c a r e f u l c o l l e c t i o n and p e t r o g r a p h i c a l study of specimens o f the dykes to determine t h a t they are m i n e r a l i z e d . T h i s i s something that g e o l o g i s t s do not always do i n t h e i r examinations of p r o p e r t i e s , u n l e s s they are p a r t i c u l a r l y i n t e r e s t e d i n lamprophyre-ore r e l a t i o n s . Therefore i n a l l p r o b a b i l i t y , much p u b l i s h e d data on ore-lamprophyre age r e l a t i o n s are q u i t e un-r e l i a b l e . I t i s a w e l l - r e c o g n i z e d f a c t t h a t the c h i l l e d edges of dykes present h i g h l y impermeable b a r r i e r s to the p e n e t r a t i o n of s o l u t i o n s i n t o the dyke w i t h the r e s u l t that any m i n e r a l i z a -t i o n of the dyke may be minor and escape n o t i c e i n a megascopio examination. v THE ORE-LAMPROPHYRE RELATIONSHIP IN RELATION TO THE METALS CONENT OP THE ASSOCIATED ORES A A. Occurrences i n which the Lamprophyres and the Ore are Contemporaneous. In these occurrences i t was decided, even though only a p o r t i o n of the lamprophyres present show d e f i n i t e p r o o f o f contemporaneity, to c o n s i d e r that the few contemporaneous dykes l i n k up p r e - v e i n and p o s t - v e i n lamprophyres so that a l l belong to the same gen e r a l p e r i o d of i n t r u s i o n . This concep-t i o n seems i n c o r r e c t i n the case of the Rossland camp where (1) Drysdale has a p p a r e n t l y found evidenoe that there were f o u r (1) D r y s d a l e , C.W. C.G.S. Memoir 77. -33-separate p e r i o d s o f lamprophyre i n t r u s i o n a l l of which cannot he contemporaneous w i t h the two m i n e r a l i z i n g p e r i o d s . Yet there i s pr o o f that some of the dykes are contemporaneous and f o r the purpose of the d i s c u s s i o n that i s to f o l l o w , the Ross-land d i s t r i c t w i l l be considered a \"contemporaneous lampro-phyre\" d i s t r i c t . Of 'the s i x mining centers w i t h contemporaneous lamprophy-r e s , the Reeves-MacDonald, S u l l i v a n , Slocan, and Ainsworth produce Pb, Zn and Ag, the Premier produces Au, Ag, (Pb and Zn) and Rossland produced Au, Gu, and Ag. In co n n e c t i o n , w i t h the Rossland camp moreover, i t should be noted t h a t the d e p o s i t s of the south b e l t of Rossland, i n which the Mayflower mine l i e s * c o n t a i n important q u a n t i t i e s o f (Pb), Zn and Ag, besi d e s v a r -i a b l e amounts o f Gu, Au and a r s e n o p y r i t e . Thus, the most oom-mon metals^are Pb, Zn, Ag, w i t h some Au and a l i t t l e Gu. There are no examples o f gold-quartz ores. B. Occurrences i n whioh Lamprophyres are Pre-Ore Only. These are ve r y few i n number and are oonfined to the Terrace and Hazelton-Smithers areas s i n c e the s i x pre-ore lampro-phyres of the Slocan and Ainsworth d i s t r i c t s are a r b i t r a r i l y a s s i g n e d a contemporaneous age owing to the g e n e r a l contempor-a n e i t y of lamprophyre i n t r u s i o n i n those d i s t r i c t s . There i s l i t t l e u n i f o r m i t y i n the ores of t h i s c l a s s . In the Terrace area, one dep o s i t c o n t a i n s barren quartz and the other, low grade Au and Ag. In the Hazelton-Smithers area, the Great Ohio c o n t a i n s Zn and Pb, the Duthie Ag, Pb and Zn and the Rocher -34-Deboule, Au, Ag, and Gu. G. Occurrences i n whioh Lamprophyres are Post-Ore Only. The m a j o r i t y of the t a b l e d lamprophyre occurrences are post-ore but onl y 22 of them are c o n s i d e r e d under t h i s heading sinoe the three Slocan examples are excluded and, i n the oase of three o t h e r s , the metals content of the ore i s un-known. In g e n e r a l , there i s a trend away from ores o f the Pb, Zn, Ag type, of which there are s i x examples, to those of Au and Gu. Four important mines (at Bridge R i v e r and Hedley) and one small mine (the Fern) produce only Au, and three mines, i n the Ymir-Nelson area, produce only Gu. Of the e i g h t r e -maining, seven c o n t a i n e i t h e r Au and Gu i n a d d i t i o n t o t h e i r o ther metals (Ag, Pb or Zn). One mine, the D o l l y Varden, produces only Ag. To enlarge f u r t h e r , ores c o n t a i n i n g Au and/or Gu, w i t h or without other metals are a s s o c i a t e d w i t h pre-ore lampro-phyres i n three and wit h contemporaneous lamprophyres i n two i n s t a n c e s while there are nine occurrences i n which the ore-lamprophyre r e l a t i o n s h i p i s u n c e r t a i n . There are, t h e r e f o r e , only f i v e occurrences i n which the a s s o c i a t e d lamprophyre i s not post-ore compared w i t h .15 i n which the lamprophyre i s po s t - o r e . Conclusions w i t h Regard to the Ore-Lamprophyre R e l a t i o n s h i p i n R e l a t i o n to the Meta l s Content of the A s s o c i a t e d Ores. With the exc e p t i o n of those of Rossland and Premier, con-temporaneous lamprophyres belong w i t h Ag, Pb, Zn ores, while -35-post-ore lamprophyres i n a rough way show a f f i n i t i e s f o r ores o o n t a i n i n g Au and Gu, w i t h or without other metals, GEOGRAPHICAL DISTRIBUTION OF LAMPROPHYRES IN B.C. AND THE GENERAL CHARACTER OF ASSOCIATED ORES It may he p o s s i b l e to deduce something of a g e n e r a l s i g -n i f i c a n c e from the r e l a t i v e i n c i d e n o e of lamprophyres i n d i f -f e r e n t p a r t s of the p r o v i n c e . I t i s evident that the m a j o r i t y of lamprophyre occurrences i n B.C. are i n the south-east, a l o n g a n o r t h - s o u t h b e l t t h a t i n c l u d e s the Rossland, Salmo, Ymir, Nelson, Slocan and Ainsworth d i s t r i c t s . F o r t y - e i g h t of the 84 p r o p e r t i e s i n d i v i d u a l l y l i s t e d i n Table I are i n t h i s b e l t and t h i s does not take i n t o c o n s i d e r a t i o n the numerous p r o p e r t i e s a t Rossland which a l l c o n t a i n lamprophyres but are not i n d i v i d u a l l y l i s t e d i n the t a b l e . Assuming 15 p r o p e r t i e s at Rossland ( a o t u a l l y there are more), the p r o p o r t i o n of lamprophyre occurrences i n the f a r - e a s t b e l t to the t o t a l num-ber i n the p r o v i n c e i s 63 to 94. Two-thirds of the lamprophyre occurrences i n B.C., t h e r e f o r e , are i n t h i s b e l t . In t h i s a rea a l s o are found a l l of the\" lamprophyres that are contem-poraneous wi t h the ore w i t h the s i n g l e e x c e p t i o n o f those i n the Premier mine. The commercial ores i n t h i s b e l t are p r e -dominantly of the mesothermal, s i l v e r - l e a d - z i n c type. Westward from the Rossland-Slocan b e l t , lamprophyres as-s o c i a t e d with Au, Gu ores are r e p o r t e d near the I n t e r n a t i o n a l Boundary i n the Greenwood and F r a n k l i n d i s t r i c t s but are not -36-known to ocour a g a i n u n t i l Hedley i s reached. In the v i c i n i t y of Hedleyt post-ore lamprophyres are f a i r l y p l e n t i f u l i n the contact metamorphic g o l d d e p o s i t s but are absent from the cop-per d e p o s i t a t Copper Mountain. There are s c a t t e r e d occurrences of lamprophyres f o r which no r e l a t i o n s to ore are d e s c r i b e d i n the C o q u i h a l l a and Tulameen d i s t r i p t s and the next major appear-ance of lamprophyres i a i n the B r i d g e R i v e r d i s t r i c t where they are l a t e r than the mesothermal to high-temperature gold-quartz d e p o s i t s . Lamprophyres are a p p a r e n t l y present to a s m a l l de-gree i n the C h i l k o and Taseko lake r e gions .but no p u b l i s h e d r e f e r e n c e to them could be found. I t i s not u n t i l the Terraoe-Hazelton-Smithers r e g i o n i s reached that lamprophyres a g a i n become p l e n t i f u l and i n t h i s r e g i o n the.development of lamprophyres i s second only to that i n the south-east p o r t i o n of the p r o v i n c e , 16 p r o p e r t i e s con-t a i n i n g them. No contemporaneous lamprophyres are r e p o r t e d , but the only pre-ore-lamprophyres of the p r o v i n c e , f i v e i n num-ber, occur here. In a d d i t i o n , one occurrence i s post-ore and the remaining ten are u n c e r t a i n . The ores are not c o n v e n i e n t l y c l a s s i f i e d but the m a j o r i t y are mesothermal and t h e i r m e t a l -l i z a t i o n ranges from Au, Ag, Cu to Pb, Zn, Ag. The next lamprophyre r e g i o n to the n o r t h i s the A l i c e Arm where seven p r o p e r t i e s c o n t a i n lamprophyres, a l l of which are e i t h e r p o s t - o r e or of u n c e r t a i n r e l a t i v e age. The ores are mainly of the epithermal to mesothermal type and produce main-l y Ag w i t h a l i t t l e Cu and Zn. -37-In the Portland Canal area, lamprophyres are described at the Premier mine where thoy are -mootly-post-ore but some are contemporaneous. The ore is epithermal to mesothermal and pro-duction is in Au, Ag, (Pb and 8 n ) . In the Taku river d i s t r i c t the Mannville deposit, con-taining a medium- to low-temperature, Zn, Cu ore, is associated with probably post-ore lamprophyres. One lamprophyre dyke, with no ore within seven miles, is reported from the Atli n d i s t r i c t . Apparently no lamprophyres occur within the Coast Range batholith nor at its western contact on Vancouver Island where low-temperature Pb, Zn, Ag deposits are generally lacking and the higher-temperature Cu and Au deposits prevail. No lamprophyres are present in the Cariboo d i s t r i c t where gold deposits occur in Pre-oambrian sediments. Regarding the Beaverdell camp, where epithermal si l v e r mineralization is present, i t was not definitely ascertained whether lamprophyres are present or absent. The objection might be raised to the foregoing jfreatment of lamprophyre distribution that many small prospects, in the Portland Canal area for example, contain lamprophyres not re-ported here. This is true but the relative proportions should s t i l l be roughly correct since there al30 w i l l be unrecorded lamprophyres at many small deposits in other d i s t r i c t s . Another pertinent point should be considered and that is the frequently-expressed opinion that lamprophyres only appear to be more plentiful in mineralized regions because they are ex--38-p03ed by mining o p e r a t i o n s , t h e i r occurrences elsewhere, mean-while , b e i n g concealed as a consequence of t h e i r s o f t , e a s i l y -weathered c h a r a c t e r . Although i t i s true that lamprophyres weather r a p i d l y , there are n e v e r t h e l e s s , numerous n a t u r a l out-crops i n such heavily-dyked r e g i o n s as Rossland and there are frequent r e f e r e n c e s i n the l i t e r a t u r e to lamprophyre outcrops i n (1) un-mined areas, such as those by Daly along the 49th p a r a l l e l , and numerous others ( F r a n k l i n M i n i n g camp, Bridge R i v e r , A t l i n d i s t r i c t , e t c . ) . I f lamprophyres are present to any important extent i n an area, there w i l l be i n d i c a t i o n s o f them on the s u r -f a c e . Conclusions w i t h Regard to Geographical D i s t r i b u t i o n and the General Charaoter o f A s s o c i a t e d Ores. Lamprophyres are twice as p l e n t i f u l i n s o u t h - e a s t e r n B.C., where mesothermal, s i l v e r - l e a d - z i n c d e p o s i t s predominate., as they are i n a l l other p a r t s of the p r o v i n c e combined, and i n ad-d i t i o n , show the c l o s e s t time r e l a t i o n to the ore. In the south-ern h a l f of the e a s t e r n contact of the Coast Range b a t h o l i t h , post-ore lamprophyres are a s s o c i a t e d w i t h the moderate- to h i g h -temperature Au d e p o s i t s there but do not r e a l l y become p l e n t i f u l a gain u n t i l the n o r t h e r n p a r t of the e a s t e r n contact i s reached where there i s a preponderance of mesothermal d e p o s i t s c o n t a i n -i n g Au, Cu, (Pb, Zn, Ag). Such important mining c e n t e r s as Ze-b a l l o s and Cariboo a p p a r e n t l y do not have lamprophyres and i n these a r e a s , gold i s the important metal. (1) Daly, R.A.: C.G.S. Mem. 38. Par+IJW*) - 3 9 -A BRIEF SUMMARY OF THE LABORATORY WORK UNDERTAKEN AND THE RESULTS OBTAINED Thirt y - t h r e e ' t h i n s e c t i o n s were examined and of these, ' 2 1 are described at considerable l e n g t h i n Appendix B. In a d d i -t i o n , f i v e p o l i s h e d s e c t i o n s were studied i n conjunction w i t h the t h i n s e o t i o n s . 'The most valuable speoimens, f o r the purpose o f studying lamprophyre-ore r e l a t i o n s , were obtained by Dr. Gunning from the S u l l i v a n , Reeves-McDonald, and Rossland mines. Most of these lamprophyre specimens are m i n e r a l i z e d and some have pieoes of the r e l a t e d ore attached to them. In a d d i t i o n , un-mi n e r a l i z e d specimens were o o l l e o t e d by Dr. Gunning from B r i t -annia mine. Specimens of lamprophyre and other dyke rocks from Premier mine were obtained through Dr. W.H. White, s p e o i -mens from the Ruth-Hope mine were cont r i b u t e d by Mr. W.M. Sharp and those from the Bridge R i v e r d i s t r i c t were c o l l e c t e d by the w r i t e r . In the oase of specimens from the Ruth-Hope, Pioneer, B r a l o r n e , B r i t a n n i a and Premier mines, i n which no m i n e r a l i z a -t i o n i s present, the pe t r o g r a p h i o a l d e s c r i p t i o n s merely serve to c l a s s i f y the rocks and to record t h e i r f e a t u r e s f o r f u t u r e reference. The d e s c r i p t i o n s of specimens from the S u l l i v a n , Reeves-McDonald and Mayflower mines, however, are more impor-tant as they record i n a d d i t i o n , observations of value to a co n s i d e r a t i o n of lamprophyre-ore r e l a t i o n s . I t i s to the l a t t e r d e s c r i p t i o n s that most a t t e n t i o n should he d i r e c t e d . In the case of the S u l l i v a n mine, specimen S35 from the south w a l l of the 3904 c r o s s - c u t c o n s i s t s of lamprophyre dyke m a t e r i a l i n contact w i t h p y r r h o t i t e - s p h a l e r i t e ore ( g e n e r a l l y o a l l e d \"low-grade o r e \" ) , the dyke i n t h i s case h e i n g a p p a r e n t l y l a t e r i n o r i g i n than the o r e A Specimen S36, from the same l o c a t i o n , c o n s i s t s o f lamprophyre which c o n t a i n s i n c l u s i o n s of \"low-grade ore\" but i s m i n e r a l i z e d by g a l e n a - r i c h \"high-grade ore\" o c c u r r i n g i n contact w i t h i t . The c o n c l u s i o n from these ob s e r v a t i o n s i s that the lamprophyre was i n t r u d e d a f t e r the \" \"low-grade ore\" but p r i o r to the galena m i n e r a l i z a t i o n and i s t h e r e f o r e c l o s e l y r e l a t e d i n time to the ore. T h i s i n t e r -p r e t a t i o n i s p l a c e d on the ore-lamprophyre r e l a t i o n s i n these specimens f o r reasons ex p l a i n e d i n d e t a i l i n Appendix B and amounts to a c o n f i r m a t i o n of the r e s u l t s o f p r e v i o u s i n v e s -(1) t i g a t i o n s a t the S u l l i v a n mine. At the Reeves-McDonald mine, the lamprophyre 3000 f e e t from the p o r t a l of the R i v e r a d i t , from which specimen 2 i s taken, cuts the ore s t r u c t u r e so that i t appears to be l a t e r than the ore yet i t c o n t a i n s p y r i t e and galena i n the amount of three peroent of the r o ck and i s i n t e n s e l y a f f e c t e d by c a r b o n a t i z a t i o n and c h l o r i t i z a t i o n as w e l l . These f e a t u r e s (1) C O . Swanson and H.C. Gunning: Geology of the S u l l i v a n Mine, C.I.M.M. B u l l . 402, Oct. 1945. i n d i o a t e a c l o s e time r e l a t i o n f o r the ore and dyke. In the Mayflower mine, Rossland D i s t r i c t ( T r a i l Greek), a lamprophyre from the main l e v e l ( t h i n s e c t i o n s M34, M35; p o l i s h e d s e c t i o n s M34, M36) cuts and i s c h i l l e d a g a i n s t heavy-s u l p h i d e ore. The lamprophyre i s however m i n e r a l i z e d w i t h c h a l c o p y r i t e , s p h a l e r i t e , p y r i t e , and galena but not by A& ap-p a r e n t l y - e a r l i e r p y r r h o t i t e and a r s e n o p y r i t e o c c u r r i n g i n the ore toward the i n t e r i o r of the ore band and consequently f a r t h e r ii possible from i t s contact w i t h the lamprophyre. Thus, it^appears- that t h i s lamprophyre too i s l a r g o l y contemporaneous w i t h the ore,- a l f k o u g / i -H ie e v i d e n c e '.5 nof concluJise and f\>e.nJiK lamprophyres and t h e i r mode of occurrence w i l l be g i v e n l a tog-. Lamprophyre Dykes. (1) (2) In the l i t e r a t u r e , McCann, C a i r n e s , and others r e f e r to the presence of lamprophyre dykes i n B r a l o r n e and Pioneer mines but do not g i v e much d e t a i l r e g a r d i n g t h e i r r e l a t i o n to the ore beyond s t a t i n g ' that they are l a t e r . Outcrops of s p e s s a r t i t e are to be found on the south s i d e of f r i d g e r i v e r (1) McCann, W.S.: C.G.S. Mem. 130, Geology and M i n e r a l Deposits of the Bridge R i v e r Map Area, B.C. (1922). (2) C a i r n e s , C.E.: C.G.S. Mem. 213, Geology and M i n e r a l Depos-i t s of the B r i d g e R i v e r M i n i n g Camp, B.C. (1937). 