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The geology and ore deposits of the Summit Camp, Boundary District, British Columbia Carswell, Henry Thomas 1957

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THE GEOLOGY AND ORE DEPOSITS OF THE SUMMIT GAMP, BOUNDARY DISTRICT, BRITISH COLUMBIA by HENRY THOMAS CARSWELL B.A., University of B r i t i s h Columbia, 1955 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE In the Department of Geology and Geography, D i v i s i o n of Geology We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1957 - I i -ABSTRACT The Summit Camp, now abandoned, i s located seven miles north of the town of Greenwood i n south-central B r i t i s h Columbia. Mineral deposits i n skarn zones of the camp were mined fo r t h e i r copper, gold, and s i l v e r values. The oldest rocks i n the Summit Camp are the contorted grey cherts of the Knob H i l l Formation of Paleozoic (?) age. The Knob H i l l Formation i s o v e r l a i n nonconformably by the Paleozoic Attwood Series, made up of the shales of the basal Rawhide Formation; the limestones, chert breccia, and limestone b r e c c i a of the Brooklyn Formation; and the p y r o c l a s t i c s , lavas, and green-stones of the Eholt Formation. The chert and limestone brec-cias of the Brooklyn Formation, interpreted by some e a r l i e r workers as the r e s u l t s of s i l i c i f i c a t i o n and tectonic breccia-t i o n respectively, are considered to be of c l a s t i c sedimentary o r i g i n . There i s a pronounced nonconformity between the Brooklyn and Eholt Formations. These sedimentary rocks were Intruded i n Mesozoic (?) time by the Emma Intrusive consisting of quartz d i o r l t e , d i o r i t e and minor gabbro. This event was followed by the emplacement of the Lion Creek Intrusive, which consists of quartz d i o r i t e and syenite. In Oligocene time the arkoses of the Kettle River Formation were deposited i n fresh-water basins i n the area. E a r l i e r rocks were intruded by Miocene (?) phonolite and pulaskite, that also gave r i s e - i l l -to flows of similar composition. Miocene (?) basic dikes are the l a t e s t rocks of the area. Mineral deposits of the camp contain magnetite, py-r i t e , pyrrhotite, chalcopyrite and tetrahedrite i n a gangue of skarn minerals. Skarn has formed from Brooklyn limestone as a r e s u l t of the addition of heat and large amounts of S i , A l , and F e + + + from the Lion Creek Intrusive. The in t r u s i v e assimilated large amounts of Ca and C0 2 i n the process. Skarn zones are controlled by proximity to the Lion Creek stock, or by a contact of limestone with other rocks, or by the presence of -channelways such as f a u l t s or permeable beds. M e t a l l i c minerals were introduced into the skarn zones along fractures and f o l i a t i o n planes with f a l l i n g temperature. Epithermal precious metal veins that occur close to the Mesozoic (?) intrusives of the Boundary D i s t r i c t are not found i n limestone. It i s believed that these veins were em-placed during a l a t e stage i n the cooling of the plutonic rocks. The e a r l i e r , higher temperature release of metals into the s skarn deposits may be the resu l t of the a s s i m i l a t i o n of CO2 that l o c a l l y prevented the s o l i d i f i c a t i o n of the s h e l l of the consolidated in t r u s i v e body. The mineralizing f l u i d s res-ponsible for the epithermal veins were trapped within the s h e l l and released at a l a t e stage by fr a c t u r i n g due to cooling. In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available- for. reference and study. I further agree that permission f o r extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by his representative. I t i s under-stood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of Geology and Geography The University of B r i t i s h Columbia, Vancouver Canada. Date A p r i l 1957*  - v i i -ACKNOWLEDGEMENTS The writer wishes to acknowledge the f i n a n c i a l help and the opportunity to do the f i e l d work f o r t h i s thesis given by Noranda Exploration Company. The assistance and advice of employees of the Company, p a r t i c u l a r l y Dr. A.M. B e l l , M.M. Menzles, A.D.K. Burton, H. Veerman, and K. Olien i s appreciated. The writer would also l i k e to express thanks to his supervisor, Dr. W.H. White, and other Faculty members of the University of B r i t i s h Columbia f o r advice during the prepara-t i o n of the th e s i s . - i v -TABLE OF CONTENTS Page Abstract i i Acknowledgements v i i I . INTRODUCTION 1 A. SUMMIT CAMP 1 B. HISTORY OF THE AREA 2 C. DESCRIPTION OF THE AREA 2 D. EXPLORATION PROGRAM 3 E. GEOLOGICAL MAPPING + P . LABORATORY WORK 5 G. PREVIOUS WORK 5 I I • GENERAL GEOLOGY A. " INTRODUCTORY STATEMENT 6 B. TABLE OF FORMATIONS 7 C. DESCRIPTION OF FORMATIONS 7 1. Knob H i l l Formation 7 2. Attwood Series 9 (a) Rawhide Formation 9 (b) Brooklyn Formation 9 (c) Eholt Formation 2.0 3 . Plutonic Rocks 30 (a) Emma Intrusive 31 (b) Lion Creek Intrusive 32; V TABLE OF CONTENTS (Cont'd) Page 4 . K e t t l e River Formation 3*+ 5. Miocene (?) Igneous Rooks 3^ (a) Phonolite Dikes 3 k (b) Pulaskite 35 (c) Basic Dikes 37 D. FAULTING 37 III.ECONOMIC GEOLOGY 38 A. DESCRIPTION OF MINES 39 1. B.C. Mine 39 2. Emma Mine 4 i 3 . Swallow Mine 44 4 . Jumbo Mine 46 5 . Pvrrhotite Showing 47 6. Pro Denoro Mine 47 7. Mountain Rose Mine 50 8 . R. B e l l Mine 51 9 . Bluebell Mine 5^ 10. Rathmullen Showings 5^ 11 • S a i l o r Boy Showing 55 12 . Shickshock Showing 55 B. PRECIOUS METAL VALUES 56 C SUMMARY OF CHARACTER OF THE SKARN 56 D. LOCALIZATION OF SKARN METASOMATISM 58 - v i -TABLE OF CONTENTS (Cont'd) E . FORMATION OF SKARN AND MINERALIZATION F. RELATIONSHIP OF SKARN DEPOSITS AND PRECIOUS METAL DEPOSITS OF THE BOUNDARY DISTRICT G. AGE OF THE SKARN DEPOSITS H. RECOMMENDATIONS FOR FURTHER SEARCH FOR ORE Appendix Bibliography-Page 59 66 67 68 76 I l l u s t r a t i o n s Figure 1 Sketch Map of Greenwood Area Figure 2 Paragenetic Diagram of Ore Deposition Plate I Plate II Plate III follows Page 1 follows Page 6k 78 79 80 Mat>s Geological Map of Summit Camp - 1,000' to 1" Legend and Index Map of 50 Scale Mine Maps Oro Denoro Mine Emma Mine Swallow Mine B.C. Mine Mountain Rose Mine Jumbo Mine -P-e-eket-J I. INTRODUCTION This thesis r e s u l t s from f i e l d work done i n the summer of 1956 for Noranda Exploration Company, and compila-t i o n and laboratory work during the winter of 1956-57' A. SUMMIT CAMP The Summit Camp i s between Eholt Creek and the North Pork of Kettle River about seven miles north-west of Grand Forks, the main town i n the Boundary D i s t r i c t of south-central B r i t i s h Columbia. The mineral deposits of t h i s D i s t r i c t are low-grade copper showings i n skarn and s i l v e r - gold - lead veins. The deposits are associated with g r a n o d i o r i t l c l n t r u s i v e s . The t o t a l recorded production of the Summit Camp i s 11,672 02. Au, 326,988 oz. Ag, and 17,980,390 l b . Cu. The mines and showings that the writer examined are the Emma, Oro Denoro, Jumbo, Mountain Rose, B.C., Rathmullen, Shickshock, S a i l o r Boy, R. B e l l , and Bluebell properties. The Lancashire Lass, which might be included among the mines of the Camp, was not v i s i t e d . The Summit Camp i s subsidiary to the better-known Phoenix Camp about three miles to the south-west, now being reopened by Granby Consolidated Mining, Smelting, and Power Company. The Phoenix deposits are si m i l a r to those of the Summit Camp, and have produced 22,000,000 COPPER PROPERTIES TEKAS B R U C C R U B Y BIG C O P P C R KING SOLOMON B U T C H E R BOY M O T H E R L O P E S U N S E T MORRISON M A R G U E R I T E B R O O K L Y N S T E M W I N D E R IDAHO K N O B H I L L - IROWSIOES 6OU)0fiOP SNOWSHOC frOLDEN C R O W N WINNIPEG E M M A OftO OCNORO LANCASHIRE LA&S . R . B E L L B L U E B E L L a c . R A T W M U L L E N SAILOR BOY SHICKSWOCK G R E Y H O U N D A H T H E R E S K E T C H MAP OF GREENWOOD A R E A SHOWING LIMESTONE AND GRANODIORITE OUT-CROPS AND MfNINO PROPERTIES. • - COPPER PROPERTIES. V - Aj -Au PROPERTIES. FIG 1. AFTER RWBROCK ,GS.C MAP 828,1905. - 2 -tons of ore averaging 1 . 