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The relationship between lamprophyre dykes and ore deposits with special reference to British Columbia Young, John W. 1948

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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 § } 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° 138° 137° 136° 135° 134° 133° 132° 131 130° 1 2 9 s 1 2 8 ° 1 2 7 ° 1 2 6 ° 1 2 5 ° 1 2 4 ° 1 2 3 ° 1 2 2 ° 1 2 1 ° 1 2 Q ° 1 1 9 ° 1 1 8 ° 117 c 1 1 6 ° 1 1 5 ° 1 1 4 ° 113 112^ 111° 110° 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 " (•) I R a l v v a y s ~ 136° 135° 134 133' 132 131 13 O c 129°Lo ' 'g»t -udel28 0 West 1 2 7 ° from 1 2 6 ° G r e e n w i c h l 2 5 c 1 2 4 1 2 3 ° 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<?a) (E) Johannsen : "Petrography". Vol. I l l , pages 32 and 137. ("37) - 3 - Orth.-Felds. Plag.-Felds. Very l i t t l e Feldspar Predominant Predominant NaCaf NaOaf "Family" Syenite Diorite Gabbro Perknite Biotite predominant Mlnette Kersantite Hornblende and/or Augite pre dominant Vogesite Spessartite (Oamptonite) Odinite Garewaite (rare) The term "oamptonite" is applied to lamprophyres of the spessartite classification which are more melanocratic than spessartite and therefore contain less feldspar. Odinite and garewaite are extremely rare. It should be emphasized that a l l gradations exist between these main types. The extremely basic lamprophyres, in which no feldspar i s present, are divided into three classes, in a l l of which o l i  vine is a prominent constituent and a l k a l i minerals are plenti f u l . Monohiquite is characterized by idiomorphic crystals of olivine and augite set in a colorless, isotropic base believed to be analoime. Hornblende and biotite may also be present. Limburgite is a type al l i e d to monohiquite but the i n t e r s t i t  i a l base is a brown glass instead of colorless analcime. A l - nBltes are olivine rich, biotite-monohiquites characterized by the presence of melilite and usually alkaline minerals in the groundmass. Ouachltite is an olivine-free variety of monchi quite, characterized by abundant biotite. _ 4 - - THEORIES AS TO THE ORIGIN OP LAMPROPHYRE ROCKS mrrsi Theories by Niggli Niggli points out, as have others, the complementary rela tion existing between aplites and lamprophyres when compared with the granite masses from which both originate. The two may be considered as the extreme acidic and basic products of fractional crystallization of granitic or granodioritic magma. He also states that lamprophyre dykes are usually later than the related aplites in their time of intrusion. With regard to the mechanics and chemistry of lamprophyre- formation, Niggli believes in the remelting or solution of early-formed ferromagnesian crystals to form.ia lamprophyric fl u i d , the ferromagnesians accumulating by gravitative settling towards the bottom of the magmatic chamber and the volatiles which dissolve them being forced down towards them by the pro gressive lowering of the solidifying batholithic hood. After the mixing of the basic crystals with the volatile f l u i d , the whole is forced out to form intrusive lamprophyres. Niggli p o i n t 3 to the usually high biotite and hornblende content of lamprophyres as evidence of the importance of water vapor and other volatiles in their formation. (1) Niggli, "Die Leichtflilchtigen Bestandtheile im Magma" - as quoted by Spurr in Bulletin of Geol. Soc. of Am. Vol 36, p.564. 032 5) (2) Niggli, "Gesteins und Mineralprovinzen" - as communicated to the writer by Dr. K. DeP. Watson. (1) (2) Theories by Grout and Reynolds Grout t h i n k s the p r o d u c t i o n i n g r a n i t i c magmas o f l a t e s i l i c e o u s r e s i d u e s ( a p l i t e and pegmatite), at the same time as l a t e b a s i c r e s i d u e s to be h i g h l y improbable. He i s an a s s i m i l - a t i o n i s t who c o n s i d e r s the occurrence of p a r t l y - a s s i m i l a t e d b a s i c i n c l u s i o n s i n some lamprophyre dykes as sug g e s t i v e that lamprophyres may be formed by the m i n g l i n g of b a s i c m a t e r i a l w i t h dyke f l u i d o f another composition. A p o i n t i n h i s favour i s t h a t the i n f i n i t e number of combinations of d i f f e r e n t k inds of i n c l u s i o n s and dyke f l u i d can account f o r the gr e a t v a r i e t y of f e a t u r e s found i n lamprophyres. Grout i s not dogmatic, how ever, and suggests t h a t i t i s l i k e l y t h a t s e v e r a l d i f f e r e n t p rocesses account f o r the v a r i e t y o f c h a r a c t e r i s t i c s of lampro phyres. D.L. Reynolds goes to an even g r e a t e r extreme i n a d v o c a t i n g a s s i m i l a t i o n than does Grout. (1) Grout: " C r i t e r i a o f O r i g i n of I n c l u s i o n s i n P l u t o n i c Rocks" B u l l . G.S.A. V o l . 48, l o . 11, p. 1549. (i931^~ ' (2) Reynolds, D1L.: " T r a n s f u s i o n Phenomena i n Lamprophyre Dykes and t h e i r B e a r i n g on P e t r o g e n e s i s . - 6 - Theories by Spurr and Comments Baaed on the F i n d i n g s of T h i s T h e s i s . (1) Spurr p r e s e n t s a l e n g t h y d i s c u s s i o n of- the r e l a t i o n be tween a l l types of dykes and m i n e r a l v e i n s , w i t h s p e c i a l con s i d e r a t i o n of the c o n t r o l exerted by w a l l - r o o k temperature on the z o n a l arrangement of ores and the accompanying f o r m a t i o n of contemporaneous dykes. In h i s view, w a l l - r o c k temperatures must be a t a c e r t a i n value f o r c e r t a i n ores to form and dykes, contemporaneous with the ore, must have a l s o r e q u i r e d the same temperature l e v e l f o r t h e i r c r y s t a l l i z a t i o n . He c i t e s s t a t i a - t i o a l evidence showing that b a a i c dykea (lamprophyre, diabaae, d i o r i t e ) are more n e a r l y oontemporaneoua w i t h ore than a c i d i c dykea and that probably a m a j o r i t y of the b a s i c dykes having a c l o s e time r e l a t i o n to ore are lamprophyres. His c o m p i l a t i o n i n c l u d e s d i s c u s s i o n of the lamprophyres of Rossland and A i n a - worth, B.C. S i m i l a r r e l a t i o n s were n o t i c e d i n the c o m p i l a t i o n of t h i s t h e s i s d u r i n g which a rough i d e a was r e t a i n e d of the r e p o r t e d occurrences of dykes other than lamprophyres. I t was found that a c i d dykes g e n e r a l l y antedate lamprophyres and t h a t l e s s c e r t a i n l y , but g e n e r a l l y , a c i d dykes are p r e - o r e . (1) Spurr, J.E.: " B a s i c Dyke I n j e c t i o n s i n Magmatic V e i n Se quences", B u l l . G. S.A. V o l . 36, 1925. p. 545. - 7 - THEORIES AS TO THE ORIGIN OF LAMPROPHYRE ROOKS (1) Theories by Bowen Bowen f i r s t p o i n t s out the two perhaps most important c h a r  a c t e r i s t i c s of the i l l - d e f i n e d and i n c l u s i v e group of rocks known as lamprophyres. These c h a r a c t e r i s t i c s a r e , t h e i r t e n  dency to a panidiomorphio or p o r p h y r l t i c t e x t u r e , the pheno c r y s t s u s u a l l y b e i n g ferromagnesian m i n e r a l s , and the tendency f o r the groundmass to be h i g h l y a l k a l i n e . Thus, there are commonly p h e n o c r y s t s o f o l i v i n e , pyroxene, hornblende, or b i o  t i t e , or any combination of the f o u r , i n a groundmass r i c h i n a l k a l i f e l d s p a r or other a l k a l i n e m i n e r a l s . We s h a l l d e a l i n the next paragraph w i t h the importance o f the a l k a l i n e components of the magma to the c r y s t a l l i z a t i o n processes of lamprophyric rocks and p o i n t out, f o r the present, t h a t Bowen b e l i e v e s the p r e v a l e n t p o r p h y r l t i c or panidiomorphio c h a r a c t e r of lamprophyres to i n d i c a t e t h a t they d i d not c r y s  t a l l i z e d i r e c t l y from a s i n g l e l i q u i d of the same composition as the rock but r e s u l t e d i n s t e a d from a r e a c t i o n between e a r l y - formed ferromagnesian c r y s t a l s and an a l k a l i n e l i q u i d e n c l o s  i n g them. The assumption that m a f i c c r y s t a l s e x i s t e d i n a suspending l i q u i d i s intended to account f o r the p r e v a i l i n g panidiomorphio or p o r p h y r i t i c c h a r a c t e r o f the s o l i d i f i e d lamprophyre. One of the reasons f o r s u s p e c t i n g that lamprophyres do not c r y s t a l l i z e d i r e c t l y from a u n i f o r m l y l i q u i d magma i s the absenoe o f proof that o h i l l e d selvages o f lamprophyre dykes (1) Bowen, N.l.:"The E v o l u t i o n of the Igneous Rocks", Chaps. 13 and 14, (1928). - 8 - have the same o v e r a l l ohemical composition as the t o t a l com p o s i t i o n o f the dyke, thereby s u g g e s t i n g that no l i q u i d e x i s t  ed which had the same composition as t h a t of the dyke. For examples of rocks o c c u r r i n g i n nature which may serve to s u b s t a n t i a t e h i s t h e o r i e s , Bowen uses the a l n O i t e s . These are n o n - f e l d s p a t h i c , p e r i d o t i t e - l i k e lamprophyres c o n t a i n i n g , u s u a l l y , idiomorphio o l i v i n e , a u g i t e , and b i o t i t e c r y s t a l s and c h a r a c t e r i s t i c a l l y m e l i l i t e t o gether w i t h a l k a l i c m i n e r a l s of d i f f e r e n t k i n d s . An example of such a l k a l i c m i n e r a l s i s analcime, which u s u a l l y forms a c o l o r l e s s , i s o t r o p i c base. Bowen's f i r s t t y p i c a l a l n o i t e i s a rock from I s l e Gadieux, Quebec, the c o n s t i t u e n t m i n e r a l s o f whioh are p l a i n l y d i v i s i b l e i n t o two g e n e t i c c l a s s e s : a u g i t e and o l i v i n e i n the f i r s t c l a s s , i n c r y s t a l s l/2 to 1 cm. i n diameter and i n the second c l a s s , b i o t i t e , m o n t i c e l l i t e , m e l i l i t e , and p e r o v s k i t e which make up more than one-half the rock, the l i q u i d which d e p o s i t e d them a t t a c k i n g and r e p l a c i n g l a r g e amounts of o l i v i n e and a u g i t e . The other example i s an a l n f l i t e from Montana i n which the o r i g i n a l m i n e r a l s are o l i v i n e and n e p h e l i t e w i t h p o s s i b l y a u g i t e , which have been a t t a c k e d by a l i q u i d which p a r t l y r e  placed them and de p o s i t e d p r i n c i p a l l y m e l i l i t e , hauyne, and p h l o g o p i t e . Bowen now proceeds, p a r t l y on the f i n d i n g s of i n v e s t i g a t e d systems and p a r t l y by a t h e o r e t i c a l p r o j e c t i o n of the r e s u l t s of these experiments to more complicated systems, to d e s c r i b e the manner i n which a l k a l i n e c o n s t i t u e n t s may a f f e c t the c r y s -- 9 - t a l l i z a t i o n of the eafemio elementa i n a melt, w i t h the r e s u l t  ant f o r m a t i o n of the l i m e - r i c h - m i n e r a l , m e l i l i t e . He f i r s t shows, that i n the t e r n a r y ayatem GaO -MgO-SiOg, a l i q u i d o o n a i s t i n g of 50 p e r c e n t f o r 3 t e r i t e ( EMgO.Si. Og) and 50 p e r  cent akermanite ( ScaO.MgO.2Si0g) c r y s t a l l i z e s i n the order f o r s t e r i t e , m o n t i c e l l i t e , m e l i l i t e ; the m e l i l i t e h a v ing a replacement r e l a t i o n to m o n t i c e l l i t e , and m o n t i c e l l i t e r e  p l a c i n g f o r s t e r i t e . T h i s d e s c r i p t i o n serves to c a l l a t t e n t i o n to the f a c t that m e l i l i t e may r e p l a c e o l i v i n e , a phenomenon a l r e a d y shown to occur i n n a t u r a l r o c k s . F i n a l l y , a q u a r t e r n - a r y diagram i s drawn, i n v o l v i n g GaO-MgO-SiOg and n e p h e l i t e , to i l l u s t r a t e the e f f e c t o f the a d d i t i o n of an a l k a l i - r i c h l i q u i d on the c r y s t a l l i z a t i o n of a s i l i c a - l i m e - m a g n e s i u m l i q u i d . B r i e f l y , the e f f e c t i s that n e p h e l i t e , being a f e l d s p a t h o i d , takes up s i l i c a thereby l e a v i n g the CaO-MgO-SiO p o r t i o n , i n e f f e c t , r i c h e r i n CaO and MgO. T h i s promotes the c r y s t a l l i z a  t i o n of l i m e - r i c h m e l i l i t e and o l i v i n e and r e t a r d s the forma t i o n of pyroxene, which i s l e s s b a s i c and which would o r d i n a r i  l y be formed i f n e p h e l i n e were not p r e s e n t to deprive the s o l u  t i o n of s i l i c a . The r e a c t i o n of s i l i c a and n e p h e l i t e mean while r e s u l t s i n the f o r m a t i o n of the a l k a l i n e m i n e r a l s (hauyne, p h l o g o p i t e , etc.) of the groundmass, The s i g n i f i c a n c e of the e f f e c t that n e p h e l i n e has i n pro moting the c r y s t a l l i z a t i o n of l i m e - r i c h m e l i l i t e i s that i t i s not n e c e s s a r y that the s o l u t i o n s be r i c h i n lime i n o rder to produce m e l i l i t e . M e l i l i t e may form from an a l k a l i - r i c h magma through the agency of r e a c t i o n e f f e c t s brought about by the a l k a l i s . T h i s f e a t u r e i s e x e m p l i f i e d i n nature by the f r e  quent a s s o c i a t i o n of n e p h e l i t e and m e l i l i t e i n rooks. The value of d i s c u s s i n g the f o r e g o i n g ideas of Bowen l i e s i n the f a c t t h a t a l k a l i n e m i n e r a l s are important i n lampro phyres and i t i s w e l l to have some conception of the p a r t they appear to p l a y i n the f o r m a t i o n of lamprophyres. Prom an ex pe r i m e n t a l and t h e o r e t i c a l approach to the s u b j e c t , Bowen has tra c e d a l i k e l y c h a i n of events, i n v o l v i n g nepheline (whose common occurrence i n these rocks j u s t i f i e s i t s use i n the d i s  cussion) , s i l i o a and the cafemic i n g r e d i e n t s , a l l o f which c r y s t a l l i z e and r e a c t to produce (1) m e l i l i t e , which i s char a c t e r i s t i c of a l n O i t e s , (2) h i g h l y - a l k a l i n e groundmass miner a l s such as analcime, hauyne, b i o t i t e and p h l o g o p i t e , and (3) the rimming of aug i t e or o l i v i n e by m e l i l i t e , one example among the many a p p a r e n t l y noted, of r e a c t i o n and replacement r e l a t i o n s which m i n e r a l s of the second g e n e t i c c l a s s have to those o f the f i r s t g e n e t i c c l a s s . — I t -* A POSSIBLE CONNECTION BETWEEN ORB-FORMING SOLUTIONS AND THE  ALKALINE SOLUTIONS BELIEVED TO BE IMPORTANT IN THE ORIGIN OF LAMPROPHYRES The