43A. near Rexmount and elsewhere i n the v a l l e y . In d e a l i n g w i t h the Bridge R i v e r mining oamp i n g e n e r a l , Cairnes p r e s e n t s a g e o l o g i c a l t i m e - t a b l e whioh p l a c e s the lamprophyre and b a s a l t -i c dykes i n T e r t i a r y time, immediately f o l l o w i n g i n t r u s i v e s of the Bendor b a t h o l i t h . I t i s p o s s i b l y from i n t r u s i v e s r e l a t e d to the Bendor b a t h o l i t h that the ore s o l u t i o n s o r i g i n a t e d a l -though t h i s i s not accepted without q u e s t i o n as there i s at l e a s t one d i s t i n c t p e r i o d of pre-Bendor i n t r u s i o n of which there a r e r e p r e s e n t a t i v e i n t r u s i v e bodies i n the d i s t r i c t from which the ore may have o r i g i n a t e d . The lamprophyre dykes a r e , how-ever, together w i t h b a s a l t i o dykes, the l a t e s t igneous i n - ' t r u s i v e a c t i v i t y i n the ar e a and f o l l o w the Bendor i n t r u s i v e w i t h which the ore s o l u t i o n s are b e l i e v e d to be a s s o c i a t e d . Ore. The important ores of the d i s t r i c t are gol d - q u a r t z v e i n s b e l o n g i n g to the high-temperature end of the mesothermal group. The quartz i s ve r y l i g h t l y m i n e r a l i z e d w i t h c h i e f l y p y r i t e and a r s e n o p y r i t e . Free g o l d o f t e n occurs i n the quartz and i s l a t e r than the s u l p h i d e s . There i s some s c h e e l i t e a t B r a l o r n e and P i o n e e r . B r a l o r n e Mine. Two p a r a l l e l b i o t i t e - l a m p r o p h y r e dykes, probably m i n e t t e s , i n t e r s e c t the Empire v e i n n e a r l y at r i g h t angles to i t and are l a t e r than the ore. Q u a r t z - a l b i t i t e or a p l i t e dykes are o f t e n a s s o c i a t e d w i t h v e i n s , e s p e c i a l l y i n the K i n g mine, and may be m i n e r a l i z e d so that they c o n s t i t u t e ore. -44A-Ploneer Mine. At l e a s t two hornblende-lamprophyres, probably v o g e s i t e s , occur underground and thereuare three or f o u r o t h e r i n t e r -s e c t i o n s w i t h lamprophyre that p r o b a b l y r e p r e s e n t separate dykes. The lamprophyre i s a l l l a t e r than the ore. Note: D e t a i l e d f i e l d d e s c r i p t i o n s of the lamprophyres a t B r a l o r n e and Pioneer are g i v e n elsewhere. (1) TERRACE AREA On T h o r n h i l l mountain, g r a n o d i o r i t e country rock i s cut by lamprophyre dykes. These are cut by q u a r t z - o r t h o c l a s e por-phyry dykes which i n t u r n are cut by q u a r t z - d i o r i t e dykes. There are two other types of s a l i c dykes, l a t e r i n age than the lamprophyre. There are an u n u s u a l l y l a r g e number of ex-amples of v e i n s f o l l o w i n g the w a l l s o f dykes but these dykes are always q u a r t z - a l b i t e or porphyry dykes. D e s c r i p t i o n o f Individual P r o p e r t i e s : On T h o r n h i l l Mountain: La L l b e r t a d -Lamprophyre dykes are o l d e r than q u a r t z - d i o r i t e dykes and both are o l d e r than the q u a r t z . The quartz i s barren. St. P a u l and X c l a i m s -Quartz v e i n s occur f o r 3000 f e e t a l o n g the w a l l o f a (1) K i n d l e , E.D.: C.G.S. Mem. 205, M i n e r a l Resources o f Terrace Area, Coast D i s t r i c t , B.C. (1937). -45A-q u a r t z - a l b i t e dyke. Lamprophyres a l s o occur and these are o l d e r than the q u a r t z - a l b i t e dyke. The quartz v e i n s c a r r y low gold and s i l v e r v a l u e s and are m i n e r a l i z e d w i t h p y r i t e , c h a l c o p y r i t e , galena and s p h a l e r i t e . Kitsumgallum Lake: Ealum Lake Mines L t d . -A l t e r e d d i o r i t e dykes were i n t r u d e d p r i o r to v e i n f ormation hut the lamprophyre dykes are l a t e r than the ore and one i s seen c u t t i n g the ore. A s m a l l dialffase dyke cuts the d i o r i t e on the Lucy O'Neil c l a i m and forms the hanging-wall o f the v e i n . The ore c o n s i s t s o f q u a r t z , p y r i t e , c h a l c o p y r i t e and has gold and s i l v e r v a l u e s . The l o c a t i o n i s a t the contact between the Coast Range d i o r i t e and the s e d i -ments. (1) ZYMOETZ RIVER AREA (Te r r a c e V i c i n i t y ) Lamprophyre dykes occur everywhere. A l a s k i t e dykes and s i l l s are as w i d e l y d i s t r i b u t e d and there are a l s o g r a n i t e , g r a n o d i o r i t e , a p l i t e , e t c . dykes. The lamprophyres are u s u a l -l y l e s s than f o u r f e e t wide and appear to be the youngest of the dykes. \"...Most of the dykes ( o f a l l types) are probably of about the same age as the Coast Range b a t h o l i t h . \" Most of (1) Hanson, G.: C.G.S. Summ. Rept. (1925), Reconnaissance i n Zymoetz R i v e r Area, Coast D i s t r i c t , B.C. -46A-the a l a s k i t e dykes and s i l l s have quartz v e i n s a l o n g both w a l l s ; some o f these v e i n s c o n t a i n galena and s p h a l e r i t e , and ot h e r s , g o l d and p y r i t e . The a r e a i s very w e l l m i n e r a l i z e d but the ve i n s are narrow and not s u f f i c i e n t l y r i c h to produce mines. The v a l u a b l e metals and mi n e r a l s present are s i l v e r , g o l d , l e a d , oopper and z i n c i n the east g r a d i n g to oopper and s c h e e l i t e and molybden-i t e to the west towards the b a t h o l i t h . No i n f o r m a t i o n i s g i v e n as to the r e l a t i v e amounts of lamprophyre dykes i n d i f f e r e n t p a r t s of the area. D e s c r i p t i o n s of P r o p e r t i e s : (1) Golden Grown Group and P r o p e r t i e s o f K l e a n z a Company. These are on the east s i d e o f the Skeena r i v e r , three m i l e s below Usk. The country rock i s g r a n o d i o r i t e which i s cut by lamprophyre dykes. The Golden Crown v e i n c o n s i s t s of quartz s p a r i n g l y m i n e r a l i z e d w i t h p y r i t e , c h a l c o p y r i t e and perhaps some a r s e n o p y r i t e . The main value i s i n g o l d . (2) Terrace Claim. On the s u r f a c e a v e i n i s exposed which c o n t a i n s q u a r t z , p y r i t e , a l i t t l e galena and s p h a l e r i t e . A oross-out 75 f e e t l o n g d r i v e n i n below the outcrop found no ore but cut occas-i o n a l lamprophyre dykes i n the g r a n o d i o r i t e . (1) Hanson, G.: C.G.S. Summ. Kept. (1925), Reconnaissance i n Zymoetz R i v e r Area, Coast D i s t r i c t , .B.C. (2) Z i n d l e , E.D.: C.G.S. Mem. 205, M i n e r a l Resouroes of Terrace Area, Coast D i s t r i c t , B.C. (1937). -47A-Ttosie Group, At f o o t o f West s l o p e o f Kleanza Mountain. The oountry rock i s g r a n o d i o r i t e out by o o o a s i o n a l lampro-phyre dykes. There i s no ore, j u s t a l t e r e d rock c o n t a i n i n g p y r i t e and a s s a y i n g o n l y a traoe i n g o l d . Golumario C o n s o l i d a t e d Gold Mines, L t d . - West slope o f Kleanza Mountain. About 80G0 f e e t o f development work was done and a 75-ton m i l l operated f o r e i g h t months. The ore c o n s i s t s o f quartz v e i n s m i n e r a l i z e d with p y r i t e and g o l d . Small amounts of c h a l c o p y r i t e and galena are present i n some p l a c e s . Country rocks are out by quartz a l b i t e , d i o r i t e and lampro-phyre dykes. C o r d i l l e r a Mine - One mile 30uth-west o f Usk. A number of s m a l l lamprophyre dykes i n t r u d e the country r o c k s . The m i n e r a l i z a t i o n c o n s i s t s of s p a r s e l y d i s t r i b u t e d b o r n i t e and c h a l c o p y r i t e i n quartz v e i n s . Summary of Terrace Area. 44 p r o p e r t i e s are d e s c r i b e d i n Memoir 205, of which ei g h t are d e s c r i b e d as c o n t a i n i n g lamprophyre dykes. -48A-(1) USK TO OEDARVALE There are a l a r g e number of s a l i c dykes of a great v a r i e t y d e s c r i b e d i n t h i s a r ea. Examples are a n d e s i n e - d i o r i t e por-phyry, a l b i t e - q u a r t z d i o r i t e and g r a n o d i o r i t e dykes. Very many examples are g i v e n o f ore f o l l o w i n g a c i d - p o r p h y r y dykes of v a r i o u s types. Lamprophyre dykes are present but are d i s -t i n c t l y i n the m i n o r i t y . Lona May olaim. The q u a r t z - a l b i t e dyke, which forms one w a l l o f the v e i n , i s a l t e r e d and out by a younger lamprophyre dyke. The ore con-t a i n s a sparse d i s s e m i n a t i o n o f p y r i t e , c h a l c o p y r i t e , galena, s p h a l e r i t e and t e t r a h e d r i t e . Algoma Group - Two m i l e s east o f Pitman f l a g s t a t i o n . A p i t sunk on a t h r e e - f o o t lamprophyre dyke, which c u t s a g r a n o d i o r i t e dyke f a i l e d to- r e v e a l any m i n e r a l s . Grotto Group. A quartz v e i n occurs a l o n g the con t a c t of a I E - f o o t ande-si n e d i o r i t e porphyry dyke i n a n d e s i t e . The quartz i s h e a v i l y m i n e r a l i z e d w i t h p y r i t e and a l i t t l e s p e o u l a r i t e . A two-foot dyke of lamprophyre occurs on the s u r f a c e 30 f e e t from the a d i t but the r e l a t i o n to ore i s not known. S i l v e r B a s i n Group. S e v e r a l s m a l l q u a r t z - a l b i t e and lamprophyre dykes occur here. , (1) K i n d l e , E.D.: C.G.S. Mem. SIS, M i n e r a l Resources, Usk to Cedarvale, Coast D i s t r i c t , B.C. (1937). -49A^ Summary. 39 p r o p e r t i e s are d e s c r i b e d of which f o u r had lamprophyres. (1) HAZELTON-SMITHERS DISTRICT The B u l k l e y e r u p t i v e s , composed o f J u r a s s l o - C r e t a o e o u s g r a n o d i o r i t e , are represented, a t the Rooher De'boule'' and Hudson Bay mountains and the Babine range. The ore occurrences i n the r e g i o n are a s s o c i a t e d w i t h them. A s s o c i a t e d w i t h the B u l k l e y e r u p t i v e s a l s o are dykes of g r a n i t e porphyry and quartz porphyry. A few lamprophyre dykes were a l s o n o t i c e d but these are c l e a r l y o f a l a t e r age, perhaps T e r t i a r y , s i n c e they are seen to be c h i l l e d a g a i n s t quartz porphyry dykes. The m i n e r a l -i z a t i o n i n the Hazelton d i s t r i c t seems to be connected w i t h the (1) i n t r u s i o n s of the quartz porphyry dykes. D e s c r i p t i o n s of P r o p e r t i e s : E\u00E2\u0080\u0094\u00E2\u0080\u0094\u00E2\u0080\u0094hi\u00E2\u0080\u0094 Great Ohio P r o p e r t y . T h i s p r o p e r t y i s on J u n i p e r Creek. The v e i n s o f t e n f o l l o w s m a l l dykes of oamptonite c u t t i n g through them on e i t h e r w a l l ; and the dykes themselves are somewhat m i n e r a l i z e d . The ore i s o f the f a i r l y h i g h temperature type s i n c e the v e i n s c o n t a i n quartz and a c t i n o l i t e as the c h i e f gangue m i n e r a l s and the m e t a l l l o m i n e r a l s i n c l u d e a r s e n o p y r i t e , p y r i t e , p y r r h o t i t e and m e r c a s s i t e . There are a l s o z i n c , copper and l e a d m i n e r a l s (1) M a l l o c h , G.S.: C.G.S. Summ. Rept. (1912), The Groundhog Coal F i e l d , B.C., Omineoa D i s t r i c t . (2) O ' N e i l l , J . J . : C.G.S. Mem. 110, P r e l i m i n a r y Report on the Economic Geology of Hazelton D i s t r i c t , B.C. ( 1 9 1 9 ) -50A-which are younger than those a l r e a d y mentioned. The gangue a l s o i n c l u d e s younger c a l c i t e and s i d e r i t e . (1) Puthie Mine - Seven and o n e - h a l f m i l e s west o f Smithers. One d i o r i t e dyke, a q u a r t z - a l b i t e porphyry dyke and numer-ous lamprophyre and a l b i t e porphyry dykes i n t r u d e the v o l c a n i c rooks. Most of the lamprophyres are l e s s than ten f e e t wide but widths up to 35 f e e t do oocur. N e a r l y a l l the lamprophyres are almost a t r i g h t - a n g l e s to the v e i n s . There are many narrow lamprophyre dykes underground, i n t e r s e c t e d by, but sometimes f o l l o w e d by, the v e i n l o d e s , the dykes i n some cases b e i n g f r a c -tured l i k e the lode and the f r a c t u r e s , l / 8 i n c h to two inches wide, being m i n e r a l i z e d w i t h s p h a l e r i t e , galena, t e t r a h e d r i t e , quartz, oarbonate and p y r i t e . Prom the d e s c r i p t i o n s i t appears that the dykes are p r e - o r e . The ore is a s i l v e r - l e a d - z i n c ore, c o n t a i n i n g galena, s p h a l e r i t e , t e t r a h e d r i t e , ruby s i l v e r , py-r i t e , a r s e n o p y r i t e and c h a l c o p y r i t e . Rocher De'boule'' Mine - On Rocher De'boule''Mt., s i x m i l e s south of New Hazelton. > Lamprophyre dykes i n t r u d e the g r a n o d i o r i t e on the D e l t a p r o p e r t y and are o l d e r than the d e p o s i t s . T h i s i s a moderate to h i g h temperature d e p o s i t i n f i s s u r e s c o n t a i n i n g hornblende and a c t i n o l i t e as a l t e r a t i o n p roducts and c h a l c o p y r i t e , magnetite, p y r r h o t i t e , a r s e n o p y r i t e , p y r i t e , t e t r a h e d r i t e , s a f f l o r i t e and molybdenite as v e i n m i n e r a l s . (1) K i n d l e , E.D.: C.G.S. Mem. 223 (1940), M i n e r a l Resources, H a z e l t o n and Smithers Areaa, B.C. -511-There i s a l s o l e s s e r m i n e r a l i z a t i o n of a l a t e r age which i n -v o l v e s mesothermal m i n e r a l s . P r o d u c t i o n o f gold, s i l v e r and copper i s recorded. S i l v e r Creek Group - E i g h t m i l e s north-west of Smithers. 1 g r a n o d i o r i t e s t o c k i n t r u d i n g bedded rooks i s cut by a lamprophyre dyke 30 f e e t wide, which has a f l a t d i p . The ore i s the limestone replacement type c o n t a i n i n g p y r r h o t i t e , s p h a l -e r i t e and p y r i t e . G l a c i e r Gulch Gold Group - F i v e m i l e s north-west of Smithers. The m i n e r a l i z a t i o n occurs i n t u f f i n a s e r i e s o f c o a l - b e a r -i n g sediments. Ho i n t r u s i v e rocks were seen i n the immediate v i o i n i t y of the m i n e r a l d e p o s i t s . The v o l c a n i c rocks a t the f o o t of the g l a c i e r are i n t r u d e d by lamprophyre dykes up to 20 f e e t wide and j o i n t planes i n these dykes c o n t a i n seams of c a l o i t e and molybdenite up to l / 2 i n c h wide. The ore m i n e r a l s are n a t i v e g o l d , tetradymite and b i s m u t h i n -i t e which r e p l a c e a l t e r e d t u f f s . Summary. 52 p r o p e r t i e s were d e s c r i b e d by K i n d l e i n Memoir 223, d e a l -i n g w i t h the Hazelton-Smithers a r e a . In these, there were f i v e r e f e r e n c e s to lamprophyre dykes. -52A-(1),(2) A L I C E ARM DISTRICT Narrow lamprophyre dykes a re common i n the A l i c e Arm d i s t -r i c t . They penetrate J u r a s s i c sediments and are of upper J u r a s s i c age or younger. South of A l i c e Arm, lamprophyre dykes are rar e but dykes and s i l l s o f g r a n o d i o r i t e and q u a r t z - d i o r i t e are p l e n t i f u l . The m i n e r a l p r o d u c t i o n o f the d i s t r i c t i s mainly s i l v e r w i t h a l s o a l i t t l e copper and z i n c . D e s c r i p t i o n s of P r o p e r t i e s : Wolf Mine. This mine i s l o c a t e d on the mountain slope n o r t h of A l i c e Arm v i l l a g e . The country rock c o n s i s t s o f a r g i l l i t e and q u a r t z -i t e which i s i n t r u d e d by many lamprophyre and d i o r i t e dykes. There are three narrow s i l v e r - b e a r i n g v e i n s and 220 f e e t of underground development work has been done on the c e n t e r v e i n . A narrow lamprophyre dyke l e s s than one fo o t wide accompanies and i n t r u d e s the ce n t e r v e i n . In a d d i t i o n , the v e i n i s cut by many lamprophyre dykes one to s i x f e e t wide and by a d i o r i t e dyke 30 f e e t wide. Two o f the c r o s s - c u t t i n g lamprophyre dykes o f f s e t the v e i n s e v e r a l f e e t . The ore o o n s i s t s of white quartz i n narrow v e i n s which c a r r i e s s u l p h i d e s , c h i e f l y i n bands, along the f o o t - w a l l o f the v e i n . The mi n e r a l s are 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 , galena, t e t r a h e d r i t e , ruby s i l v e r and n a t i v e s i l v e r . (1) Hanson, G.: C.G.S. Summ. Rept. (1923) P a r t A, Reconnais-sance between Skeena R i v e r and Stewart, B.C. (2) Hanson, G.: C.G.S. Summ. Rept. (1928), M i n e r a l D e p o s i t s o f A l i c e Arm D i s t r i c t , B.C. -53A-E8peranza Mine. T h i s mine i s on the west s i d e o f the K i t s a u l t r i v e r , one m i l e from A l i c e Arm. I t has produced ore from stopes. The country rock i s a r g i l l i t e i n t r u d e d by narrow lamprophyre dykes whioh a l l s t r i k e n o r t h - e a s t . The ore c o n s i s t s o f quartz v e i n s which f o l l o w the f o l d axes and c o n t a i n a r s e n o p y r i t e , p y r r h o t i t e , p y r i t e , c h a l c o -p y r i t e , s p h a l e r i t e , galena, t e t r a h e d r i t e , ruby s i l v e r and n a t i v e s i l v e r . Some s c h e e l i t e occurs i n the ore but there has been no p r o d u c t i o n o f tungsten. LaRose Mine. T h i s mine i s on the east slope of Haystack mountain, on the west s i d e of K i t s a u l t r i v e r , e i g h t m i l e s from A l i c e Arm. Small amounts of ore have been shipped by p r o s p e c t o r s . The ore d e p o s i t , which i s a v e i n i n a shear zone, i s out by lamprophyre dykes. The m i n e r a l s are a r s e n o p y r i t e , p y r i t e , c h a l c o p y r i t e , p y r r h o t i t e , s p h a l e r i t e , galena, t e t r a h e d r i t e , n a t i v e s i l v e r . A l i c e JSroup and T i g e r Group. Both these p r o p e r t i e s have lamprophyres. (1) UPPER KITSAULT VALLEY ( A l l o e Arm D i s t r i c t ) The lamprophyre dykes are b l a c k and resemble diabase but ver y few t y p i c a l diabase dykes are p r e s e n t . No type-names f o r (1) Hanson, G.: C.G.S. Summ. Rept. (1921) a, Upper K i t s a u l t V a l l e y . -54A-f o r the lamprophyre were g i v e n but the c o n s t i t u e n t m i n e r a l s are o l i g o c l a s e - a n d e s i n e l a t h s and well-formed hornblende and a u g i t e c r y s t a l s . Some of the lamrpophyres are cut by m i n e r a l v e i n s , others cut the vei n s but are themselves cut by f a u l t s . Others are l a t e r than both v e i n s and f a u l t s . The Coast-Range b a t h o l i t h i s a few m i l e s to the e a s t . D e s c r i p t i o n s of P r o p e r t i e s : N orth S t a r Group. The country rook i s grey b r e c c i a . Lamprophyre dykes p a r a -l l e l the v e i n and i n some p l a c e s form i t s f o o t - or hanging-w a l l . The ore c o n s i s t s o f a q u a r t z - p y r i t e v e i n which c o n t a i n s the r i c h s i l v e r m i n e r a l s and b a r i t e . D o l l y Varden. Numerous re v e r s e f a u l t s and l a t e normal f a u l t s cut up the v e i n . At the main v e i n , \"...Lamprophyre dykes cut the v e i n , some of which antedate and some postdate the f a u l t s . \" The mine was a produoer. The main v e i n was t r a c e d f o r 1500 f e e t and was 8 to ,80 f e e t wide. I t i s a s i l v e r - b e a r i n g q u a r t z -p y r i t e v e i n e s s e n t i a l l y , w i t h r a r e s p h a l e r i t e , galena, ohalco-p y r i t e and t e t r a h e d r i t e . Quartz i s the predominant gangue m i n e r a l , w i t h a l s o c a l c i t e , b a r i t e and j a s p e r i n s m a l l amounts. -55A-(l),(2) PORTLAND CANAL AREA The commonest dykes are known as lamprophyre dykes. They are younger than the quartz-diorite dykes and commonly also younger than mineral deposits. Some are very like the felsites of the d i s t r i c t and are presumably related to them. Most of the so-called lamprophyres are narrow, dark-colored dykes suoh as are commonly present along the ast border of the Coast Range batholith and most of them may be related to the Coast Range intrusives. An uncommon type, a minette, occurs in the Silver Chord group. It is two feet wide and contains biotite, ortho-(1) clase and albite. Note: There i s a variety of silver, oopper, lead and zinc ores in the di s t r i c t but the descriptions do not present any relationship of the ore to the lamprophyres. Narrow, dark lamprophyre dykes are f a i r l y common and are the youngest rocks in the area. Some are older and some young-er than the ore deposits with which they are occasionally associated. The ores are veins and replacement deposits con-taining gold, silver and copper and are of the epithermal type. PREMIER MINE*3* ' ^ Ore. The deposit i s intermediate between epithermal and meso-(1) Hanson, G.: C.G.S. Mem. 175, Portland Canal Area, B.C. ((935) (2) Hanson, G.: C.G.S. Mem. 159, Bear River and Stewart Map Areas, Cassiar District, B.C. (1929). (3) Langille, E.G.: Some Controls of Ore Deposits at the Premier Mine, Western Miner, June, 1945. (4) Burton, W.D.: Ore Deposition at Premier Mine, B.C. Econom-ic Geology, Vol. 21, No. 6. (1926) -56A-thermal i n type and the ore m i n e r a l s are p r i m a r i l y p y r i t e i galena, s p h a l e r i t e and the r i o h s i l v e r m i n e r a l s . The most p r o d u c t i v e ore i s that o c c u r r i n g as f a i r l y s o l i d s u l p h i d e i n replacement type v e i n s ten to 30 f e e t wide i n f e l d s p a r por-phyry. The f e l d s p a r porphyry c o n s t i t u t e s a s t o c k o f the Coast Range b a t h o l i t h which has been i n t r u d e d i n t o v o l c a n i c s of the J u r a s s i c H a z e l t o n group. The ore s o l u t i o n s are be-l i e v e d to have o r i g i n a t e d from l a t e r g r a n o d i o r i t e of the Coast Range b a t h o l i t h which i n t r u d e s the e a r l i e r f e l d s p a r porphyry and v o l o a n i o s . The Lamprophyre Dykes. The m a j o r i t y o f lamprophyre dykes o c c u r r i n g i n the mine are p o s t - m i n e r a l but a few are d e f i n i t e l y m i n e r a l i z e d , so t h a t some, at l e a s t , are p r e - m i n e r a l . The lamprophyre dykes have a f a i r l y constant a t t i t u d e , g e n e r a l l y s t r i k i n g North 60 de-grees West and d i p p i n g 50 degrees s o u t h - e a s t e r l y and appear to be the r e s u l t of a p e r i o d of north-west f r a c t u r i n g a t the c l o s i n g stages o f the emplacement of the Coast Range batho-l i t h . The lamprophyre dykes are r e l a t e d to a north-west set of shear zones i n which much of the ore occurs s i n c e they both have the same g e n e r a l s t r i k e and d i p . The c l o s e time r e l a t i o n that some o f the lamprophyre dykes have to the ore i s i l l u s t r a t e d by some obs e r v a t i o n s by B u r t -(1) on who s t a t e s that\"...some e a r l i e r dykes i n t e r s e c t the min-( l ) Op. c i t . p 587 57A. e r a l i z e d zone i n a number o f p l a c e s and are s l i g h t l y m i n e r a l -i z e d near the edges as w e l l as showing s i m i l a r a l t e r a t i o n e f f e c t s to those induced i n the porphyry and greenstone as a r e s u l t o f the a c t i o n o f m i n e r a l i z i n g s o l u t i o n s . \" Burton s t a t e s f u r t h e r t h a t hypogene m i n e r a l i z a t i o n commonly spreads out on the hanging-wall and f o o t - w a l l o f the c r o s s - c u t t i n g dykes. I t