5 $ copper (Seraphim 1 9 5 6 ) . B. HISTORY OF THE AREA The e a r l i e s t mining a c t i v i t y i n the Boundary D i s t r i c t was placer mining. In 1 8 9 1 , the Motherlode, Phoenix, and Summit Camps were discovered, and shortly afterward smelters were b u i l t at Greenwood and Grand Forks. Summit City, located on the highway near1 the Oro Denoro Mine, was established i n the l a t e 1890's and became the centre of the mining population of the Summit Camp. Judging from the ruins of the abandoned s e t t l e -ment, i t had a population of about f i f t y persons. About 1904- the Columbia and Northwestern Railway and the Phoenix-Eholt and Phoenix-Greenwood railway spurs were completed. Construction lent impetus to mining, which seems to have reached a peak about 1 9 1 0 , then slackened u n t i l 1 9 2 2 , when i t ceased except for sporadic l e a s i n g . The Greenwood smelter shut down i n 1 9 1 8 . Attwood Copper Mines Ltd. conducted exploration work throughout the Boundary D i s t r i c t i n 1 9 5 1 - 5 3 . Late i n 1955 Noranda Ex-pl o r a t i o n Company optioned f i f t y claims i n the Summit Camp and began exploration. C. DESCRIPTION OF THE AREA The topography of the map-area i s subdued and not rugged, with elevations ranging from 1 , 3 0 0 to k,000 feet above sea-level. The country i s i n summer generally dry - 3 -and hot, the runoff being discharged by minor creeks. West of the divide running through Eholt and Emma Mine these creeks are t r i b u t a r i e s of Boundary Creek, and east of the divide they feed the North Fork of Kettle River. Timber and brush are thick i n the creek v a l l e y s , i n the wet drift-covered depressions, and to a le s s e r extent on north slopes, while d r i e r southerly-facing slopes are sparsely covered with grass and scattered trees. Bedrock i s mantled with a maximum thickness of ten feet of d r i f t on the slopes, but i n depressions d r i f t may be as much as 100 feet thick (White, 195JO . The g l a c i a l o r i g i n of the d r i f t i s attested to by the heterogeneity of the rock fragments i n i t , and by numerous e r r a t i c s . A drumlinoid traps the small pond near Loon Lake. In the drift-covered bottoms outcrop i s extremely scarce, but on slopes free of thick woods rock exposures are more p l e n t i -f u l . Access to the map-area i s provided by paved high-way. Within the area the o.ld railway grades, wagon roads, and logging roads allow easy transport by truck or jeep to most points. A f o o t - t r a i l was cut to the Lime Creek area i n 1956. D. EXPLORATION PROGRAM During the summer of 1956 Noranda Exploration Company carried on an intensive search f o r copper deposits _ 4 _ i n the map-area. The operation was based at the nearby town of Greenwood. Geological, s e l f - p o t e n t i a l , mag-netometer., and soil-sampling surveys were carr i e d out on cut l i n e s spaced at ^00 feet. In the l a t e summer a d r i l l i n g program was started, the targets being geo-physical and geochemical anomalies. E. GEOLOGICAL MAPPING Two hundred scale geological mapping was ca r r i e d on by traversing p i c k e t - l i n e s . Although the l i n e s were surveyed only by chain and compass, accuracy seems s u f f i c i e n t for the 1,000 scale compilation. Roughly, the area mapped at 200 scale i s bounded by a c i r c l e of ^-,000 foot radius with i t s centre at the Bluebell Mine. The remainder of the geology shown on the 1,000 scale sheet i s 1,000 scale reconnaissance work. In addition to t h i s mapping program, the old surface workings were mapped by plane-table on separate sheets, which were t i e d i n by a plane-table traverse. The caved portal of the Oro Denoro adit was opened l a t e i n 195&, and the accessible workings mapped by M.M. Menzies of Noranda Exploration Company. Surface mapping of the area was moderately d i f f i c u l t because of the s c a r c i t y of outcrop and the prevalence of low-grade metamorphism. On the other hand, rocks are l i t t l e weathered, and road and railway cuts o f f e r good exposures. - 5 -F. LABORATORY WORK Laboratory work at The University of B r i t i s h Columbia during the winter of 1956-57 was based on a c o l l e c t i o n of 170 specimens. Fifty-?flve t h i n sections, four polished t h i n sections, and thir t e e n polished sec-tions were examined. G. PREVIOUS WORK The e a r l i e s t geological work In the Boundary Dis-t r i c t was done by R.W. Brock, who mapped the entire D i s t r i c t on a scale of one mile to the Inch i n 1901 (Brock, i 9 0 2 ) . R.A. Daly mapped a five-mile wide s t r i p along the International Boundary on a one-mile scale i n 1906 (Daly, 1912) . In 1912, Le Roy mapped the Phoenix Camp at 400 feet to the Inch. In 1937, Mcnaughton mapped the Greenwood-Phoenix area at 800 feet to the inch and published his findings i n a paper (194-5) i n which he agreed with the geological interpretations of Le Roy. In 1951, Attwood Copper Mines Ltd. began explora-t i o n of the Phoenix, Summit, and Deadwood Camps. White and A l l e n (195*0 published a paper on geological methods used i n t h i s exploration program, which proved very use-f u l to the writer while conducting a soil-sampling program for Noranda. Geological work done for Attwood was summarized by Seraphim i n a paper published i n 1956. - 6 -I I . GENERAL GEOLOGY A. INTRODUCTORY STATEMENT The rocks of the map-area range i n age from Paleo-zoic to T e r t i a r y . The oldest rocks i n the area are known as the Knob H i l l Formation. It outcrops at only one place i n the map-area. The rock, exposed at the formation's upper contact, i s a contorted grey chert. The contact between the overlying Attwood Series i s probably nonconformable. The Attwood Series, of Late Paleozoic age (?), i s represented i n the map area by the Brooklyn and Eholt Formations. The Brooklyn Formation consists of limestone, chert breccia, and limestone breccia. This formation i s overlain nonconformably by the Eholt Formation made up of py r o c l a s t l c s , water-lain py r o c l a s t i c s , b a s a l t i c lavas, and the c h l o r i t i z e d equiva-lents of these rocks. Outside the map-area, the Attwood Series contains the basal Rawhide Formation, which con-s i s t s of several hundred feet of shale. Paleozoic