w r i t e r proposes to make use o f the f o r e g o i n g summary of the p a r t played by a l k a l i n e s o l u t i o n s i n forming lampro phyres to present a theory which w i l l c o r r e l a t e the a l k a l i n e s o l u t i o n s w i t h those that a p p a r e n t l y form ore d e p o s i t s . I t w i l l be nec e s s a r y f i r s t to p o i n t out that the mechanics of formation suggested by Bowen f o r h i s o l i v i n e - b e a r i n g lampro- (1) phyres are not adaptable t o a th e o r y that proposes a r e l a t i o n between a l k a l i n e , lamprophyre-forming s o l u t i o n s and a c i d , ore- forming s o l u t i o n s . In Bowen's lamprophyre-forming process, the a l k a l i n e l i q u i d develops a l o n g with the b a s i c o r y s t a l s as a r e s u l t of a r e a c t i o n between hornblende c r y s t a l s and a h o t t e r l i q u i d s a t u r a t e d w i t h olivkie, pyroxene and perhaps b a s i c p l a g i o c l a s e i n t o which the hornblende s i n k s . The added horn blende, due to the e f f e c t o f the b a s i c elements that i t con t r i b u t e s , a c c e l e r a t e s the c r y s t a l l i z a t i o n of o l i v i n e , pyroxene and perhaps b a s i c p l a g i o c l a s e from the l i q u i d , the net e f f e c t on the l i q u i d , consequently, being an i n c r e a s e i n i t s a l k a l i n  i t y . I f t h i s mixture of ferromagnesian c r y s t a l s and a l k a l i c l i q u i d be injected, i n t o c o l d e r rocks, i t s r a p i d c o o l i n g might g i v e suoh rooks as the o l i v i n e - b e a r i n g lamprophyres d i s c u s s e d i n the pre c e d i n g s e o t i o n . Hence, i t i s evi d e n t t h a t Bowen does (1) Op. c i t . Chap. XIV. not suppose a separate and d i s t i n o t e x i s t e n c e of ferromagnesian c r y s t a l s and a l k a l i n e l i q u i d but r a t h e r , that the ma f i c c r y s  t a l s and the a l k a l i n e f l u i d develop together and at the same time. The theory now to be proposed, r e q u i r e s a p r o d u c t i o n o f the a l k a l i n e l i q u i d that w i l l e v e n t u a l l y mingle w i t h the f e r r o  magnesian c r y s t a l s , by a process e n t i r e l y unconnected w i t h the o ferjrmagnesian crystals. (A s i m i l a r j o i n i n g o f the two phases a f t e r the separate f o r m a t i o n o f each has been proposed by N i g g l i . ) The manner of fo r m a t i o n of the v o l a t i l e , a l k a l i n e l i q u i d i n t h i s case, however, w i l l be d i f f e r e n t , and w i l l be r e l a t e d to the processes by which ore-forming s o l u t i o n s appar e n t l y o r i g i n a t e i n a b a t h o l i t h . (2) Again, an a r t i c l e by Bowen w i l l be drawn upon f o r the fundamental f a c t s and co n c e p t i o n s . In t h i s a r t i c l e , Bowen t r a c e s what he conceives to be the s u c c e s s i v e stages i n the for m a 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 , from the time the r e s i d u a l magmatic l i q u i d begins to form i n a c r y s t a l l i z i n g b a t h o l i t h to the f i n a l d i s p o s i t i o n of the m i n e r a l i z i n g f l u i d s a f t e r t h e y : . have deposited t h e i r v a l u a b l e metals. The "pe g m a t i t i c l i q u i d " , or the r e s i d u a l magmatic l i q u i d l e f t a f t e r c r y s t a l l i z a t i o n of the magma i s w e l l advanced, i s h i g h l y a l k a l i n e . I t i s a l k a l i n e because h y d r o l y t i c a c t i o n by water on the m e t a l l i c s i l i o a t e e l i (1) See page 4- . (2) Bowen, N.I. "The Broader Story o f D i f f e r e n t i a t i o n , B r i e f l y T o l d , " Ore Deposits o f the Western Sta t e s - Chap. I I I . - 1 3 - produces m e t a l l i c hydroxides, as shown hy the f o l l o w i n g equa t i o n : Na 23i0. 4+ HgO = SiO + 8_KaOH There are a l s o a o i d h y p e r f u s i b l e s present i n the l i q u i d such as C1,F, and S, but, due to the l a r g e q u a n t i t y of water and met a l l i c s i l i c a t e s present i n the r e s i d u a l l i q u i d , there are more than enough bases to n e u t r a l i z e the aoids.. The l i q u i d w i l l c o n t a i n the f o l l o w i n g ions t o g e t h e r w i t h others of l e s s abundance: H +, W , K, Ca + + , Mg + +, Fe\ Fe"** , A l + + + 01"* F~, S~", S0~~ , OH~ The next phase i s the b o i l i n g of t h i s p e g m a t i t i o l i q u i d , brought about by the i n c r e a s e i n i t s vapor p r e s s u r e due to con tinu e d c r y s t a l l i z a t i o n from the l i q u i d . As the l i q u i d b o i l s , the more*acid components come o f f f i r s t and i n l a r g e r quan t i t i e s than the b a s i c c o n s t i t u e n t s s i n c e they are more v o l a  t i l e . T h i s i s i l l u s t r a t e d by the e q u i l i b r i u m between K C l , HgO, HOI, and KQH i n whioh HgO and HCl are the most v o l a t i l e substances and pass i n t o the vapor phase more r a p i d l y , l e a v i n g the r e s i d u a l l i q u i d , i n t h i s case, r i c h e r i n XC1 and KOH. Therefore, the most abundant substances i n the gas are water vapor, halogen s a l t s , and a c i d s . The elements most prominent i n the gas are H, 0, CI, S i , F, S, B, K, Na, Fe, T i and A l . I t i s now necessary, a c c o r d i n g to Bowen, to p i c t u r e a " F r a c t i o n a l D i s t i l l a t i o n Column" set up i n the i n t e r s t i c e s of the surrounding magmatic hood and i n f r a c t u r e s i n the o v e r l y  i n g c o untry rock, i n which the a c i d vapors, fo r c e d outward by the b o i l i n g at the source, s e l e c t i v e l y drop t h e i r l e s s v o l a  t i l e components i n t o the l i q u i d phase as c o o l e r p l a c e s are reached so that the gas c o n t i n u i n g on i s s u c c e s s i v e l y e n r i c h  ed i n the more v o l a t i l e substances. The l i q u i d which u l t i m a t e  l y forms by condensation a t more remote p o i n t s w i l l be h i g h i n water, halogen compounds, and a c i d s and i t i s t h i s l i q u i d which i s considered to be the agent r e s p o n s i b l e f o r the forma- - t l o n of ore d e p o s i t s of igneous o r i g i n . I t i s w i t h the r e s i d u a l a l k a l i n e l i q u i d or " p e g m a t i t i c l i q u i d " l e f t behind at the b o i l i n g source that we are most concerned. This l i q u i d was a l k a l i n e b e f o r e b o i l i n g took p l a c e and i t should now be even more a l k a l i n e s i n c e the more v o l a  t i l e , a c i d p o r t i o n s of the o r i g i n a l l i q u i d have been v a p o r i z e d . A f t e r continued b o i l i n g the l i q u i d presumably c o n t a i n s the + + +++ ++ p o s i t i v e ions Na , K , A l and muoh s m a l l e r amounts of Ga , +•+• + + *ff+ Mg , Fe , and Fe s i n c e the i n c r e a s e i n c o n c e n t r a t i o n o f Ga, Mg, Fe., and A l i n the l i q u i d should be r e t a r d e d by t h e i r c r y s t a l l i z a t i o n as b a s i c aluminum s i l i c a t e s . The tendency o f the whole process then, appears to be towards enrichment o f the l i q u i d i n the a l k a l i metals, Na and K. I f the process i s h a l t e d by the f o r c i n g - o u t of the l i q u i d as i n t r u s i o n s i n t o the surrounding rocks, a p l i t e dykes, hi g h i n a l k a l i f e l d s p a r and quartz w i l l perhaps be formed. I f the b o i l i n g and c r y s t a l l i z a  t i o n c o n t i n u e , however, i t i s p o s s i b l e that a stage might be reached at which a l a r g e p a r t of the v o l a t i l e h a l i d e s , a c i d s , and much of the water have been b o i l e d o f f , the mafic o o n s t i t -- \ 5- •uenta have been c o n s i d e r a b l y reduced by c r y s t a l l i z a t i o n w i t h f a l l i n g temperature, and the end product i s a h i g h l y a l k a l i n e l i q u i d , much e n r i c h e d i n K and Na and s t i l l r e l a t i v e l y high i n v o l a t i l e s . Such a l i q u i d should be capable o f t r a n s p o r t  i n g accumulations of mafic m i n e r a l s , p r e v i o u s l y formed and accumulated i n another p o r t i o n of the b a t h o l i t h , and r e a c t i n g w i t h them to form lamprophyre i n t r u s i v e bodies. I f the above process be considered to take p l a c e ( i . e . the p r o d u c t i o n of ore d e p o s i t s by a c i d i c s o l u t i o n s accompanied by f o r m a t i o n of lamprophyres by the a s s o c i a t e d a l k a l i n e s o l u t i o n s ) , i t i s p o s s i b l e to see reasons f o r the frequently^-observed, c l o s e t i m e - r e l a t i o n between o r e - f o r m a t i o n and lamprophyre em placement. I t would e x p l a i n the tendency f o r lamprophyres to be l a t e r than the ore sinoe the b o i l i n g process, which i s be l i e v e d to produce the a c i d o r e - b e a r i n g s o l u t i o n s , should con t i n u e f o r some time before a h i g h l y a l k a l i n e r e s i d u e would be produced. I t i s more awkward to attempt an e x p l a n a t i o n , by t h i s h ypothesis, of lamprophyre dykes which pre-date the are. Another p i c t u r e must be u t i l i z e d , such as the l a t e r a l movement of lamprophyric f l u i d from a more remote p o r t i o n of the batho l i t h to the present l o c a l e of the ore; the ore, however, b e i n g perhaps produced by a separate and l a t e r b o i l i n g p rocess tak i n g p l a c e more n e a r l y beneath the ore l o c a l i t y . Lamprophyres r e l a t e d to t h i s l a t e r ore-forming process may or may not be formed, or i f formed, they may or may not be represented i n the ore d e p o s i t by post-ore lamprophyre dykes. - 1 6 - AN ATTEMPTED APPLICATION OF BOWEN'S ALKALINE SOLUTION  REACTION THEORY TO THE PRESENT WORK In Bowen's discussion of lamprophyres, only the ultra- basic type, alndite, was considered and in such a rook type, his reasoning seems well-supported by phenomena observed in naturally-occurring rocks. It seems logical that, in a gen eral way, conclusions reached Involving one member of a group of rocks such as lamprophyres should have some value In any consideration of the other members of the group, Bowen did not, however, attempt to show how the supposed effect of a highly-alkaline liquid reacting with pre-formed mafic crystals in the formation of alnOite could be applied to the formation of the more common lamprophyres. It w i l l be interesting, therefore, to attempt to find features in the rocks studied by the present writer which may indicate that similar processes took place in their formation, or conversely, to present evi dence discrediting such a theory. The Evldenoe of Phenocrysts and Groundmass Minerals In the  Rooks of this Thesis. Nearly a l l the rocks studied are porphyritio and invariab ly the phenoorysts persist into the chilled margins of the dykes, indicating, as in most porphyritic rocks, that the phenocrysts were crystallized and grew to a large size while the main portion of the dyke was s t i l l liquid. Regarding evi dence in these rocks of reaction between the phenocrysts and - 1*7 - the a l k a l i n e l i q u i d i n which they were supposedly suspended, the d i f f i c u l t y a r i s e s of d i s t i n g u i s h i n g the products of such a r e a o t i o n from those which might form i n the d e u t e r i c r e a c  t i o n of c r y s t a l s w i t h a suspending l i q u i d of a n o n - a l k a l i n e composition. (a) Reeves-McDonald Specimens. There, are numerous examples of r e a c t i o n - r i m s i n the rocks s t u d i e d i n t h i s i n v e s t i g a t i o n , p a r t i c u l a r l y i n the o l i v i n e phenocrysts of rocks from the Reeves-McDonald mine, d e s c r i b e d i n Appendix B. The reaction-rimming i n t h i s case, i s spec t a c u l a r and although the d e f i n i t e l y - i d e n t i f i e d r e a c t i o n prod u c t s are those o r d i n a r i l y encountered i n o l i v i n e pseudomorphs, there i s some doubt as to the i d e n t i t y of some of the r e a o t i o n products, n o t a b l y the "carbonate" of the outer a l t e r a t i o n rim i n t h i n s e c t i o n 1 and the unknown a l t e r a t i o n product d e s c r i b e d i n t h i n s e c t i o n 3 which, however, occurs a t the c e n t e r o f the pseudomorph and consequently i s l e s s l i k e l y to be due to l a t e - magmatio a l t e r a t i o n of the type i n which we are i n t e r e s t e d , D i o p s i d e phenocrysts of the rock i n t h i n s e c t i o n 1 are darkened by i n c i p i e n t a l t e r a t i o n which, however, i s u n i d e n t i f i e d . B i o  t i t e phenocrysts of t h i n s e c t i o n 1 are i r r e g u l a r l y penetrated or corroded (but not rimmed) by m a t e r i a l i d e n t i f i e d as carbon ate and c h l o r i t e , and andesine i s h i g h l y a l t e r e d to c 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 a l i t t l e c h l o r i t e . The c o n c l u s i o n t h e r e f o r e , i n regard to reaction-rimming of phenocrysts i n the specimens from Reeves-McDonald i s t h a t , u n l e s s the unknown min-- 1 8 - e r a l s secondary a f t e r o l i v i n e and pyroxene can be i d e n t i f i e d as types p e c u l i a r to a r e a c t i o n of o l i v i n e w i t h a l k a l i n e l i  q u i d , no a p p l i c a t i o n of Bowen's hyp o t h e s i s i s p o s s i b l e . F u r  thermore, the f e l d s p a r of the groundmass i s predominantly an desine and the groundmass c o n t a i n s no a l k a l i n e m i n e r a l s other than a s m a l l p r o p o r t i o n ( one percent of the rock) of a l k a l i n e f e l d s p a r and some of the s m a l l e r b i o t i t e g r a i n s , which how ever do not appear to be second g e n e r a t i o n c r y s t a l s as they grade i n s i z e downward from the b i o t i t e phenocrysts. (b) Mayflower Specimen, In t h i n - s e c t i o n s of t h i s rock, d i o p s i d e composing o r i g i n  a l l y 25 percent of the rock, i s 50 percent a l t e r e d at the un- mineralize'd c e n t e r of the dyke. The a l t e r a t i o n product i s a l  most a l l u r a l i t e which grew from the o u t e r edge inward w i t h p a r a l l e l o r i e n t a t i o n on the d i o p s i d e . There were a l s o formed, however, a p p a r e n t l y by a l t e r a t i o n of d i o p s i d e , small amounts of 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 . Of these p r o d u c t s , only the b i o t i t e i s a l k a l i n e , but as i t i s c o n f i n e d to the pseudomorphs, where i t i s enclosed by c h l o r i t e , i t s occurrence does not suggest r e a c t i o n of the d i o