pppears then, that some of the lamprophyre dykes are l a t e r than the main pa r t o f the m i n e r a l i z a t i o n p e r i o d s i n c e they cut aoross the ore zone but that c o n t i n u i n g c i r c u l a t i o n of s o l u -t i o n s i n the ore zone have m i n e r a l i z e d the s o l i d i f i e d dykes. This i s good evidence that the i n t r u s i o n o f some of the lampro-phyre dykes i s n e a r l y contemporaneous withv. the f o r m a t i o n of ore. (1) I t has a l s o been observed that some post-ore dykes de-l i m i t s i l v e r and gold v a l u e s i n the v e i n . The v e i n may con-tin u e on the o t h e r si d e o f the c r o s s - c u t t i n g dyke w i t h the same s t r u c t u r e and, m e g a s c o p i e a l l y , the same mineralogy t h a t i t had b e f o r e encountering the dyke, but w i t h the s i l v e r and gold v a l u e s reduced very c o n s i d e r a b l y . S i m i l a r phenomena have (2) been d e s c r i b e d a t Rossland where they were a t t r i b u t e d to i n -t r u s i o n of the dyke a f t e r v e i n formation but p r i o r to the l a t e r m i n e r a l i z a t i o n whioh formed the g o l d . Other Dykes Pr e s e n t. A p l i t e and c o a r s e - g r a i n e d d i o r i t e dykes a l s o occupy the 7---, Oral l i J Dr. W.H. White: P e r s o n a l Communication. (2) Drysdale, C.W.: C.G.S. Mem. 77. ( i 9'5) Ross land, B.C. -58A-n o r t h - e a s t f r a c t u r e s . The lamprophyre dykes cut the d i o r i t e type, i n d i c a t i n g t h e i r r e l a t i v e ages. Furthermore, the d i o r i t e dyke3 o c c u r r i n g w i t h i n the b a t h o l i t h i c rocks tend to merge wit h the host rock,whereas the lamprophyres, i n the same en-vironment, present d i s t i n c t , extremely f i n e - g r a i n e d , c h i l l e d edges showing that the host rock was comparatively c o o l a t the time i t was i n t r u d e d by the lamprophyre dykes. \" I t would seem, t h e r e f o r e , that the lamprophyre dykes and the contemporaneous Premier m i n e r a l i z i n g p e r i o d or p e r i o d s were v e r y l a t e phases of b a t h o l i t h i c a c t i o n . Although the lamprophyre dykes do not appear to exert a d i r e c t c o n t r o l on Premier ore-bodies, i t i s not s u r p r i s i n g t h a t , c o n s i d e r i n g t h e i r s i m i l a r i t y i n age, o r i -g i n and a t t i t u d e , w i t h the m i n e r a l i z e d north-west shear zones, (1) they are o f t e n a s s o c i a t e d w i t h o r e - b o d i e s . \" (2) TAKU RIVER AREA The on l y occurrence of lamprophyre d e s c r i b e d i s t h a t a t the M a n v l l l e ore-body, where b a s i o dykes o f lamprophyre type cut both the r h y o l i t e and the a n d e s i t e and are the youngest rocks of the s e r i e s . The only e f f e c t they seem to have on the ore-bodies i s to cause t h e i r s h a t t e r i n g and impoverishment w i t h i n c l u d e d dyke rock i n the.areas of i n t e r s e c t i o n . The ore i s probably a medium to low temperature type of d e p o s i t formed at a p p r e c i a b l e depth. Zi n c blende, c h a l c o p y r i t e , (1) L a n g i l l e , E.G.: Some C o n t r o l s of Ore Deposits a t the Prem-i e r Mine , Western Miner, June, 1945. (2) Mandy, J.T.: B.C. Dept. of Mines, B u l l . No 1, \u00E2\u0080\u00A21930, Report on the Taku R i v e r Area, A t l i n M ining D i v i s i o n . -59A-and p y r i t e w i t h minor q u a n t i t i e s of galena ooour i n v e r y f i n e -g r a i n e d t e x t u r e . A decided handing i s c h a r a c t e r i s t i c of these (1) ore b o d i e s . (2) ATLIN DISTRICT Only one lamprophyre occurrence i s d e s o r i b e d . T h i s i s on Mt. C l i v e , on the west sid e of Taku Arm, j u s t n o r t h of Graham I n l e t . No ore d e p o s i t i s r e l a t e d t o i t and the n e a r e s t depos-i t s to i t , r e f e r r e d to i n t h i s memoir, are seven m i l e s away. \"In p l a c e s , as on the n o r t h - e a s t e r n corner of Mt. C l i v e , b a s i c d i f f e r e n t i a t i o n products of the g r a n o - d i o r i t e occur as dykes c u t t i n g the g r a n o d i o r i t e and the surrounding Laberge beds.\" One such dyke on m i c r o s c o p i c examination was d e s c r i b e d as a hornblende k e r s a n t i t e , a t y p i c a l hypidiomorphic dyke rock c o n s i s t i n g mainly of p l a g i o c l a s e , b i o t i t e and hornblende. The p l a g i o o l a s e occurs i n long, l a t h - l i k e , a l l o t r i o m o r p h i e or hy-pidiomorphic forms. B i o t i t e and hornblende occur as a l l o t r i o -morphie p a r t i c l e s s o a t t e r e d between the f e l d s p a r s which form a (2) s o r t of web or base c o n t a i n i n g them. The d e s c r i p t i o n s o f the mining p r o p e r t i e s , i n c l u d i n g the Engineer mine do not mention lamprophyres. There i s one exam-p l e of s i l v e r ore composed of m i n e r a l i z e d diabase dyke. (1) Op. c i t . b i 5. (2) C a i r n e s , D.D.: C.G.S. Mem. 38, P o r t i o n s o f the A t l i n D i s t r i c t , B.C. (1913) -6 OA-CD MO. 8 OREBODIES, BRITANNIA MINES The dykes present i n No.8 orehody a r e : 1. A n d e s i t e dykes. These cut the ore hut some are m i n e r a l i z e d . 2. F e l s i t e porphyry dykes. These are p r o b a b l y l a t e r than the m i n e r a l i z a t i o n . 3. Lamprophyrio dykes. There are a number of narrow lamprophyrio dykes which s t r i k e north-west and d i p s t e e p l y to the west. They cut both the a n d e s i t e and the f e l s i t e dykes and are l a t e r than a l l of the m i n e r a l i z a t i o n . Note: During a v i s i t to B r i t a n n i a i n 1947, Dr. Sunning c o l l e c t e d specimens o f dykes i n d i c a t e d to him as b e i n g the lamprophyrio dykes d e s c r i b e d by I r v i n e . T h i n s e o t i o n s of these specimens have been examined.. The rocks do not appear to be lamprophyrio but, i n s t e a d , are f i n e - g r a i n e d , amygdaloid-a l , a n d e s i t i c rocks c o n t a i n i n g andesine l a t h s , ) . l mm. l o n g , as the l a r g e s t - g r a i n e d and most p l e n t i f u l c o n s t i t u e n t , t o g e t h e r w i t h a u g i t e , minor amounts of quartz and a c c e s s o r y magnetite. As Mr. I r v i n e was not present at the time o f Dr. Gunning's v i s i t , there i s a p o s s i b i l i t y t h a t those present at the mine then were not f a m i l i a r w i t h the c o r r e c t l o c a t i o n of the lampro-p h y r i o dykes which Mr. I r v i n e d e s c r i b e d s and that the wrong (1) I r v i n e , W.T.: Geology and Development of the No.8 Orebodies, B r i t a n n i a Mines, B.C., C.I.M.M. B u l l e t i n , 1946. -61A-dykes were p o i n t e d out to Dr. Gunning. B.C. COAST AMD ISLANDS BETWEEN THE STRAIT OF \u00E2\u0080\u0094m\u00E2\u0080\u0094 GEORGIA AND QUEEN CHARLOTTE SOUND There are dykea of a p l i t e , pegmatite, granophyre and f e l -a i t e i n the a r e a . Al80, there i a a vaat number o f dark dykes whoae i n t r u s i o n marked the c l o s e of igneous a c t i v i t y i n the d i s t r i c t . They cut the ore-bodies and although they have a t h i n selvage o f p y r i t e , they played a subordinate p a r t , i f any, i n m i n e r a l i z a t i o n . They are lamprophyrio i n appearance ( g r e y i s h - g r e e n to b l a c k ) , yet p l a g i o c l a s e e n t e r s i n t o t h e i r composition to a g r e a t e r extent than i n those dykes to which Rosenbusch a p p l i e s the term \"lamprophyre\". The phenocrysts are u s u a l l y p l a g i o c l a s e , l e s s f r e q u e n t l y o r t h o c l a s e , horn-blende or a u g i t e . B i o t i t e i s v e r y r a r e . These rocks might be c a l l e d diabases and d i o r i t e p o r p h y r i t e . (1) B a n c r o f t , J.A.\u00E2\u0080\u00A2 C.G.S. Mem. 23, Geology of the Coast and I s l a n d s between the S t r a i t of Georgia and Queen C h a r l o t t e Sound, B.C. (1913). -62A-BIBLIOGRAPHY OF PUBLICATIONS OTHER TEAM THOSE DISCUSSED IN THE TEXT Annotated i n P a r t Grout, F.F. ......Petrography and P e t r o l o g y , Geol. Soc. o f Am. B u l l . V o l . 48, No. 11, pp. 1521-1571 (Nov. 1937). Harker, A N a t u r a l H i s t o r y of Igneous Rooks, (1909) p. 112, pp. 117-118. Holmes, A Nomenclature of P e t r o l o g y , Murphy and Co., 1920. H u l i n , C D . . . . . . . F a c t o r s i n the l o c a l i z a t i o n of Mineraliz-ed D i s t r i c t s . A b s t r a c t , Econ. Geol. V o l . 39, No. 1 (Jan. - Feb., 1944). M e t a l l i z a t i o n from B a s i c Magmas, a Theory of Genesis f o r Hydrothermal and Emanation Types of Ore D e p o s i t s . C a l i f . Univ. Dept. of'Geol. Sciences B u l l . V o l . 18, No. 9, pp. 233-274, March, 1929. (Note: This i s out of p r i n t , a c c o r d i n g to a p e r s o n a l communication from Dr. H u l i n ( A p r i l , 1948.). Ore Genesis and Ore Shoots. E n g i n e e r i n g and Mining J o u r n a l , V o l . 127, pp. 228-230, 3.17-320 (1929). Barber, W.B.......On the Lamprophyres and A s s o c i a t e d Igneous Rocks of the Rossland M i n i n g D i s t r i c t , B.C. American G e o l o g i s t , V o l . XXXIII, p. 335. (1904). - P e t r o g r a p h i c d e s c r i p t i o n s o f lampro- \u00E2\u0080\u00A2 phyres. B a n c r o f t , M.F., Walker, J.F., Gunning, H.C....... Lardeau Map Area, B.C. G.S.C. Memoir 161 (1930). B a n c r o f t , M.F Gold B e a r i n g Deposits on the West Coast of Vancouver I s l a n d between Esperanza I n l e t and A l b e r n i Creek (1937). Brook, R.W1. Summary Report, Kootenay D i s t r i c t , G. G. S. Ann. Rept., V o l . X I I I , P. 70A (1900). P r e l i m i n a r y Report of Rossland, B.C., M i n i n g D i s t r i c t . C.G.S. Pub. No. 939, p.14 (1906). -63A-BIBLIOGRAPHY (oont'd) Bruoe, E.L Geology and Ore Dep o s i t s o f Rossland, B.C. B. C. Dept. o f Mines, B u l l . Ho. 4, 1917. - A Ph.D. Thesis on the Rossland Mines. Camsell, C Camp Hedley, Osoyoos Mining D i s t r i c t , B.C. C. G.S. Summary Report, 1907. C o c k f i e l d , W.E...Lode Cold Deposits o f F a i r v i e w Camp, Camp McKinney and V i d e t t e Lake Area, and the Dividend-Lakeview P r o p e r t y near Osoyoos, B.C. C.G.S. Memoir 179 (1935). - Apparently no lamprophyres are prese n t . Clapp, C H Southern Vancouver I s l a n d . C.G.S. Memoir 13, (1912). Dolmage, V C h i l k o Lake and V i c i n i t y , C.G.S. Summ. Rept, 1924. Part A. - A p p a r e n t l y no lamprophyres are r e p o r t e d . Geology and Ore Deposits o f Copper Mountain, B.C. (1934) C.G.S. Memoir 171. - Ho lamprophyres are re p o r t e d . The Cariboo and Bridge R i v e r G o l d f i e l d s , B.C. Trans. C.I.M.M. 1934, pp. 405-430. Drysdale, CW... .Rossland M i n i n g Camp. C.G.S. Summ. Rept, 1913. Anyox Map Area, Skeena M i n i n g D i s t r i c t . C.G.S. Summ. Rept. 1916. pp. 44-45. Hanson, G The Premier Mine. Trans. C.I.M.M. V o l . 25, pp. 225-232 (1922). The D o l l y Varden Mine. Trans. C.I.M.M. V o l . 25 (1922). Bowser R i v e r Area and the Horth P a r t o f P o r t -land Canal Area, B.C. C.G.S. Summ. Rept., 1931, pp. 14-21. Willow R i v e r Map Area, Cariboo D i s t r i c t , B.C. General Beology and Lode D e p o s i t s . C.G.S. Summ. Rept. 1933. -64A-BIBLIOGRAPHY (cont'd) Horwood, H.0..... Geology and M i n e r a l D eposits of the B.C. N i c k e l Mine, Yale D i s t r i c t , B.C. (1936). C.G.S. Memoir 190. - No r e f e r e n c e to lamprophyres could he found. James* H. T.. Features o f Pioneer Geology. The Miner, V o l . 7, No. 8, Aug. 1934, p. 347. B r i t a n n i a Beach Map Area, B.C. C.G.S. Memoir 158 (1929). Johnston, W.A. and Uglow, W.L P l a c e r and Ve i n Gold Deposits o f B a r k e r v i l l e , B.C. (1926). C.G.S. Memoir 149. Joralemon, I.B...Veins and F a u l t s i n B r a l o r n e Mine. Trans. A. I.M.E. Vol.. 115 (1935) pp. 90-103. - No d i s c u s s i o n of lamprophyres. A p l i t e dyke m a t e r i a l i s o f t e n i n c l u d e d i n the v e i n s . Le Roy. O.E .Phoenix Camp and Slocan D i s t r i c t . C.G.S. Summ. Rept., 1908 and 1910. Geology and Ore Deposits o f Phoenix, Boundary D i s t r i c t , B.C. (1912). C.G.S. MEMOIR 21. Mother Lode and Sunset Mines, Boundary D i s t r i c t , B. C. (1913). C.G.S. Memoir 19. MoConell, R.G....Texada I s l a n d , B.C. C.G.S. Memoir 58 (1914). - No lamprophyres r e p o r t e d . McNaughton, R.A..... Greenwood-Phoenix Area. C.G.S. Paper 45-20 (1945). Ransome, F.L. and C a l k i n s , F.C Cranbrook Area, U.S.G.S. P r o f e s s i o n a l Paper 62, 1908. Rice, H.M.A Cranbrook Map Area, B.C. (1937). C.G.S. Mem-o i r 207. Shannon, E.V....Petrography of Some Lamprophyfic Dyke Rocks, Coeur D'Alene Mining D i s t r i c t , Idaho. Proceedings of U.S. Nat. Museum, V o l . 57 (1917 - 1921). - Gives a l s o some r e l a t i o n s to ore d e p o s i t s . S t o c k w e l l , G.H. .Mayo, Yukon T e r r i t o r y , C.G.S. Summ. Rept, 1925. - App a r e n t l y no r e f e r e n c e s to lamprophyres are contained i n t h i s r e p o r t . -65A-BIBLIOGRAPHY (cont'd) Stevenson, J.S Twin-J Mine. Western Miner, V o l . 18, No.3, p. 38. March, 1945. Umpleby, J.B... Cranbrook Area,, J o u r n a l o f Geology, V o l . 20, (1912). Wilhelm, V.H... The Geology of the P o r t l a n d Canal D i s t r i c t , M ining and S c i e n t i f i c P r ess, V o l . 122 (1921). Wright, F.E.... The Unuk R i v e r M i n e r a l Region of B.C. G.S.C. Summ. Rept. (1905) Pp. 46g53. APPENDIX B MEGASCOPIC, PETROGRAPHIC AND FIELD-RELATION DESCRIPTIONS OF THE PYXES STUDIED TABLE OF CONTENTS Page Reeves-McDonald Mine IB S u l l i v a n Mine. 15B Mayflower Mine. E5B Le R o i Mine. 32B Br a l o r n e Mine 36B Pioneer Mine &3B Premier Mine 54B Ruth-Hope Mine 62B Photomicrographs \u00C2\u00A368 -SB-REBVBS-MODONALD MINE DYKE fflOO 1 FROM PORTAL OF \"RIVER ADIT\" - u n m i n e r a l i z e d -Megascopio D e s c r i p t i o n This specimen c o n s i s t s o f f i n e - g r a i n e d , \"black-coloured, f r e s h - a p p e a r i n g rock which c o n t a i n s g l i s t e n i n g b i o t i t e pheno-c r y s t s and o v a l pseudomorphs a f t e r o l i v i n e . Pseudomorphs a f t e r o l i v i n e have a maximum l e n g t h o f l / 5 i n c h , hut most are 2 mm. lo n g or l e s s . I n c l u s i o n s , up to two inches i n diameter, of both quartz and a f i n e - g r a i n e d , s i l i c e o u s rock are co n t a i n e d i n the lamprophyre. Thin S e o t i o n No. 1. The approximate m i n e r a l o g i o a l composition of t h i s rook p r i o r to a l t e r a t i o n was: O l i v i n e 35 $ B i o t i t e . 30 $ \u00E2\u0080\u00A2 D i o p s i d e 2 $ Andesine 20 $ A l k a l i F e l d s p a r 1 $ Quartz 10 $ w i t h a c c e s s o r y a p a t i t e and opaque m i n e r a l . A l t e r a t i o n has been e x t e n s i v e , o l i v i n e undergoing 50 to 100$ change and andesine 15-30$. The t e x t u r e i s p o r p h y r i t i c , w i t h o l i v i n e and b i o t i t e pheno-c r y s t s o c c u r r i n g i n a groundmass composed mainly o f andesine. -SB-L e a s e r amounts of a l k a l i n e f e l d s p a r , i n t e r s t i t i a l q u a r t z , d i o p s i d e , a p a t i t e and opaque m i n e r a l are a l s o p r e s e n t i n the groundmass. O l i v i n e -The most s t r i k i n g feature, of the rook i s the presence of l a r g e phenocrysts of o l i v i n e and pseudomorphs d e r i v e d from o l i v i n e ( P l a t e s 1 and 3). They are the l a r g e s t g r a i n s i n the s l i d e , b e i n g up to two mm. l o n g and they show remarkable a l -t e r a t i o n e f f e c t s . U n a l t e r e d , f r a c t u r e d o l i v i n e remains i n the center of the pseudomorph, w i t h i t s borders roughly p a r a l l e l to the o r i g i n a l o u t l i n e of the phenocryst,- surrounded by two d i s t i n c t , c o n c e n t r i c zones of a l t e r a t i o n p r o d u c t s . The o u t e r zone, much the l a r g e r of the two, c o n s i s t s of a brownish-black p u l v e r u l e n t mass which i s white i n r e f l e c t e d l i g h t . Although i n d i v i d u a l g r a i n s i n the mass are too s m a l l to be d i s t i n g u i s h -ed, the m a t e r i a l appears to have a h i g h b i r e f r i n g e n c e and the r e f r a c t i v e index as obtained by the use of immersion o i l s i s between 1,58 and 1.59. The mass shows a f a i n t c o n c e n t r i c band-i n g which i s due to f o u r or f i v e r e p e t i t i o n s of a l t e r n a t i n g dark and l i g h t c o l o r e d l a y e r s . Pine secondary magnetite p a r -t i c l e s are disseminated nea.r both the i n n e r and -outer edge o f t h i s zone. I t i s p o s s i b l e that the m a t e r i a l i n t h i s outer zone i s a carbonate, the l a o k of a great range i n i t s measured i n -d i c e s b e i n g perhaps due to the extremely f i n e - g r a i n e d aggregate nature of the m a t e r i a l . The outer zone grades r a p i d l y i n t o the c o l o r l e s s , low--4B-r e l i e f m a t e r i a l of the i n n e r zone which has a sharp, smooth contact w i t h o l i v i n e . The m i n e r a l of the i n n e r zone i s c o l o r -l e s s a n t i g o r i t e which under crossed n i c o l s shows a f i b r o u s s t r u c t u r e , b i r e f r i n g e n c e up to f i r t order yellow, and p a r a l l e l e x t i n c t i o n . I t i s b i a x i a l n e g a t i v e w i t h 2 V v a r y i n g from 30 degrees to 50 degrees. I t s index of r e f r a c t i o n as determined w i t h immersion o i l s i s between 1.55 and 1.56. O l i v i n e i n t h i s lamprophyre has a n e g a t i v e o p t i c s i g n and a l a r g e 2 V, between 85 degrees and 90 degrees. The. n e g a t i v e s i g n i n d i c a t e s that the o l i v i n e i s a f e r r i f e r o u s v a r i e t y . B i o t i t e -B i o t i t e occurs predominantly as phenocrysts which are up to two mm. l o n g but approximately 20 peroent of i t i s i n the form of s m a l l e r g r a i n s around 0.3 mm. i n s i z e . A l l the b i o t i t e g r a i n s , both l a r g e and s m a l l , are well-formed, although t h e i r borders a r e o f t e n i r r e g u l a r l y p enetrated by b l e b s of mixed o a l c i t e and c h l o r i t e , g i v i n g them a corroded appearance. I t i s p o s s i b l e that some o f t h i s o a l c i t e developed through a l -t e r a t i o n of small a u g i t e g r a i n s which f r e q u e n t l y occur enclosed p a r t i a l l y or wholly by b i o t i t e . There i s a f a i r l y w e l l - d e v e l -oped s p l i t t i n g of b i o t i t e p l a t e s a l o n g cleavage p l a n e s w i t h a development of elongated o a l c i t e bodies i n the c r a c k s . B i o t i t e i s brown and the l a t h s always have narrow, dark-brown h i S r < i e r s r e l a t i v e l y l i g h t brown i n t e r i o r s . Andesine -Andesine occurs i n f a i r l y l a r g e g r a i n s which average 0.2 - 5 B -mm. i n l e n g t h . The c r y s t a l s are faintly zoned and twinning a f t e r the a l b i t e law i s p r e s e n t to a s m a l l degree. Andesine i s about 50 peroent a l t e r e d . The a l t e r a t i o n products a r e : 1. o a l c i t e i n the form o f l a r g e * pure g r a i n s . 2. o a l c i t e , c l a y - m i n e r a l and p o s s i b l y o h l o r i t e i n t i m a t e l y mixed together. 