rocks were intruded i n Mesozoic (?) time by the Emma and Lion Creek Intrusives. The Intrusives are overlain by the Ollgocene Kettle River Formation, which i s composed of arkose. The Kettle River Formation does not outcrop i n the Summit Camp. Country rocks are intruded by Miocene (?) pulaskite sheets and stocks and phonolite dikes. The pulaskite intrusives gave r i s e to flows of - 7 -the same rock. A l l e a r l i e r rocks are cut by l a t e dikes of varying but usually b a s a l t i c character. B. TABLE OF FORMATIONS CENOZOIC Miocene (?) Basic dikes Pulaskite flows, dikes, and sheets; phonolite dikes Oligocene K e t t l e River Formation - arkose MESOZOIC (?) Lio n Creek Intrusive Emma Intrusive PALEOZOIC Attwood Series: Eholt Formation - greenstone, basalt, and.esite, t u f f , agg-lomerate, volcanic breccia Brooklyn Formation - lime-stone, chert breccia, limestone breccia, and minor andesite flows Rawhide Formation - shale Knob H i l l Formation - chert C. DESCRIPTION OF FORMATIONS 1. Knob H i l l Formation* The Knob H i l l Formation outcrops i n the. map-area at only one place — about 1,000 feet east of the Shickshock showing, north of Lime Creek. The rock i s a strongly contorted grey chert. The strat a , up to two inches i n width, have i n t h e i r l e s s contorted parts a general north-west d i p. * Detailed descriptions of t h i n and polished sections are incorporated i n the appendix. - 8 -The contact of the Knob H i l l with younger rocks i s obscured to the north by talus and d r i f t , but i t appears to contact the overlying Eholt Formation with l i t t l e i f any intervening thickness of Brooklyn rocks. To the south the Knob H i l l rocks contact Brooklyn limestone that strikes north and dips v e r t i c a l l y . The actual l i n e of contact i s obscured by d r i f t . . The Knob H i l l chert had here a 55-degree south-west dip at the time of deposition of lime-stone: these formations, then, are nonconformable. It would appear that the outcrop of Knob H i l l chert represents a h i l l i n the old pre-Brooklyn erosion surface where lower horizons of Brooklyn sediments were not deposited. The small-scale crumpling of the Knob H i l l Formation does not p e r s i s t into younger rocks. This suggests that considerable f o l d i n g must have occurred i n the hiatus between deposition of the Knob H i l l and Brooklyn Formations. In the Phoenix Camp, the Knob H i l l Formation consists la r g e l y of cherty andesites, interpreted by Seraphim ( 1 9 5 6 ) , p. 685» as of p y r o c l a s t i c o r i g i n , and massive andesites. Seraphim suggests that the environment of deposition of these rocks was marine. The age of the Knob H i l l Formation i s unknown, but thought to be Paleozoic. - 9 -2 . Attwood Series (a) Rawhide Formation The Rawhide Formation does not outcrop i n the map-area. In the Phoenix Camp i t occurs as a sequence of shales several hundred feet thick that i s overlain conformably by the Brooklyn Formation, ( b ) Brooklyn Formation The Brooklyn Formation consists of Time-stone, chert breccia, and limestone breccia. Limestone: Brooklyn limestone outcrops over large areas i n the Summit Camp. The rock i s i n general r e c r y s t a l l i z e d and consists mainly of c a l c i t e , with minor c h l o r i t e and quartz. The following analyses are given by Le Roy (1912) f o r Phoenix. Table 1 Brooklyn Mine Knobhill-Ironsides Mine 90 . 41$ 98.40$ 0.16$ 0.31$ MgC03 trace trace Insoluble, mainly s i l i c a 10.00$ 1.50$ 10 -The colour of the rock Is generally white, hut may be brownish or grey. The limestone i n the v i c i n i t y of the H. B e l l Mine contains t h i n beds of massive chert as well as lenses of chert breccia and nearby exposures contain shaly partings. The limestone i s strongly contorted i n t h i s area as a resu l t of emplacement of a ^volcanic neck. In places where r e c r y s t a l l i z a t i o n has not occurred, poorly preserved c r i n o i d stems and brachiopods are found that roughly date the Brooklyn Formation as Paleozoic or T r i a s s i c . Because r e c r y s t a l l i z a t i o n has ob l i t e r a t e d most of the primary structures, attitudes may not be often recorded, and tops are not ce r t a i n . On the h i l l north of the R.Bell Mine a porphyrltic andeslte flow with a minimum thick-ness of kO feet occurs i n limestone. Chert Breccia:: The rock here termed chert breccia i s des-cribed by Seraphim (1956) and Le Roy (1912) as l y i n g at the base of the Brooklyn Formation i n the Phoenix Camp, with minor lenses at higher stratigraphic l e v e l s . However, i n the Summit Camp chert breccia appears to occur as lenses d i s t r i b u t e d at various horizons within the limestone. The presence of a major basal horizon - I l -l s possible, however, because the base of the Brooklyn i s exposed at only one place, and here at a topographic high i n the surface of deposi-t i o n . In the Summit Camp the chert breccia i s simi-l a r to that of the Phoenix Camp. I t s largest out-crop i s i n the area around Lime Creek, but minor lenses occur i n limestone to the south-west along the s t r i k e of the bedding. Chert breccia from a cut on the old railway grade north of the Phoenix Boad bears a strong l i t h o l o g i c a l s i m i l a r i t y to some of the breccias of the Phoenix Camp. In t h i s rock the fragments of chert range i n shape from angular and faceted to spherical and exhibit varying degrees of roundness (Plate I, c ) . Surfaces of the pebbles are polished or f i n e l y p i t t e d . The pebbles range i n diameter from f i v e millimeters to three c e n t i -meters and i n colour from white through pink, red, and smoky to black. In a nearby outcrop, jasper pebbles predominate. Fragments abut i n many places with no sign of coalescence. Banding i n pebbles i s haphazard i n or i e n t a t i o n and angular fragments of limestone are f a i r l y common. The pebbles occur i n a carbonate matrix that comprises only about f i v e percent of the volume. - 12 -At the gradational contact of t h i s rock with limestone, the c a l c i t e matrix comprises more of the rock, chert pebbles are smaller and more rounded, and quartz v e i n l e t s occur. A specimen from a lens of chert conglomerate 1 ,500 feet east of the B.C. Mine consists of quartzite fragments up to 1 .5 centimeters i n diameter embedded i n a r e c r y s t a l l i z e d carbonate matrix with minor c h l o r i t e (Plates I, d; I I I , c ) . The matrix comprises 5 ° percent of the rock. The pebbles are rounded and faceted or roughly spheri-c a l . A l l pebbles show strongly p i t t e d surfaces that i n t h i n section appear as crenulations of t h e i r borders. The quartzite i s inequigranular and some pebbles contain a le s s e r order of frag-ments. The pebbles exhibit bedding, which i s not p a r a l l e l i n the various fragments. The long axes of f l a t pebbles are f o l i a t e d i n the plane of bedd-ing of nearby limestone. Veinlets and patches of secondary c a l c i t e occur In the quartzite pebbles and single grains of quartz occur i n the c a l c i t e matrix. C a l c i t e i s r e c r y s t a l l i z e d and somewhat strained. The strongly p i t t e d surfaces of the pebbles are probably