p s i d e phenocryst w i t h en c l o s i n g a l k a l i n e l i q u i d . T h i s apparent a l t e r a t i o n of d i o p s i d e to b i o t i t e i s not g e n e r a l throughout the r o c k nor does the b i o  t i t e ever r i m the d i o p s i d e * The p o s s i b i l i t y a l s o must be r e  cognized t h a t t h i s a l t e r a t i o n was e f f e c t e d by the hydrothermal m i n e r a l i z i n g s o l u t i o n s which acted on the dyke, even though m e t a l l i c m i n e r a l i z a t i o n does not extend to the dyke's c e n t e r . (c) Rossland Specimen, Biotite of this rock is shreddy and irregular in shape, a fact whioh might suggest i t s corrosion hy containing li q u i d . T a r c 5 on There 4 e , however, no reaction rimming -e* the biotite. The odorless base and slightly-crystallized feldspar i s alkalio, therefore there is no argument against an applioation of Bowen's theory here except for the lack of reaction rims on biotite grains. Hornblende of the rock is highly chloritized but this is apparently due to the penetration of hydrothermal solutions along a fracture in the rock, (d) Sullivan Specimen (unmineralized). Biotite, comprising 80 percent of the rock, is unaltered. It comprises 97 percent of the groundmass, the other constit uent, in almost negligible amount, is i n t e r s t i t i a l among the biotite grains and is a colorless, cryptocrystalline to a l  most Isotropio base, whose refringence could not be determined as being greater or less than balsam. (e) Bralorne and Pioneer Specimens. The biotite and pyroxene phenocrysts are unaltered. (f) Ruth-Hope Specimens. There i s , in these specimens, a very peculiar occurrence of large, greenish prochlorite(?) phenocrysts in a ground composed of oalcite and an unknown, cordierite-llke mineral. A few small shreds of apparently-residual biotite occur, but not in olose association with the prochlorite(?). - 2 o - (g) Premier Specimens. In specimen 3, hornblende phenocrysts are somewhat c h l o r - i t i z e d and a l s o f r e q u e n t l y have long f e l d s p a r l a t h s r e s t i n g against them on a l l s i d e s , the f e l d s p a r l a t h s appearing to r i m the hornblende g r a i n s . The r e f r i n g e n c e o f t h i s f e l d s p a r i s app a r e n t l y l e s s than balsam, although only one plaoe was found i n which i t was p o s s i b l e to make an o b s e r v a t i o n . Oonoluslons i n Regard to R e a c t i o n Rims A review o f these rooks r e v e a l s no d i a g n o s t i c evidence o f a c t i o n by u n u s u a l l y a l k a l i n e s o l u t i o n s on the b a s i c phenocrysts. I t must be remembered, however, t h a t late-magmatic, r e s i d u a l f l u i d s of any c r y s t a l l i z i n g rock are more a l k a l i n e than the mi n e r a l s that have been c r y s t a l l i z i n g so that d e u t e r i c r e a c t i o n e f f e c t s w i l l resemble those we have been seeking. The onl y s u g g e s t i o n that can be made, t h e r e f o r e , i s that r e a c t i o n rims are perhaps more h i g h l y developed i n these lamprophyres than i s u s u a l l y the case i n rocks s u b j e c t e d only to d e u t e r i c a l t e r  a t i o n . - 2 1 - LAMPROPHYRE OCCURRENCES. IN BRITISH COLUMBIA  AND THEIR RELATIONS TO ORE DEPOSITS — AS COMPILED PROM PUBLICATIONS A p e r u s a l o f most of the a v a i l a b l e g e o l o g i c a l l i t e r a t u r e d e a l i n g with B.C. has produoed the i n f o r m a t i o n appearing i n Appendix A. In oompiling t h i s i n f o r m a t i o n , the procedure has been to g i v e a l i t t l e g e n e r a l i n f o r m a t i o n on the lamprophyres and the geology of the map ar e a or mining d i s t r i c t * together w i t h a s h o r t d e s c r i p t i o n of those p r o p e r t i e s on whioh lampro phyres occur. In d e s c r i b i n g the i n d i v i d u a l p r o p e r t i e s , the lamprophyrio i n t r u s i v e s and t h e i r r e l a t i o n s h i p to ore i n time and space are f i r s t d e a l t with, then a b r i e f d e s c r i p t i o n o f the ore i s g i v e n . At the end of each s e c t i o n d e a l i n g w i t h a p a r t i c u l a r mining camp, there i s g e n e r a l l y a s h o r t summary g i v  ing the t o t a l number of p r o p e r t y d e s c r i p t i o n s f o r the ar e a and the number of these i n which the occurrence of lamprophyres i s mentioned." Table I i s intended to p r o v i d e a condensation of the more important f a c t s appearing i n the d e s c r i p t i o n s . T h i s t a b l e l i s t s the p r o p e r t i e s i n g e o g r a p h i c a l order and i n d i c a t e s wheth er the lamprophyres o o o u r r i n g on them are pre-ore or post-ore and whether the ore i s of the high, medium or low temperature type. The d e s i g n a t i o n of the d e p o s i t s as high-, low-, and med ium-temperature i s debatable except f o r some of the more im por t a n t mines s i n c e s u f f i c i e n t i n f o r m a t i o n i s not a v a i l a b l e i n the d e s c r i p t i o n s o f smal l p r o p e r t i e s . In the i n c o m p l e t e l y - i d e s c r i b e d , s m a l l p r o p e r t i e s , the c l a s s i f i c a t i o n i s o f t e n based on the mineralogy alone, as i n d i c a t e d i n the l i s t o f a b b r e v i a  t i o n s . I t w i l l be n o t i c e d that the d e s c r i p t i o n s are arranged i n a g e o g r a p h i c a l manner, those of sout h - e a s t e r n B.C., from the I n t e r n a t i o n a l Boundary to the B i g Bend country, being p l a c e d f i r s t , f ollowed by those i n the g e n e r a l v i c i n i t y o f the e a s t  ern Coast Range b a t h o l i t h c o n t a c t , from the southern extrem i t y a t Hedley, to the n o r t h end, i n the A t l i n d i s t r i c t . Memoirs and Summary Reports of the Canadian G e o l o g i c a l Survey were found to be the best sources o f i n f o r m a t i o n , a l  though m i s c e l l a n e o u s p u b l i c a t i o n s were v a l u a b l e i n some cases. A l l Memoirs and Summary Reports were searched and any r e p o r t d e a l i n g w i t h B.C. was examined f o r r e f e r e n c e s to lamprophyres. The index was c o n s u l t e d f i r s t and then the pages o f the "Gener a l Geology" s e o t i o n on which appear "Minor I n t r u s i v e s and DyxesJ were rood. I f lamprophyres were d e s c r i b e d there, the " D e s c r i p  t i o n s o f P r o p e r t i e s " were read f o r f u r t h e r d e t a i l s . I f , how ever, no lamprophyres were de s c r i b e d under "General Geology" i t was u a B l l y assumed that the area under c o n s i d e r a t i o n contained no lamprophyres and the r e p o r t was s e t a s i d e . I t i s e v i d e n t , t h e r e f o r e , that a f a i r l y c a r e f u l s earch was made and that areas such as Vancouver I s l a n d , the Cariboo, e t c , , i n whioh a non exi s t e n c e o f lamprophyre dyxes i s a assumed i n t h i s t h e s i s , are at l e a s t devoid of important lamprophyre con o e n t r a t i o n s a l t h o u g h - 2 3 - they may oontain minor ooou.rreno.es whioh have been overlooked. A complete reading of a l l reports, especially the "Descriptions of Properties", would be necessary in order to be certain that lamprophyres are not reported in these areas. TABLE I THE MORS IMPORTANT FEATURES OF LAMPROPHYRE OCCURRENCES  IN MINERALIZED AREAS OF B.C. List of Abbreviations: E * = epithermal, high-temperature end. * Based on a min eralization consisting largely of sphalerite, gal ena, argentite, ruby silver, native silver. M B mesothermal. Based on a mineralization consisting largely of quartz, galena, sphalerite, pyrite, chalcopyrite. M * 2 mesothermal, high-temperature end. Based on miner alization consisting largely of pyrite, galena, sphalerite, pyrrhotite. M(?) •» doubtfully mesothermal. Based on a mineralization consisting largely of quartz, pyrite, free gold. H = hypothermal, * = lamprophyres are considered contemporaneous with the ore. TABLE I D i s t r i c t P r o p e r t y Lamprophyre P r e - ' P o s t - Ore Ore Un c e r t a i n Type of Ore C h i e f Metals Remarks Boundary Creek F r a n k l i n M i n i n g Camp Rossland M i n i n g Camp Salmo Map Area Ymir Min i n g Camp Snowshoe mine Jewel mine M c K i n l e y mine x x (1) . J u r a s s i c lamprophyre dykes. (2) . Main, l a t e - J u r a s s i c p e r i o d of m i n e r a l i z a t i o n . (3) . 01igocene(?) lamprophyre dykes. (4) . Miocene lamprophyre dykes. (5) . Second, main, l a t e - M i o c e n e (?) p e r i o d of m i n e r a l i z a t i o n ' (6) . P r e - P l i o c e n e lamprophyres Reeves- MoDonald mine W i l c o x mine Ymir B e l l e Ymir P P o r t o R i c o F e r n 7 other prop e r t i e s x H- E H M * . M- M~ M- M(?) M(?) Cu Au»Ag (?) Cu,Au and (Pb)Zn,1 Ag Zn,Ptf Mg) Au.Pb Pb,Zn Au,Ag, Au Au Ore i s J u r a s s i c , lamp rophyre i s p o s t - M i o  cene, t h e r e f o r e i s pr o b a b l y unconnected w i t h ore. M a j o r i t y of lampro phyre dykes are l a t e r , but some are e a r l i e r than the ore and snrme are i n t r a - m i n e r a l i z a - t i o n . One of the two dykes i s m i n e r a l i z e d , the other u n m i n e r a l i z e d . F a u l t i n g a l o n g some lamprophyre dykes i s a conspicuous f e a t u r e . Pb Dykes are p r o b a b l y p r e - o r e . TABLE I. (CONT'D) D i s t r i c t P r o p e r t y Lamprophyre  T P r e - 7 P o s t - ' . TJn- TType of Ore I Ore '.certain! Ore Ch i e f ' Metals Remarks Ymir Kel son Area N e l s o n Map A r e a N e l s o n Map Area, E a s t H a l f Nevada Im p e r i a l Claims Second Re l i e f mine Center S t a r mine Dundee mine Golden Age S t a r and Alma mine Kootenay Gold Mines L t d . Athabaska Mine Royal Canad i a n Group Eureka mine Queen V i c  t o r i a Mine Kootenay Bonanza Mines, L t d . Spokane mine x x x M- H M* M-' M( ?) M( ?) M- M- H M+ Pb,Zn Cu Pb,Zn' ;Pb,Zn (Pb.Zn Su Pb,(Cu) Pb,Zn A lamprophyre forms H.W. of v e i n i n one open-cut. O c c a s i o n a l l y the v e i n w a l / i s a lamprophyre dyke. A p l i t e s are p r e - o r e * Cu (Ag.Cu) Pb,Zn B a s i c lamprophyre dykes. Limestone re placement ore. \ i TABLE I. (GONT'p) D i s t r i c t /; P r o p e r t y Pre-' Ore Lamprophyre P o s t - Ore Un certain Type o f Ore Chief Metals Remarks S u l l i v a n * mine L.H. Mine Antoine C l a i m Comstock 'x(?) Group F i s h e r *x(?) Maiden Mountain Con Group Richmond Eureka Group H M* M(?) E< Ruth-Hope' Group S i l v e r s m i t h - S l o c a n - S t a r * Group Reco Group 2 other prope E n t e r p r i s e mine M M r t i e s M Pb.Zn (?) (Zn) (?) Ag»Zn, Pb (?) Pb.Zn Pb.Zn (?) (?) Pb.Zn Ag Most are l a t e r , some are i n t r a - m i n e r a l i z a * t i o n . The country rock i s lamprophyre(?) Ore occurs m a i n l y where the lode l a y be tween lamprophyre and g r a n i t e c o u n t r y rock. B a s i c b i o t i t e dyke o f t  en forms H.W. o f l o d e . Dyke f o l l o w s lode and changes from H.W. to F.W. s i d e . Lodes i n p l a c e s t u r n t o f o l l o w f o r m a t i o n a l planes e s p e c i a l l y re ar b a s i c dykes. Lamprophyres c l o s e l y r e l a t e d i n time t o the pe r i o d of v e i n d e p o s i t t i o n . Lamprophyres n e a r l y contemporaneous w i t h ore. I n t i m a t e l y a s s o c  i a t e d i n p l a c e s w i t h the v e i n s t r u c t u r e . Most lamprophyres are pre - m i n e r a l and are i n  vol v e d i n the f a u l t i n g that d i s r u p t s the lode. 2 others are p o s t - o r e . TABES" I. { COST 'JD ) D i s t r i c t P r o p e r t y Pre Ore Lamprophyre - 'Post-' Un-Post Ore  c e r t a i n 'Type of Ore Ch i e f Metals Remarks Ainsworth M i n i n g Camp * Kootenay Lake D i s t r i c t Upper Ar row Lake F i e l d Map Area Hedley D i s t r i c t Jacks.Qh„ Group M e t l a k a h t l a c l a i m Whitewater & Whitewater Deep Groups Whitewater mine S t a r mine B l u e b e l l * mine B l u e b e l l mine K i r b y group B i g Ledge C o n s o l i d a t e d The Y/aterloo m i ning c l a i m N i c k e l P l a t e mine Sunnyside mine K i n g s t o n group x(?) X M M - H- Mt M- H- M* H* H* Pb.Zn Zn( Pb) Zn, Pb(Ag) Zn,Pb (?) (?) Pb.Zn, Ag Zn.Pb Zn Cu,2n, Pb Au(Cu) Au (?) Dykes and ore v e r y near l y contemporaneous. In the upper l e v e l s o f Whitewater mine. Magnetic ore r e p l a c e s b a s i c dyke rook i n low er l e v e l s . Dykes and ore are prob a b l y n e a r l y contempor aneous. Ore i s l i m e s t o n e r e  placement type. In l i m e s t o n e . Ore i s bl a n k e t type* r e p l a c i n g l i m e s t o n e . Contact metamorphic d e p o s i t . the same the same. i (ft TABLE r."T("€,OITT'"'"I>") D i s t r i c t P r o p e r t y Lamprophyre •Pre- •Post-'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.» 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£ 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<ie dyke may equally w e l f be pre.-ore.. The "Rossland No.2 lamprophyre" ( t h i n s e c t i o n 133) was obtained from a narrow dyke outcropping 50 f e e t n o r t h of a cav ed g l o r y - h o l e i n the LeRoi mine, the a c t u a l i n t e r s e c t i o n of the dyke w i t h the ore having been destroyed by mining o p e r a t i o n s . The l o o a t i o n of the specimen i s , however, a p a r e n t l y w i t h i n the range of p o s s i b l e m i n e r a l i z a t i o n stemming from the ore. The t h i n - s e c t i o n shows a c c e s s o r y p y r r h o t i t e g r a i n s and two g r a i n s of s p h a l e r i t e but the evidence i s i n s u f f i c i e n t f o r one to decide whether or not the dyke was i n t r u d e d i n the ore-forming p e r i o d . Of the remaining d e s c r i p t i o n s , which are l e s s important be cause there i s no m i n e r a l i z a t i o n of the lamprophyres, those d e a l i n g w i t h Pioneer and B r a l o r n e are of some i n t e r e s t as they provide p e t r o l o g i c data concerning c o l o u r a t i o n and apparent a l  t e r a t i o n o f c h i l l e d margins of the lamprophyres. These phenom ena are d e s c r i b e d i n Appendix B. The laboratory-work d e s c r i p t i o n s p e r t a i n i n g to the Ruth-- A-Z - Hope and Premier mines have v a l u e only f o r d e t e r m i n i n g whether the rooks are lamprophyres or not. The Premier lamprophyres s t u d i e d are g e n e r a l l y t r a n s i t o r y between v o g e s i t e and q u a r t z - hornblende-syenite whereas the Ruth-Hope rook i s a c h l o r i t e p h e n o c r y s t - b e a r i n g rock of p e c u l i a r p e t r o g r a p h i c appearance which a p p a r e n t l y c o n t a i n s no f e l d s p a r . The B r i t a n n i a t h i n s e c t i o n s were not d e s c r i b e d as they are o b v i o u s l y not of lamprophyric m a t e r i a l but of amygdaloidal, a n d e s i t i c to b a s a l t i c , v o l c a n i c dyke rock. APPENDIX A COMPILATION TABLE OF CONTENTS Page 49th P a r a l l e l , i n S e l k i r k Range ~ l A Boundary Creek D i s t r i c t 1A F r a n k l i n M i n i n g Camp 3A ^oasland M i n i n g Camp...... 4A Salmo Map Area 7A Ymir M i n i n g Camp 9A Ymir-Nelson. . 