3 . c l a y - m i n e r a l a l t e r a t i o n i n the form of d u s t - l i k e patches on the s u r f a c e of the andesine. A l k a l i F e l d s p a r -There are a few s m a l l g r a i n s of a f e l d s p a r whioh has an index d e f i n i t e l y lower than balsam. The g r a i n s are too s m a l l to give a s a t i s f a c t o r y f i g u r e . Quartz -Quartz occurs as c l e a r g r a i n s , g e n e r a l l y between 0.1 and 0 , 3 mm. i n dimension, whioh take t h e i r a ngular shape from the f e l d s p a r g r a i n s between which they have grown. Diopside -A o o l o r l e s s pyroxene resembling d i o p s i d e i s s c a t t e r e d i n the groundmass i n the form of s m a l l , r e c t a n g u l a r prism and f o u r or e i g h t - s i d e d c r o s s - s e o t i o n s . Very f r e q u e n t l y , s m a l l d i o p -s i d e g r a i n s are crowded together, around and i n oontaot w i t h o l i v i n e pseudomorphs. Deopside i s f r e q u e n t l y darkened by i n -c i p i e n t a l t e r a t i o n . A p a t i t e -W e l l formed, l a r g e a p a t i t e g r a i n s up to 0.2 mm. l o n g are p l e n t i f u l , A few g r a i n s are 0.6 mm. l o n g . -6B-. Opaque Mineral -Angular grains of a mineral which i s blaok and opaque i n transmitted l i g h t are scattered sparsely through the rock. In r e f l e c t e d l i g h t they are almost black i n color but have a faint, bronze t i n t . -7B-DYKE 4100 1 FROM PORTAL OF RIVER ADIT - w i t h a d h e r i n g g r a n i t i c i n -c l u s i o n -Thin S e c t i o n s Nos. 3 and 4. Another specimen o f the lamprophyre dyke 4100 f e e t from the p o r t a l was examined i n which a p o r t i o n of a g r a n i t i c i n c l u s i o n s e v e r a l inches i n diameter i s adhering to the lamprophyre. This specimen was taken from a l o c a t i o n i n the dyke o n l y a few f e e t away from that of the specimen s t u d i e d i n t h i n s e c t i o n No. 1. T h e r e f o r e , the lamprophyre i s almost i d e n t i c a l i n the two specimens hut there are some s l i g h t d i f f e r e n c e s which perhaps are due to some extent to the presence of the g r a n i t i c i n c l u s -i o n . These d i f f e r e n c e s w i l l he d e s c r i b e d below. A l t e r a t i o n of O l i v i n e . Pseudomorphs a f t e r o l i v i n e are of the same l a r g e s i z e as i n Se c t i o n 1 but the a l t e r a t i o n i s d i f f e r e n t . In s e c t i o n 3, no r e s i d u a l o l i v i n e remains and alth o u g h the two d i s t i n c t outer zones of a n t i g o r i t e and carbonate(?) are present, they are i n much s m a l l e r amount. The i n t e r i o r a r e a surrounded by the two rims c o n t a i n s a t a l c - l i k e m a t e r i a l i n two of the pseudomorphs, whereas the remaining pseudomorphs c o n t a i n a d i f f e r e n t m a t e r i a l . The t a l c - l i k e m i n e r a l has. the f o l l o w i n g p r o p e r t i e s i n t h i n s e c t i o n . I t i s n e a r l y c o l o r l e s s but has a s l i g h t g r e e n i s h -grey t i n g e , i t s r e l i e f i s low to f a i r and v a r i e s d i s t i n c t l y as the stage i s r o t a t e d . The s t r u c t u r e i s f i b r o u s but the f i b e r s are s u f f i c i e n t l y broad to g i v e i n t e r f e r e n c e f i g u r e s whioh are -SB-n e g ative and e i t h e r u n i a x i a l or b i a x i a l w i t h 3 V very c l o s e to zero. The f i b e r s have p a r a l l e l e x t i n c t i o n and are l e n g t h slow. The maximum b i r e f r i n g e n c e i s 0.035. These p r o p e r t i e s agree w i t h t a l o except f o r the s l i g h t c o l o r and v a r i a b l e r e -l i e f . The unknown m i n e r a l more commonly o c c u r r i n g i n the c e n t r a l p o r t i o n o f pseudomorphs i s c o l o r l e s s , has a v e r y low r e l i e f which does not v a r y a p p r e c i a b l y on r o t a t i o n and an index g r e a t e r than balsam. The s t r u c t u r e i s a l s o f i b r o u s but the f i b e r s are very f i n e and no i n t e r f e r e n c e f i g u r e was obtained. The f i b e r s have p a r a l l e l e x t i n c t i o n and are l e n g t h f a s t . The maximum b i r e f r i n g e n c e i s 0.03. In t h i n s e c t i o n Ho. 4 of the same rock specimen, c o n s i d -e r a b l e r e s i d u a l o l i v i n e does remain, the two outer c o n c e n t r i c zones of a n t i g o r i t e and carbonate(?) are present to a s m a l l degree and there are a l s o the two products, t a l c ( ? ) and the unknown, d e s c r i b e d i n s e c t i o n 3 but they are not so p l e n t i f u l as they were i n s e c t i o n 3. B i o t i t e . -In both s e c t i o n s 3 and 4, the b i o t i t e shows be g i n n i n g stages of c h l o r i t i z a t i o n . Green borders on the b i o t i t e g r a i n s are w e l l developed and t h i s e f f e c t i s most pronounced near the c o n t a c t w i t h the g r a n i t i c i n c l u s i o n . C h l o r i t i z a t i o n o f the b i o t i t e i n t h i n s e c t i o n 1 was almost e n t i r e l y l a c k i n g . -9B-REBVES-MACDONALD MINE DYKE 3000'FROM PORTAL OF RIVER ADIT - m i n e r a l i z e d -In the hand specimen, t h i s rock i s v e r y s i m i l a r to t h a t of the dyke 4100' from the p o r t a l , ( d e s c r i b e d above) except t h a t i t has a g r e y i s h - g r e e n c o l o r and c o n t a i n s b l a c k r a t h e r than g r e y - c o l o r e d pseudomorphs a f t e r o l i v i n e . These d i f f e r e n c e s are due to a l t e r a t i o n of the dyke by m i n e r a l i z i n g s o l u t i o n s which a l s o deposited g r a i n s of m e t a l l i c m i n e r a l s , b a r e l y v i s i b l e to the naked eye, i n the groundmass of the rook. Thin S e c t i o n No.2. P o l i s h e d S e c t i o n No.2(a). This lamprophyre dyke has been m i n e r a l i z e d w i t h p y r i t e and galena. In t h i n s e c t i o n No. 2, i t s composition i s : Talc-Hematite Pseudomorphs 30 fo B i o t i t e . . . . . ., 15 fo Carbonate 40 f> F e l d s p a r , 5 f> Quartz 2 fo Sulphides 3 fo A p a t i t e aocessory Magnetite a c c e s s o r y The o r i g i n a l o l i v i n e has been completely a l t e r e d and the o r i g -i n a l f e l d s p a r almost completely a l t e r e d . The rock seems to be s i m i l a r to that of \" R i v e r A d i t 4100' -10B from p o r t a l \" except t h a t : 1. d i o p s i d e i s absent 2. a p a t i t e i s more p l e n t i f u l 3. b i o t i t e i s bleached and c h l o r i t i z e d s l i g h t l y and has a g r e a t e r development o f c a l o i t e a l o n g cleavage p l a n e s . 4. a l t e r a t i o n o f the groundmass t o carbonate i s much more complete. 5. s u l p h i d e s have been i n t r o d u c e d . Talc-Hematite Pseudomorphs -The pseudomorphs, 1 to 2 mm. i n s i z e , have a r o u g h l y oval shape s i m i l a r to t h a t o f the l a r g e o l i v i n e phenocrysts i n the lamprophyre 4100' from the p o r t a l . No r e s i d u a l o l i v i n e r e -mains, the t r a n s f o r m a t i o n to t a l c and hematite has been com-p l e t e and none of the a l t e r a t i o n p roducts are prese n t which were found i n the a l t e r e d o l i v i n e o f the dyke 4100' from the p o r t a l . The t a l c i s c o l o r l e s s and occurs i n broad f i b e r s which have p a r a l l e l e x t i n c t i o n and are l e n g t h slow. 2 V i s 20 degrees and the o p t i c s i g n i s n e g a t i v e . The maximum b i r e f r i n g -ence i s 0.04 and the i n d i c e s as determined by the use of im-mersion o i l s are Np- 1.55, Ng* 1.58. T h i s s m a l l range f o r the i n d i c e s i s probably due to the constant o r i e n t a t i o n of cleavage f l a k e s i n the immersion o i l s . The pseudomorphs have a d i s t i n c t i v e appearance i n hand specimen and on p o l i s h e d s u r f a c e s . They have a dark red c o l o r -11B-whioh i s e s p e c i a l l y n o t i c e a b l e i n p o l i s h e d s e c t i o n under i n -d i r e c t r e f l e c t e d l i g h t . T h i s c o l o r i s due to the very f i n e g r a i n s of a m e t a l l i c m i n e r a l , a p p a r e n t l y hematite, which are b r i g h t red i n - i n d i r e o t l y r e f l e c t e d l i g h t and occur i n the t a l c w i t h an arrangement sugge s t i n g \"mesh-structure\". Most of the hematite g r a i n s are opaque i n t r a n s m i t t e d l i g h t but a few of the t h i n n e s t g r a i n s are t r a n s l u c e n t and red i n t r a n s m i t t e d l i g h t . A s s o c i a t e d w i t h the hematite are a few magnetite g r a i n s . Grains of p y r i t e and galena such as occur abundantly i n the groundmass of the r o c k are extremely r a r e i n the pseudo-morphs. B i o t i t e -B i o t i t e has a p a l e , bleached-brown c o l o r and about 20 per-cent of the g r a i n s have a green c o l o r and lowered b i r e f r i n g e n c e i n d i c a t i n g a t r a n s f o r m a t i o n to c h l o r i t e . There i s s p l i t t i n g and o a l o i t e growth along the cleavage to a g r e a t e r degree than i n the 4100' lamprophyre, some of the g r a i n s being s p l i t i n t o separated shreds. Carbonate -Carbonate i s very p l e n t i f u l and i s the l a r g e s t component of the groundmass. It. i s , no doubt, i n p a r t d e r i v e d from the late-magmatic a l t e r a t i o n of f e l d s p a r . However, 4s the carbon-ate i s so much more ext e n s i v e than i s u s u a l l y the case, i t i s most probable that a l a r g e p r o p o r t i o n i s due to c a r b o n a t i z a t i o n by m i n e r a l i z i n g s o l u t i o n s . F e l d s p a r was the m i n e r a l most -12B-a f f e c t e d by t h i s metasomatism. Carbonate c o n t a i n s i n t e r m i x e d o l a y m i n e r a l , a p a t i t e , quartz and r e s i d u a l f e l d s p a r . In a d d i t i o n , the s u l p h i d e g r a i n s whioh a p p a r e n t l y have been in t r o d u c e d by m i n e r a l i z i n g s o l u t i o n s , are c l o s e l y a s s o c i a t e d w i t h the carbonate and most o f t e n occur between the carbonate and r e s i d u a l f e l d s p a r or quartz g r a i n s . Clay M i n e r a l -There a r e , among the c a l c i t e g r a i n s , f i n e - g r a i n e d masses o f c l a y m i n e r a l which are brownish by t r a n s m i t t e d l i g h t and white by r e f l e c t e d l i g h t . F e l d s p a r -Very l i t t l e f e l d s p a r i s l e f t and i t i s much clouded by a l t e r a t i o n . -No twinning could be seen although there were shadowy suggestions of i t . The r e f r a c t i v e index appears to be g r e a t e r than balsam but t h i s too i s i n doubt. One i n t e r -f e r e n c e f i g u r e with 2 V = 90\u00C2\u00B0 was obt a i n e d . Quartz -A few g r a i n s of quartz are s c a t t e r e d i n the matrix. The g r a i n s are f r e s h but c o n t a i n s m a l l i n c l u s i o n s which have been a l t e r e d . A p a t i t e -U n a l t e r e d , euhedral a p a t i t e g r a i n s a re extremely p l e n t i f u l . Magnetite -Very few s m a l l g r a i n s o f acce s s o r y magnetite occur i n the groundmass. -13B S u l p h i d e s -The m e t a l l i c m i n e r a l i z a t i o n of the lamprophyre c o n s i s t s p r i m a r i l y o f a s c a t t e r i n g o f p y r i t e and galena g r a i n s i n the carbonatized groundmass. Very r a r e l y do s u l p h i d e s occur i n the pseudomorphs a f t e r o l i v i n e . The two s u l p h i d e s are i n the approximate r a t i o of two p y r i t e to one galena and together corn-r i s e about three percent o f the rock. In s i z e , the g r a i n s are .05 mm. on the average but a few g r a i n s are up to 0.5 mm. i n maximum dimension. O c c a s i o n a l l y p y r i t e and galena are i n c l o s e a s s o c i a t i o n w i t h each other, one m i n e r a l e n c l o s i n g the other, or a g r a i n of galena may occur i n contact w i t h and have a smoothly curved contact a g a i n s t a g r a i n of p y r i t e . In the m a j o r i t y o f eases, however, i n d i v i d u a l p y r i t e and galena g r a i n s occur independent-l y o f each other, being widely separated from mutual contact by the c a r b o n a t e - f e l d s p a r - q u a r t z groundmass i n which most o f them occur. I t i s d i f f i c u l t to judge from the appearance o f the s u l -phide g r a i n s whether or not they were formed by replacement o f rock m i n e r a l s , nor i s there any c o n c e n t r a t i o n o f s u l p h i d e s along f r a c t u r e s or towards any p a r t i c u l a r p o r t i o n of the s l i d e . The q u i t e uniform d i s s e m i n a t i o n o f the s u l p h i d e s i n the ground-mass i s not u n l i k e t h a t o f o r i g i n a l opaque m i n e r a l g r a i n s c r y s t a l l i z i n g d i r e c t l y from the rock magma. However, no euhed-r a l g r a i n s were seen as would be expected i n c r y s t a l l i z a t i o n from a magma; the g r a i n s a re g e n e r a l l y i r r e g u l a r l y rounded - 1 4 B -and q u i t e commonly send out curved* t a p e r i n g tongues i n t o the e n c l o s i n g m a t e r i a l . U s u a l l y * .the s u l p h i d e g r a i n s are found between areas o f carbonate on one s i d e and a r e l i c of f e l d s p a r on the other s i d e . Sometimes the s u l p h i d e a l s o p r o j e c t s i n t o b i o t i t e g r a i n s and, i n one case, p y r i t e cut r i g h t through a b i o t i t e g r a i n i n a d i r e c t i o n p e r p e n d i c u l a r to the b i o t i t e cleavage. There i s , however, no replacement o f b i o t i t e a l o n g the cleavage or around the edges of the g r a i n as i s the case i n the m i n e r a l i z e d lamprophyre from the S u l l i v a n mine. The most probable i n t e r p r e t a t i o n o f the occurrence of s u l -phides i n t h i s lamprophyre i s that the whole dyke mass was soaked w i t h m i n e r a l i z i n g s o l u t i o n s , c a u s i n g the extreme a l t e r -a t i o n of the o l i v i n e , c a r b o n a t i z a t i o n of the groundmass, c h l o r - -i t i z a t i o n of the b i o t i t e and d e p o s i t i o n o f the s u l p h i d e s . SULLIVAN MINE 3904 Crosscut, Sou//, Wo// + 1 3 ' ) 3/)CK OF- XzStZ\u00E2\u0080\u0094Jt-f~ L.OOR or X-Cu-r Saa/e: /\"=6 L. 00 ki Sou//j HEY I I /7rji//;/e ana Ji Ifs/onC b e d s Low -grade rock- 6e c/d/nqf a fOCf r-rJm/naf/C < -^r PI A///7effe A/o/e : 7*e /8 - //7C/7 rec/onj rerr-e y J-^Oivrr \u00C2\u00AB*//f^ e?trc/cjy rr>, r; /> p * > c \u00E2\u0080\u009E f/c ^r^.-fe s>efe. of\" l%f s t / / \u00C2\u00BB e ~Jie /there. S/7 *7/' -16B-SULLIVAN MINE DYKE 3904 CROSSCUT, SOUTH WALI - i n con t a c t with \"low-grade\" ore -Thin S e o t i o n Ho. S.35. The R e l a t i o n Between the Lamprophyre and the Ore* T h i s specimen from the S u l l i v a n mine i s of b i o t i t e lampro-phyre to which a p i e c e of banded \"low-grade\" s u l p h i d e ore i s f i r m l y a t t a c h e d ( P l a t e 3 ) . The lamprophyre dyke i s l a t e r than the ore as i3 a t t e s t e d by i t s q u a r t e r - i n c h c h i l l e d border a g a i n s t the ore and by the fl o w - and e d d y - l i n e s t r a c e d i n the lamprophyre by b i o t i t e and s u l p h i d e g r a i n s . I t i s even poss-i b l e to deduce the d i r e c t i o n i n which the lamprophyre f l u i d t r a v e l l e d by ob s e r v i n g the r i p p l e - m a r k - l i k e eddies produoed i n the lamprophyre by promontories and embayments o f the ore s u r -f a c e . There i s some i n c r e a s e i n the su l p h i d e content of the lampro phyre at the contact but t h i s added m a t e r i a l occurs as f i n e (.04 mm.) p y r r h o t i t e p a r t i c l e s arranged i n s t r e a m e r - l i k e bands which l i e p a r a l l e l to the c o n t a c t . Such an appearance does not suggest impregnation of the s o l i d i f i e d lamprophyre by s u l p h i d e s from the ore s o l u t i o n s but r a t h e r suggests that the p a r t i c l e s had d i s i n t e g r a t e d and been plucked from the s o l i d ore by mov-i n g lamprophyrio f l u i d . Another f e a t u r e which i n d i c a t e s that the ore i s pre-dyke i s the apparent absence of any replacement of lamprophyre by ore m i n e r a l s . There i s no embayment and no - 1 7 B -v e l n i n g of the dyke by ore, the pronounced sedimentary handing i n the ore continues.without d e v i a t i o n r i g h t up to the c o n t a c t where i t suddenly s t o p s . I t i s p o s s i b l e however, i f one wish-es to p o s t u l a t e a post-dyke age f o r the ore, t h a t the ore s o l -u t i o n s r e p l a c e d the host rock c o n s t i t u e n t s but were i n e q u i -l i b r i u m w i t h the m i n e r a l s of the lamprophyre a t the c o n d i t i o n s o b t a i n i n g during ore f o r m a t i o n . I t i s more l i k e l y , though, i n the l i g h t of a l l the evidence, that the lamprophyre i s p o s t -ore. D e s c r i p t i o n of the Ore The ore of t h i s specimen i s composed mainly of s u l p h i d e s (70 p e r c e n t ) . The s u l p h i d e s are p y r r h o t i t e , s p h a l e r i t e and a l i t t l e galena, w i t h q u a r t z , f e l d s p a r and b i o t i t e as the c h i e f gangue m i n e r a l s together w i t h minor amounts of amphibole and c h l o r i t e . The ore i s s t r o n g l y banded, a r e s u l t of p r e f e r e n t -i a l replacement along bedding planes o f the sedimentary host rock. There i s a l a r g e amount of o a l c i t e i n the ore adjacent to the c o n t a c t , whereas there i s v e r y l i t t l e or no o a l o i t e i n the ore elsewhere and no comparable amounts o f c a l c i t e i n the lamprophyre. The presence o f t h i s o a l c i t e may be due to e i t h e r the metasomatio e f f e c t s of emanations from the f l u i d lampro-phyre or to s o l u t i o n s of another o r i g i n t r a v e l l i n g a l o n g the c o n t a c t . D e s c r i p t i o n o f the Lamprophyre The lamprophyre i t s e l f i s unique among the specimens so f a r s t u d i e d i n that i t i s so l a r g e l y composed of b i o t i t e w i t h a l --18B most n e g l i g i b l e amounts of o r y p t o o r y s t a l l i n e , c o l o r l e s s base. I t s composition i s : Phenocrysts B i o t i t e . . . 7 % \"Amphibole Aggregations\"........ 10 $ Groundmass B i o t i t e 80 $ C o l o r l e s s Base 2 % A p a t i t e . a c c e s s o r y P y r r h o t i t e \u00E2\u0080\u00A2 .accessory B i o t i t e , euhedral both i n phenocrysts and i n the groundmass, i s v e r y bleached, p l e o c h r o i c from straw-yellow to c o l o r l e s s and has dark rims. I t has not been c h l o r i t i z e d . The phenocrysts are up to 0.6 mm. l o n g but there are a l l g r a d a t i o n s from t h i s s i z e down to o r y p t o o r y s t a l l i n e . There are o n l y three a r e a s , a l l except one b e i n g at the contact, i n which could be d e t e c t e d m a t e r i a l which might con-t a i n f e l d s p a r . This m a t e r i a l i s c o l o r l e s s , shows no d i s c e r n -i b l e g r a i n i n g but g i v e s s p h e r u l i t i o e f f e c t s under c r o s s e d -n i c o l s . The only other major element i n the lamprophyre c o n s i s t s o f aggregates, of v a r i o u s minerals grouped together i n masses which are v a r i o u s l y t a b u l a r , rhombic, hexagonal or p a r t l y rounded i n shape and up to 2 mm. i n s i z e . Some of these con-t a i n a dozen or more c o l o r l e s s amphibole g r a i n s but the major-i t y have v a r y i n g amounts of o a l c i t e , c h l o r i t e , q u a r t z , b i o t i t e -19B-and p y r r h o t i t e as w e l l . The c h l o r i t e , and p o s s i b l y the o a l -c i t e , are derived from amphibole by a l t e r a t i o n . The quartz occurrences are r a r e and the o r i g i n o f the quartz i s i n doubt. These aggregations may be a l t e r e d i n c l u s i o n s of country rock p i c k e d up by the lamprophyrio f l u i d . The amphibole g r a i n s have c h a r a c t e r i s t i o diamond-shaped c r o s s - s e c t i o n s and oleavage. They are c o l o r l e s s but v e r y f a i n t l y p l e o c h r o i c to a f e e b l e y e l l o w c o l o r . The amphibole i s o p t i c a l l y n e g a t i v e , has 3 V\" \u00C2\u00AB 85\u00C2\u00B0, maximum e x t i n c t i o n angle of 88 degrees and upper f i r s t - o r d e r i n t e r f e r e n c e c o l o r s . There appears to be no c o l o r l e s s amphibole i n d i v i d u a l s i n the ground-mass, they a l l occur i n the a g g r e g a t i o n s . C h l o r i t e , whioh i s a f t e r amphibole, i s c o l o r l e s s but v e r y f a i n t l y p l e o c h r o i c and has anomalous brown and blue i n t e r f e r -ence c o l o r s . P y r r h o t i t e , where i t occurs i n the aggregates ( P l a t e 3 ) , has a l o n g , r a m i f y i n g , b l a d e - l i k e h a b i t which may be due to c r y s t a l l i z a t i o n between angular g r a i n s of an e a r l i e r age or the p y r r h o t i t e may be pseudomorphic a f t e r r e p l a c e d amphibole or b i o t i t e c r y s t a l s . P y r r h o t i t e i n the groundmass of the lampro-phyrd i s very s p a r s e l y d i s t r i b u t e d as 0.04 mm. g r a i n s . Ho magnetite was seen. A p a t i t e i s p l e n t i f u l i n the groundmass. -20B-DYKE, 3904 CROSSCUT - contains i n c l u s i o n s of \"low-grade\" ore and i s m i n e r a l i z e d -Thin S e c t i o n S.36. P o l i s h e d S e c t i o n S 36. In t h i s specimen, b i o t i t e lamprophyre c o n t a i n s t h r e e -q u a r t e r - i n c h i n c l u s i o