due to an overgrowth of s i l i c a not evident i n specimens from other outcrops. The - 13 -quartz grains on the surfaces of pebbles enlarged by secondary growth exhibit c r y s t a l faces toward the c a l c i t e matrix. Coalescence of adjacent quartzite pebbles was observed i n the s i l i c e o u s residue l e f t a f t e r solution of the matrix i n HCl. The quartz grains which grew to form the bridge between the c l o s e l y packed pebbles exhibit c r y s t a l faces. This minor deposition of remobilized or secondary s i l i c a may account f o r the coalescence of "jas-perold" fragments noted by Le Roy ( 1 9 1 2 ) . In an exposure on the highway a bed of tuffaceous shale intercalated i n chert breccia was observed. Chert breccia deposited a f t e r the shale had been l a i d down contains fragments of the shale, and the shale bed shows signs of a minor period of erosion. Chert breccia occurring i n the Lime Creek area i s much coarser (fragments up to ten c e n t i -meters i n diameter) and more markedly angular than the types described above. However, i t exhibits a s i m i l a r degree of heterogeneity of colour of fragments. Because the chert breccia has been i n t e r -preted as the r e s u l t of s i l i c i f i c a t i o n , fracture control of s i l i c a content of these rocks was - Ik -looked f o r i n the f i e l d . No major control of s i l i c a content by f a u l t s , b r e c c i a zones or joi n t s was observed. The chert breccia near Lime Creek, though near a f a u l t , shows no evidence of s i l i c i -f l c a t i o n . A few minor quartz v e i n l e t s accompany s i l i c a overgrowth and occur i n limestone and skarn associated with mineral deposits, but such s i l i c a occurs only as comb quartz or chalcedony. The chert breccia of the Phoenix Camp has been interpreted by Brock (1902) , Le Roy (1912) , and McNaughton (19^5) a s jasperbid. This was defined by Spurr (1898) as "... a rock consisting e s s e n t i a l l y of c r y p t o c r y s t a l l i n e , chalcedonic or phenocrystalline s i l i c a which has formed by the replacement of other material, o r d i n a r i l y c a l c i t e or dolomite." Spurr notes that the macroscopic character of jasperoid simulates that of a chert breccia or chert conglomerate with a c a l c i t e matrix. In the Aspen D i s t r i c t described by Spurr s i l i c i f l c a t i o n Is c o n t r o l l e d by f a u l t s and breccia zones that allowed access to the s i l i c a - b e a r i n g solutions. Jasperoidal n u c l e i coalesce to form s o l i d chert layers p a r a l l e l to the zones of shearing. The ore deposits of the Aspen D i s t r i c t are invariably accompanied by jasperoid. - 15 -In the Ehoenix Camp, Le Hoy observed what he Interpreted as coalescence of jasper-oi d a l n u c l e i , residual fragments of limestone i n jasperoid, concentration of s i l i c i f i c a t i o n along j o i n t s , and the invasion of int r u s i v e and volcanic rocks by sim i l a r s i l i c i f i c a t i o n . He attributed s i l i c i f i c a t i o n to solutions ascending along fractures and states that the s i l i c e o u s rocks of the Knob H i l l Formation are probably the re-sult of complete s i l i c i f i c a t i o n of porous t u f f s by the same solutions. McNaughton (19^5) , i n addition to Le Roy's data, noted open spaces supposedly due to con-t r a c t i o n during replacement, and a few fragments of igneous rocks i n jasperoid. He agrees with Le Roy that the rock here termed chert breccia i s the re s u l t of s i l i c i f i c a t i o n . On the other hand, Seraphim (1956) main-tains that these rocks are of sedimentary o r i g i n , and refers to them as "sharpstone conglomerate". Some of the reasons for Seraphim's theory are: (i) The chert fragments are banded, and i n ad-jacent fragments orientation of banding Is haphazard. (II) The composition of the fragments varies - 16 -over short distances, the rocks being s l a t e , jasper, chert, and ra r e l y , igneous rocks. ( i i i ) "Several outcrops containing Interbedded fragmental rock and s i l t s t o n e or shaley s i l t s t o n e show good scour and f i l l structure". (iv) Limestone 'remnants' may be of sedimentary o r i g i n . (v) Fragments that appear to be windworn pebbles occur i n the sharpstone conglomerate. (vi) Coalescence was not observed by Seraphim. Dr. W.H. White pointed out to the writer an outcrop i n Phoenix where chert breccia ex-h i b i t s a gradational contact with limestone breccia. Both rocks here appear to be of sedi-mentary o r i g i n . To the observations made by Seraphim i n the Phoenix Camp that favour a sedimentary o r i g i n for chert breccia, the writer can add the following observations from the Summit Camp: (i) Chert pebbles occur i n contact with (each other without coalescence ( i n the absence of s i l i c a overgrowth). ( i i ) No evidence of s i l l c i f i e d zones along f r a c -tures was observed. ( i i i ) Orientation of flattened pebbles i n chert breccia conforms to the bedding of limestone. - 17 -(iv) Some pebbles have indisputable sedimentary shapes. Most of Seraphim's observations were cor-roborated i n the Summit Camp. Limestone Breccia: Limestone breccia occurs as lenses i n massive limestone. The lenses commonly grade Into chert breccia. The limestone fragments are angular to rounded, range i n diameter from one to ten c e n t i -meters, and consist of c a l c i t e of varying grain-size with minor c h l o r i t e and b i o t i t e (Plate I; a, b ). Angular fragments predominate, but rounded forms are common. In one exposure, limestone fragments exhibit "pillow structure", as i f they had been deposited c l a s t i c a ^ l y while s t i l l s o f t . This structure i s believed to be the re s u l t of fra c t u r i n g and r e c r y s t a l l l z a t i o n of c a l c i t e along the f r a c t u r e s . Breccias consisting predominantly of lime-stone fragments are commonly p y r i t i z e d . At the B. C. Mine, well-mineralized limestone i s i n part of brecciated character. I t i s possible that the c l a s t i c nature of the rock made i t susceptible to replacement by ore-bearing solutions. 