13A Nelson Map Area 15A Windermere Map Area 19A Slocan M i n i n g Camp.... 19A Ainsworth M i n i n g Camp 33A Xootenay Lake D i s t r i c t 35A Upper Arrow Lake.. 36A F i e l d Map Area. 36A B i g Bend Map Area 37A Hedley D i s t r i c t 38A Tulameen D i s t r i c t , 40A C o q u i h a l l a Area. 41A A l n b i t e Dyke Near Semlin, Thompson R i v e r . . . . . . . . . 41A Bridge R i v e r D i s t r i c t 42A Terrace Area 44A Hazelton-Smithers D i s t r i c t 49A A l i c e Arm D i s t r i c t 52A Port land-Canal Area*. 55A Taku R i v e r Area :.... 58A A t l i n D i s t r i c t . . . . . . 59A B r i t a n n i a 60A Coast and I s l a n d s of B.C.. 61A Bibliography $2 A -1A- 49TH PARALLEL, IN SELKIRK'RANGE, NEAR PEND D'OREILLE m — - AND COLUMBIA RIVERS This memoir presents i n t e r e s t i n g and complete d e s c r i p t i o n s of the m i n e r a l o g i c a l and chemical composition of lamprophyre dykes oc c u r r i n g i n t h i s area together w i t h t h e i r f i e l d r e l a  t i o n s but there i s no s p e c i a l reference to ore deposits i n the d e s c r i p t i o n s nor does Daly discuss t h e o r i e s as to the o r i  g i n of the lamprophyre. (2) BOUNDARY CREEK DISTRICT This d i s t r i c t i s j u s t north of the I n t e r n a t i o n a l Boundary i n the general area surrounding the c i t y of Greenwood. In the area, Brock s t a t e s that a l k a l i - s y e n i t e ( p u l a s k i t e type) occurs as i n t r u s i v e s and dykes and that there are a l s o dark lampro phyre dykes and l i g h t b o s t o n i t e - l i k e dykes which are probably connected w i t h the a l k a l i - s y e n i t e . A l l of these are of post l o w e r - T e r t i a r y age. The ore i s d i v i d e d i n t o two types, (1) Large, low-grade copper deposits c o n t a i n i n g p y r i t e , p y r r h o t i t e and magnetite, (E) Gold and s i l v e r bearing veins c o n t a i n i n g c h a l c o p y r i t e , p y r i t e , galena, s p h a l e r i t e , t e t r a h e d r i t e , r i c h s i l v e r minerals, (1) Daly, R.H. : C.G.S. Memoir 3 8 , Eof'th American C o r d i l l e r a , 49th P a r a l l e l , Part 1, 1912. (S) Brock, R.W.: C.G.S. Summary Report, 190E, P r e l i m i n a r y Re port on the Boundary Creek D i s t r i c t , B.C. P. 90. -2A- telluridea and native gold. Both these types are of Tertiary age and number(l) i s said to be related to the alkali-syenite while deposits of type (2) have alkali-syenite dykes associated with them and perhaps are also genetically related to the alkali-syenite. lamprophyre dykes are found in both types of deposit, occur ring in some but not a l l of the mines. In detail the occur rences are: No.(l) Type of Deposit Greenwood or Phoenix Gamp. Snowshoe mine - some dykes of porphyry and dark lampro phyre out the rocks, Deadwood Camp. Mother lode mine - heavily dyked by the pink a l k a l i - syenite porphyry, no lamprophyres mentioned. No.(2) Type of Deposit Jewel mine - Alkali-porphyry dykes occur in the mine and also small dark lamprophyre dykes. The lam prophyres are numerous, small, out the ore and are later than the ore. No. 7 mine - Contains many small black dykes, too decom posed for determination together with a grey syenite-porphyry dyke. - 3 1 - (1) FRANKLIN MINING GAMP T h i s oamp i s i n the West Kootenays, on the e a s t f o r k of the n o r t h f o r k o f the K e t t l e R i v e r . In t h i s a rea a l l formations are out hy p u l a s k i t e dykes and p l u g s . The youngest dykes of a l l are lamprophyres, i n c l u d i n g minettes and a u g i t e - m i o r o d i o r i t e , the former h e a r i n g a genetio r e l a t i o n s h i p to the p u l a s k i t e . Note: the lamprophyres are l a t e r than Miooene flows, whereas the only ore d e p o s i t s that have a nearby lamprophyre dyke ( a t the McKinley Mine), are o f J u r a s s i c age and t h e r e f o r e oan not be connected w i t h the p o s t - Miocene lamprophyre. A lamprophyre-minette i s exposed on McKinley Mountain f o r over a m i l e i n l e n g t h . I t v a r i e d from ten f e e t to 150 f e e t wide. Outcrops decompose r e a d i l y ( t h e r e i s a photograph show in g d i f f e r e n t i a l e r o s i o n ) and specimens f o r m i c r o s c o p i c study had to be c o l l e c t e d from No. 1 tunnel o f the MoKinley mine where a 4|- f o o t dyke f o l l o w s a lime s t o n e - t u f f c o n t a c t . F i e l d r e l a t i o n s p o i n t to the c l o s e oonnectlon of the lam prophyres, g e o l o g i c a l l y and p e t r o l o g i o a l l y , w i t h the gre a t Rossland a l k a l i - s y e n i t e and g r a n i t e b a t h o l i t h s to the east In the G ranite range which p r o b a b l y u n d e r l i e F r a n k l i n d i s t r i c t . There i s no d e t a i l e d d e s c r i p t i o n given o f the lamprophyre occurrence i n the MoKinley o r ot h e r mines o f the d i s t r i c t . (1) Drysdale, C.W.: C.G.S. Mem. 56, Geology of F r a n k l i n M i n i n g Camp, B.C.(1915). -4A~ (1),(2),(3) ROSSLAND MINING OAMP The Rossland campi in whioh were located many important gold-oopper mines suoh as the LeRoi, Center Star and Josie, i s famous for the number and diversity of the lamprophyre dykes (2) contained in the area. According to Barber there was a greater variety of fresh lamprophyre to be found here than any where in North America. Description of Lamprophyre. Lamprophyre dykes occur by the hundreds and in some sec tions of the mines there is a lamprophyre dyke in every 25 feet of section. A l l the lamprophyre dykes trend north and south with very l i t t l e deviation,and have nearly vertical dips whereas the ore trend is consistently in an east-west direc tion. In some sections of the mines where lamprophyre is very plentiful, the cross-cutting dykes reduce the ore proportion so much as to make the ore worthless for mining. In size, the dykes vary from the width of a knife blade to the immense Josie and Nickel Plate dykes whiph are up to 225 feet wide. There i s often a change in character in different parts of the same dyke, mica dykes in depth becoming non-mioa dykes higher up. The principal types are minettes (Tramway and Black dykes), (1) Drysdale, C.W.: C.G.S. Mem. 77, Geology and Ore Deposits of Rossland, B.C. (1915). (2) Barber, W.B.: American Geologist, Vol. XXXIII, p. 335. 0904-) (3) Bruce, E.3S.: Dept. of Mines Bulletin No. 4, (1917) Geology and Ore Deposits of Rossland, B.C. - 5 A - k e r s a n t i t e s ( J o s i e and N i c k e l P l a t e dykes)» v o g e s i t e s (Upper Center S t a r Dyke), s p e s s a r t i t e s (Spokane and White dykes) and o d i n i t e s hut there are a l s o a l l g r a d a t i o n s between these. Type o f Ore* The ore i s of the h i g h temperature replacement type, con s i s t i n g of v e i n s of massive p y r r h o t i t e and c h a l c o p y r i t e w i t h some p y r i t e and a l i t t l e a r s e n o p y r i t e i n a gangue of a l t e r e d country rook. R e l a t i o n between Lamprophyre and Ore* The f o l l o w i n g t a b l e , taken from Drysdale's memoir, g i v e s h i s c o n c e p t i o n of the c h r o n o l o g i c a l order i n which the country rook formations, the i n t r u s i v e s and the ore were formed: AGE OP ORE DEPOSITS 1. Marine sedimentation and igneous a c t i v i t y of the Carbon i f e r o u s p e r i o d (Mount Roberts f o r m a t i o n ) . 2. Deformation at olose of the P a l a e o z o i c . 3 . T r i a s s i c e r o s i o n and i n t r u s i o n of a u g i t e p o r p h y r i t e . 4. J u r a s s i c mountain-making r e v o l u t i o n , i n t r u s i o n o f T r a i l b a t h o l i t h and a l l i e d i n j e c t i o n s , e x t r u s i o n of l a v a s and t u f f s , i n t r u s i o n of lamprophyrio dykes. 5. F i r s t main p e r i o d o f ' m i n e r a l i z a t i o n . Replacement by s u l - phides along f i s s u r e and shear zones formed c h i e f l y i n the cover rocks of the T r a i l b a t h o l i t h and along f o r m a t i o n a l c o n t a c t s . 6. Cretaceous e r o s i o n c y o l e and removal of p r o b a b l y s e v e r a l thousand f e e t of cover rocks of b a t h o l i t h b r i n g i n g p o s s i b l y the upper extensions o f some of the present v e i n s c l o s e to the s u r f a c e . Land s u r f a c e brought down to one o f low r e l i e f . 7. Laramide mountain-making r e v o l u t i o n and r e - e l e v a t i o n of Columbia range. F a u l t i n g of v e i n s . 8. Eocene e r o s i o n and c o n t i n e n t a l sedimentation. Sophie and Lake Mountain conglomerate. 9. Oligocene (?) deformation, i n t r u s i o n of p o r p h y r l t i c mon  z o n i t e stocks and lamprophyre dykes; e r o s i o n i n t e r v a l . 10* Miocene vulcanism. I n t r u s i o n of C o r y e l l b a t h o l i t h and p u l - a s k i t e porphyry dykes; I n t r u s i o n of lamprophyrio dykes. 11 . Seoond main p e r i o d of m i n e r a l i z a t i o n . Secondary e n r i c h --6A- ment by ascending a l k a l i n e s o l u t i o n s c o n t a i n i n g f r e e g o l d . IE, I n t r u s i o n of Sheppard a l k a l i c g r a n i t e s t o c k s and dykes. 13. Blook f a u l t i n g and i n t r u s i o n o f youngest lamprophyres. 14. P l i o c e n e e r o s i o n c y c l e . P r o d u c t i o n o f present mature to l a t e mature upland topography and removal of upward exten s i o n s o f v e i n s i n upthrust f a u l t b l o c k o r ' h o r s t 1 . 15. Late P l i o c e n e u p l i f t and e r o s i o n of deep v a l l e y s . 16. P l e i s t o c e n e g l a c i a t i o n : removal of p o s s i b l e o x i d a t i o n zone of d e p o s i t s : accumulation of moraini e m a t e r i a l . 17. Reoent weathering and o x i d a t i o n . I t i s to be noted i n connection w i t h t h i s t a b l e t h a t the T r a i l g r a n o d i o r i t e b a t h o l i t h , which i s i d e n t i c a l w i t h the N e l  son g r a n i t e , i s a p p a r e n t l y the u l t i m a t e souroe of the o r e - b e a r i n g s o l u t i o n s . The o r e - b e a r i n g s o l u t i o n s came i n a f t e r the i n t r u s i o n of the f i r s t g e n e r a t i o n o f lamprophyre dykes which are a l s o probably g e n e t i c a l l y r e l a t e d to the g r a n o d i o r i t e . The two suooeeding i n t r u s i v e c y c l e s ( t h a t o f the p o r p h y r l t i c monzonite and the C o r y e l l p u l a s k i t e b a t h o l i t h ) are each f o l l o w  ed by t h e i r , a s s o c i a t e d lamprophyre dykes and there i s a second p e r i o d of m i n e r a l i z a t i o n whioh comes a f t e r the i n t r u s i o n of the C o r y e l l b a t h o l i t h . In c o n n e c t i o n w i t h the d i f f e r e n t types o f lamprophyre " i t seems probable that the s u b - a l k a l i c v a r i e t i e s ( k e r s a n t i t e and s p e s s a r t i t e ) are g e n e t i c a l l y r e l a t e d to the Nelson g r a n o d i o r  i t e : the int e r m e d i a t e v a r i e t i e s correspond to the monzonite and the a l k a l i c v a r i e t i e s (minette and v o g e s i t e ) to the a l - ( 1 ) k a l i c s y e n i t e or p u l a s k i t e . " T h i s r e l a t i o n s h i p may be deduced from c o m p o s i t i o n a l s i m i l a r i t i e s . (1) D r y s d a l e , C.W.: C.G.S. Mem. 77, Geology and Ore Dep o s i t s o f Rossland, B.C. (1915), p. S43. -7A- I t was n o t i c e d that lamprophyre dykes seemed to he e q u a l l y abundant throughout the ar e a of the sheet and that t h e i r d i s t r i  b u t i o n gave no i n d i c a t i o n of a l o c a l o r i g i n . The m a j o r i t y o f the dykes are l a t e r than the ore but some are o l d e r s i n c e they are i n c l u d e d i n the ore* cut o f f by ore and some are m i n e r a l i z e d . In some plaoes underground, where ore i n t e r s e c t e d e a r l i e r - formed dykes, the ore was bunched up a g a i n s t the dyke i n d i c a t  i n g a damming e f f e c t of the dyke. A l s o , where lamprophyres of an i n t e r m e d i a t e age were encountered, the a a r l i e r - f o r m e d s u l  phide m i n e r a l i z a t i o n was continuous beyond the dyke but the gol d v a l u e s , a p p a r e n t l y Introduced by m i n e r a l i z a t i o n o f a l a t e r age, stopped at the dyke. (1) SAIMO MAP AREA A good d e s c r i p t i o n o f the c h a r a c t e r i s t i c s and f i e l d r e l a  t i o n s of lamprophyre and a p l i t e dykes i n the map a r e a together w i t h a very s a t i s f a c t o r y account of a s p e c i f i c oocurrence of lamprophyre i n the Reeves-MoDonald Mine i s c o n t a i n e d i n Walker's memoir. In the g e n e r a l are?, a p l i t e dykes, a s s o c i a t e d w i t h g r a n i t e i n t r u s i o n s , out the country rock and are most abundant i n the most h i g h l y metamorphosed areas. A p l i t e dykes are cut by m i n e r a l v e i n s and by s t i l l l a t e r lamprophyre dykes. (1) Walker, J.P.: C.G.S. Mem. 172, Geology and M i n e r a l Deposits of the Salmo Map Area, B.C. (1934). - 8 A - "Lamprophyre dykes eut a l l other rockae and a l s o m i n e r a l d e p o s i t s . They are g e n e r a l l y f i n e - g r a i n e d , dark grey to b l a c k rooks i n which b i o t i t e and a u g i t e phenocrysts are v i s i b l e to (1) the naked eye." As a r u l e they are c o n s i d e r a b l y a l t e r e d and weather r a p i d l y . Reeves-McDonald Mine. Ore. The ore c o n s i s t s o f "low grade, disseminated replacements o f limestone by 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 and gal e n a , " o c c u r r i n g i n the lower p a r t o f Pend O r e i l l e S e r i e s . A t y p i c a l assay i s : z i n o - 6 . 2 $ , l e a d - 1 . 6 $ , s i l v e r - 0 . 