n s of \"low-grade\" s u l p h i d e ore and, i n a d d i t i o n , appears to be i t s e l f m i n e r a l i z e d by g a l e n a - r i c h ore of an age l a t e r than that of the lamprophyre. D e s c r i p t i o n of the Lamprophyre. The d e s c r i p t i o n of the lamprophyre of specimen S 35 a p p l i e s e q u a l l y w e l l to the rock of t h i s specimen w i t h the ex-c e r p t i o n t h a t the sulphide contained i n the o a l c i t e - q u a r t z -c h l o r i t e aggregates i s p y r i t e i n s t e a d of p y r r h o t i t e . In a d d i -t i o n , a few s m a l l galena g r a i n s a re a s s o c i a t e d w i t h the p y r i t e . The \"aggregations\" have the same s i z e (0.3 mm. to 2 mm.) as those i n the pre v i o u s specimen and as before are d i s t r i b u t e d i r r e g u l a r l y through the s e o t i o n . No amphibole was observed i n them i n t h i s oase but some c h l o r i t e i s pseudomorphic a f t e r amphibole and i n d i c a t e s that amphibole was o r i g i n a l l y p r e s e n t . \"\"Cow-Grade1' Ore I n c l u s i o n s . In a d d i t i o n to the small aggregations d e s c r i b e d above, there are l a r g e (j? - 2 Inch diameter) i n c l u s i o n s of ore. These c o n s i s t o f s u l p h i d e s p r i m a r i l y (70 p e r c e n t ) , but c o n t a i n a l s o c a l c i t e , t r e m o l i t e , c h l o r i t e and quartz i n that order of abun-dance. The su l p h i d e i s mostly p y r i t e and s p h a l e r i t e but - S I B -* s m a l l e r amounts of galena a r e - a l s o p r e s e n t . No p y r r h o t i t e was : ;seen. Rough handing due to the replacement o f sedimentary beds i s d i s c e r n i b l e i n the i n c l u s i o n s . The presence of these i n c l u s i o n s i n the.lamprophyre i s p r o o f t h a t the lamprophyre i s younger than the \"low-grade\" ore. Judging from the s i m i l a r i t i e s i n the n o n - m e t a l l i c m i n e r a l s o c c u r r i n g i n both the l a r g e ore i n c l u s i o n s and i n the s m a l l e r aggregations, the two might be of the same o r i g i n . But the m e t a l l i c m i n e r a l s present are d i f f e r e n t and t h e i r c r y s t a l form i s d i f f e r e n t . In the l a r g e ore i n c l u s i o n s , p y r i t e , s p h a l e r i t e and galena are present whereas the s m a l l aggregations c o n t a i n o n l y p y r i t e and sometimes a few specks of galena. A l s o , the p y r i t e i n the aggregations i s c r y s t a l l i z e d i n l o n g , narrow b l a d e - l i k e forms t o t a l l y u n l i k e the normal c u b i c h a b i t p r e v a l -ent i n the ore i n c l u s i o n s . I t i s p o s s i b l e that the s m a l l ag-g r e g a t i o n s , as suggested f o r specimen S 3 5 , are i n c l u s i o n s o f m i n e r a l i z e d country rook which were picked up by the lampro-p h y r i o f l u i d . The \"High-Grade\" Ore Band. The f e a t u r e of the specimen which arouses s p e c i a l i n t e r e s t i s the presence of a t h i n c o a t i n g of \" r i c h \" ore a l o n g one s i d e o f the lamprophyre. T h i s l a y e r i s l / l 6 i n o h or l e s s i n t h i c k -ness and c o n s i s t s p r i m a r i l y of galena. There are a l s o s m a l l e r amounts of s p h a l e r i t e and p y r i t e w i t h the galena. This i s the o n l y p l a c e i n the specimen i n which galena i s more p l e n t i f u l than the other two s u l p h i d e s . The gangue mi n e r a l s p r e s e n t are 22B-e o l o r l e s s c h l o r i t e , carbonate, quartz and v e r y l i t t l e b i o t i t e . The p r o p o r t i o n of gangue i n the ore i s c o n s i d e r a b l y h i g h e r than i t i s i n the \"low-grade\" ore i n c l u s i o n s s i n c e the percentage of s u l p h i d e s present i s l e s s than 40 percent. The s u l p h i d e s are not c r y s t a l l i z e d i n suoh a massive form as they are i n the i n c l u s i o n s , the galena p a r t i c u l a r l y o c c u r r i n g i n f i n e g r a i n s of i r r e g u l a r l y rounded, sometimes t w i s t e d h a b i t . D e s c r i p t i o n of the Contact Zone. At the contact w i t h t h e \"high-grade\" ore, the lamprophyre appears to have flow s t r u c t u r e p a r a l l e l to the c o n t a c t . I t i s , however, i m p e r f e c t l y deyeloped, the b i o t i t e phenocrysts showing some tendency to be p a r a l l e l to the c o n t a c t but the problem being somewhat confused i n the t h i n s e c t i o n by the f a c t t h a t the \"contact i s s h a r p l y bent w i t h the r e s u l t t h a t some b i o t i t e l a t h s do not f a l l Into l i n e . However, i t seems f a i r l y c l e a r i n the p o l i s h e d s e o t i o n that there i s l i n e a t i o n p a r a l l e l to the c o n t a c t . A c h i l l e d margin a g a i n s t the ore i s not e v i d e n t i n t h i s specimen. The galena m i n e r a l i z a t i o n seems t o be post-lamprophyre. In the p o l i s h e d s e c t i o n , there i s a t a p e r i n g tongue of galena l / 8 i n c h i n l e n g t h which p r o j e c t s i n t o the lamprophyre near one of the \"low-grade\" i n c l u s i o n s . This seems to be v e r y good e v i -dence that the galena i s l a t e r i n o r i g i n than the lamprophyre. Another phenomenon, which oan be observed i n both the t h i n seo-t i o n and the p o l i s h e d - s e c t i o n , i s the presence of s m a l l galena and some p y r i t e g r a i n s i n the lamprophyre which are d e f i n i t e l y -23B oonfined to a narrow zone a l o n g the c o n t a c t . This zone i s one-quarter i n c h t h i c k and although i t i s somewhat l i g h t e r i n c o l o r , i t i s r e c o g n i z a b l y lamprophyre due to the presence o f brown b i o t i t e l a t h s . The galena g r a i n s are g e n e r a l l y l e s s than .02 mm. i n s i z e and v e r y i r r e g u l a r l y rounded i n shape. On s t u d y i n g the galena g r a i n s i n t h i n s e c t i o n i t can be seen that they do not r e p l a c e b i o t i t e c r y s t a l s to any e x t e n t . Three or four i n s t a n c e s were seen, however, i n which narrow galena bands are l o c a l i z e d a long the edges of b i o t i t e g r a i n s . This type of occurrence suggests that the c o n t a c t between the b i o t i t e c r y s t a l and the f i n e groundmass was a focus f o r the d e p o s i t i o n of galena. The galena a l s o appears to cut i n t o - the b i o t i t e to a s l i g h t extent. One example was seen of a d i f f e r -ent r e l a t i o n between b i o t i t e and galena i n which a narrow, t r a n s v e r s e crack i n the b i o t i t e was f i l l e d w i t h galena. Re-placement of b i o t i t e a l o n g cleavage planes was not seen. P r a c t i c a l l y a l l the galena (and the s m a l l amount of p y r i t e a s s o c i a t e d w i t h i t ) occurs i n the extremely f i n e - g r a i n e d groundmass of the lamprophyre. I t does not seem f e a s i b l e to e x p l a i n the presence of galena g r a i n s i n the lamprophyre by assuming a mechanical process of p l u c k i n g of galena from the s o l i d i f i e d ore by supposedly young-er lamprophyre. I f t h i s had occured, the galena g r a i n s should be more angular than they a r e , and i n a d d i t i o n should be accom-panied by s p h a l e r i t e and p y r i t e , both of which are p l e n t i f u l i n the adhering band of ore. In t h i s connection, i t i s ex-\u00E2\u0080\u00A224B-tremely important to note t h a t the galena i n the ore hand i t -s e l f has a replacement r e l a t i o n to the c h l o r i t e and b i o t i t e of the ore and a l s o , but l e s s c o n c l u s i v e l y , to the p y r i t e and s p h a l e r i t e of the ore, The above ob s e r v a t i o n s l e a d one to the f a i r l y c e r t a i n con-c l u s i o n that the t h i n ore band had s o l i d i f i e d p r i o r to the i n -t r u s i o n of the lamprophyre but contained o n l y p y r i t e and s p h a l e r i t e at that time. At a subsequent stage, a f t e r the lamprophyre had s o l i d i f i e d , galena m i n e r a l i z a t i o n took p l a c e , oausing the replacement of p r e v i o u s l y formed m i n e r a l s of the ore band by galena and an i n t r o d u c t i o n of galena i n t o the lamprophyre i n a t h i n zone a l o n g the c o n t a c t . The presence of galena i n the low-grade i n c l u s i o n s must be e x p l a i n e d by p o s t u l a t i n g a s m a l l amount of galena m i n e r a l i z a t i o n before the i n t r o d u c t i o n of the lamprophyre. I t i s to be noted here that there i s very much more galena i n the \"low-grade\" i n -c l u s i o n nearest to the \"high-grade\" ore band than i n those f a r t h e r away from the c o n t a c t . With the p o l i s h e d s e o t i o n miorosoope, t h i s galena can be seen to r e p l a c e p y r i t e of the i n c l u s i o n . -25B-ROSSLAND DISTRICT - MAYFLOWER MINE MAIN LEVEL Thin S e o t i o n No. M54 - c o n t a c t a g a i n s t ore. P o l i s h e d S e o t i o n M54 - lamprophyre a t c o n t a c t . T h i n S e c t i o n No. M35 - middle of dyke. P o l i s h e d S e c t i o n M56 - the ore a t c o n t a c t . INTRODUCTION. A study was made o f specimens from a lamprophyre dyke which cuts and i s c h i l l e d a g a i n s t heavy s u l p h i d e ore. The lamprophyre, a b l a c k , f r e s h - a p p e a r i n g k e r s a n t i t e , w i t h b i o t i t e phenocrysts, appears to have been m i n e r a l i z e d a l o n g i t s con-t a c t w i t h the ore. M i c r o s c o p i o a l l y , the lamprophyre i n the middle of the dyke i s seen to c o n t a i n phenocrysts of b i o t i t e and d i o p s i d e , about 0.6 mm. long , i n a h o l o c r y s t a l l l n e , e q u i g r a n u l a r groundmass composed p r i m a r i l y o f euhedral f e l d s p a r and b i o t i t e . The g r a i n - s i z e of the groundmass i n the middle of the dyke averages 0,15 mm. but at the dyke's edge the g r a i n i s much f i n e r and o c c a s i o n a l l y the f e l d s p a r i s c r y p t o c r y s t a l l i n e and s p h e r u l i t i o . D e s c r i p t i o n o f the Lamprophyre ( T h i n S e c t i o n s Nos. M34 and M55) The composition of un m i n e r a l i z e d lamprophyre i s as f o l l o w s : Phenocrysts D i o p s i d e .25 a]o (50 percent a l t e r e d to u r a l i t e , b i o t i t e , c h l o r i t e ) -26B Phenocrysts (cont'd) B i o t i t e . . 20 $ Groundmass F e l d s p a r 30 fo ( m a j o r i t y i s p l a g i o -B i o t l t e . . 15 % c l a s e ) Quartz. 5 % O a l c i t e . . . . . . . . . . . . . . . . 5 fo Magnetite a c c e s s o r y D i o p s i d e . -D i o p s i d e occurs as phenocrysts which commonly are i n the form of r e o t a n g u l a r l o n g i t u d i n a l s e c t i o n s and e i g h t - s i d e d c r o s s - s e c t i o n s . I t i s c o l o r l e s s , and non-pleoohroic w i t h a maximum e x t i n c t i o n angle of 43 degrees. At the c e n t e r of the dyke, d i o p s i d e i s 50 peroent a l t e r e d , p r i m a r i l y to a green, p l e o c h r o i c , n o n - f i b r o u s u r a l i t e which commenced to grow a t the edges of d i o p s i d e g r a i n s , spread toward the i n t e r i o r and form-ed i n p a r a l l e l p o s i t i o n on the diqpside. There a l s o appears to be some a l t e r a t i o n o f another k i n d , to b i o t i t e , c h l o r i t e and a l i t t l e o a l c i t e , s i n c e pseudomorphs a f t e r pyroxene c o n t a i n minute shreds o f b i o t i t e surrounded by c h l o r i t e . At the con-t a c t w i t h ore, where the a l t e r a t i o n of pyroxene i s almost complete, there are pseudomorphs a f t e r d i o p s i d e which c o n t a i n Pennine, quartz, a p u l v e r u l e n t white m a t e r i a l , p y r i t e and very l i t t l e r e s i d u a l pyroxene, a l l of which are i n t i m a t e l y mixed tog e t h e r . 8 --27B-B i o t l t e -At the center of the dyke, b i o t i t e o f both phenocrysts and groundmass i s u n i f o r m l y dark brown i n c o l o r and s t r o n g l y p l e o -c h r o i c from very dark brown to grey, but near the co n t a c t w i t h ore, i t i s bleached to a brownish-grey c o l o r and i s h i g h l y c h l o r i t i z e d . F e l d s p a r -The m a j o r i t y o f the f e l d s p a r g r a i n s are twinned and the maximum e x t i n c t i o n angle of 23 degrees i n d i c a t e s an andesine compositon f o r the p l a g i o c l a s e . I t i s but s l i g h t l y zoned. Both at the middle of the dyke and at the con t a c t , there i s moderate a l t e r a t i o n to both c a l c i t e and p u l v e r u l e n t c l a y mater-i a l . Quartz -C l e a r quartz g r a i n s are i n t e r s t i t i a l to and have been form-ed l a t e r than the f e l d s p a r and b i o t i t e o f the groundmass. C a l o l t e -C a l c i t e occurs both as l a r g e (0.2 mm.), pure g r a i n s which i n some cases seem to have r e p l a c e d e n t i r e f e l d s p a r g r a i n s , and as s m a l l , c o n t o r t e d g r a i n s i n s i d e p l a g i o c l a s e c r y s t a l s . Opaque M i n e r a l s -At the dyke cen t e r , n e a r l y a l l the opaque g r a i n s are magne-t i t e although there are a few p y r i t e g r a i n s . D e s c r i p t i o n o f the Ore - P o l i s h e d S e o t i o n No. M36. The ore i n cont a c t with the lamprophyre c o n s i s t s p r i m a r i l y of massive s u l p h i d e s w i t h p o s s i b l y 20 percent o f gangue. The - 2 8 B -most p l e n t i f u l s u l p h i d e s are p y r r h o t i t e , a r s e n o p y r i t e and o h a l c o p y r i t e , each amounting to approximately 20 percent of the ore. In a d d i t i o n , l e s s e r amounts of p y r i t e and s p h a l e r i t e are present, each composing about f i v e percent of the ore. A few g r a i n s of galena are a l s o p r e s e n t , There i s a rough handing of the s u l p h i d e s p a r a l l e l to the contact w i t h lamprophyre. T h i s handing r e s u l t s from the l o c a l -i z a t i o n of c h a l c o p y r i t e i n a zone p a r a l l e l to and immediately adjacent to the c o n t a c t , the p y r r h o t i t e and a r s e n o p y r i t e , meanwhile b e i n g c o n f i n e d to the i n t e r i o r o f the ore specimen. The minor amounts of p y r i t e , s p h a l e r i t e and galena which occur i n the ore, are i n the c h a l c o p y r i t e zone. Towards the i n t e r i o r of the ore specimen, the on l y s u l p h i d e s present i n a p p r e c i a b l e amount are p y r r h o t i t e and a r s e n o p y r i t e . T h i s zoning of the s u l p h i d e s i n the ore appears t o have some s i g n i f i c a n c e i n the l i g h t of the f a c t t h a t , as w i l l be seen l a t e r , the only s u l -phides o c c u r r i n g i n the lamprophyre are those of the c h a l c o -p y r i t e zone. D e s c r i p t i o n o f the M i n e r a l i z e d Lamprophyre near the Contact w i t h Ore. Thi n S e o t i o n Ho. M34. P o l i s h e d S e c t i o n Ho. M34. The piece of massive s u l p h i d e ore o r i g i n a l l y i n c o n t a c t w i t h the lamprophyre i n the specimen has been separated from the lamprophyre and the co n t a c t i s seen to be a s l i g h t l y con-v o l u t e d s u r f a c e w i t h a somewhat p o l i s h e d appearance due to the - 2 9 B -presenoe of o a l c i t e and probably c h l o r i t e a l o n g the c o n t a c t p l a n e . The f o l l o w i n g d e s c r i p t i o n i s best i l l u s t r a t e d by p o l i s h e d s e c t i o n No. M34. This s e c t i o n shows the lamprophyre f o r a d i s -tance o f one and one-half inches i n from the c o n t a c t . B i o t i t e phenocrysts have a rough o r i e n t a t i o n p a r a l l e l to the co n t a c t and t h i s i s probably w e l l enough developed to c o n s t i t u t e e v i -dence of f l o w banding. In a d d i t i o n , there i s a q u a r t e r - i n c h wide, darkened zone at the c o n t a c t , f o l l o w e d by a q u a r t e r - i n o h wide, l i g h t e r - c o l o r e d zone which separates the dark zone from the dark-green main mass of the lamprophyre. As f a r as can be seen i n the p o l i s h e d s e c t i o n , the g r a i n s i z e o f the lamprophyre does not d i m i n i s h a p p r e c i a b l y towards the contact. The g r a i n s i z e a t the middle of the dyke, however, i s g r e a t e r than that a t the c o n t a c t , as oan be seen by a comparison of t h i n s e c t i o n s M34 and M35. The a l t e r a t i o n of the lamprophyre at the contact c o n s i s t s l a r g e l y of c h l o r i t i z a t i o n which can be seen to haye e s p e c i a l l y a f f e c t e d b i o t i t e . There i s a l s o a c o n s i d e r a b l e darkening'of the s l i d e by d u s t - l i k e b l a c k m a t e r i a l which i s not white i n r e -f l e c t e d l i g h t . C a r b o n a t i z a t i o n i s n e a r l y absent. The lamprophyre d e f i n i t e l y appears to be m i n e r a l i z e d as there are g r a i n s of c h a l c o p y r i t e , s p h a l e r i t e and galena i n the rock which are most p l e n t i f u l at the contact but which p e r s i s t i n d i m i n i s h i n g q u a n t i t y f o r a d i s t a n c e of one and one-half inches away from the c o n t a c t . T h i s d i s t a n c e i s the t o t a l t h i c k --30B-ness of the specimen a v a i l a b l e so i t i s l i k e l y that s u l p h i d e g r a i n s occur even f a r t h e r from the contact. They are not, however, present i n the specimen from the dyke c e n t e r . Two l a r g e g r a i n s , one of c h a l c o p y r i t e and the other of s p h a l e r i t e , occur, i n the lamprophyre r i g h t at the c o n t a c t (see p o l i s h e d s e o t i o n M34). They are one-eighth of an i n c h l o n g and are much elongated p a r a l l e l to the c o n t a c t . The appearance of the c h a l c o p y r i t e g r a i n suggests that i t i s a t o n g u e - l i k e i n t r u s i v e of the s u l p h i d e i n t o the lamprophyre, making a f l a t angle with the contact. To support t h i s con-c e p t i o n i s the f a c t that a t h i n s e p a r a t i o n , a p p a r e n t l y of lamprophyre, e x i s t s between the c h a l c o p y r i t e and the a c t u a l contact plane. . L e s s e r amounts of galena and p y r i t e a l s o occur i n the two l a r g e g r a i n s i n a s s o c i a t i o n w i t h the c h a l c o p y r i t e and s p h a l -e r i t e . In a d d i t i o n , s m a l l e r g r a i n s of a l l these s u l p h i d e s are disseminated i n the lamprophyre. 