18 -Le Roy ( 1 9 1 2 ) a t t r i b u t e d the limestone brec-c i a of the Phoenix Camp to f a u l t i n g . No r e l a t i o n of limestone breccia to known f a u l t s was observed i n the Summit Camp. Seraphim ( 1 9 5 & ) designated two 1 0 0-foot thick lenses of t h i s rock found i n the Phoenix Camp as Stemwinder Limestone and interpreted i t with reservations as a sedimentary breccia. He noted that some fragments appear to be broken apart i n places but based h i s conclusions mainly on the association of limestone breccia with chert breccia, which he believes to be un-doubtedly of sedimentary o r i g i n . The writer observed complete gradation of limestone breccia to chert breccia i n the Summit Camp. I t i s therefore believed that the limestone breccia i s of sedimentary o r i g i n . O r i g i n of the Brooklyn Formation: The association of massive limestone with c l a s t i c limestone fragments or chert fragments i s not uncommon. Seraphim ( I 9 5 6 ) v i s u a l i z e s the massive limestone as having been deposited i n quieter, deeper water than the c l a s t i c phases: Rapid erosion and deposition l a t e r formed the Upper Brooklyn conglomerates and greywacke. The upper limestone 'breccia' bands may have formed from erosion of the Lower Brooklyn limestone or of the larger bands of Knob H i l l limestone than now exposed. - 19 -I t i s considered probable that the massive limestone was deposited under quiet shallow marine conditions whereas the lenses of breccia were the r e s u l t of sudden short influxes of s i l i -ceous terrigenous debris. Associated strong l o c a l marine currents eroded the calcareous sedi-ments of the sea f l o o r , and deposited t h e i r loads as a gravel or rubble of unsorted chert, quartzite, limestone, shale, and igneous rock fragments. The chert and quartzite pebbles are probably derived from the s i l i c e o u s rocks of the Knob H i l l Forma-t i o n . Although chert conglomerate i s i n places associated with chert layers i n limestone, these do not appear to have been the main source of the chert pebbles. The fragments show signs of long transport and there i s no evidence of a period of erosion a f t e r chert deposition. I t seems un l i k e l y , therefore, that the chert f r a g -ments were derived from the primary beds. A l -though erosion of a l l the c l a s t i c p a r t i c l e s i n a marine environment i s not precluded, the presence of rounded pebbles of very hard rocks and wind-worn pebbles indicates a t e r r e s t r i a l o r i g i n for some of the chert fragments. - 20 -Structure of the Brooklyn Formation: The sc a r c i t y of r e l i a b l e attitudes i n the Brooklyn Formation makes in t e r p r e t a t i o n of struc-ture d i f f i c u l t . At best i t might be said that the prevalence of bedding that s t r i k e s north-east and dips steeply north-west or v e r t i c a l l y i n d i -cates a general homoclinal structure or a series of i s o c l i n a l f o l d s with t h e i r a x i a l planes dipping v e r t i c a l l y . Because Seraphim (unpublished map) found to the south of the map-area north-plunging folds that can be projected into the Summit Camp, i t i s probable that the l a t t e r idea i s more nearly correct. Strong contortion of limestone occurs i n the v i c i n i t y of the volcanic neck at the B. B e l l Mine. Here, folded chert beds have minor f a u l t s with off s e t s of a few inches whereas the less competent limestone i s unfractured. A few small drag folds were noted elsewhere i n limestone. Because of the obscurity of the structure and lack of outcrop of the base of the Brooklyn Forma-t i o n , no estimate of i t s thickness i s attempted. Seraphim (195&) suggests a thickness of 3,700 feet, (c) Eholt Formation The name 'Eholt Formation' i s hereby proposed for a sequence of volcanics formerly included i n - 21 -the Brooklyn Formation (Seraphim, 195&). The reasons for the separation of the two units are the presence of pronounced nonconformity between the two and the marked difference i n l i t h o l o g y . The name 'Eholt' i s taken from a railway s t a t i o n i n the map-area. The term, of course, has purely l o c a l s i g n i f i c a n c e . Brock (1902, p.97) describes the Eholt rocks of the entire area as follows: This series of rocks consists of green t u f f s and volcanic conglomerates and breccias, f i n e ash and mud beds, flows of green porphyrite and probably some interbedded limestones and a r g i l l i t e s . The t u f f s , conglomerates and breccias consist of a mixture of pebbles and boulders of porphyrite material with a great many fragments (probably a large proportion) of the rocks through which the volcanics burst. Pebbles and boul-ders of limestone, a r g i l l i t e , jasper, and chert are common. Such of serpentine and old granite and old conglomerate are much rare r . In form the pebbles and boulders are rounded, subangular, angular, and of i r r e g u l a r and f a n t a s t i c o u t l i n e . . . Sometimes the matrix seems to be formed of porphyrite injected between the boul-ders ... .Owing to the a l t e r a t i o n of these rocks,... i t i s not possible to separate the porphyrites from the p y r o c l a s t i c s , on the map. In the Summit Camp the Eholt Formation con-s i s t s of t u f f s , agglomerates, water-lain pyroclas-t i c s , volcanic breccias, andesitlc and b a s a l t i c flows, and the c h l o r i t i z e d equivalents of these rocks. Some of these units are shown on the map - 22 -where possible, the remainder of the Eholt Formation being designated as undifferentiated. The map-unit 'undifferentiated greenstone, basalt, andesite, and p y r o c l a s t i c s ' includes c h l o r i t i z e d types of a l l f a d e s i n addition to the few recognizable lavas. These s t r a t i f i e d rocks consist of a series of interbedded lenses. S t r a t i f i e d Eholt P y r o c l a s t i c s : The t u f f s and agglomerates and t h e i r meta-morphosed equivalents l o c a l l y comprise a large part of the Eholt Formation. The agglomerates are characterized by a high percentage of frag-ments of country rocks, mainly quartzite probably of Knob H i l l o r i g i n , whereas few fragments of Eholt lavas occur. Other fragments are of shale, limestone, and t u f f . The matrix of the agglomer-ates i s generally composed of f i n e t u f f , but i n a few places the matrix i s of andesite. The fr a g -ments range i n size from one millimeter to t e n centimeters. The macroscopic appearance of most of these agglomerates i s not obviously fragmental, the fragments being i n d i s t i n c t due to metamorphism of the rock as a whole. Where the rock has been sub-jected to strong stress, agglomerates composed predominantly of quartzite fragments simulate - 23 -the appearance i n hand specimen of a contorted impure quartzite. Such contorted rocks outcrop over small areas on the h i l l between B.C. Creek and the western branch of Rathmullen Creek. The shapes of the fragments vary from angular to more common rounded and spheroidal forms sug-gestive of aqueous deposition. These rounded shapes are exhibited by quartzite fragments. One specimen from 200 feet west of the B.C. Mine has quartzite fragments undoubtedly deposited by water. The pebbles, spheroidal or faceted with smooth rounded surfaces, occur i n a tuffaceous matrix as t h i n ( f i v e to f i f t e e n centimeters) s t r a t a i n t e r -calated with bedded t u f f (Plate I I ; c ) . In a t h i n section of the agglomerate i r r e g u l a r quartzite fragments which have suffered l i t t l e transport by water can be seen as well as water-worn pebbles. The matrix of the agglomerates i n general i s tuffaceous and fine-grained, containing larger quartz grains derived from the same source as the larger pebbles. Being fine-grained and for the most part altered, the matrix i s not e a s i l y i n t e r -preted, but appears to be composed of minute broken and corroded c r y s t a l s of plagioclase, orthoclase, and fragments of volcanic glass that i n a few i n -stances exhibit shard texture. - 24 -One agglomeratic t u f f simulates macroscoplcally a granite haying inclusions of quartzite and t u f f . This rock actually contains large (up to two m i l l i -meters) broken c r y s t a l s of orthoclase, plagioclase, quartz, and