5 ounces to the ton. D e s c r i p t i o n o f the Lamprophyre and the M i n e r a l i z a t i o n , In h i s r e p o r t on t h i s mine, Walker g i v e s a d e s c r i p t i o n o f the R i v e r A d i t from i t s p o r t a l to the f a c e . The t u n n e l passes eastward through limestone w i t h o n l y s t r e a k s of z i n c and le a d ( ? ) carbonates i n the brown oxides i n some p l a c e s and i n other p l a c e s the limestone i s barren. "At 3060 f e e t from the p o r t a l , p y r i t e occurs i n a 70 f o o t dyke which appears to be a lampro phyre but may be an a l t e r e d basio dyke o f a g r e a t e r age (Note: (2) t h i s dyke cuts and i s c h i l l e d a g a i n s t the o r e ) . The m i n e r a l  i z a t i o n continues i n the limestone beyond the dyke, and 18 (1) Walker, J.F.: C.G.S. Mem. 172, Geology and M i n e r a l Deposits of Salmo Map Area, B.C. ( 1934 ) , p. \& (2) Dr. H.C. Gunnlngj P e r s o n a l communication. -9A- f e e t beyond the dyke where a t e n - f o o t lamprophyre dyke cuts the m i n e r a l i z a t i o n i t c o n s i s t s of p y r i t e , p o s s i b l y some, 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 g a l ena." This m i n e r a l i z a t i o n continues east o f the s m a l l dyke f o r 180 f e e t and i s 50 f e e t wide i n p l a c e s . Diamond d r i l l i n g showed the m i n e r a l i z a t i o n to continue east f o r a f u r t h e r 130 f e e t but t h e r e a f t e r v e r y l i t t l e m i n e r a l i z a t i o n was encountered. In the other a d i t s of the mine, there i s good ore but there i s no r e f e r e n c e to lamprophyre dykes i n them. (1) YMIR MINING- OAMP There are many d i a s c h i s t i c dykes g e n e t i c a l l y connected to the Nelson b a t h o l i t h which grade from a p l i t e s to lamprophyres. lamprophyre dykes occur throughout the whole area and are prob a b l y of two ages - the o l d e r r e l a t e d to the Nelson b a t h o l i t h and the younger, more a l k a l i c , to the C o r y e l l b a t h o l i t h of Ter t i a r y age. The T e r t i a r y and l a t e r lamprophyres are l a t e r t h an the main p e r i o d of m i n e r a l i z a t i o n (connected w i t h the Nelson b a t h o l i t h ) and are of l i t t l e eoonomio importance. The lamprophyre dykes a r e g e n e r a l l y p e r s i s t e n t dykes w i t h steep d i p s , found c h i e f l y i n oover rooks o f the b a t h o l i t h . M i n e tte, k e r s a n t i t e , s p e s s a r t i t e and v o g e s i t e are a l l mentioned. "The lamprophyre dykes bear important s t r u c t u r a l r e l a t i o n s to (1) Drys d a l e , C.W.: C.G.S. Mem. 94, Ymir M i n i n g Gamp, B.C.(1917), . p. 35 -10A- some of the ore-bodies as, f o r i n s t a n c e , i n the Porto Rioo and (1) F e r n mines". No mention was made of the r e l a t i o n s of a p l i t e dykes to ore. The ores are gold, s i l v e r and l e a d ores whioh are d i v i d e d i n t o two types of which number one i s the more important. 1. A u r i f e r o u s galena, p y r i t e , s p h a l e r i t e . 2. Quartz ore w i t h f r e e g old - a l s o a l i t t l e p y r r  h o t i t e , c h a l c o p y r i t e , p y r i t e . T h i s type i s a s s o c i a t e d w i t h i n t r u s i v e dykes i n the Rossland v o l c a n i c s group. Wlloox Mine. The rocks are t r a v e r s e d by lamprophyre and a p l i t i c dykes, c h i e f l y the former ( m i n e t t e s ) . A v e r y p e r s i s t e n t 40 f e e t wide lamprophyre probably forms the western l i m i t of No. 1 ore shoot. A f a u l t of 30 f e e t displacement f o l l o w s a l o n g t h i s dyke. - F o u r t h o f J u l y v e i n - No. 1 t u n n e l . Boundary of ore shoot d e l i m i t e d by a k e r s a n t i t e dyke but the best v a l u e s i n the shoot are i n the end f a r t h e s t away from the lamprophyre. - No. 2 tunnel passes through 471 f e e t of barren ground, c u t t i n g s e v e r a l lamprophyres (kersan t i t e , v o g e s i t e ) . The ore i s enoountered f a r t h e r on. (1) Drysdale, C.W.: C.G.S. Mem. 94, Ymir M i n i n g Camp,B.C.(1917). -11A- The ore of the Wiloox Mine c o n s i s t s erf p y r i t e , galena, Fez03 and o c c a s i o n a l l y z i n c blende i n a gangue o f s i l i o i f i e d country rock. The p r i n c i p a l v a l u e s are i n g o l d , of whioh 70$ i s f r e e g o l d . Ymir B e l l e . Lamprophyres occur i n t h i s mine. The ore i s p y r i t e , galena, z i n c blende and q u a r t z . Ymir. Lamprophyre dykes w i t h branches occur through the work ings . A d e s c r i p t i o n i s g i v e n o f the i n t e r s e c t i o n of a f o u r - f o o t lamprophyre w i t h the v e i n lode which may be summed up best by a diagram: The ore i s galena, p y r i t e , z i n o blende and has g o l d , s i l  v e r and l e a d v a l u e s . Porto R i c o . T h i s mine had extremely r i c h o r e . For one-half m i l e on the s u r f a c e , the ore i s opened up at i n t e r v a l s and i n v a r i a b l y i s a g a i n s t a narrow, f i n e - g r a i n e d , oherty lamprophjtre ( a l t e r e d / ^ O t f / / /OStare Corry'a/^^y^ /.a/TT/brofiJyre tO^yAc 2 /eef or" Co/o//e. -ISA- augite-kersantite), about two feet wide with the same st r i k e and dip as the vein. The dyke usually forms the hanging-wall but sometimes ore is on both sides and sometimes the lampro phyre also i s put through the m i l l . Drysdale does not state whether the lamprophyre i s mineralized or not but he does imply that the lamprophyre i s pre-ore as "the mineralizing solutions followed along the underside of the dyke." The ore i s i n true fissure-type veins and contains quartz, pyrite and free gold. Fern. The ore i s along a granite porphyry dyke whioh usually forms the hanging-wall. The ore has terminated at a l a t e r lamprophyre-dyke which coincides with a f a u l t plane and had not been picked up on the other side of the lamprophyre f a u l t . In Ho. 2 tunnel, the gold values were highest near the lampro phyre dyke. The ore consists of quartz, pyrite and free gold i n f i s  sure veins. Blaok Oook, St e r l i n g , Iowna, Foghorn, Bluestone, Ollnoher, Evening Star. Lamprophyre dykes occur on these seven properties. Appar ently they are l a t e r than the ore. - 1 3 A - ( 1 ) YMIR -. NELSON AREA There are some r e f e r e n c e s to lamprophyre dykes i n the d e t a i l e d d e s c r i p t i o n s of p r o p e r t i e s i n t h i s memoir. Nevada-Imperial Claims. A shear zone i s explored on the s u r f a c e by open c u t s . In out 1 6 , the hanging-wall i s a mioa-lamprophyre dyke and the shear-zone i s w e l l m i n e r a l i z e d w i t h q u a r t z , galena, z i n c - blende and p y r i t e . In cut 1 7 , the dyke does not occur and the shear-zone has no d e f i n e d w a l l s but i s m i n e r a l i z e d w i t h some p y r i t e and galena. There are numerous other c u t s w i t h v a r y i n g degrees of m i n e r a l i z a t i o n on the claims but i n none of them i s the occurrence of lamprophyre mentioned. Second R e l i e f Mine. The "Second R e l i e f v e i n " , which s u p p l i e d almost a l l the p r o d u c t i o n , f o l l o w s the hanging-wall of a d i o r i t e - p o r p h y r y dyke. The common dykes on the p r o p e r t y are g r a n i t e - p o r p h y r y and quartz-porphyry} there are a l s o s e v e r a l mica- and horn- blende-lamprophyres. The lamprophyres are deemed to be the youngest of the dyke rocks and one of them cuts the Second Re l i e f v e i n . The ore c o n s i s t s of p y r i t e , p y r r h o t i t e , c h a l c o p y r i t e and p o s s i b l y molybdenite i n a gangue o f country rook and quartz c a r r y i n g some magnetite and, i n p l a c e s , garnet and e p i d o t e . Center Star Mine. A number of lamprophyre dykes occur on the 3 0 0 l e v e l . One ( 1 ) Cookfield,W.E.: C.G.S. Mem. 1 9 1 , The Lode Gold D e p o s i t s of Ymir Nelson Area, B.C. ( 1 9 3 6 ) . -14A- o f these out through the v e i n and i s d i s t i n c t l y younger than the v e i n . The v e i n s c o n s i s t of quartz w i t h p y r i t e , galena, z i n c blende and p y r r h o t i t e . Dundee Mine. The d e p o s i t i s a f i s s u r e v e i n c u t t i n g Pend d ' O r e i l l e s c h i s t and s m a l l tongues of the Nelson g r a n o d i o r i t e . The v e i n i s i n t e r s e c t e d by, and o f f s e t by, s e v e r a l lamprophyre dykes. The ore c o n s i s t s of fragments of country rock cemented by q u a r t z . The s u l p h i d e s are p y r i t e , galena and z i n c blende. Golden Age. S e v e r a l a u g i t e - k e r s a n t i t e dykes occur on the p r o p e r t y . O c c a s i o n a l l y , the v e i n w a l l i s a lamprophyre dyke. The d e p o s i t c o n s i s t s of p o o r l y d e f i n e d shear-zones c o n t a i n  i n g s t r i n g e r s and bunches of q u a r t z . The zones 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 z i n c blende. S t a r and Alma M Claims. A lamprophyre dyke, one f o o t wide, cu t s across the shear. The ore c o n t a i n s p y r i t e , c h a l c o p y r i t e and m a l a c h i t e . Summary of Ymir-Nelson Area. Of 34 p r o p e r t i e s d e s c r i b e d i n t h i s r e p o r t , s i x are des c r i b e d as c o n t a i n i n g lamprophyre dykes. --15A- (1) NELSON MAP AREA Lamprophyre Dykea* Lamprophyre dykea have a widespread development i n the whole area and are the youngeat rooka. They cut the ore-bodie3 i n c o n t r a d i a t i n o t i o n to l i t h o l o g i o a l l y s i m i l a r dyke8 i n the Slocan d i s t r i c t and at Sheep Creek whioh are o l d e r than the v e i n f i s s u r e s . The dykes v a r y from a f r a c t i o n o f an i n c h to 20 f e e t i n width and from 100 f e e t t o 1000 f e e t i n l e n g t h . Ore. The ores are o f three types: 1. g o l d - s i l v e r 2. c o p p e r - g o l d - s i l v e r 3. s i l v e r - c o p p e r (1) D e s c r i p t i o n of P r o p e r t i e s , Nelson Map Area 1. G o l d - S i l v e r Deposits Kootenay Gold Mines, L t d . - 5 m i l e s west o f Nelson. The v e i n s are cut by m i n e t t e s . The ore c o n t a i n s p y r i t e mostly, w i t h s m a l l q u a n t i t i e s o f galena, c h a l c o p y r i t e and v e r y r a r e l y , s o h e e l i t e . Athabaska Mine.-9 m i l e s from Nelson on east s l o p e of Morning Mt. A minette dyke cuts the ore and a p l i t e dykes are presen t whioh are pre-ore. The ore c o n s i s t s o f galena, zino-blende and p y r i t e . (1) LeRoy, (D.E.: C.G.S. Summ. Rept., (1911) Geology o f Nelson Map Area. .^ISA- Royal Canadian group. A b a s i c mica dyke cuts and s l i g h t l y f a u l t s the ore. 2. C o p p e r - G o l d - S i l v e r Deposits Eureka Mine - 8 m i l e s from Nelson. S e v e r a l b a s i c mica dykes cut and sometimes f a u l t the ore. Queen Y i o t o r i a Mine. The ore zone i s cut by b a s i c lamprophyre dykes. The ore i s o f the limestone replacement type and i s o f f a i r l y h i g h - temperature o r i g i n . The m i 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 m a l l amounts of magnetite and p y r r h o t i t e . Gangue m i n e r a l s are garnet, a c t i n o l i t e , e p i d o t e , quartz and o a l c i t e . 3. S i l v e r - C o p p e r D e p o s i t s The Kootenay Bonanza Mines L t d . - on Toad Mountain. Lamprophyres occur on t h i s p r o p e r t y . The ore c o n t a i n s t e t r a h e d r i t e , c h a l c o p y r i t e , p y r i t e and galena. (1) NELSON MAP AREA, EAST HALF * D e s c r i p t i o n of Dykes. The o n l y dykes d e s c r i b e d , other than lamprophyre dykes, are a few s m a l l f e l d s p a r - p o r p h y r y dykes. The lamprophyre occurs i n dykes and s i l l s which are f i n e - g r a i n e d and dark green w i t h b i o t i t e and hornblende the most conspicuous m i n e r a l s . (1) R i c e , H.M.A.: CL G i S i MSm. 228, Nelson Map Area, East H a l f , B.C. (1941) -17A- Many of them are g r e a t l y a l t e r e d w i t h the p r o d u c t i o n of c h l o r - (1) i t e and e p i d o t e . R i c e b e l i e v e s them to be r e l a t e d to the Mc Gregor s y e n i t e i n t r u s i v e s o f T e r t i a r y age. Ore. The ore has s i l v e r - l e a d - z i n c v a l u e s and i s of two types: 1. q u a % t z - c a l c i t e v e i n s w i t h c h a l c o p y r i t e i p y r i t e , p y r r h o t i t e and a l i t t l e galena and s p h a l e r i t e . T h i s type i s the l e s s important. 2. disseminated d e p o s i t s o f o h a l e o p y r i t e , p y r i t e and p y r r h o t i t e . The better-known mines i n the ar e a are the S u l l i v a n , Stem- winder, North S t a r and Bayonne. The occurrences o f lampro phyre i n these mines are not d e s c r i b e d i n t h i s memoir and the only r e f e r e n c e to lamprophyre found was that i n the Spokane mine. The p r o p e r t y d e s c r i p t i o n s i n t h i s memoir ar e , however, q u i t e s h o r t and incomplete so f a r as the d e t a i l e d geology i s concerned. 34 p r o p e r t i e s are d e s c r i b e d i n the memoir. Spokane Mine. L i t t l e i n f o r m a t i o n i s g i v e n . Four sma l l lamprophyre dykes c r o s s the v e i n f i s s u r e and have been f r a c t u r e d by l a t e move ment a l o n g the f i s s u r e . The d e p o s i t c o n s i s t s o f a q u a r t z - b e a r i n g f i s s u r e m i n e r a l  i z e d w i t h galena, s p h a l e r i t e , p y r i t e and a l i t t l e c h a l c o p y r i t e . (1) Rioe, H.M.A., &310.S. Mem.228, Nelson Map Area, East H a l f , B.C. (1941). -18A- (1) S u l l i v a n Mine* Lamprophyre dykes are present i n the S u l l i v a n mine hut no i n f o r m a t i o n oould be found r e g a r d i n g t h e i r number and s i z e . I t i s s t a t e d i n t h i s a r t i c l e t h a t the lamprophyres p r o b a b l y were i n t r u d e d toward the end of the m i n e r a l i z i n g p e r i o d . I n t e r e s t i n g phenomena are d e s c r i b e d i n connection w i t h one b i o t i t e lamprophyre o c c u r r i n g i n 3904 c r o s s - o u t . This dyke outs sediments 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 r h o t i t e and s p h a l r - e r i t e and i s l a t e r than the m i n e r a l i z a t i o n . However, a seam of galena ocours i n the dyke a l o n g a f a u l t plane, the galena being post-dyke i n age as i t p a r t i a l l y r e p l a c e s b i o t i t e o f the lamprophyre. The dyke i s a l s o carbonated at the c o n t a c t w i t h galena. Therefore, the dyke has been i n t r u d e d between the two types of m i n e r a l i z a t i o n , and as these events are con s i d e r e d by the authors to be probably c o n s e c u t i v e stages i n one, long-continued p e r i o d of m i n e r a l i z a t i o n r a t h e r than two d i s t i n c t m i n e r a l i z a t i o n epochs, i t appears t h a t the dyke and ore are, i n the l a r g e sense, contemporaneous. Note: D e s c r i p t i o n s of other specimens of t h i s same dyke may be found i n Appendix B. Ore. The d e p o s i t i s of the hypothermal type, p y r r h o t i t e , s p h a l  e r i t e and galena, the c h i e f s u l p h i d e s present, r e p l a o i n g a r  g i l l a c e o u s sediments along t h e i r bedding p l a n e s . (1) Swanson, 0.0. and Gunning, H.O.: Geology o f the S u l l i v a n Mine, C.I.M.M. B u l l . 