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 and galena i s p r o b a b l y the order of t h e i r abundance, p y r i t e having the most widespread and uniform d i s t r i b u t i o n . The g r a i n s are i r r e g u l a r i n shape but are u s u a l l y rounded and average .05 mm. i n s i z e . The disseminated s u l p h i d e g r a i n s , as seen i n t h i n s e c t i o n , do not r e p l a c e any o r i g i n a l m i n e r a l of the lamprophyre but r a t h e r occur i n the f i n e - g r a i n e d , a l t e r e d groundmass. In some cases, s u l p h i d e g r a i n s are p a r t i a l l y surrounded by a v e r y s m a l l amount of quartz but more commonly there i s no a s s o o i a t -31B-ed quartz and the s u l p h i d e i s surrounded by i n d e f i n i t e , c h l o r -i t i z e d m a t e r i a l . T h i s manner of occurrence may suggest a primary, magmatic o r i g i n i n the case of p y r i t e g r a i n s and i t may w e l l be that some of the p y r i t e i s due to i t s c r y s t a l l i z a -t i o n as an o r i g i n a l component of the lamprophyre. However, p y r i t e i s more p l e n t i f u l near the c o n t a c t than i n the specimen from the dyke ce n t e r , an i n d i c a t i o n that some of the p y r i t e was i n t r o d u c e d from o u t i s d e the lamprophyre. Furthermore, the appearance of the c h a l c o p y r i t e , s p h a l e r i t e and galena g r a i n s i n p o l i s h e d s e c t i o n , i n which the three m i n e r a l s are intergrown, very muoh resembles s u l p h i d e occurrences formed by m i n e r a l i z i n g s o l u t i o n s . Another, more minor occurrence o f p y r i t e i s that i n s i d e penninized pseudomorphs which are probably a f t e r d i o p s i d e . The pseudomorphs o o n t a i n quartz and a p u l v e r u l e n t white m a t e r i a l as w e l l . T h i s occurrence i s found i n the v i c i n i t y of the l a r g -er f r a c t u r e i n t h i n s e c t i o n No. 34. In a d d i t i o n to the occurrence i n disseminated g r a i n s , the same s u l p h i d e s are to be found i n two t h i n f r a c t u r e s l e s s than 0,1 mm. In width which penetrate the lamprophyre at an angle of about 45 degrees to the c o n t a c t and are f i l l e d p r i m a r i l y by quartz and some c h l o r i t e . From a c o n s i d e r a t i o n of the f o r e g o i n g d e s c r i p t i o n and the f a c t t h a t p y r r h o t i t e and a r s e n o p y r i t e were not seen to be present i n the lamprophyre, the c o n c l u s i o n might be drawn that the lamprophyre was s u b j e c t e d to o n l y the l a t e r stage o f the -32B-m i n e r a l i z i n g p e r i o d , i n which only 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 and galena were c r y s t a l l i z i n g . The sequence of events could, t h e r e f o r e , he: 1. Formation of p y r r h o t i t e and a r s e n o p y r i t e ore i n the lode. 2. I n t r u s i o n o f the lamprophyre w i t h consequent f l o w \"band-i n g and s l i g h t c h i l l i n g a g a i n s t the ore. 3. The l a t e r m i n e r a l i z i n g p e r i o d i n which c h a l c o p y r i t e , s p h a l e r i t e and galena formed i n the ore lode and a l s o penetrated the lamprophyre, the a l t e r a t i o n of the lampro-phyre ( o h l o r i t i z a t i o n ) p r e c e d i n g or accompanying the i n ^ t r o d u c t i o n of s u l p h i d e s . The evidence presented above does not, however, prove an i n t r a - m i n e r a l i z a t i o n age f o r the dyke sinoe i t i s e q u a l l y pos-s i b l e t h a t the lamprophyre had completely s o l i d i f i e d before the ore s o l u t i o n s a r r i v e d and that i t had then been s e l e c t i v e l y m i n e r a l i a e d by only those m i n e r a l s t h a t now appear i n the dyke. A comparable process i s the impregnation of w a l l rock by some of the min e r a l s present i n a v e i n while others take no p a r t i n the w a l l - r o c k a l t e r a t i o n . ROSSLAND DISTRICT - LEHQI MIME ON THE SURFACE - 50' FROM A LODE -\"Rossland - No. 2 Lamprophyre\"-A s h o r t d e s c r i p t i o n , o f the f i e l d occurrence of t h i s dyke ap-pears on page 41. Me g a s o o p i c a l l y , the rock i s extremely, f i n e -g r a i n e d , dense, u n u s u a l l y hard and b l a c k i n c o l o r . Large b i o -t i t e phenocrysts up to l / 5 i n c h i n l e n g t h produce good flow f o l i a t i o n . Thin S e o t i o n No. L33. This rock, although lamprophyrio i n composition, l a c k s i n i t s ferromagnesian c r y s t a l s ( b i o t i t e ) the euhedral q u a l i t y which i s u s u a l l y found i n lamprophyres ( P l a t e 5). The b i o t i t e g r a i n s , e s p e c i a l l y those of the groundmass, are very i r r e g u l a r -33B-although i t i s u s u a l l y p o s s i b l e to make out the e l o n g a t i o n d i r e o t i o n o f l o n g i t u d i n a l s e c t i o n s . I t d i f f e r s also\u00C2\u00BB from the lamprophyres so f a r s t u d i e d i i n t h a t i t con t a i n s no apa-t i t e . I t a l s o c o n t a i n s no c a l c i t e even though the presence of c h l o r i t e disseminated through the rook i n d i c a t e s that the rock i s not e n t i r e l y f r e s h . The composition i s : B i o t i t e phenocrysts. 3 fo D o u b t f u l Pseudomorphs 2 fo Groundmass: B i o t i t e . . . . . 35 fo Hornblende ( o h l o r i t i z e d ) . . . 1 5 $ C o l o r l e s s base ( f e l d s p a r and near-g l a s s ) 40 fo Unknown , a few g r a i n s P y r r h o t i t e , s p h a l e r i t e a c c e s s o r y B i o t i t e -B i o t i t e phenocrysts average 1.5- 2 mm. i n s i z e , are u n i -f o r m l y brown and c o n t a i n no i n c l u s i o n s . In the groundmass, the average g r a i n s i z e i s .06 mm. but i t grades down to crypt\u00C2\u00A9-o r y s t a l l i n e . A good d e a l o f the b i o t i t e i s concentrated i n brownish areas and s t r e a k s as aggregates of g r a i n s some o f which g i v e a s p h e r u l i t i c e f f e c t w i t h crossed n i c o l s . The m a j o r i t y o f the b i o t i t e i s , however, u n i f o r m l y d i s t r i b u t e d i n the groundmass as i r r e g u l a r , shreddy g r a i n s . D o u b t f u l Pseudomorphs --34B-D p u b t f u l Pseudomorphs -There are about a dozen pseudomorph-like areas, 1.0 mm. In s i z e , which c o n t a i n e i t h e r dark green c h l o r i t e or serpen-t i n e together w i t h some p y r r h o t i t e g r a i n s . The shapes of the areas are dot d i a g n o s t i c of any m i n e r a l t h e r e f o r e they may not be pseudomorphs. O h l o r i t i z e d Hornblende -Green hornblende which has been h i g h l y o h l o r i t i z e d i s s p a r s e l y d i s t r i b u t e d through the rock but there i s a heavy c o n c e n t r a t i o n of i t i n and near a miorosoopio f r a c t u r e . I t i s p l e o c h r o i c (dark green to yellow-green) has a maximum ex-t i n c t i o n angle to cleavage of 26 degrees and i t s h i g h e s t i n -t e r f e r e n c e c o l o r i s f i r s t - o r d e r y e llow. A few s m a l l c r o s s -s e c t i o n s were seen which s t i l l show the 60 degree cleavage but most of the g r a i n s have l o s t t h i s c h a r a c t e r i s t i c through c h l o r i t i z a t i o n . O o l o r l e s a Base -About h a l f of the c o l o r l e s s ground i s n e a r l y i s o t r o p i c and i s t h e r e f o r e indeterminate a l t h o u g h i t s r e f r i n g e n c e i s l e s s than balsam and i t s r e l i e f i s low. The remaining h a l f o f the c o l o r l e s s base has weak a n i s o t r o p i s m , low f i r s t - o r d e r grey i n t e r f e r e n c e c o l o r and forms g r a i n s which have the r e c t a n g u l a r shape of f e l d s p a r . The index i s l e s s than balsam and the r e -l i e f i s low. The g r a i n s i z e i s .06 mm. A very l i t t l e a l b i t e t w i n n ing can be seen and i t was p o s s i b l e to get an e x t i n c t i o n angle to the twinning of 17 degrees, a l s o one p o s i t i v e , b i -35B-a x i a l f i g u r e w i t h 2 V approximately 60 degrees. Therefore a l b i t e i s a p p a r e n t l y present but i t s p r o p o r t i o n to the a l k a l i f e l d s p a r whioh pr o b a b l y Is present i n the f i n e r g r a i n s could not be determined. Owing to the a l k a l i n e c h a r a c t e r o f the rock and the s c a r c i t y of twinning, the f e l d s p a r i s l i k e l y to be predominantly a l k a l i c and the rock may be a minette. Unknown -An undetermined c l e a r , c o l o r l e s s , u n i a x i a l n e g ative miner-a l with index g r e a t e r than balsam, v e r y low r e l i e f and b r i g h t f i r s t - o r d e r white i n t e r f e r e n c e c o l o r occurs i n c l u s t e r s o f a dozen or so rounded to broad t a b u l a r g r a i n s , each .03 mm. i n s i z e which are u s u a l l y s l i g h t l y separated from each other. A d i s t i n c t i v e f e a t u r e i s the presence i n i n d i v i d u a l g r a i n s o f very t h i n , w i d e l y spaced-, p e r f e c t l y s t r a i g h t i n c l u s i o n s a l l o f which are p a r a l l e l to the s t r a i g h t s i d e of the g r a i n s . The e x t i n c t i o n i s p a r a l l e l to these i n c l u s i o n s . No cleavage i s evident although i n some i n s t a n c e s the i n c l u s i o n s are r e g u l a r enough i n t h e i r s pacing to suggest that they occupy cleavage t r a c e s . Opaques -No magnetite i s i n the rock and n e a r l y a l l the opaque g r a i n s appear to be p y r r h o t i t e . Two g r a i n s o f s p h a l e r i t e were seen. There i s no l o c a l i z a t i o n of the opaques i n any p a r t i c u l a r p a r t of the t h i n - s e c t i o n . -36B-BRALORNE MINE FIELD AND MEGASCOPIC DESCRIPTION OF LAMPROPHYRE DYKES. Two lamprophyre dykes are known to occur i n the B r a l o r n e mine, both i n the Empire s e o t i o n . They have about the same a t t i t u d e and are about 1000 f e e t a p a r t . The more w e s t e r l y o f the two dykes was examined. I t i s a b i o t i t e lamprophyre, u s u a l l y two f e e t wide, which s t r i k e s n e a r l y n o r t h and i s near-l y v e r t i c a l but dips s l i g h t l y to the ea s t . I t Is l a t e r than the ore and cuts across the east-west t r e n d i n g Empire v e i n almost a t r i g h t angles. Where examined, i n 1151 East d r i f t , the dyke\"is d i s p l a c e d about one f o o t by l a t e movement al o n g the v e i n f r a c t u r e . The ore a t t h i s p o i n t i s low-grade, prob-a b l y sub-commercial, and c o n s i s t s o f quartz and gougey, s i l i -c i f i e d , a l b i t l z e d country rock i n a narrow shear zone, one f o o t wide. The lamprophyre has a ve r y dark, g r e e n i s h - g r e y c o l o r and contains many g l i s t e n i n g , b l a c k b i o t i t e phenocrysts up to l / l O i n c h i n diameter. There i s e x c e l l e n t flow f o l i a t i o n o f the b i o t i t e phenocrysts i n a band extending f o u r or f i v e inches i n from the w a l l . The groundmass at the margins i s s t r o n g l y c h i l l e d but the phenocrysts i n the c h i l l e d margins are only very s l i g h t l y s m a l l e r and s l i g h t l y l e s s p l e n t i f u l than i n the dyke i n t e r i o r . The dyke c o n t a i n s i r r e g u l a r i n c l u s i o n s o f s i l i c i f i e d \" a l b i t i t e \" . There i s a seam of s o f t , v e r y b l a c k , b i o t i t e - b e a r i n g , lamprophyre about one-half i n c h wide which occurs between the -37B-niain lamprophyre dyke and the v e i n m a t e r i a l on one w a l l and appears to he d i s t i n c t l y d i f f e r e n t from the main lamprophyre dyke. This m a t e r i a l i s l a r g e l y c r y p t o c r y s t a l l i n e and i s pr o b a b l y c h l o r i t i c i n composition. ( T h i n s e c t i o n s 15 and 15a) E x t e n s i v e groundmass c h l o r i t i z a t i o n such as t h i s does not seem to be a common product of o r d i n a r y d e u t e r i c a l t e r a t i o n , nor of a l t e r a t i o n by weathering s o l u t i o n s i n lamprophyres o f t h i s k i n d . The h i g h l y o h l o r i t i z e d m a t e r i a l as i t occurs here, suggests a l t e r a t i o n of the lamprophyre by hydrothermal s o l u -t i o n s p a s s i n g along the co n t a c t between the ore and the lampro-phyre. As t h i s lamprophyre dyke i s s t r o n g l y c h i l l e d a g a i n s t the ore, i t would seem t h a t the suggested l i q u i d cannot be-l o n g to a l a t e phase o f the m i n e r a l i z i n g p e r i o d which produoed the ore, although there i s a less-marked c h i l l i n g present i n the \"contemporaneous\" lamprophyre specimen from the Mayflower mine. I t i s a l s o d i f f i c u l t to conceive the a l t e r a t i o n of the groundmass of a lamprophyre to form c h l o r i t e without any a l -t e r a t i o n of the enclosed b i o t i t e and pyroxene phenocrysts as i s the case here, although t h i s too may be p o s s i b l e . There-f o r e , i n view of the r a t h e r sharp contact between the narrow b l a c k band and the main mass of lamprophyre i t appears most l i k e l y t h a t t h i s b l a c k seam i s a l a t e r lamprophyre of a h i g h l y mafic composition whioh came i n along the w a l l of the main dyke. I t was not n o t i c e d whether t h i s dark seam was a l s o present between the main lamprophyre dyke and the country rock. -38B--PETROGRAPHIC DESCRIPTIONS 1151 E a s t D r i f t Thin S e c t i o n s Nos. 11 and 15. A lamprophyre dyke, two f e e t wide, i n t e r s e c t s a sub-com-m e r c i a l s i l i c i f i e d shear i n \" a l b i t i t e \" . The dyke cuts through the v e i n and i s t h e r e f o r e younger and has been d i s p l a c e d two f e e t h o r i z o n t a l l y by post-dyke movement along the shear. Two s e c t i o n s were s t u d i e d m i c r o s c o p i c a l l y ; number 11, of lamprophyre at i t s immediate contact w i t h a l b i t i t e and number 13, a t the c e n t e r of the dyke. This rock i s a b i o t i t e - l a m p r o p h y r e (minette or k e r s a n t i t e ) but the nature of the f e l d s p a r cannot be a c c u r a t e l y determined s i n c e i t i s i n a g l a s s i n S e c t i o n 11 and i s i n the form of small s h e a f - l i k e s p h e r u l i t e s i n S e c t i o n 13. I t Is most l i k e l y , however, that the rock i s minette r a t h e r than k e r s a n t i t e be-cause the r e f r i n g e n c e of the s h e a f - l i k e f e l d s p a r c r y s t a l s i s l e s s than balsam i n a l l the oases observed. A uniform ground-mass composed mainly of granophyre and s m a l l b i o t i t e hornblende l a t h s makes up 80 percent of the rock. The phenocrysts are b i o t i t e , pyroxene and a p a t i t e . The composition of Thin S e c t i o n No. 13 i s : \u00E2\u0080\u00A2Qranophyro 40 $ Hornblende of groundmass.... 12 fo B i o t i t e of groundmass....... 20 f> B i o t i t e phenocrysts 5 fo Pyroxene phenocrysts 5 fo -39B-A p a t i t e P y r i t e O a l c i t e 1 % 2 fo (excludes the v e i n -8 fo l e t s ) Magnetite a c c e s s o r y Groundmass The d i s t i n c t i v e f e a t u r e of t h i s rock i s the ground, com-p r i s i n g 80 percent o f the rock, which c o n t a i n s : B i o t i t e c r y s t a l s , i n the form o f well-shaped, equigr ;anular l a t h s l e s s than 0.2 mm. l o n g and s i x - s i d e d c r o s s - s e c t i o n s are enclosed i n the granophyre accompanied by hornblende. The s m a l l b i o t i t e and hornblende l a t h s show flow l i n e a t i o n whioh i s most pronounced near the contact and grades to l e s s and l e s s pronounced l i n e a t i o n away from the dyke-wall u n t i l , at the dyke c e n t e r , l i n e a t i o n i s no l o n g e r e v i d e n t . The b i o t i t e and hornblende g r a i n s have a remarkably dense and uniform d i s -t r i b u t i o n i n the groundmass, although the p r o p o r t i o n of b i o -t i t e i n r e l a t i o n to hornblende v a r i e s a good d e a l i n d i f f e r e n t p a r t s o f the s l i d e . Hornblende. Dark brown hornblende occurs i n the form of needles and diamond-shaped c r o s s - s e c t i o n s w i t h the same s i z e range as the b i o t i t e . The maximum e x t i n c t i o n angle to l o n g i -t u d i n a l s e c t i o n s i s around 13 degrees and some twinning i s hornblende b i o t i t e granophyre 25 fo 15 fo 50 fo p r e s e n t . - 4 0 B -\u00E2\u0080\u00A2Oranophyrs, o c c u r r i n g o n l y i n S e c t i o n 1 3 , moat commonly con a i 8 t s of s h e a f - l i k e groupings o f r a d i a l f i b e r s which are t h i n n e r than the s l i d e hut show p a r a l l e l and n e a r l y p a r a l l e l e x t i n c t i o n , grey i n t e r f e r e n c e c o l o r and no twinning. The g l a s s of S e c t i o n 11 i s c o l o r l e s s though s l i g h t l y darker than balsam and has an index u s u a l l y l e s s than balsam. Phenocrysts The b i o t i t e phenocrysts ( 0 . 2 to 1 mm, long) are the l a r g -est g r a i n s of the rock. B i o t i t e ( o f both ground and pheno-c r y s t s ) , i s brown-colored and f r e s h - a p p e a r i n g , has no dark-brown r e s o r p t i o n rims nor green c h l o r i t i c b o r d e r s . I n c l u s i o n s of l a r g e a p a t i t e g r a i n s i n b i o t i t e a re extremely common and there i s a l s o a good d e a l o f p e n e t r a t i o n of b i o t i t e c r y s t a l s by pyroxene g r a i n s . Pyroxene, o c c u r r i n g i n g r a i n s averaging 0,5 mm. i n dimen-s i o n , i s c o l o r l e s s . The c h a r a c t e r i s t i c pyroxene h a b i t (squares, r e c t a n g l e s and e i g h t - s i d e d s e c t i o n s ) i s much i n evidence but the pyroxene cleavage does not show up very w e l l , though i t was observed i n two or three cases. T h i s l a c k appears to be due to the l o s s of a l a r g e p a r t of the pyroxene (as w e l l as some b i o t i t e and some q u e s t i o n a b l e o l i v i n e ) i n g r i n d i n g the s l i c e , w i t h the consequence that e x t i n c t i o n angles to the cleavage of pyroxene could not be p r o p e r l y measured. Twinning i s f r e q u e n t l y present i n pyroxene. Some remnants remain of l a r g e g r a i n s which had the p o l y -- 4 1 B -- 4 1 B -gonal o u t l i n e commonly a s s o c i a t e d w i t h o l i v i n e . One such remnant ( i n S e c t i o n 11) showed p a r a l l e l e x t i n c t i o n to c l e a v -age and 2 V = .90\u00C2\u00B0. A p a t i t e forms some very l a r g e c r y s t a l s , up to 0.3 mm. i n diameter, which are comparable to phenocrysts i n t h e i r s i z e . These give u n i a x i a l n e g a t i v e i n t e r f e r e n c e f i g u r e s . A p a t i t e i s c l o s e l y a s s o c i a t e d w i t h b i o t i t e , o c c u r r i n g e i t h e r as i n -e l u s i o n s i n or as g r a i n s p e n e t r a t i n g , c o n t a c t i n g or neighbour-i n g the b i o t i t e . O a l c i t e i s almost absent\" from the groundmass s i n c e i t occurs mainly as l a r g e g r a i n s . I t i s a p p a r e n t l y i n p a r t secondary a f t e r pyroxene, completely f i l l i n g apparent pseudo-morphs a f t e r pyroxene. In another type of occurrence, seen i n S e c t i o n 11, there are both l a r g e and small o a l c i t e bodies, v e r y elongated, o r i e n t e d p a r a l l e l to the l i n e a t i o n o f the b i o t i t e n e e d l e s . These elongated g r a i n s do not appear to be secondary a f t e r an o r i g i n a l dyke m i n e r a l . The absence of secondary o a l c i t e from the groundmass i s i n keeping w i t h the ge n e r a l f r e s h n e s s of the rock. Two seams c o n t a i n i n g mostly o a l c i t e but some p y r i t e as w e l l t r a v e r s e S e c t i o n 13. These seams may have been formed by a post v e i n - m i n e r a l i z a t i o n process i n v o l v i n g the c i r c u l a t i n g ground-waters. However, the presence o f p y r i t e i n them suggests the f a i n t p o s s i b i l i t y t h a t the l a t e s t - a p p e a r i n g hydrothermal s o l u t i o n s of the ore p e r i o d had acted upon the dyke. -42B-Opaque M i n e r a l s In S e o t i o n No. 13, there i s a l i t t l e magnetite among the sm a l l e r g r a i n s o f m e t a l l i c s , but a l l o f the l a r g e g r a i n s (0.1 - 0 , 3 mm.) and n e a r l y a l l the s m a l l e r g r a i n s ( l e s s than 0.1 mm.), are p y r i t e . Most of the p y r i t e i s i n the form of i r r e g -u l a r g r a i n s s c a t t e r e d without any d e f i n i t e arrangement i n the groundmass. Some, however, appear to r e p l a c e b i o t i t e c r y s -t a l s ( a g a i n without any apparent l o c a l i z a t i o n i n any p a r t of the s l i d e ) , as they p a r t i a l l y rim b i o t i t e c r y s t a l s , w i t h s l i g h t p e n e t r a t i o n , and o c c a s i o n a l l y v e i n the b i o t i t e . In s e c t i o n No. 11 from the c o n t a c t with country rock, how-ever, there i s no p y r i t e ; the onl y opaque m i n e r a l i s magne<-t i t e , most of which occurs as innumerable s m a l l (0.02 mm.) g r a i n s of g e n e r a l l y r e c t a n g u l a r h a b i t , u n i f o r m l y disseminated i n the lamprophyre. Therefore, i t i s h i g h l y probable that the o r i g i n o f p y r i t e i n s e c t i o n No. 13 i s connected w i t h the f o u r or f i v e roughly p a r a l l e l f r a c t u r e s whioh t r a v e r s e t h a t s e o t i o n and are f i l l e d w i t h c a l c i t e and p y r i t e . In t h i s c onnection, i t i s a l s o s i g n i f i c a n t that c a l c i t e g r a i n s are more p l e n t i f u l i n S e o t i o n 13 than i n S e c t i o n 11. Thin S e c t i o n s No. 15 and 15(a). These are s e c t i o n s of the same lamprophyre dyke as t h a t from which s e c t i o n s 11 and 13 were made but, i n s e o t i o n s 15 and 15(a), v e i n m a t e r i a l c o n s i s t i n g of quar t z , s e r i c i t i z e d f e l d s p a r , o a l c i t e and p y r i t e i s atta c h e d to the lamprophyre. The v e i n m a t e r i a l i s not of commercial grade. -43B The lamprophyre i s extremely f i n e - g r a i n e d a t the oontaot . but minute b i o t i t e c r y s t a l s are p l e n t i f u l and there are