minor magnetite, and large agglomera-t i c fragments a l l cemented by a small amount of fine-grained t u f f . The rocks referred to as t u f f and i n places designated on the map a l l contain some amount of agglomeratic fragments and consist mainly of ma-t e r i a l s imilar to the matrix of the agglomerates. White t u f f composed mainly of quartz grains occurs on the h i l l north of Emma Mine. This rock i s found also as xenoliths i n Emma quartz d i o r i t e . Fine-grained t u f f from the l o c a l i t y near the B.C. Mine has a f i n e l y s t r a t i f i e d appearance att r i b u t e d to aqueous deposition. Coarse agglomeratic t u f f s outcropping 1,000 feet to the south-west exhibit rough s t r a t i f i c a t i o n into layers about one c e n t i -meter thick. The tuffaceous phase of the s t r a t i f i e d v o l -canics has been i n places strongly a l t e r e d to clinochlore, pennine, c a l c i t e , s e r i c i t e , b i o t i t e , k a o l i n l t e , and epidote. Replacing minerals take the form of a fine-grained mat of c r y s t a l s , or, i n the case of c a l c i t e , of ir r e g u l a r patches and - 25 -v e i n l e t s . Agglomeratic fragments are rarely strong-l y altered, but are cut by v e i n l e t s of the products of a l t e r a t i o n . Such altered agglomerate i s usually recognizable i n the hand specimen. In consequence, most of the rocks mapped as greenstone are prob-ably derived from t u f f and lavas rather than from agglomerate. Extreme a l t e r a t i o n associated with shearing was noted i n a few places, the r e s u l t i n g rock being a fine-grained c h l o r i t e s c h i s t . Lavas: Recognizable Eholt lavas are less common than p y r o c l a s t i c s . They are t y p i c a l l y b a s a l t i c and less commonly an d e s i t i c . One outcrop of andesite ex-h i b i t s flow banding, but the lavas are i n general devoid of primary structures. A few basalt dikes that cut chert breccia north of Lime Creek may be connected with Eholt vulcanism. Due to the s i m i l a r i t y between Eholt basalts and basic dikes of known post-pulaskite age, some Eholt volcanic rocks may be wrongly i n -cluded i n the T e r t i a r y map-unit. Volcanic Breccia and Tuff Pipes: Two volcanic pipes were found i n the map-area. They are f i l l e d with p y r o c l a s t i c material s i m i l a r to that occurring- i n the s t r a t i f i e d p y r o c l a s t i c s , 26 -and are surrounded by beds of these p y r o c l a s t i c s . One of these necks i s located 3,000 feet north-east of the B.C. Mine and Is oval i n plan with a long axis of about 2,000 feet and a short of about 1,000 f e e t . I t i s intruded by pulaskite and l a t e r dikes. The Eholt volcanic breccia i s made up of mainly angular but i n part rounded f r a g -ments up to f i f t e e n centimeters i n diameter. The fragments are of fine-grained pink syenite of un-known o r i g i n , chert, quartzite, shale, and t u f f . The rock i s s l i g h t l y f o l i a t e d and i n general s i l i -c i f i e d . Microscopic patches of carbonate, probably primary, and hematitic v e i n l e t s occur i n the t u f f fragments.. Although the limestone-neck contact i s obscured by pulaskite intrusions and d r i f t , the geological body i s interpreted as a volcanic pipe on the basis of the angularity, coarseness, and heterogeneity of composition of the breccia fragments. In addition, the breccia contains the carbonate remnants found i n another volcanic body more d e f i n i t e l y i d e n t i f i e d as a pipe. This second pipe occurs immediately north-west of the E. B e l l Mine. I t i s i r r e g u l a r but roughly c i r c u l a r i n plan with a diameter of about 2,000 feet, and i s cut by three types of l a t e r dikes. The contact of the volcanic pipe with older - 2? -rocks i s exposed 6 0 0 feet of the main shaft of the R. B e l l Mine. The only e f f e c t of thermal metamorphism on impure limestone at the contact i s s l i g h t r e c r y s t a l l i z a t i o n . The limestone i s strongly deformed, however, exhibiting contortion and tectonic b r e c c i a t i o n . The t u f f s , breccias, and agglomerates f i l l i n g t h i s pipe have i n places a f o l i a t e d appearance. In general the rocks are dark green and dense, with vague rounded to angular fragments. Although the fragments are commonly c h l o r i t i z e d and epidotized, dacite, quartzite, and limestone types can be recog-nized. The matrix i s i n part andesitic and i n part tuffaceous. The tuffaceous phases of the rock are composed of small c r y s t a l fragments of ortho-clase and plagioclase; rounded chert, jasper, and quartzite fragments; c a l c i t e and c r y s t a l s of pyro-xene. A t h i n section of a finer-grained t u f f con-tains 70 percent of broken feldspar c r y s t a l s strongly alt e r e d to p h y l l o s l l i c a t e s and magnetite, quartzite fragments and fragments of corroded and r e c r y s t a l -l i z e d arenaceous limestone i n a very fine-grained tuffaceous matrix. The rock i s p a r t l y a l t e r e d to clinochlore and epidote. Macroscoplcally the same rock shows strong patches of epidotization, and c a l c i t e and hematite. The rocks of the pipe contain disseminated p y r i t e . - 28 -The Interpretation of t h i s rock as a volcanic neck i s based on the contortion and b r e c c i a t l o n of limestone about the body, r e c r y s t a l l i z a t l o n of limestone at the contact, the rudely c i r c u l a r shape of the body, and the strong a l t e r a t i o n i n the neck that sets i t apart from other Eholt rocks. The concentration of c h l o r i t i z a t i o n and e p i -d o t i z a t i o n i n the rocks of the pipe i s believed to be connected with the formation of skarn at the R. B e l l Mine. Because neither impure limestone i n contact with the pipe nor limestone fragments within the pipe have been converted to skarn i t i s u n l i k e l y that the skarn zone at the R. B e l l Mine i s a res u l t of Eholt vulcanism. The limestone-pipe contact may have served as a channel f o r metasomatizlng f l u i d s connected with the i n t r u s i o n of Lion Creek rocks. A small outcrop of coarse volcanic breccia 1,000 feet west of the Emma Mine along the Phoenix-Eholt grade may be part of a t h i r d volcanic pipe. Py r o c l a s t i c rocks are very common i n the v i c i n i t y . O r i g i n of the Eholt Rocks: The opening stages of Eholt vulcanism were probably marked by quiet extrusion of basic lavas interspersed with stages of explosive vulcanism. - 29 -The occurrence of the breccia pipes described above indicate that the f i n a l stage of Eholt vulcanism was explosive. The f a i r degree of sphericity and rounding of many of the agglomeratic fragments suggests that many of the py r o c l a s t i c s are water-l a i n . The rounded quartzite fragments, which are common i n the agglomerates, probably were derived from the same source as the pebbles of the chert breccia, and were i n part deposited by water as pebbles i n a matrix of water-lain volcanic ash. Structure of the Eholt Formation: The contact between the Brooklyn and Eholt Formations i s i n part i n t r u s i v e as described above, but i n general the contact i s a nonconformable