402, Oct., 1945. -19A- (1) WINDERMERE MAP AREA On the r i d g e n o r t h - e a s t o f Mount Brewer there are two s m a l l lamprophyre dykes t e n inches wide. They are r o t t e n i n appearance but appear com p a r a t i v e l y f r e s h under the microscope. No d e s c r i p t i o n of the r e l a t i o n s h i p to ore d e p o s i t s was g i v e n . The ore i n the area i s s i l v e r - l e a d - z i n c ore and the m i n e r a l s are galena, s p h a l e r i t e , p y r i t e , t e t r a h e d r i t e , q u a r t z , c a l c i t e , b a r i t e and s i d e r i t e . ( 2 ) SLOCAN MINING OAMP S a l i c dykes and s i l l s , g r a n i t e and a c i d g r a n o d i o r i t e mostly, are i n great number i n the a r e a , e s p e c i a l l y i n the v i c i n i t y of m e t a l l i f e r o u s d e p o s i t s . M a f i c dykes, a l l lampro phyres, are l e s s abundant than s a l i o . S a l i c dykes s t r i k e n o r t h  west, p a r a l l e l to the r e g i o n a l 3 t r i k e o f the e n c l o s i n g r o c k s , whereas mafic dykes (lamprophyres) g e n e r a l l y s t r i k e n o r t h - e a s t , p a r a l l e l to the course o f the m e t a l l i f e r o u s v e i n s . D e s c r i p t i o n of lamprophyres. The lamprophyres weather more r e a d i l y than the e n o l o s i n g rooks and the weathering, p a r t i c u l a r l y of o l i v i n e , had produced a pseudo-amydgaloidal t e x t u r e . The most common type i s a dark- green, medium-grained lamprophyre c o n t a i n i n g e s s e n t i a l l y o l i v  i n e , pyroxene and b i o t i t e i n v a r y i n g p r o p o r t i o n s , w i t h acoessory (1) Walker, J.F.:CG.S. Mem. 148, Geology and M i n e r a l Deposits o f Windermere Map Area, B.C., (1986). (2) C a i r n e s , C.E.: C.G.S. Mem. 173, Slocan M i n i n g Camp, B.C.(1934) -30A- magnetite, l i m o n i t e and p y r r h o t i t e . L i t t l e quartz i s gener a l l y p resent and may he p a r t l y or e n t i r e l y secondary. F e l d  spar when presen t i s i n subordinate amounts and i s o a l c i c p l a g i o o l a s e . Amphibole i s s c a r c e . These lamprophyres y i e l d dykes r a r e l y g r e a t e r than a few f e e t wide, though a t the Slocan Sovereign they are 50 f e e t wide. They more commonly f o l l o w or p a r a l l e l the course of the m e t a l l i f e r o u s v e i n s than that of the e n c l o s i n g rooks. Consequently they s t r i k e n e a r l y normal to the s a l i c dykes and i n most cases cut a c r o s s them. They are more abundant i n the Slooan S e r i e s ( o f sediments) but s i m i l a r m a f i c dykes occur i n the Nelson g r a n i t e . The second type o f lamprophyre, observed i n g r a n i t i c areas ( F i s h e r Maiden and Comstook Mines), c o n t a i n s no o l i v i n e but has abundant hornblende together w i t h b i o t i t e , c a l c i c p l a g i o  c l a s e and a c c e s s o r y q u a r t z , magnetite, i l m e n i t e and e p i d o t e . The t h i r d type of lamprophyre c o n s i s t s almost e n t i r e l y o f secondary m i n e r a l s . I t i s l i g h t to dark grey and c o n t a i n s numerous l i g h t green s t r e a k s and brownish spots. The l i g h t green s t r e a k s are due to the chromium-bearing mica, m a r i p o s i t e and the brown spots to o x i d a t i o n of i r o n s u l p h i d e s and f e r r u g  inous carbonates. Under the microscope t h i s type i s l a r g e l y composed of f e r r u g i n o u s magnesium carbonate w i t h a s s o c i a t e d c o l o r l e s s mica ( m a r i p o s i t e ) , a l i t t l e quartz and sometimes s e r  p e n t i n e , o h l o r i t e , s u l p h i d e s and commonly c a l c i t e . These are best seen near the Whitewater and Jackson mines. T h e i r o r i  g i n a l composition i s i n doubt but they appear to grade i n t o -21A- the dark-green lamprophyre i n some outerops. The l a s t type of mafic dyke i s "Minette", which i s found near Sandon. These dykes are a few inches wide, d a r k - c o l o r e d and c o n t a i n a l a r g e amount of b l a c k mica. In most oases they are h i g h l y a l t e r e d . Age of Dykes. The s a l i o dykes and most of the mafic dykes are p r e m i n e r a l as they are out by the f i s s u r e s which p r o v i d e d e n t r y f o r the m i n e r a l - b e a r i n g s o l u t i o n s . The mafio dykes, however, are on the whole the younger of the two dyke-types s i n c e they cut the s a l i o . S a l i c dykes, abundant i n the Slocan S e r i e s (sediments), are scarce i n the g r a n i t e areas whereas mafic dykes are about e q u a l l y prominent i n both f o r m a t i o n s . The s a l i c dykes are considered to r e p r e s e n t a l a t e stage i n the i n t r u s i o n of the Nelson b a t h o l i t h s i n c e many of them bear l i t h o l o g i o a l resem blance to the l a t e r members of the b a t h o l i t h . The f o l l o w i n g paragraph i s quoted d i r e c t l y from Gairnes to present the evidence f o r a c l o s e time r e l a t i o n s h i p between lamprophyre and ore. The minor i n t r u s i v e s are much l e s s deformed than the p r e - b a t h o l i t h i c formations they i n t r u d e , undoubtedly because the. l a t t e r were deformed before i n t r u s i o n of the Nelson b a t h o l i t h . Developments underground have, however, shown that minor i n  t r u s i v e s were, i n p l a c e s , i n v o l v e d i n s h e a r i n g that a f f e c t e d o l d e r f o r m a t i o n s . In a number of i n s t a n c e s , both i n the Slocan s e r i e s and the Nelson g r a n i t e , mafic dykes have been observed to be f o l l o w e d by f i s s u r e s and shear zones p r o v i d i n g access f o r m i n e r a l i z i n g s o l u t i o n s . T h i s f e a t u r e has, i n f a c t , appeared so s i g n i f i c a n t i n mining o p e r a t i o n s as to suggest some connexion between these dykes and m i n e r a l i z a t i o n . I t appears u n l i k e l y t h a t the mafic dykes are the source of ore m i n e r a l i z a t i o n , f o r they are f r e e of ore m i n e r a l s except where they have been f r a c - (0 Ob.Cit- £1Z -82A- t u r e d . They were, however, probably i n t r u d e d d u r i n g a p e r i o d of deformation j u s t b e f o r e and p o s s i b l y extending i n t o the pe r i o d o f m i n e r a l i z a t i o n ; i n some oases, where t h e i r i n t r u s  io n d i d not oompletely h e a l the o r i g i n a l planes of weakness ' or where they themselves were l e s s competent than the rocks they i n t r u d e d , f u r t h e r f r a c t u r i n g or s h e a r i n g ooeureed along. them and provided channels f o r o r e - b e a r i n g s o l u t i o n s . A few, sm a l l , ifiafio dykes o f d e f i n i t e l y p o s t - m i n e r a l age were observ ed o u t t i n g across the o r e - b e a r i n g f i s s u r e s or shear zones as, f o r example, at the E n t e r p r i s e and Anna.mines. At the V and M p r o p e r t y a s i m i l a r dyke i s int r u d e d a l o n g a f a u l t which d i s  p l a c e s a v e i n . Type of Ore. The ore oocurs i n v e i n s , v e i n l o d e s , f i s s u r e f i l l i n g s and replacements. The p r o d u c t i o n i3 i n s i l v e r - l e a d - z i n c and the mine r a l s are mainly galena, blende, q u a r t z , c a l c i t e , s i d e r i t e but a l s o grey copper, ruby s i l v e r , p y r i t e . Better-known mines of the d i s t r i o t are the S i l v e r s m i t h , A r l i n g t o n , Standard, Van Roi, Whitewater. D e s c r i p t i o n of P r o p e r t i e s , S l o c a n D i s t r i c t . ( 1 ) * The "L.H. mine". The mine i s l o c a t e d f i v e and one-half m i l e s from S i l v e r t o n at an e l e v a t i o n o f 5,350 f e e t . 1700 f e e t o f d r i f t i n g and c r o s s - c u t t i n g had been done. Lamprophyre. The country rock of the mine i s p l a i n l y an e a r l y b a s i c d i f  f e r e n t i a t e , c o n s o l i d a t e d and l a t e r sheared d y n a m i c a l l y . I t i s a hard, massive porphyry, s i m i l a r i n appearance to a s i l l rock found i n Number 7 t u n n e l o f the Standard mine which has the composition of a k e r s a n t i t e . ( l ) B a n c r o f t , M.P.: C.G.S. Summ. Rept. (1917) , I n v e s t i g a t i o n s i n S l o c a n D i s t r i c t , B.C. - 2 3 A . The lamprophyre dykes of the West Kootenay are considered to he the "basic d i f f e r e n t i a t e s o f the g r e a t e r g r a n i t e massives and m i n e r a l i z a t i o n i s only another phase of t h i s prolonged process of magmatic i n v a s i o n , b e g i n n i n g w i t h J u r a s s i c . Type of Ore. P y r r h o t i t e , p y r i t e , a r s e n o p y r i t e and quartz formed i n a gangue o f country rook i n a zone 20 to 40 f e e t wide which f o l l o w s the master j o i n t i n g . (1) A. SLOCAN MINING DIVISION Antoine Claim. A dark green lamprophyre dyke, f i v e f e e t wide, i s cut by the v e i n lode on No. 5 l e v e l . The lode c o n t a i n s s i d e r i t e w i t h a l i t t l e p y r i t e and z i n c blende. Cornstook Group - 10 m i l e s from S i l v e r t o n . The p r o p e r t y i s i n the t i p of a body of g r a n i t e , a member of the Nelson b a t h o l i t h . The lode i n t e r s e c t s f i n e - g r a i n e d hornblende g r a n i t e and f o l l o w s , i n p l a c e s , a dyke of b i o t i t e lamprophyre. The ore c o n s i s t s of b r e c c i a t e d g r a n i t e p a r t l y cemented by quartz c o n t a i n i n g s t r e a k s of ore m i n e r a l s . The ore appeared to oocur mainly where the lode l a y between g r a n i t e and the b a s i c (lamprophyre) dyke. (1) C a i r n e s , C.B.: C.G.S. Mem. 184, D e s c r i p t i o n s o f P r o p e r t i e s , . Slocan M i n ing Camp, B.C. (1935), p. 1. - 2 4 A - ffl3her Maiden - 8 m i l e s from S i l v e r t o n on S i l v e r t o n Creek. The d e p o s i t i s i n rocks of the Nelson b a t h o l i t h . A b a s i c h o r n b l e n d e - b i o t i t e dyke f o l l o w s p a r t s of the lode and may have had some i n f l u e n c e on the p o s i t i o n of the ore bodies. Lengths of 50 to 100 f e e t o f ore have the b a s i c dyke as hanging-wall. The ore c o n t a i n s z i n c - b l e n d e , a r g e n t i t e , ruby and n a t i v e s i l v e r and galena. Mountain Con Croup - At extreme head of Carpenter Creek. The g r a n i t e of the Nelson b a t h o l i t h i n whioh the c l a i m s l i e i s i n t e r s e c t e d a l o n g the course o f the Mountain Con lode by a lamprophyre dyke, composed of b i o t i t e , b r o n z i t e , f e l d s p a r and a l i t t l e q u artz, w i t h secondary c a l c i t e , t a l o ( ? ) and b a s t i t e . ' The dyke occurs i n p l a c e s on the hanging-wall, and i n p l a c e s on the f o o t - w a l l , s i d e o f the v e i n and appears to have been i n t r u d e d along the course o f the f i s s u r e . Subsequent movement r e s u l t e d i n the s h e a r i n g o f the dyke and d e p o s i t i o n of the v e i n matter. Riohmond-Eureka Group - E a s t f o r k of Sandon Creek. The u n d e r l y i n g sediments of the Slocan s e r i e s are i n t e r  sected by q u a r t z - d i o r i t e porphyry dykes and a few b a s i c lampro phyre and minette dykes. In p l a c e s the lode turns to f o l l o w f o r m a t l o n a l planes, e s p e c i a l l y near the b a s i c dykes. The m e t a l l i c m i n e r a l s are galena, z i n c - b l e n d e , p y r i t e and a l i t t l e c h a l c o p y r i t e . Ruth-Hope Group - South-west of Sandon. The u n d e r l y i n g rocks are massive a r g i l l a c e o u s and q u a r t z --25A- i t i o s t r a t a of the Slooan s e r i e s , which i n many p l a c e s are ca l c a r e o u s . The sediments a r e i n t e r s e c t e d by many dykes, c h i e f l y of q u a r t z - f e l d s p a r porphyry but i n c l u d i n g some darker, mostly s m a l l , dykes v a r y i n g i n composition from minettes to b a s i c lamprophyres. The dark dykes are n o t a b l y i r r e g u l a r , appear to be l a t e r than the l i g h t - c o l o u r e d dykes, and to be r a t h e r c l o s e l y r e l a t e d i n time to the p e r i o d o f v e i n d e p o s i  t i o n . Ore d e p o s i t i o n was l a t e r than the a c i d dykes, but they exerted a s t r u c t u r a l c o n t r o l over the courses f o l l o w e d by the lodes and the l o c a t i o n of the ore d e p o s i t s . The ore co n t a i n s galena, blende, grey copper, c h a l c o p y r i t e and p y r i t e w i t h quartz and a l i t t l e a n g l e s i t e as gangue miner a l s . The f o l l o w i n g d i s c u s s i o n of the Ruth-Hope p r o p e r t y i s i n  s e r t e d here to present some reasons f o r b e l i e v i n g that the lamprophyre i s r a t h e r c l o s e l y r e l a t e d i n time to the p e r i o d of v e i n d e p o s i t i o n . These obser v a t i o n s have been c o n t r i b u t e d by Mr. W.M.Sharp, M.A.Sc, who i s working on the d e t a i l e d geology of the mine. Some of the lamprophyres i n the mine are co n s i d e r e d to have been i n t r u d e d v e r y s h o r t l y a f t e r the i n t r o d u c t i o n of ore be cause they have been a f f e c t e d by the normal f a u l t i n g t h a t took place d u r i n g the ore-forming period- or s h o r t l y a f t e r . The reason f o r c o n s i d e r i n g t h i s normal f a u l t i n g t o be very c l o s e to the ore i n age i s that replacement ore r e f l e c t s the d r a g - f o l d -26A- p a t t e r n a s s o c i a t e d w i t h the normal f a u l t i n g , w i t h v e r y s l i g h t b r e o c i a t i o n of the ore. The same d r a g - f o l d i n g i n the q u a r t z - f e l d s p a r porphyry, on the o t h e r hand, i s accompanied by s l i g h t c r a c k l i n g o f the porphyry. The i n f e r e n c e here i s that miner a l i z a t i o n was probably J o i n g on at the same time as normal f a u l t i n g , and, as the lamprophyre i s cut by the normal f a u l t  i n g , i t must t h e r e f o r e have been i n t r u d e d d u r i n g or s h o r t l y a f t e r the ore-forming p e r i o d . The absence of hydrothermal m i n e r a l i z a t i o n of the lamprophyre i n contaot w i t h the lode s t r u o t u r e i s good evidence t h a t the lamprophyre i s not com p l e t e l y p r e-ore. S i l v e r s m i t h - S l o c a n S t a r Group - £ mile south of Sandon. The sediments are i n t r u d e d by a c i d p o r p h y r i e s and lampro phyres. The lamprophyres v a r y i n composition from minettes i n whioh b i o