a l s o a few g r a i n s o f a p a t i t e , pyroxene and b i o t i t e as l a r g e as those o o c u r r i n g i n the i n t e r i o r o f the dyke and these are not a l t e r -ed. B i o t i t e c r y s t a l s show flow l i n e a t i o n p a r a l l e l to the conta c t ( P l a t e 4 ) . The contact between the dyke and ore seems to have been a channel f o r s o l u t i o n s because the lamprophyre i s h i g h l y s e r -p e n t i n i z e d and/or o h l o r i t i z e d there, r e s u l t i n g i n the form a t i o n of a green, orange, y e l l o w and c o l o r l e s s , n o n - p l e o c h r o i c o r y p t o -o r y s t a l l i n e mass which shows flow banding due to c o l o r v a r i a -t i o n s p a r a l l e l to the co n t a c t . The m a t e r i a l immediately adjao-ent to the v e i n has a y e l l o w c o l o r and seems to be the most h i g h l y a l t e r e d m a t e r i a l . The c o l o r changes from y e l l o w through brown to green away from the cont a c t where the a l t e r a t i o n be-comes l e s s i n t e n s e . There are no changes i n the v e i n m a t e r i a l towards the con-t a c t . Serpentinous lamprophyre sends out p r o j e c t i n g tongues i n t o the v e i n m a t e r i a l i n one p l a c e . I n c l u s i o n s of v e i n mate-r i a l occur i n the lamprophyre and these do not appear to have been a l t e r e d by the lamprophyre f l u i d . PIONEER MINE FIELD AND MEGASOOPIO DESCRIPTION OF LAMPROPHYRES There are at l e a s t two lamprophyre dykes o c c u r r i n g under-ground at Pioneer. These are 400 f e e t a p a r t and are b e l i e v e d -44B-by the mine engineers to be two separate dykes. In a d d i t i o n , there are t u n n e l and d r i l l - h o l e i n t e r s e c t i o n s w i t h lamprophyre dykes i n two other p a r t s of the mine but i t i s not known f o r sure whether these are c o n t i n u a t i o n s of the two known dykes. The dykes at P i o n e e r are post-ore as they cut a c r o s s and are c h i l l e d a g a i n s t the v e i n - q u a r t z . They are u n l i k e the B r a l o r n e dykes i n that they i n t e r s e c t the ore s t r u c t u r e s a t a f l a t angle and f r e q u e n t l y f o l l o w along the w a l l of the v e i n f o r d i s t a n c e s up to 40 f e e t before c u t t i n g through the quartz to the opposite s i d e . The a t t i t u d e s o f the lamprophyre dykes and the v e i n s are shown i n the p l a n (back p o c k e t ) . The widths of the dykes vary from s i x inches to two f e e t . A l l the lamprophyres c o n t a i n hornblende as the most p l e n t i f u l ferromagnesian m i n e r a l . I t occurs only i n the groundmass, however, and the s m a l l e r amounts of b i o t i t e and o c c a s i o n a l l y pyroxene, o c c u r r i n g as phenocrysts, are more conspicuous. Accurate f e l d s p a r i d e n t i f i c a t i o n was impossible as f e l d s p a r i s u s u a l l y contained i n g l a s s or granophyre and the r a r e l y - o c c u r -r i n g c r y s t a l s are too s m a l l to g i v e i n t e r f e r e n c e f i g u r e s . Indices of r e f r a c t i o n of f e l d s p a r c r y s t a l s , g l a s s and grano-phyre were l e s s than balsam i n a l l observed cases, t h e r e f o r e the dyke3 are most probably v o g e s i t e s . Pioneer lamprophyres are very s o f t , crumbly and grey i n c o l o r , e s p e c i a l l y along the w a l l s and e s p e c i a l l y i n the o l d e r workings where they have been exposed to the a i r f o r a l o n g e r time. R e l a t i v e l y r e c e n t l y - e x p o s e d rock was obtained near the -45B-new- 27 v e i n on 20 l e v e l (specimen 25) and i n t h i s , the dyke i s b l a c k and c o a r s e - t e x t u r e d a t i t s c e n t e r . B i o t i t e phenocrysts up to l / l O i n c h i n diameter are p l e n t i f u l i n a l l the dykes, and t h e r e i s pronounced flow handing due to p a r a l l e l i s m of the b i o t i t e phenocrysts. The g r a i n s i z e of the groundmass i s much s m a l l e r and the r o c k more dense near the w a l l s but the b i o t i t e phenocrysts do not change much i n s i z e nor i n q u a n t i t y as the w a l l i s approaohed. Pronounced c o l o r banding i n the c h i l l e d edges, p a r a l l e l to the c o n t a c t f o l i a t i o n , i s a remarkable f e a t u r e i n n e a r l y a l l P i o n e e r lamprophyres. The c o l o r bands va r y from l / 2 to l l / 2 inches i n width and i n the c h i l l e d edge of specimen 25, where the c o l o r s are best developed, the sequence i s : a l i g h t g r e e n i s h - g r e y c o l o r at the w a l l , then a r e d d i s h and f i n a l l y a dark green c o l o r t h at grades i n t o the i n t e n s e l y b l a c k , f r e s h -appearing lamprophyre of the dyke i n t e r i o r . T h i s c o l o r band-ing was not found i n the dykes from other p r o p e r t i e s . I t i s probably due to a combination of the e f f e c t s of primary, flow-banded, c o m p o s i t i o n a l v a r i a t i o n s of the lamprophyre and s e l e c t i v e a l t e r a t i o n by s o l u t i o n s moving along the c o n t a c t , the more mobile c o n s t i t u e n t s p e n e t r a t i n g the dyke more deeply and producing changes there d i f f e r e n t from the changes pro-duced elsewhere by l e s s p e n e t r a t i v e c o n s t i t u e n t s . Thin s e c -t i o n s showed the c o m p o s i t i o n a l d i f f e r e n c e s between the i n t e r -i o r and the outer p o r t i o n s of the dyke to be minor, amounting at most to f i v e percent l e s s of both b i o t i t e and hornblende -46B-at the w a l l and 15 percent more c a l c i t e . The extreme c h i l l i n g a g a i n s t the ore i n these dykes m i l i -t a t e s a g a i n s t a theory that l a t e , v e i n - f o r m i n g s o l u t i o n s caused the a l t e r a t i o n yet the c o l o r handing i s so marked and the p e n e t r a t i o n i s so deep ( t h r e e i n c h e s ) , that f a i r l y potent s o l u t i o n s must have been r e s p o n s i b l e . A more c a r e f u l study i n the mine might r e v e a l a connection between the presence of c o l o r banding and the a s s o c i a t i o n o f ore w i t h the dykes. PETROGRAPHIC DESCRIPTIONS 15 F.W. V e i n . Sta. 1543 - Middle of dyke -T h i n S e o t i o n 17. Specimen 17 i s most l i k e l y a v o g e s t i e , as hornblende Is more p l e n t i f u l than b i o t i t e and the f e l d s p a r i s most probably an o r t h o c l a s e - f e l d s p a r . The approximate m i n e r a l o g i c a l composition i s : B i o t i t e Phenocrysts 5 $ Groundmass F e l d s p a r . . . . . . . 65 fo (probably m a j o r i t y i s o r t h o c l a s e - f e l d s p a r ) Hornblende.... 8 5 $ Quartz 1 fo C a l c i t e . . . 3 $ Magnetite........ 3 fo A p a t i t e , pyroxene.... .accessory -47B-B i o t i t e i s r e s t r i c t e d to the phenooryst phase i n which i t occurs as c r y s t a l s up to 4 ram. l o n g which are ve r y much l a r g -er than the g r a i n s of the groundmass. There are some s m a l l e r b i o t i t e g r a i n s but the s m a l l e s t o f these are s t i l l s l i g h t l y l a r g e r than the hornblende needles o f the groundmass. There does not seem to be any sm a l l b i o t i t e g r a i n s i n the ground-mass; i f there are any, they are ve r y inconspicuous and could not be d e f i n i t e l y i d e n t i f i e d . B i o t i t e phenocrysts are brown, do not show c h l o r i t i c borders nor dark r e s o r p t i o n rims but do c o n t a i n numerous a p a t i t e i n c l u s i o n s . Hourglass s t r u c t u r e near the e x t i n c t i o n p o s i t i o n i s ve r y prominent. Hornblende - The groundmass c o n t a i n s as i t s l a r g e s t g r a i n s , hornblende l a t h s up to 0.3 mm. long. Although they range i n s i z e down to specks which are d i s c e r n i b l e only w i t h the h i g h power o b j e c t i v e , the m a j o r i t y are of the l a r g e s i z e which under low power show great u n i f o r m i t y i n s i z e and d i s t r i b u t -i o n i n the groundmass. Hornblende c r y s t a l s are s t r o n g l y eu-h e d r a l , forming c l e a r - c u t l a t h s and diamond-shaped c r o s s -s e c t i o n s which have not s u f f e r e d i n t e r f e r e n c e d u r i n g t h e i r growth. The maximum e x t i n c t i o n angle measured to l o n g i t u d i n -a l s e c t i o n s was 17 degrees. A s i n g l e twinning l i n e b i s e c t i n g the l a t h i s f r e q u e n t l y seen. F e l d s p a r - The most abundant component of the groundmass i s f e l d s p a r which forms p a r a l l e l , b ranching and r a d i a l aggre-gates of coarse f i b e r s . The r e f r a c t i v e index i s q u i t e d e f i n -i t e l y l e s s than that o f balsam and i t was p o s s i b l e to o b t a i n -48B-one f a i r l y s a t i s f a c t o r y i n t e r f e r e n c e f i g u r e which had 2 V near 90\u00C2\u00B0. Simple, Carlsbad-type twinning i s f r e q u e n t l y seen but there i s no p o l y s y n t h e t i o twinning. T h e r e f o r e , i t i s most probable t h a t the f e l d s p a r i s an o r t h o c l a s e - f e l d s p a r . Quartz There are a few c u r v i n g g r a i n s of quartz up to 0.2 mm. i n s i z e among the f e l d s p a r f i b e r s of the groundmass. They do not appear to be intergrown w i t h f e l d s p a r . A u n i -a x i a l p o s i t i v e f i g u r e was obtained from s e v e r a l o f the g r a i n s . C a l c i t e - There i s one mass of pure, c o a r s e - g r a i n e d c a l -c i t e , f o u r and one-half mm, i n diameter, completely surround-ed by a narrow zone which l a c k s the u s u a l hornblende oonoen-t r a t i o n of the groundmass but i s composed e n t i r e l y of spheru-l i t i c f e l d s p a r f i b e r s . C a l c i t e a l s o occurs s c a t t e r e d through-ou t the groundmass as i r r e g u l a r l y rounded, impure g r a i n s approximately 0.2 mm. i n s i z e . Magnetite i s abundant. Euhedral to subhedral g r a i n s w i t h square c r o s s - s e c t i o n s are v e r y u n i f o r m l y disseminated i n the groundmass. They are b l a c k i n r e f l e c t e d l i g h t . A p a t i t e occurs mostly i n or i n con t a c t w i t h b i o t i t e c r y s -t a l s a lthough there are a few g r a i n s disseminated i n the groundmass. Grains are .05 to 0.1 mm. i n diameter, an unusual-l y l a r g e s i z e i n comparison w i t h the s i z e o f the other g r a i n s of the s l i d e . Pyroxene - Three c o l o r l e s s , h i g h l y b i r e f r i n g e n t g r a i n s resembling pyroxene or o l i v i n e are to be found i n t h i s s l i d e . They are p a r t i a l l y a l t e r e d to c a l c i t e and i t i s p o s s i b l e -49B-t h e r e f o r e that many o f the c a l o i t e b l e b s o f the groundmass were d e r i v e d through the a l t e r a t i o n of the same m a t e r i a l 0that occurs i n these three g r a i n s . C r y s t a l l i t e s - Curved, branching c r y s t a l l i t e s which are bla c k i n t r a n s m i t t e d l i g h t are v i s i b l e i n the f e l d s p a r . 2351 South D r i f t . S t a . 2241 Thin S e c t i o n No. 32. F.W. oontaot a g a i n s t q u a r t z . This i s e i t h e r a v o g e s i t e or a s p e s s a r t i t e but i t i s probably the former as the c l e a r g l a s s which c o n t a i n s the f e l d s p a r has an index c o n s i d e r a b l y l e s s than balsam, about 1.50. I t i s a remarkably f r e s h rook, no c a l c i t e whatever o c c u r r i n g i n the s l i d e and a l l the m i n e r a l s being p r a c t i c a l l y u n a l t e r e d . A l l o r y s t a l s are euhedral. The m i n e r a l percentages a r e : B i o t i t e phenocrysts,. 10 fo D i o p s i d e phenocrysts , 10 fo Groundmass Hornblende l a t h s , . . . . , 25 fo Glass groundmass 50 fo Glass g l o b u l e s . . . . . 3 f> Granophyre g l o b u l e s . . . 2 fo A p a t i t e . , . . a c c e s s o r y NOTE: magnetite i s almost e n t i r e l y l a c k i n g . B i o t i t e i s s i m i l a r to that i n the other occurrences of Pio n e e r lamprophyre. I t i s brown, has no dark borders, con--50B-t a i n a numerous a p a t i t e i n c l u s i o n s and i s almost e n t i r e l y r e s t r i c t e d to the phenocryst phase, the g r a i n s b e i n g g e n e r a l -l y 0.2 to 1 mm, i n s i z e . There are a few s c a t t e r e d b a s a l p l a t e s 0.03 mm. i n diameter i n the groundmass. Diop s i d e occurs as c l e a r , c o l o r l e s s phenocrysts (0.2 to 1 mm.). There i s s l i g h t a l t e r a t i o n to white p u l v e r u l e n t mater-i a l , but no c a l c i t e . A few 0.03 mm. g r a i n s can be seen i n the groundmass. Hornblende l a t h s , 0.2 mm. l o n g , and diamond-shaped c r o s s -s e c t i o n s which are too s m a l l to give a f i g u r e , are c o n f i n e d to the groundmass, being u n i f o r m l y disseminated -in the g l a s s where they produce v e r y good flow l i n e a t i o n . I t i s a v e r y dark brown b a r k e v i t i c hornblende showing f a i r p l e o c h r o i s m and o c c a s i o n a l twinning. The g l a s s i s o o l o r l e s s and c l e a r although i t has a f a i n t brownish t i n g e i n t h i c k e r p o r t i o n s of the s l i d e . I f oontains very f i n e , c o l o r l e s s , n e e d l e - l i k e c r y p t o c r y s t a l s . There are no granophyric phases i n t h i s s l i d e except i n the g l o b u l e s d e s c r i b e d i n a l a t e r paragraph. The index of the g l a s s i s l e s s than balsam. Gla33 g l o b u l e s , 0.1 to 0.3 mm. i n diameter, occur through-out the s l i d e . They c o n s i s t o f c l e a r , c o l o r l e s s g l a s s w i t h index number l e s s than balsam (n - approximately 1.45), which co n t a i n s c r y s t a l l i t e s . There are no hornblende c r y s t a l s i n the g l o b u l e s but the groundmass c r y s t a l s abut a g a i n s t the g l o b u l e s and there i s a c o n c e n t r a t i o n of v e r y few magnetite -51B-g r a i n a ooGurring i n the s l i d e , a g a i n a t the hordera of the g l o b u l e s . Some g l o h u l e a c o n t a i n a smoky brown s t a i n . Grranop^yrio g l o b u l e s , a v e r a g i n g 1 mm. i n diameter, are o u t l i n e d by a t i r e - l i k e l a y e r o f p u l v e r u l e n t white m a t e r i a l . Hornblende c r y s t a l s of the groundmass penetrate i n t o the g l o b u l e s , occur i n s i d e the g l o b u l e s and m a i n t a i n t h e r e i n the same l i n e a t i o n which they have i n the surrounding groundmass. The groundmass of the g l o b u l e s i s a darker brown than that of the main rock but i s granophyrio r a t h e r than g l a s s y . A p a t i t e occurs o c c a s i o n a l l y i n the main mass of the rock as w e l l as i n s i d e the b i o t i t e phenocrysts. T h i n Seotion No. 31. Center of dyke. This t h i n s e o t i o n i s of m a t e r i a l from the c e n t e r of the dyke; t h i n s e c t i o n No. 32 being from the f o o t - w a l l of the same dyke. The m a t e r i a l i n t h i n s e o t i o n No. 31 d i f f e r s from that i n No. 32, as would be expected, i n that i t has l e s s o d o r l e s s g l a s s and more granophyre. A more s u r p r i s i n g d i f -f e r e n c e , however, i s t h a t , i n the c e n t e r of the dyke, d i o p s i d e phenocrysts are-almost completely a l t e r e d to o a l c i t e whereas there i s no c a l c i t e whatever i n the t h i n s e c t i o n from the f o o t -w a l l of the dyke. This f e a t u r e must not be c o n s i d e r e d a char-a c t e r i s t i c of t h i s dyke, however, sino e only twp t h i n s e c t i o n s were examined and. the, c a l c i t e content of the rock may be h i g h l y v a r i a b l e . -52B. The composition of this thin section i s : Phenoorysts Biotite Oalcite (after pyroxene) 5 fo 5 % Groundmass Brownish Hornblende Colorless Granophyre Nodules Felsic Maieria] 30 $ 50 $ 3 % Iron Ore, apatite accessory Biotite - Biotite phenocrysts have the same characteristics as those in section 32 except that they are larger, being up to 2 mm. long. Calcite - The majority of the calcite in the slide i s in large grains up to 1 mm. long, some of which have a form which suggests that they are pseudomorphs after pyroxene. However, as the calcite is clear and is not accompanied by another min-eral which could account for the iron and magnesium of the original pyroxene, there i s considerable doubt that these bodies are actually pseudomorphs after pyroxene. Some of the \"pseudomorphs\" are surrounded by a darkened rim consisting of dark, dusty material and a compressed mass of hornblende laths. This gives the impression that either expansion has occurred in the original mineral of the \"pseudomorph\" during its crys-t a l l i z a t i o n or that hornblende laths floating in the residual magmatic fluid had come to rest against the original mineral. -53B-Hornblende - The hornblende, as i n s e c t i o n 32, i s confined to the groundmass, and i s i n a l l respects s i m i l a r . I t occurs i n g r a i n s , the l a r g e s t of which are 0.3 mm. long. The gra i n s e x h i b i t flow l i n e a t i o n around the la r g e b i o t i t e phenocrysts. Sali-e- m a t e r i a l - About one h a l f of the s l i d e i s composed of s l i g h t l y c r y s t a l l i z e d s a l i c m a t e r i a l which, most commonly, i s n e a r l y a glas s or, at best, i s f a i n t l y a n i s o t r o p i c w i t h no v i s i b l e c r y s t a l s t r u c t u r e . O c c a s i o n a l l y though, there are s h e a f - l i k e aggregates of c r y s t a l s w i t h r e f r i n g e n c e below that of balsam. This o a l i o m a t o r i a l , throughout the s l i d e , has a light-brown c o l o r under moderate m a g n i f i c a t i o n s but the c o l o r i s apparently produced by minute, dark brown g r a i n s , probably of hornblende, which l i e between adjacent m i c r o o r y s t a l s o f the aggregates. Oolorless Granophyre - There are, s c a t t e r e d through the rock, some nodules, 0.04 mm. In diameter on the average, of c l e a r , c o l o r l e s s granophyre. The nodules are composed of very s m a l l , equigranular g r a i n s , some appearing to be quartz and others, w i t h r e f r i n g e n c e l e s s than balsam, appearing to be a l k a l i n e f e l d s p a r . The gr a i n s are, however, too small f o r pr ope trident i f i c a t i o n . The granophyre shows s p h e r u l i t i o cross-es with the n i c o l s crossed. A p a t i t e - A p a t i t e i s the same as i n s e c t i o n 32. Grains are .04 mm. wide and 0.3 mm. long and give u n i a x i a l negative i n -t e r f e r e n c e f i g u r e s . A p a t i t e i s e s p e c i a l l y a s s o c i a t e d w i t h b i o t i t e . -54B-Magnetlte - Accessory magnetite is plentiful. PREMIER MINS 9 0 STOPE Thin Seotion No. P5 - Interior of dyke. This is a specimen of dyke rock from the 9 0 stope, on the second level from the bottom of the mine. It is a fine-grained, greenish-grey rock with a carbonatized appearance, containing small hornblende phenocrysts visible to the naked eye. The composition of this thin section is as follows: Feldspar. , 60 fo Quartz 5 fo Hornblende , 20$ Chlorite 10 fo Carbonate 5 fo Pyrite, magnetite.......accessory The texture is porphyritic. Idiomorphic hornblende pheno-crysts are present in a matrix composed largely of small feld-spar laths (Plate 6). Only a few of the feldspar crystals are large enough to be classed as phenocrysts. Feldspar - Feldspar forms a felted mass of crystals whioh in some portions of the slide comprises 70-80 percent of the rock and in other places only 40-50 peroent. On the average, the proportion of feldspar Is about 60 percent. Most of the laths are less than 0.2 mm. in length. Simple Carlsbad-type -55B-twinning i s present as w e l l as a l i t t l e p o l y s y n t h e t i e twin-n i n g . P o l y s y n t h e t i c twinning, however, i s r a r e and i s obscur-ed by k a o l i n i z a t i o n w i t h the r e s u l t that no e x t i n c t i o n angles were obtained. The r e f r a c t i v e i n d i c e s o f the m a j o r i t y of f e l d s p a r c r y s t a l s were below that of balsam, a f a c t which, i n c o n j u n c t i o n w i t h the s c a r c i t y o f p o l y s y n t h e t i e twinning, i n -d i c a t e s a s o d i c and p o s s i b l y a p o t a s s i c composition f o r the m a j o r i t y of the f e l d s p a r . The f e l d s p a r g r a i n s are k a o l i n i z e d , e s p e c i a l l y the i n t e r i o r p o r t i o n s o f the l a r g e r grains.. Quartz - Quartz occurs as s m a l l , i n t e r s t i t i a l g r a i n s among the f e l d s p a r c r y s t a l s . Hornblende - Hornblende occurs as prominent, euhedral phenocrysts averaging 0.6 mm. i n l e n g t h but ranging up to 2 mm. i n l e n g t h . I t i s p l e o c h r o i o , brown t o greenish-brown and i s somewhat o h l o r i t i z e d . Long f e l d s p a r l a t h s f r e q u e n t l y r e s t a g a i n s t the s t r a i g h t edges of hornblende g r a i n s w i t h an a t t i -tude p a r a l l e l to the edges sugges t i n g that early-formed f e l d -spar l a t h s had come to r e s t a g a i n s t the hornblende c r y s t a l when most o f the rock was s t i l l f l u i d . C h l o r i t e - A green c h l o r i t e , some of which i s pennine, comprises 10 percent of the rock. I t occurs i n p a r t l y a l t e r e d hornblende g r a i n s , and i n both l a r g e and s m a l l g r a i n s , some of which appear to be pseudomorphs a f t e r hornblende. In the l a t t e r occurrence i t i s u s u a l l y a s s o c i a t e d w i t h carbonate. Carbonate - Carbonate ooours mostly as pure g r a i n s assoc-i a t e d w i t h the f e l d s p a r of the groundmass but a l s o as rounded, -56B-i r r e g u l a r g r a i n s i n s i d e c h l o r i t e g r a i n s . Name o f the Rook. This rock may be c l a s s e d as a v o g e s i t e lamprophyre a l -though i t has perhaps, too low a p r o p o r t i o n of ferromagnesian c o n s t i t u e n t s f o r a t y p i c a l lamprophyre. N e v e r t h e l e s s , i t has a h i g h a l k a l i p r o p o r t i o n , s i n c e the m a j o r i t y of f e l d s p a r i s a l k a l i c , and i t t h e r e f o r e f u l f i l l s the requirements f o r a lamprophyre i n regard to i t s chemical composition. The rook might be c l a s s i f i e d as a h o r n b l e n d e - q u a r t z - s y e n i t e except that the p r o p o r t i o n of ferromagnesian m i n e r a l s i s too h i g h f o r a t y p i c a l s y e n i t e . In view of the lamprophyrio t e x t u r e of the rock, together, with i t s r e l a t i v e l y h i g h p r o p o r t i o n of ferromagnesian m i n e r a l s and i t s a l k a l i c composition i t i s perhaps best to c a l l the rook a v o g e s i t e lamprophyre. This d e s i g n a t i o n should be q u a l i f i e d w i t h the statement t h a t the rock i s t r a n s i t i o n a l to a quartz s y e n i t e . 