sedimentary one i n the Summit Camp. The fac t that the attitudes of bedding and f o l i a t i o n i n the two formations do not match i s evidence supporting t h i s i n t e r p r e t a t i o n . In addition, Dr. W.H. White (personal communication) found an ancient weathered zone between the two formations on the h i l l north of the Phoenix Boad. The contact i s well-exposed at the B.C. Mine, where, although unaccompanied by ancient weathering, i t i s d e f i n i t e l y uneven. Due to strong a l t e r a t i o n of the rocks, the nature of t h e i r f o l d i n g i s obscure. Despite strong contortion, the general s t r i k e of the rocks can be seen to be northerly. Because of the obscure structure of these rocks no estimate of t h e i r thickness i s attempted. Mine r a l i z a t i o n of the Eholt Formation: Eholt rocks contain few mineral deposits. None are economic. A few "gopher holes" have been sunk on pyrite concentrations associated with shearing and contortion i n the Lime Creek and Rathmullen Creek areas, but, judging from the old workings, work was soon abandoned. Extensive p y r i t i z a t i o n was indicated by s e l f - p o t e n t i a l work over the Lime Creek showings. Disseminated p y r i t e i s common i n Eholt greenstones. On the h i l l north of Emma Mine and at the R. B e l l Mine, s l i g h t skarn metasomatism of Eholt rocks Is evident. The skarn i s mineralized by magnetite and sulphides. Plutonic Rocks In describing the plutonic rocks of the area, Brock ( 1 9 0 2 , p. 107) states: "From the way i n which t h i s rock makes i t s appearance i n a l l parts of the d i s t r i c t i t i s evident that the whole of i t , at no mean depth, i s underlain by t h i s rock." The age of these rocks has been suggested to be Mesozoic on the basis of c o r r e l a t i o n with s i m i l a r intrusives of the south-central Province. In the Summit - 31 -Camp these rocks have been divided into two map-units of s l i g h t l y d i f f e r e n t age. The age re l a t i o n s were established by the discovery of xenoliths of one plutonic type i n the other (Plate I I ; b ) . (a) Emma Intrusive The name "Emma Intrusive" i s proposed f o r a small stock and a few dikes outcropping near the Emma Mine. The stock extends below the Oro Denoro Mine. The rocks of the complex are of diverse types. The most abundant rock type i s quartz d i o r i t e , but d i o r i t e and gabbro also make up part of the i n t r u s i v e . Quartz gabbro occurs at only, one outcrop. The texture i s i n general porphyritie, the l i g h t -coloured and strongly a l t e r e d plagioclase c r y s t a l s forming the phenocrysts. The groundmass consists of varying amounts of quartz, plagioclase, b i o t i t e or hornblende, c h l o r i t e s , and accessory magnetite. Magnetite Is par t l y altered to hematite. Plagio-clase c r y s t a l s are commonly altered to a mass of fine-grained p h y l l o s l l i c a t e s that obscures the o r i g i n a l character of the feldspar, and the mafic minerals are more or less c h l o r i t i z e d . The rocks of t h i s map-unit are heterogeneous, but most have i n common such features as pheno-crysts of plagioclase i n a medium- to fine-grained matrix and appreciable content of quartz ( f i v e to - 32 -f o r t y percent). Plagioclase i s near andesine i n composition. I t i s possible that these rocks are part of a complex that includes basic phases. The contact of Emma Intrusive with Brooklyn and Eholt rocks i s accompanied by an only s l i g h t l y c h i l l e d margin. Angular t u f f and s l i g h t l y meta-somatized limestone xenoliths are found within the Emma Intrusive, (b) L i o n Creek Intrusive The rocks of t h i s map-unit consist of quartz d i o r i t e and syenite f o r which the name"Lion Creek Int r u s i v e " i s proposed. Lion Creek i s the name of the tributary of Eholt Creek that flows west from Emma Mine. Lion Creek rocks outcrop as a stock (western boundary not mapped) i n the v i c i n i t y of the Oro Denoro and Emma Mines and as a body of syenite 1,500 feet west of the B.C. Mine. The most abundant rock of t h i s map-unit i s quartz d i o r i t e with a t y p i c a l l y coarse-grained, s l i g h t l y inequigranular texture. The rock i s t y p i c a l l y l e u o c r a t i c . The primary mineral com-po s i t i o n Is, i n order of abundance, plagioclase averaging kn.^ i n composition, quartz, hornblende, b i o t i t e , orthoclase, muscovite, and accessory magnetite (Plate I I I ; c ) . Quartz i s commonly i n t e r -s t i t i a l , and i n some places replaces feldspars as - 33 -Irregular patches. Feldspars are i n most cases strongly altered to sericit§, k a o l i n i t e , and other p h y l l o s i l l c a t e s . Mafic minerals are i n part c h l o r i t i z e d . The coarse-grained b i o t i t e syenite that out-crops near the B.C. Mine has orthoclase as the predominant feldspar, but the les s abundant plagio-clase has a composition (A114.5) w l t h i n the range of andesine. The rock contains almost ten percent of quartz. Because the plagioclases are of s i m i l a r composition and both rocks are leuc o c r a t i c , the quartz d i o r i t e and b i o t i t e syenite are assumed to be genetically related.. A 20-foot thick dike of very coarse-grained granite porphyry cuts limestone on the Phoenix-Eholt grade south of the Oro Denoro. Althoughthe dike was mapped as Lion Creek, i t s true r e l a t i o n to other igneous rocks i s unknown. The syenite and quartz d i o r i t e occurring In the open p i t s of the Oro Denoro Mine are strongly e p i -dotized, hematitized and carbonatitized near the extremely vague skarn contact. This indicates that the Lion Creek Intrusive may have been res-ponsible f o r the formation of skarn. A few narrow Lio n Creek dikes cut skarn i n the Oro Denoro p i t s . The main stock has a very f l a t l y dipping roof beneath the Oro Denoro Mine as can be seen i n underground workings and deduced from d r i l l i n g i n the v i c i n i t y . BrOck ( 1 9 0 2 , p.121) states that i t occurs at no great depth below the B.C. Mine. Kettle Elver Formation The Kettle Elver Formation does not outcrop i n the map-area, but occurs i n the Boundary D i s t r i c t . Its age i s established as Oligocene by plant f o s s i l dating (Le Boy, 1912, p.Mf). In the Phoenix Camp the formation i s composed of arkose and has a thickness of a few hundred f e e t . K ettle Elver rocks throughout the south of the Province are interpreted as having been deposited i n fresh-water basins. At Phoenix, the Kettle Elver Formation i s overlain with s l i g h t disconformity by Miocene (?) flows. Miocene (?) Igneous Bocks These rocks, which are i n part the "Midway Volcanic and Hypabyssal" rocks of Seraphim ( 1 9 5 6 ) , include i n the Summit Camp pulaskite flows, sheets and stocks; phonolite dikes; and a few l a t e b a s a l t i c dikes. (a) Phonolite Dikes Three narrow dikes of phonolite occur i n the map-area: one intruding the volcanic neck near the E. B e l l Mine, another cutting Ehoit, Emma, and Lion Creek rocks 1 , 0 0 0 feet west of the Emma Mine, and a - 3 5 -t h i r d outcropping near the Mountain Rose p i t . In hand specimen the rock has a very fine-grained satiny texture