t i t e and o r t h o c l a s e are the predominant m i n e r a l s to more b a s i c lamprophyres i n which o l i v i n e and/or pyroxene and b i o t i t e are conspicuous. In oo n t r a s t w i t h the a c i d i n  t r u s i v e s these b a s i c dykes are n o t a b l y i r r e g u l a r i n t h e i r i n d i v i d u a l s t r u c t u r e s and dimensions. They appear to be young er than the a c i d i n t r u s i v e s and are sm a l l e r , a v e r a g i n g probably l e s s than a f o o t i n t h i c k n e s s . They are, as on other proper t i e s , i n t i m a t e l y a s s o c i a t e d i n p l a c e s w i t h the lode s t r u c t u r e s , an a s s o c i a t i o n t h a t suggests that t h e i r p e r i o d of i n t r u s i o n was separated by no great i n t e r v a l from the p e r i o d of m i n e r a l  i z a t i o n . - 2 7 A - The Remainder of the Lamprophyre Qcourrences i n Slooan Mining  D i v i s i o n . On the Reoo Group t h e r e i s a mioa lamprophyre younger i n age than the quartz-porphyry dykes. On the Slooan King group there i s a b a s i c lamprophyre dyke. On the Slooan Sovereign c l a i m , a r&mprophyre dyke f o l l o w s r a t h e r c l o s e l y the course of the lode. Summary of Slooan Mining D i v i s i o n , Slooan M i n i n g Camp. There are 105 d e s c r i p t i o n s o f d i f f e r e n t p r o p e r t i e s under the heading, "Slocan M i n i n g D i v i s i o n " and of these o n l y ten oontained r e f e r e n c e s to lamprophyre dykes. These r e f e r e n c e s have been summarized above. There were, i n a d d i t i o n , f o u r or f i v e r e f e r e n c e s to " b a s i c dykes" which presumably means lamprophyre dykes. These, however, were not c o n s i d e r e d i n t h i s c o m p i l a t i o n due to t h e i r u n c e r t a i n i d e n t i t y . The v a s t m a j o r i t y of the p r o p e r t i e s c o n t a i n numerous quartz-porphyry and q u a r t z - f e l d s p a r - p o r p h y r y dykes which are pre-lamprophyre i n age. (1) B. SLOCAN CITY MINING DIVISION E n t e r p r i s e Mine - 8 m i l e s from E n t e r p r i s e Landing. The g r a n i t i c rocks u n d e r l y i n g the p r o p e r t y are i n t e r s e c t e d by a few, s m a l l , b a s i c dykes, v a r y i n g from hornblende porphyr- i t e to o l i v i n e and o l i v i n e - d i a l l a g e lamprophyres. One a t l e a s t , and p r o b a b l y two narrow dykes of the lamprophyre types were (1) C a i r n e s , C.E.: C.G.S. Mem. 184 (1935), D e s c r i p t i o n s of P r o p e r t i e s , Slocan M i n i n g Camp, B.C. Chap. I I , p. 166. -28A- observed to cut a c r o s s the l o d e . Others are pre- m i n e r a l and are i n v o l v e d i n the f a u l t i n g t h a t d i s r u p t s t h i s l o d e . The ore m i n e r a l s are galena, z i n c blende, p y r i t e , c h a l c o  p y r i t e , grey copper. References to "Ba s i c Dykes". There are r e f e r e n c e s to " b a s i c dykes" on s i x other p r o p e r t  i e s . I t i s not s t a t e d whether these are lamprophyres or not. Of these s i x occurrences, two f o l l o w the l o d e , one i s i n t e r  sected and d i s p l a c e d by the lode and the remainder are not d e s c r i b e d . Summary of Slooan O i t y M i n i n g D i v i s i o n , Slooan Mining Camp. The t o t a l number of p r o p e r t i e s d e a l t w i t h i s 40. Of these, only one i s s t a t e d to c o n t a i n lamprophyre and s i x have b a s i c dykes which may or may not be lamprophyres. (1) C. AINSWORTH MINING DIVISION Jackson Group. The u n d e r l y i n g Slocan sediments are cut by dykes and s i l l s of quartz porphyry that' are commonly c l o s e l y a l i g n e d w i t h the sedimentary f o r m a t i o n s , and h i g h l y a l t e r e d g r e e n i s h dykes of more b a s i c composition that cut a c r o s s the sediments more n e a r l y p a r a l l e l w i t h the v e i n - b e a r i n g l o d e s . Underground, the - a s s o c i a t i o n o f these green dykes w i t h the o r e - b e a r i n g p o r t i o n s of the Jackson lode i s a noteworthy f e a t u r e . (1) C a i r n e s , C.E.: C.G.S. Mem. 184 (1935), D e s c r i p t i o n s o f P r o p e r t i e s , Slocan M i n i n g Camp, B.C. -29A- The more p r o d u c t i v e p a r t e of the Jaokson lode are f o l l o w e d f o r c o n s i d e r a b l e d i s t a n c e s by narrow, g r e e n i s h dykes. These dykes are sheared and completely a l t e r e d and c o n s i s t o h i e f l y of oarbonate, q u a r t z , and a g r e e n i s h micaceous m i n e r a l resem b l i n g m a r i p o s i t e . One such dyke, two f e e t wide, i s o v e r l a i n and u n d e r l a i n by ore and s l i g h t l y m i n e r a l i z e d by galena. The a s s o c i a t i o n of these g r e e n i s h dykes w i t h thelode and, i n par t i c u l a r , w i t h the more p r o d u c t i v e p a r t s o f the lode may have some g e n e t i c as w e l l as s t r u c t u r a l s i g n i f i c a n c e . Here, as elsewhere i n the d i s t r i c t , such dykes have been found i n c l o s e a s s o c i a t i o n w i t h f i s s u r e v e i n d e p o s i t s and though i n no case have they seemed to be d i r e c t l y r e s p o n s i b l e f o r the m i n e r a l  i z a t i o n yet t h e i r a s s o c i a t i o n has, i n many i n s t a n c e s , suggest ed that t h e i r p e r i o d of i n t r u s i o n c l o s e l y preceded the i n c u r  s i o n of m i n e r a l - b e a r i n g s o l u t i o n s ; t h at t h e i r source has t e e n one w i t h these s o l u t i o n s ; and t h a t the f i s s u r e s they have f o l  lowed have been a l o n g l i n e s or zones of weakness which, i f not completely healed by the dykes or i f reopened by f u r t h e r f r a c  t u r i n g and f i s s u r i n g i n v o l v i n g the dykes themselves, have per m i t t e d access to the l a t e r o r e - b e a r i n g s o l u t i o n s . The ore m i n e r a l s are galena, z i n c blende, c h a l c o p y r i t e , p y r i t e i n a gangue of s i d e r i t e , quartz and crushed rock. M e t l a k a h t l a Claim - At. mouth of Whitewater Creek. The Slocan sediments are cut by a green lamprophyre dyke. At one p o i n t on the M e t l a k a h t l a c l a i m a narrow s i l i o e o u s band or v e i n three f e e t ahove the base of the dyke c o n t a i n s dissem--30A- i n a t e d p y r i t e and galena. P r i n o i p a l work on t h i a c l a i m has been done on a m i n e r a l i z e d zone unassociated w i t h the lamprophyre. The zone was m i n e r a l  i z e d w i t h a p h a l e r i t e , p y r i t e and a l i t t l e galena. Whitewater and Whitewater Deep Groups., The rocks are s l a t e s and impure l i m e s t o n e s o f the Slooan s e r i e s . One b a s i c dyke, 40 f e e t wide, occurs underground. The dyke i s v e r y muoh l i k e , i f not i d e n t i o a l with, one observ- /v\et\akahtla ed on the M e t l a k a h t l a c l a i m . (Note: the,, dyke here r e f e r r e d to i s c a l l e d "lamprophyre" i n the p r e c e d i n g s e o t i o n . ) S e v e r a l other s i m i l a r b a s i c dykes of p e c u l i a r g r e e n i s h hue were a l s o observed. The g r e e n i s h c o l o r i s due to m a r i p o s i t e ( ? ) . Other wise the rocks are composed c h i e f l y of carbonates. West of the r a i s e from No. 11 l e v e l , c o m p a r a t i v e l y l i t t l e m i n e r a l i z a t i o n has been encountered on No. 10 l e v e l except near the face where the lode f i l l i n g c a r r i e s some ore m i n e r a l s i n the v i c i n i t y o f one or more of the carbonate-mariposite dykes r e f e r r e d to above. (1) \A/h; le water Note: M.S. Hedley c a l l s these^dykes lamprophyres. (1) The Whitewater Mine - Slooan D i s t r i c t  Upper Mine Geology - above 13 l e v e l . Lamprophyre. The lode here i s an i r r e g u l a r zone of she a r i n g and f r a c - (1) Hedley, M.S.: B.C. Dept. o f Mines, B u l l e t i n No. 22, (1945) Geology o f the Whitewater and Lucky Jim Mine Areas, Slocan D i s t r i c t . -31A- t u r i n g i n s l a t e s . A p o r p h y r i t i o lamprophyre* so extremely dktered t o carbonate, s e r i o i t e s and l o c a l l y m a r i p o s i t e that i d e n t i f i c a t i o n i s d i f f i o u l t , f o l l o w s the lode on 10 and 11 l e v e l s and a p p a r e n t l y d i d so on the upper, worked-out l e v e l s as w e l l . I t occurs as sheets and le n s e s w i t h i n the lode and l o c a l l y i n the w a l l . I t was intruded p r i o r to m i n e r a l i z a t i o n and must o r i g i n a l l y have been a r a t h e r complex body which now i s muoh broken up by displacements a l o n g the l o d e . Ore. The ore c o n s i s t s of galena and s p h a l e r i t e and a l i t t l e grey copper. There i s some p y r i t e and c h a l c o p y r i t e . The gangue i s c h i e f l y s i d e r i t e but some quartz occurs. Lower Mine. Geology - below 13 l e v e l , the dip of the lode changes from 60 degrees to 20 degrees. The f o o t - w a l l of the lode i s s l a t e and the hanging-wall, l i m e s t o n e . Ore. There are three types of ore i n the lower mine. (1) Same as i n the upper mine - t h i s type i s not so im p o r t a n t . (2) Massive replacement of limestone by s p h a l e r i t e and s i d e r i t e . Galena amounts to l / 5 of the s p h a l e r i t e . T h i s i s c a l l e d " s p a t h i c " ore and i s the most important. (3) Magnetic ore, formed by replacement, c o n s i s t s o f s p h a l  e r i t e and l i t t l e g alena i n a gangue of magnetite, p y r r h o t i t e , p y r i t e and some s i l i c a t e m i n e r a l s . T h i s -38A< ore r e p l a c e s dyke rock, p a r t of the i r r e g u l a r lampro phyre i n t r u s i v e which extends through the mine. The magnetite ore i s mostly i f not a l l a replacement of dyke rock. In some p a r t s the replacement i s g r a d a t i o n a l and i n others i t i s s h a r p l y hounded by extremely a l t e r e d dyke. In most i n s t a n c e s the ore grades i n t o rock whioh, although con s i s t i n g almost e n t i r e l y of carbonate and s e r i o i t e , as a r u l e r e t a i n s i t s igneous t e x t u r e and i s r e c o g n i z a b l y porph y r i t ' i c underground. The dyke i s much wider i n the main magnetite ore body and f o r the most p a r t , elsewhere e x i s t s as sheared rem nants w i t h i n the lo d e . (1) Other References to "Ba s i c Dykes" i n Ainsworth M i n i n g D i v i s i o n . One pro p e r t y c o n t a i n s a "narrow, f i n e - g r a i n e d b a s i o dyke" which p a r t l y d e f i n e s the hanging-wall o f the l o d e . One p r o p e r t y c o n t a i n s " a l t e r e d , g r e e n i s h , b a s i c dyke rock" which d e f i n e s the hanging-wall o f a l o d e . On another p r o p e r t y , a narrow band of h i g h l y a l t e r e d , dark, micaceous rock i s a s s o c i a t e d w i t h the main lode and i s prob a b l y a b a s i c dyke. Another p r o p e r t y has " s m a l l b a s i c dykes". F i n a l l y , a p r o p e r t y c o n t a i n s a c i d and b a s i c dykes. The b a s i c dykes out a c r o s s the s t r i k e o f the rock s . Summary of Ainsworth M i n i n g D i v i s i o n , Slooan M i n i n g Gamp. There are 74 d e s c r i p t i o n s of p r o p e r t i e s and of these, f i v e (1) C a i r n e s , C.E.; C.G.S. Mem. 184 (1935), D e s c r i p t i o n s o f P r o p e r t i e s , Slooan Mining Camp, B.C. Chapter I I I . 33A c o n t a i n r e f e r e n c e s to lamprophyre and f i v e a d d i t i o n a l d e s c r i p  t i o n s c o n t a i n r e f e r e n c e s to " b a s i c dykes". Owing to t h e i r s i m i l  a r i t y i n mode of occurrence t o the lamprophyre dykes of near by p a r t s of Slocan M i n i ng Oamp, i t seems h i g h l y probable t h a t these " b a s i c dykes" were o r i g i n a l l y lamprophyre dykes which are now a l t e r e d too h i g h l y f o r i d e n t i f i c a t i o n . Numerous a c i d dykes occur on the m a j o r i t y o f the pr o p e r  t i e s . (1) AINSWORTH MINING OAMP  D e s c r i p t i o n of Dykes. Lamprophyrio dykes can be t r a c e d up to hundreds of f e e t i n l e n g t h and are l e s s than e i g h t or 10 f e e t wide. There are two s e t s i one i n the bedding and the other c r o s s c u t t i n g the bedding. The most common dyke rock type i s oamptonite which co n t a i n s phenocrysts of hornblende and b i o t i t e . M i c r o s c o p i c  a l l y , hornblende i s the s t r o n g l y p l e o c h r o i c , dark brown v a r  i e t y o c c u r r i n g as phenocrysts i n a f i n e - g r a i n e d ground of b i o t i t e and andesine. A p a t i t e and magnetite are q u i t e abun dant a c c e s s o r i e s . Ore. The ore d e p o s i t s are tr u e f i s s u r e v e i n s and limestone replacements. Most are of the t r u e f i s s u r e v e i n type but both types are of the same age and have the same ore m i n e r a l s . (1) S c h o f i e l d , S.J.: C.G.S. Mem. 117 (1920), Geology and Ore De p o s i t s of Ainsworth M i n i n g Camp, B.C. -34A- The minerals are galena and z i n c blende i n o a l o i t e , s i d e r i t e , q uartz, f l u o r i t e . T y p i c a l mines i n the area are the Star, Highlander, F l o r e n c e , Spokane, B l u e b e l l . Age of Dykes and R e l a t i o n to Ore. The age of the lamprophyre i s i n doubt but i t i s not much o l d e r than e a r l y Cretaceous. The lamprophyre dykes are h i g h  l y a l t e r e d by the m i n e r a l - b e a r i n g s o l u t i o n s which are respon s i b l e f o r the ore d e p o s i t s of the Ainsworth camp. S c h o f i e l d ooncluded t h a t the ore d e p o s i t s are a s s o c i a t e d w i t h J u r a s s i c and Cretaceous b a t h o l i t h s and the dykes are a s s o c i a t e d w i t h the c o o l i n g stages of the Nelson g r a n i t e b a t h o l i t h but at a stage p r e v i o u s to the one i n which ore d e p o s i t s were formed. St a r Mine. In the lower t u n n e l , a lamprophyre occurs which has very l a r g e hornblende phenocrysts and contains a g r e a t number of i n c l u s i o n s of Nelson g r a n i t e . B l u e b e l l Mine. Although the lamprophyre o c c u r r i n g here i s so a l t e r e d and r o t t e n t h a t i t s r e l a t i o n to ore i s i n doubt, i t i s claimed that the dyke cuts the ore. But S o h o f i e l d t h i n k s , because of the p o s i t i o n o f the dyke as a bounding w a l l of the ore body and i t s i n t e n s e a l t e r a t i o n , i t must be pre-ore. Therefore, he concluded t h a t the dykes and ore were n e a r l y contemporaneous and he a l s o b e l i e v e s t h a t the dykes have no g e n e t i c c o n n e c t i o n with ore d e p o s i t i o n . -35A- (1) JEOOTENAY LAKE DISTRICT The Nelson b a t h o l i t h outcrops a l o n g the west edge of the map a r e a and i s p o s t - T r i a s s i c i n age. M i n e r a l i z a t i o n and the i n t r u s i o n of lamprophyre dykes appear to be a very l a t e stage o f the b a t h o l i t h i n t r u s i o n . D e s c r i p t i o n o f P r o p e r t i e s  B l u e b e l l Mine.