910 DRIFT Thin S e o t i o n No. PI - I n t e r i o r of dyke. T h i s specimen of dyke rock i s from the 910 d r i f t a t Premier, the second l e v e l from the bottom, i n the r e c e n t l y -worked p a r t of the mine. The rock i s a p h a n i t i o , has a d i s -t i n c t l y green c o l o r and appears to be c a r b o n a t i z e d . The composition of t h i s specimen i s as f o l l o w s : F e l d s p a r . , 75$ Quartz 3$ -57B-O h l o r i t e Carbonate 20 $ 5 $ Magnetite, p y r i t e a c c e s s o r y This rock c o n s i s t s p r i m a r i l y o f a mass of s m a l l f e l d s p a r l a t h s , together with l e s s e r amounts of both l a r g e and s m a l l , green c h l o r i t e g r a i n s . Some of the l a r g e r c h l o r i t e g r a i n s appear to be pseudomorphic a f t e r hornblende and there are i n -stances of f e l d s p a r l a t h s r e s t i n g a g a i n s t the l a r g e c h l o r i t e g r a i n s i n a manner s i m i l a r to the \"wrapping-around\" o f the hornblende phenocrysts by f e l d s p a r l a t h s seen i n t h i n s e c t i o n No. 3. The rock has c e r t a i n s i m i l a r i t i e s i n appearance to t h a t i n t h i n s e c t i o n No. 3 but has a s t i l l h i gher p r o p o r t i o n of f e l d s p a r . F e l d s p a r - The f e l d s p a r l a t h s average 0.2 mm. i n l e n g t h and form a groundmass of i n t e r l o c k i n g l a t h s . They are l e s s clouded by a l t e r a t i o n than those i n t h i n s e c t i o n 3 and i t could be seen that about f i v e peroent of them are p b l y s y n t h e t -i c a l l y twinned. The twinned f e l d s p a r i s a l b i t e and the r e -maining untwinned f e l d s p a r a l s o has a r e f r i n g e n c e l e s s than balsam and i s o r t h o c l a s e . Quartz - Quartz occurs i n t e r s t i t i a l l y . C h l o r i t e - C h l o r i t e occurs mostly as s m a l l , i r r e g u l a r l y -shaped g r a i n s ( l e s s than 0.1 mm. i n s i z e ) s c a t t e r e d through the groundmass but a l s o i n l e s s e r amount as l a r g e (0.3-0.4 mm.) g r a i n s which may be pseudomorphic a f t e r hornblende pheno--58B-c r y s t s . As there i s no i d e n t i f i a b l e r e s i d u a l hornblende or b i o t i t e , i t i s not known f o r sure what m i n e r a l was a l t e r e d to form the c h l o r i t e . Carbonate - Most of the oarbonate i s s c a t t e r e d among the f e l d s p a r g r a i n s but some of i t i s i n a s s o c i a t i o n w i t h c h l o r i t e . Opaque Spots - Small dark-grey, powdery, opaque spots a v e r a g i n g 0.02 mm. i n s i z e are u n i f o r m l y d i s t r i b u t e d i n l a r g e number through the r o c k . They are white i n r e f l e c t e d l i g h t . Owing to the f a c t t h a t c h l o r i t i z a t i o n of the o r i g i n a l mafio m i n e r a l s has l a r g e l y destroyed any euhedral q u a l i t y they may have had, i t i s impossible to judge a c c u r a t e l y the o r i g i n a l t e x t u r a l c h a r a c t e r i s t i c s of the rock. There i s a f a i r l y s t r o n g suggestion, however, that p r i o r to o h l o r i t i z a -t i o n t h i s rock was somewhat s i m i l a r , t e x t u r a l l y , to specimen No. 3. In view of the f a c t that the m a j o r i t y of the f e l d s p a r i s o r t h o c l a s e - f e l d s p a r , the rock might be c a l l e d a v o g e s i t e but as the ferromagnesian p r o p o r t i o n i s so low (20 peroent) and as the texture i s not c l e a r l y lamprophyrio i t i s perhaps b e t t e r to c l a s s i f y t h i s r o c k as a s y e n i t e . In t h i s case, a l s o , the name should be q u a l i f i e d by s t a t i n g that i t i s t r a n s -i t i o n a l to a v o g e s i t e s i n c e the p r o p o r t i o n of ferromagnesian m i n e r a l s i s l a r g e f o r a s y e n i t e . Thin S e o t i o n No. R l l . - Contaot of dyke wi t h m i n e r a l i z e d por-phyry. T h i s i s a specimen, from Dr. W.H. White's c o l l e c t i o n , of -59BV dyke rook such as i s termed lamprophyre at the Premier mine. M e g a s c o p i c a l l y , i t i s a v e r y f i n e - g r a i n e d , almost a p h a n i t i c , dark g r e e n i s h - g r e y rock which co n t a i n s s m a l l w h i t i s h g r a i n s of carbonate and s m a l l p a r t i c l e s of p y r i t e . I t i s i n c o n t a c t w i t h porphyry which i s m i n e r a l i z e d w i t h p y r i t e . M i c r o s c o p i c a l l y , the dyke i s seen to be l a r g e l y (65 per-oent) composed of an indeterminate, g r e y - o o l o r e d groundmass whioh i s clouded by a l t e r a t i o n so that i t appears white i n r e f l e c t e d l i g h t . The groundmass showsiino a n i s o t r o p i s m i n i t s present s t a t e . Under hi g h m a g n i f i c a t i o n there can be seen c o l o r l e s s , n e e d l e - l i k e c r y s t a l s , 0.01 mm. t h i c k to almost sub-microscopic i n s i z e , v e r y t h i n l y d i s t r i b u t e d i n the groundmass, g i v i n g i t , i n p l a c e s , a f e l t e d appearance. The o n l y e s s e n t i a l m i n e r a l s which could be i d e n t i f i e d are o a l c i t e , f e l d s p a r and q u a r t z . They g e n e r a l l y occur i n g r a i n s of .05 mm. dimensions. F e l d s p a r i s the only euhedral m i n e r a l i n the s l i d e , the l a r g e s t c r y s t a l s of which rank as micro-phenocrysts. The composition of the rock i s : C a l c i t e 20 f> F e l d s p a r . 10 $ Quartz 5 fo I s o t r o p i o Groundmass 65 fo A p a t i t e , p y r i t e , magnetite - a c c e s s o r i e s . Quartz - Quartz i s u n i f o r m l y d i s t r i b u t e d i n the form of rounded g r a i n s , .05 mm. i n diameter. -60B-F e l d s p a r - F e l d s p a r l a t h s are up to 0.8 mm. l o n g and are untwinned; no i n t e r f e r e n c e f i g u r e s nor r e f r a c t i v e i n d i c e s could he obtained f o r i t . O a l c i t e - O a l c i t e has formed by groundmass a l t e r a t i o n , which was most e f f e c t i v e around edges of quartz and f e l d s p a r g r a i n s , and by p a r t i a l or complete replacement of f e l d s p a r l a t h s by c a l c i t e . C a l c i t e i s p r o f u s e l y s c a t t e r e d through the rook i n g r a i n s of .02 to 0.1 mm. diameter, which o f t e n have c l e a r i n t e r i o r s and cloudy, i n c o m p l e t e l y transformed outer zones. I s o t r o p i c Groundmass - The v e r y f i n e c o l o r l e s s n eedles whioh sometimes give a f a i n t l y d i s c e r n i b l e f e l t e d appearance to the groundmass seem at f i r s t glance to be the s m a l l e s t r e p r e s e n t a t i v e s - of f e l d s p a r g r a i n s g r a d i n g downward i n s i z e from the micro-phenoorysts. However, the i n t e r f e r e n c e c o l o r of these t i n y needles i s too h i g h f o r f e l d s p a r as i t i s f i r s t -o rder white i n g r a i n s which are l e s s than .01 mm. t h i c k . The needles have p a r a l l e l e x t i n c t i o n and they may t h e r e f o r e be b i o t i t e or some other ferromagnesian m i n e r a l . The ferromag-n e s i a n c o n s t i t u e n t s of t h i s rock, which must be i n a p p r e c i a b l e amount to give the. rook 3uch a dark c o l o r , are contained i n the groundmass where they are i n s u f f i c i e n t l y o r y s t a l l i z e d to permit i d e n t i f i c a t i o n . A p a t i t e , p y r i t e , magnetite - O c c a s i o n a l euhedral g r a i n s o f a p a t i t e can be seen as w e l l as 0.15 mm. g r a i n s of p y r i t e and .05 mm., square and diamond-shaped, euhedrons of magnetite. -61B-A tear-shaped i n e l u a i o n or amygdule, 1.5-mm. i n diameter, occurs i n the s e c t i o n . I t c o n t a i n s s m a l l o a l c i t e and s e r i o i t e g r a i n s p o i k i l i t i c a l l y enclosed by a g r a i n of a n e a r l y c o l o r -l e s s m i n e r a l which i s b i a x i a l and has dark grey i n t e r f e r e n c e c o l o r . The rock has flow s t r u c t u r e due to alignment of f e l d s p a r l a t h s and some elongated carbonate g r a i n s . The specimen i s , u n f o r t u n a t e l y , from the c h i l l e d edge of the dyke, and i s i n s u f f i c i e n t l y c r y s t a l l i z e d to permit a de-t e r m i n a t i o n of i t s composition or i t s i d e n t i f i c a t i o n as a lamprophyre.' I t s dark green c o l o r suggests that i t i s f a i r l y b a s i c i n composition, y e t there are no ferromagnesian c r y s t a l s p r e s e n t . I t has been observed, i n a l l lamprophyres s t u d i e d , that t h e i r c h i l l e d edges i n v a r i a b l y c o n t a i n ferromagnesian c r y s t a l s which are o n l y s l i g h t l y s m a l l e r than phenocrysts o c c u r r i n g i n the c e n t e r o f the dyke, even though a l l the s a l i c c o n s t i t u e n t s be u n c r y s t a l l i z e d . The l a c k of ferromagnesian c r y s t a l s i n t h i s specimen i s t h e r e f o r e i n d i r e c t evidence that the rock i s not a lamprophyre but i t must be discounted owing to the p o s s i b i l i t y t h a t a n o n - p o r p h y r i t i c , very f i n e - g r a i n e d lamprophyre might have no mafic c r y s t a l s i n i t s c h i l l e d bor-ders even though they occur at the c e n t e r . -62B RUTH MINE, SLOOAN DISTRICT LAMPROPHYRE SILL - 5 LEVEL A d s i c u s s i o n of the f i e l d r e l a t i o n s i s g i v e n i n Appendix A. Thin S e c t i o n s Nos. 1 and 2. Speoimen No. 1 i s from a lamprophyre s i l l near i t s con-t a c t w i t h the Ruth lode and specimen No. 2 i s from the same s i l l , f o u r f e e t away from the c o n t a c t . The onl y d i f f e r e n c e between the two specimens i s t h a t No. 2 has v e r y many l a r g e , e l l i p t i c a l , carbonate aggregations, a l l o r i e n t e d normal to the s i l l w a l l s whereas i n No. 1, there are onl y three such bodies. M e g a s c o p i c a l l y , the r o c k has a grey c o l o r due to intense carbonati-zation. No c o n s t i t u e n t m i n e r a l s are d i s -c e r n i b l e other than c a l c i t e . The o u t s t a n d i n g f e a t u r e of t h i s rock i s the occurrence i n i t of l a r g e , p ale-green c h l o r i t e c r y s t a l s up to 1 mm. long which c o n s t i t u t e about 45 percent of the rook and are the onl y ferromagnesian c r y s t a l s present except f o r a few s m a l l shreds of b i o t i t e . T h i s c h l o r i t e may have been formed through a l -t e r a t i o n of o r i g i n a l b i o t i t e s i n c e there are s m a l l b i o t i t e shreds i n s e o t i o n 2 and because the c h l o r i t e l a t h s resemble b i o t i t e i n t h e i r shape. On the other hand, as these shreds o f b i o t i t e do not show p a r t i c u l a r l y c l o s e a s s o c i a t i o n with the o h l o r i t e , i t i s not o e r t a i n that c h l o r i t e i s a f t e r b i o t i t e . No f e l d s p a r could be found i n e i t h e r s e c t i o n . -63B-The composition of t h i n s e c t i o n 2 i s : C h l o r i t e . 45 fo C a l c i t e , i n Oval Aggregations.... 20 fo C a l c i t e i n the Rock 20 fo Unknown 10 fo Quartz 3 fo B i o t i t e , p h l o g o p i t e ...a few g r a i n s C h l o r i t e - T h i s m i n e r a l i s p r o b a b l y p r o o h l o r i t e . I t has a p a l e - g r e e n i s h c o l o r , d i s t i n c t pleochroism, f i r s t - o r d e r white i n t e r f e r e n c e c o l o r , one p e r f e c t cleavage and an e x t i n c t i o n angle of 2\u00C2\u00B0-5\u00C2\u00B0. The l a t h s are l e n g t h f a s t , the o p t i c s i g n i s p o s i t i y e and the f i g u r e e i t h e r u n i a x i a l or b i a x i a l w i t h 2 V l e s s than f i v e degrees. The m i n e r a l occurs i n b i o t i t e - l i k e l a t h s and l a r g e , i r r e g u l a r b a s a l s e c t i o n s which are almost b l a c k under crossed n i c o l s . The r e f r i n g e n c e as determined w i t h immersion o i l s i s between 1.59 and 1.66. The c h l o r i t e l a t h s show a d i s t i n c t tendency to l i n e a t i o n s i m i l a r to that o f the carbonate e l l i p s o i d s but not to such a high degree. In a d d i t i o n , c h l o r i t e may a l s o occur i n r a d i a t i n g groups of l a r g e c r y s t a l s which u s u a l l y show s p h e r u l i t i c ex-t i n c t i o n e f f e c t s . The occurrence of c h l o r i t e i n t h i s r o c k i s very n o v e l and i s the more remarkable 3inoe i t i s accompanied by no other ferromagnesian m i n e r a l except the few g r a i n s o f b i o t i t e . C a l c i t e - C a l c i t e i s present i n two forms. One, as c l e a r , -64B-ooarae g r a i n s s c a t t e r e d through the rock and the other, as l a r g e (up to l / 3 i n c h long) e l l i p s o i d a l a g g r e g a t i o n s , each composed of a g r a n u l a t e d mass of s m a l l o a l c i t e g r a i n s . These e l l i p s o i d s have p a r a l l e l o r i e n t a t i o n i n a d i r e c t i o n normal to the w a l l s of the s i l l . The c a l c i t e i n the e l l i p s o i d s i s dark-ened by m a t e r i a l which i s white i n r e f l e c t e d l i g h t . The o a l -(1) c i t e i n the e l l i p s o i d s i s thought to have been formed by secondary s o l u t i o n s moving through a system of p a r a l l e l f r a c -t u r e s , which was i n t e r s e c t e d by another set of f r a c t u r e s , thu3 cau s i n g the f o r m a t i o n of oval-shaped o r i e n t e d masses wherever two f r a c t u r e s meet. Unknown - A m i n e r a l v e r y s i m i l a r to c o r d i e r i t e i n appear-ance but with a d e f i n i t e l y p o s i t i v e o p t i c s i g n i s i r r e g u l a r l y d i s t r i b u t e d i n the r o c k i n anhedral g r a i n s , 0.4 mm. i n d i a -meter. Very many f i n e s e r i c i t i o g r a i n s are i n v a r i a b l y c o n t a i n -ed i n the m i n e r a l . The o p t i c a l p r o p e r t i e s a r e : c o l o r l e s s , no v i s i b l e cleavage, r e l i e f very low, index v e r y c l o s e to balsam but probably a l i t t l e g r e a t e r than balsam, i n t e r f e r e n c e c o l o r f i r s t - o r d e r grey, u n i a x i a l or 2 V v e r y s m a l l , o p t i c s i g n p o s i -t i v e . The m i n e r a l may be a f e l d s p a r but i t i s v e r y hard to prove i t . Quartz - Quartz occurs as i n t e r s t i t i a l g r a i n s among the c a l c i t e and c h l o r i t e c r y s t a l s . B i o t i t e - B i o t i t e g r a i n s , seen best i n s e c t i o n 2, d e f i n i t e -(1) Sharp, W.; P e r s o n a l Communication. -65B-l y appear to be r e l i c s of a l t e r a t i o n as they are never eu-h e d r a l hut are u s u a l l y i n the form of s m a l l shreds. B i o t i t e , however, r a r e l y occurs i n s i d e g r a i n s of c h l o r i t e as would be expected i f the c h l o r i t e were a r e s u l t of b i o t i t e a l t e r a t i o n . The c o l o r of the b i o t i t e i s brown. In t h i n s e c t i o n 1, the o h l o r i t i c m a t e r i a l f r e q u e n t l y has a b i r e f r i n g e n c e too h i g h f o r c h l o r i t e . T h i s occurrence may represent the t r a n s i t i o n stage between b i o t i t e and c h l o r i t e . P h l o g o p i t e - A few g r a i n s , t e n t a t i v e l y i d e n t i f i e d as p h l o g o p i t e , occur i n t h i n s e c t i o n 2. They are lath-shaped, a l -most c o l o r l e s s , have p a r a l l e l e x t i n c t i o n and are l e n g t h f a s t . The h i g h e s t i n t e r f e r e n c e c o l o r observed was second-order blue and the i n t e r f e r e n c e f i g u r e i s almost u n i a x i a l , n e g a t i v e w i t h 9 one r i n g . Opaque M i n e r a l s - There are v e r y few, i r r e g u l a r l y d i s t r i b u t -ed b l a c k opaque g r a i n s which are p r o b a b l y magnetite. I n c l u s i o n s - A few i n c l u s i o n s c o n s i s t i n g of g r a n u l a t e d quartz g r a i n s t o g e t h e r w i t h a l i t t l e muscovite and carbonate occur i n the rock. These are up to one-quarter i n c h i n diameter and have no s p e c i f i c o r i e n t a t i o n such as that of the c a l c i t e aggregations. -66B-P l a t e 1. x 50 Reeves lamprophyre, U.S. 1. Shows the two zones of a l t e r a -t i o n surrounding r e s i d u a l o l i v i n e . A l s o v i s i b l e are b i o t i t e , d i o p s i d e , a p a t i t e and m e t a l l i c g r a i n s i n a ground o f f e l d s p a r , carbonate and quartz. P l a t e 2. x 50 Reeves lamprophyre, T. S. 1. S i m i l a r to P l a t e 1. P a r t l y a l t e r e d d i o p s i d e g r a i n s are more p l e n t i f u l and are c o n c e n t r a t -ed around edge o f a l t e r e d o l i v i n e g r a i n . -61B-P l a t e 3. x 20 S u l l i v a n , 3904 c r o s s - o u t . T.S. S35. B i o t i t e - l a m p r o p h y r e at top i n contact w i t h e a r l i e r \"low-grade\" ore a t bottom. I l l u s t r a t e s flow-banding i n the lamprophyre. P l a t e 4. x 55 B r a l o r n e , 1351 East D r i f t . T.S. 15(a). O h l o r i t i c lampro-phyre (blaok) i n contact w i t h v e i n quartz ( w h i t e ) . B i o t i t e phenooryst and flow-banding are v i s i b l e i n the lamprophyre. -68B-Plate 5. x 60 \"Hossland No.2\" lamprophyre. T.S. H33. Anhedral hiotite (dark) with feldspar (white). Biotite phenooryst on the right. Plate 6. x55 Premier, 90 stope. T.S. P3. Kersantite containing horn-blende phenocrysts in a groundmass of kaolinized feldspar, carbonate, chlorite and a l i t t l e i n t e r s t i t i a l quartz. "@en . "Thesis/Dissertation"@en . "10.14288/1.0053525"@en . "eng"@en . "Geological Sciences"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "The relationship between lamprophyre dykes and ore deposits with special reference to British Columbia"@en . "Text"@en . "http://hdl.handle.net/2429/41598"@en .