- This i s one of the o l d e s t mines i n B.C. and a gr e a t deal of l e a d - z i n o - s i l v e r ore has been removed a t i n t e r  m i t t e n t stages i n i t s l i f e t i m e . I t i s l o c a t e d at R i o n d e l on the east s i d e o f Xootenay Lake. The country rock i s Lardeau s e r i e s s t r a t a , c o n s i s t i n g o f s c h i s t , q u a r t z i t e and lim e s t o n e . Lamprophyre dykes are com mon and g e n e r a l l y f o l l o w two pronounced systems o f j o i n t i n g , one, n o r t h 70 degrees west and the other, south 85 degrees west. The lamprophyre i s pos t - o r e . S e v e r a l s m a l l g r a n i t i c dykes are p r e - m i n e r a l i z a t i o n . The ore c o n s i s t s of i r r e g u l a r replacements i n the upper p a r t o f a limestone band, 150-200 f e e t t h i c k . P y r r h o t i t e , py r i t e , s p h a l e r i t e , galena, 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 are the m e t a l l i c m i n e r a l s ; the gangue i s quartz and lim e s t o n e . K i r b y Group.- T h i s group i s one mile n o r t h - e a s t of the B l u e b e l l mine. Lamprophyre dykes appear to be l a t e r than the ore. The ore c o n s i s t s of p y r i t e , s p h a l e r i t e , galena i n bedded shear zones of q u a r t z i t e , s c h i s t s and c a l c a r e o u s s o h i s t . (1) Walker, J.F. and Gunning, H.C.: C.G.S. Summ. Rept.,(1928), Kootenay lake D i s t r i c t , B.C. - 3 6 A ^ BIG LEDGE (CONSOLIDATED) PROPERTY, UPPER ARROW ~ ~ ~ ( 1 ) ' LAKE T h i s p r o p e r t y i s l o c a t e d on the west s i d e of Arrow Lake, 17 m i l e s south o f Arrowhead. The ore c o n s i s t s of m i n e r a l i z e d hands i n Precambrian limestone and co n t a i n s p y r r h o t i t e as the most p l e n t i f u l , f o l l o w e d by p y r i t e as the second most p l e n t i  f u l s u l p h i d e . S p h a l e r i t e a l s o i s present i n s m a l l e r q u a n t i t y . One lamprophyre, three to f o u r f e e t wide, was observed and two others of a s i m i l a r c h a r a c t e r are re p o r t e d to occur elsewhere on the pr o p e r t y . The lamprophyre c a r r i e s l a r g e c r y s t a l s o f t i t a n a u g i t e , p l a g i o c l a s e near andesine, c a l o i t e , i l m e n i t e , p y r i t e and an abundance of r a d i a t i n g masses o f s e r  pentine and c h l o r i t e . No quartz was noted. The dyke appears to cut a l l other rooks except, p o s s i b l y , the pe g m a t i t i c i n  t r u s i v e s . (Note: the dyke's r e l a t i o n to ore was not noted.) (2) FIELD MAP AREA There i s a l a c c o l i t h i c i n t r u s i v e o f n e p h e l i n e - s y e n i t e to which 12 dykes are g e n e t i c a l l y connected. The dykes are i n two groups, one, the b o s t o n i t e - t i n g u a i t e group and the other, the lamprophyre group. The lamprophyre group c o n s i s t s of minette, v o g e s i t e , monohiquite, f o u r c h i t e , o u a o h i t i t e , oamp t o n i t e and n e p h e l i n e - b a s a l t . (Note: A l l e n ' s p e t r o g r a p h i c (1) C a i r n e s , C.E. and Gunning, H.O.: C.G.S. Summ, Rept., (1928) B i g Ledge (Consolidated) Property, Upper Arrow Lake, Kootenay D i s t r i c t , B.C. (2) A l l e n , J.A.: Mem. 55, Geology o f F i e l d Map Area, B.C. and A l b e r t a (1914). -37A d e s c r i p t i o n s i n d i o a t e the presence o f f e l d s p a r i n the mon- (1) c h i q u i t e and f o u r o h i t e . A c c o r d i n g to both Johannsen and (2) Harker, there i s no f e l d s p a r i n these two types of lampro phyre .) The Waterloo M i n i n g Claim - T h i s i s l o c a t e d near Moose Creek on Z i n c Mountain, not f a r from Mount Goodsir. The ore c o n t a i n s p y r r h o t 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 , p y r i t e and galena and i s a b l a n k e t - t y p e d e p o s i t r e p l a c i n g limestone. The d e p o s i t i s r o o f e d by mica-porphyry ( o u a o h i t i t e ) which has i r r e g u l a r s t r e a k s and fragments impregnated w i t h p y r i t e c r y s t a l s . ( 2 ) BIG BEND MAP AREA Lamprophyre dykes are s p a r i n g l y developed i n the B i g Bend (4) map a r e a . Daly d e s o r i b e d two s m a l l dykes of "dark, g r e e n i s h - grey, somewhat p o r p h y r i t i c , medium g r a i n e d minette" and a b a s a l t i o s i l l at A l b e r t Canyon gorge on the C.P.H. main l i n e . There i s a dark-grey, f i n e - g r a i n e d lamprophyre dyke i n S i l v e r Creek, about 1|- m i l e s below the f o r k s , which c o n s i s t s o f b i o t i t e , quartz and a l t e r a t i o n products ( c a l o i t e c h i e f l y ) . F l u o r i t e and quartz were observed i n amygdales. I t p r o b a b l y resembles the minette a t A l b e r t Canyon gorge. I t i s g r e a t l y (1) Johannsen, A,: Petrography, V o l . I I I . (2) Harker, A.: P e t r o l o g y f o r Students. (no&) (3) Gunning, H.C.: C.G.S. Summ. Rept. (1928), Geology and M i n e r a l D e p o s i t s o f the B i g Bend Map Area, B.C. (4) Daly, R.A.; C.G.S. Mem. 68. ^oU^* A fa»,Uof,s a/'*y c. r. e 38A- a l t e r e d . (1),(2) HEDLEY DISTRICT !—m— D e s c r i p t i o n of Lamprophyre. The types o f lamprophyre present are k e r s a n t i t e s and oamp- t o n i t e s . They are l e s s than three f e e t wide, are not remark a b l y p e r s i s t e n t and occupy t i g h t l y c l o s e d f i s s u r e s . P l a g i o c l a s e i s the most abundant c o n s t i t u e n t , both as phenoerysts and i n the groundmass;* hornblende or a u g i t e i s second i n importance. B i o t i t e , when i t i s present, occurs r a r e l y as phenocrysts, but norm a l l y i s i n the groundmass i n sm a l l f l a k e s where i t i s r e l a t i v e l y abundant. P l a g i o c l a s e , hornblende and pyroxene show as a r u l e , good c r y s t a l form and the t e x t u r e of the rock i s e i t h e r p o r p h y r i t i c or panidimor- p h i c . The hornblende of the k e r s a n t i t e s i s dark to l i g h t green and not s t r o n g l y p l e o c h r o i c . Ore. The ore i s c l o s e l y a s s o c i a t e d w i t h the d i o r i t e - g a b b r o stocks which g a r n e t i z e d the limestone and i s of the o o n t a c t - metamorphic type i n limestone, a high-temperature, deep-seat ed type o f d e p o s i t . S t r u c t u r a l c o n t r o l i s pro v i d e d by the bedding o f the limestone i n c o n j u n c t i o n w i t h the d i o r i t e - gabbro dykes. The v a l u e s are a l l i n g o l d which oocurs i n (1) CamseH, C : C.G.S. Mem. 2, The Geology and Ore Dep o s i t s of Hedley M i n i n g D i s t r i c t , B.C. (1910). (2) Camsell, 0. : C.G.S. Summ. Rept. (1907), Camp Hedley, Osoy- oos M i n i n g D i s t r i c t , B.C. -39A- a r s e n o p y r i t e almost e n t i r e l y . Other m i n e r a l s are p y r r h o t i t e , s p e o u l a r i t e and c h a l c o p y r i t e . R e l a t i o n between Lamprophyres and Ore. The lamprophyre dykes f o l l o w c l o s e l y a f t e r the i n t r u s i o n of the stocks of d i o r i t e or gabbro w i t h whioh the ore i s r e l a t e d . Whether the lamprophyre i s l a t e r or e a r l i e r than the m i n e r a l i z a t i o n i s not s t a t e d except i n the Sunnyside mine, i n whioh the lamprophyre i s l a t e r . The ore i s cut by s m a l l , b l a o k lamprophyre dykes and by dark green andesite dykes. In the & i o k e l P l a t e mine the limestone i s int r u d e d by white gabbro sheets and dykes and there are other dykes of v a r i o u s kinds.. The most common are hard, blaok, lamprophyre dykes of no uniform s t r i k e , a l s o a n d e s i t e and one or two keratophyre dykes. At l e a s t one lamprophyre dyke i n the H i o k e l P l a t e mine i s post-ore s i n c e a s e o t i o n o f the mine a l o n g IJo. 3 tun- (1) n e l shows the dyke c u t t i n g the ore. The K i n g s t o n Group. Lamprophyre dykes cut the sedimentary rocks i n which the ore occurs. The lamprophyres are accompanied by a great many sheets and dykes o f d i o r i t e and gabbro but a p p a r e n t l y are l a t e r than the d i o r i t e and gabbro. The ores are the oontaot metamorphic type a s s o c i a t e d w i t h i n t r u s i o n s o f d i o r i t e . The outcrop of a payable ore-body has (1) Camsell, C.: C.G.S. Mem. 2, The Geology and Ore Deposits of Hedley M i n i n g D i s t r i c t , B.C. (1910), p. 155. 40A- been found i n the sedimentary rooks a l o n g s i d e a b l a c k lampro phyre dyke which s t r i k e s n o r t h and south a c r o s s the s i d e of a h i l l . About 600 f e e t of t u n n e l i n g has been done on t h i s prop e r t y but no ore was shipped. Other P r o p e r t i e s Two other p r o p e r t i e s d e a l t w i t h i n Memoir 2 had no lampro phyre. (1) TULAMfiJEN DISTRICT "Small dykes of g e n e r a l l y b a s i c composition but v a r y i n g c o n s t i t u e n t m i n e r a l s w i l l be d e s c r i b e d under the g e n e r a l name of lamprophyres". They are a l l d a r k - c o l o r e d , the c h i e f con s t i t u e n t s i d e n t i f i e d i n the f i e l d are f e l d s p a r , hornblende, and sometimes b i o t i t e and a u g i t e . The dykes are a l l o f s m a l l s i z e and are not l i m i t e d to any a r e a or formation. The major i t y show s l i g h t p o r p h y r l t i c tendency, most of the phenocrysts b e i n g the ferromagnesian m i n e r a l s , l e s s o f t e n the f e l d s p a r s . The lamprophyre dykes have no d e f i n i t e age, they cut a l l other rocks except that they have not been seen to cut o l i v i n e - b a s a l t . The youngest must be at l e a s t Miocene i n age. The ore d e p o s i t s i n the d i s t r i c t are g o l d ores and g o l d - copper ores, the l a t t e r b e i n g more important. Note: This r e p o r t g i v e s no d e s c r i p t i o n of ore d e p o s i t s i n r e l a t i o n to lamprophyre dykes. (1) Camsell, C.: C.G.S. Mem. 26, Geology and M i n e r a l Deposits o f the Tulameen D i s t r i c t , B.C. (1913). -41A-, (1) COQUIHALLA AREA Th i s i s the r e g i o n immediately to the east o f Hope, B.C. There are dykes o f d i o r i t e porphyry and lamprophyre. Some of the dykes are c a l l e d lamprophyres because of an abnormally h i g h percentage o f dark c o n s t i t u e n t s and a l t e r a t i o n p r o d u c t s , although the m i n e r a l c o n s t i t u e n t s are s i m i l a r to those of the more p l e n t i f u l o r d i n a r y dykes. T y p i c a l l y , the lamprophyres i n t e r s e c t Cache Creek rocks i n the r a i l w a y s e c t i o n . There are examples near J e s s i c a . These c o n t a i n brownish hornblende and o l i g o c l a s e w i t h magnetite and a p a t i t e as prominent a c c e s s o r i e s . Gold ores are the most important d e p o s i t s of the d i s t r i c t . A r s e n o p y r i t e (with which gold i s a s s o c i a t e d ) , p y r i t e , c h a l c o  p y r i t e and p y r r h o t i t e are the ore m i n e r a l s . There are a l s o some economic d e p o s i t s o f s i l v e r , oopper and molybdenum. Note: T h i s r e p o r t g i v e s no d e s c r i p t i o n s of ore d e p o s i t s i n r e l a t i o n to lamprophyre dykes. ALNfllTE DYKE NEAR SBMLIN, ON THOMPSON RIVER Th i s i s an occurrence of a l n O i t e , a r a r e type of lampro phyre, two m i l e s east of Semlin on the n o r t h s i d e of the Thomp son R i v e r . I t i s i n N i c o l a v o l c a n i c s ( J u r a s s i c - T r i a s s i c ) and (1) C a i r n e s , C.E.: BeG.S. Mem. 139, C o q u i h a l l a Area, B.C.(1984). (2) Drysda l e , C.W.: C.G.S. Summ. Rept., (1912), Geology o f the Thompson R i v e r V a l l e y below Kamioops Lake, B.C. -42A- there are no ore d e p o s i t s nearby. The a l n O i t e dyke i s of Mesozoic or T e r t i a r y age. I t i s f o u r f e e t wide. I t c o n s i s t s of " . . . . l a r g e phenocrysts o f b i o t i t e , o l i v i n e , and a u g i t e i n a f i n e g r a i n e d groundmass o f the same m i n e r a l s . The a u g i t e shows z o n a l s t r u c t u r e and the o l i v i n e has l a r g e l y broken down to s e r p e n t i n e . P e r o v s k i t e i s present i n s m a l l , dusty square o u t l i n e s and m e l i l i t e occurs i n lath-shaped forms which show o b s c u r e l y the pegged-in s t r u c  t u r e . The m e l i l i t e i s p a r t l y decomposed to o a l c i t e . Magne t i t e i s disseminated i n s m a l l g r a i n s through the groundmass. F e l d s p a r i s e n t i r e l y wanting i n the rock." BRIDGE RIVER DISTRICT The w r i t e r v i s i t e d the B r i d g e R i v e r d i s t r i c t i n November, 1947, i n order to c o l l e c t specimens o f lamprophyre o c c u r r i n g underground a t B r a l o r n e and Pioneer. A d e s c r i p t i o n of these is in r\^>\>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———hi— 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, •1930, 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 —m— 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.• 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- • 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 £68 -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 $ • 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° 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—Jt- 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 <j/or- co/c/frrn o -f r»t>rerr-e y J-^Oivrr «*//f^ e?trc/cj<rrJ f>y rr>, r; <? rtf/, z e cf r r c i : f &/>/> p * > c „ f/c ^r^.-fe s>efe. of" l%f s t / / » 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 • .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" « 85°, 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-•24B- 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» 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©- 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 : •Qranophyro 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 - •Oranophyrs, 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°. 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°. 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°-5°. 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. 

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