and a brown colour. The rock "con-tains a few c a v i t i e s that appear to be the r e s u l t of weathering out of phencrysts. In t h i n section the rock proves to be composed of a fine-grained ground-mass of orthoclase, plagioclase, b i o t l t e and aegerinaugite with larger c r y s t a l s of nephellne and a few phenocrysts of pigeonite. Phonolite Is sim i l a r i n composition to pulaskite, described below. These rocks are therefore believed to be very closely related, (b) Pulaskite Pulaskite i s defined as: "... an a l k a l i n e rock composed of soda-orthoclase, soda-microcline, and microperthite and a n t i p e r t h i t e . I t may contain subordinate nepheline, sodallte, or r a r e l y , nosean." (Williams et a l f 195+)• Both extrusive and i n t r u s -ive phases of pulaskite occur i n the map-area. The intrusive phase i s brown to grey i n colour and i s commonly porphyritic with a f i n e - to medium-grained matrix. The minerals are, i n order of abundance, small laths and phenocrysts of perthite and cryptoperthite; a l b i t e of the same habit; nepheline as inclusions i n early minerals; b i o t l t e ; hornblende; riebeckite; aegerinaugite, euhedral - 36 -magnetite; rare i n t e r s t i t i a l quartz; and very rare plgeonite. Feldspars are cloudy and strongly altered to p h y l l o s i l l c a t e s , and maflcs are a l t e r e d to pennine and cli n o c h l o r e . Where the rock i s c h i l l e d against country rocks i t i s green and porphyritic with an aphanitic matrix. Intrusive pulaskite occurs i n the map-area as extensively outcropping sheets and stocks. Pulaskite flows have a similar mineralogical composition but maflcs are more abundant and occur as larger c r y s t a l s , and the feldspar phenocrysts are larger (up to one centimeter)(Plate I I ; d ) . The lavas are s l i g h t l y v e s i c u l a r and amygdaloidal where seen east of Eholt s t a t i o n along the Canadian P a c i f i c Railway. Pulaskite lavas can be d e f i n i t e l y distinguished from the in t r u s i v e phase only by str u c t u r a l features. Pulaskite lavas occur toward the north of the map-sheet. A disconformable contact between the flows and older rocks showing s l i g h t ancient wea-thering i s v i s i b l e at many places i n railway cuts. The lavas i n a few places exhibit flow banding which indicates that a t i l t i n g of some 35 degrees to the north-east has occurred since the outflow of the lava. Phonolite and pulaskite have probably become - 37 -un&ersilicated and gained the calcium of t h e i r nepheline, pigeonite, and aegerinaugite by the ass i m i l a t i o n of limestone. Large rounded inclusions of limestone occur i n one of the phonolite dikes. The high soda content of the plagioclase, which would be expected to be c a l c i c as a re s u l t of as s i m i l a t i o n of limestone, can be explained by Shand's (1930) hypothesis of sinking of the dense c a l c i c plagioclase formed. Less dense soda plagio-clase would r i s e to take i t s place. (c) Basic Dikes Included i n t h i s map-unit are fine-grained basic dike rocks of obscure r e l a t i o n s h i p to the other igneous rocks of the area. At lea s t some such rocks occur as dikes i n pulaskite. The dike rocks are porphyritic andesites and basalts and commonly contain disseminated p y r i t e . They may be related to the Miocene basalts that occur i n many parts of i n t e r i o r B r i t i s h Columbia. FAULTING Major f a u l t s are indicated at two places near Lime Creek. The possible f a u l t on the slope to the south of the creek was inferred on topographic evidence a f t e r examination of a e r i a l photographs. The probable f a u l t i n Lime Creek v a l l e y shows apparent o f f s e t , and - 38 -shearing and p y r i t i z a t i o n are v i s i b l e along the trace. Minor f a u l t s and shear zones are v i s i b l e at many places i n the map-area, esp e c i a l l y i n mine workings. In some cases these f a u l t s and associated j o i n t s control copper mineralizat ion. I I I . ECONOMIC GEOLOGY The word "skarn" i s used i n t h i s thesis as a term for a contact metasomatic or pyrtometasomatic rock com-posed mainly of lime silicates.. In the Summit Camp, skarn has formed by the metasomatism of massive limestone beds. The metasomatic ef f e c t s are believed to be the re s u l t of the in t r u s i o n of Lioij Creek rocks. Figure 1 shows that i n the Boundary Camp economic copper deposits are associated with limestone outcrops within the projected boundary of the g r a n i t i c body. Low temperature precious metal veins occur i n rocks other than limestone close to the intrusives or within them. Deposits of t h i s type have not been discovered i n the Summit Camp. A genetic r e l a t i o n s h i p between the Oro Denoro-Emma-Jumbo skarn zone and the Lion Creek quartz d i o r i t e stock i s indicated by f i e l d r e l a t i o n s . Mineral deposits not within t h i s main skarn zone and not obviously related to igneous a c t i v i t y are probably the re s u l t of igneous emanations that deposited ore minerals under c e r t a i n s t r u c t u r a l conditions. - 39 -A. DESCRIPTION OP MINES Table II Recorded Production of Mines of the Summit Camp* Property Year Ore Shipped or Treated Gold (oz.) S i l v e r (oz.) Copper (lb.) Emma 1901-21 254,597 6,804 78,065 5,132,118 Emma-Sluebell 192? 24 1 12 1,027 Bluebell 1938-39 389 259 122 930 Oro Denoro 1903-17 136,447 3 , 7 ^ 30,652 3 ,727 ,19^ B.C.. 1900-19 103,476 1,002 214,275 9,025,707 Mountain Rose 1904-10 11,629 6 178 48 , 51^ H. B e l l 1901 1902 294 560 ? 3,559 45,927 ? Jumbo 1905 — — — — Rathmullen 1898 — — — S a i l o r Boy 1899 — — — — Shickshock 1899-1906 1. B.C. Mine The B.C. Mine i s i n the centre of the map-area. The deposit, which yielded ore of high grade for the Boundary D i s t r i c t , i s i n Brooklyn limestone and has a hangingwall of Eholt agglomerate. The aver-age grade for ore extracted up to 1901 was 5*6 percent Data from Index No. 3. B.C. Dept. Mines. 1956, Table I and B.C. Reports of Minister of Mines for 1894-1939. - ko -Cu, 2 .^5 oz. Ag, and .015 oz. Au. The workings (see 50 scale mine map) consist of a large open p i t (now flooded), a shaft, and many-trenches. About ^50 feet south-west of the main work-ings i s a smaller second shaft. Access to the mine i s provided by a good d i r t road. The following s t r u c t u r a l d e s c r i p t i o n i s from Brock's (1902) observations during the operation of the mine i n 1901. The main ore body i s 65 feet wide and 200 feet long, becoming smaller with depth. The walls of the ore body are merely commercial walls, but the "marble l i n e " i s sharp. The mineralized zone i s cut by numerous sheets of pulaskite that contain no inclusions of ore. Diamond d r i l l i n g to a depth of 911 feet indicated the presence of ore below the ^ 0 0 -foot l e v e l , but increasing amounts of pulaskite i n -trusive proved discouraging. Granodiorlte was encountered i n d r i l l i n g . A few dikes s i m i l a r to those of known post-pulaskite age are exposed i n the main p i t . The gangue i s limestone, skarn, and, accord-ing to Brock (1902) , probably i n part a l t e r e d Eholt greenstone. Brock noted the following minerals i n the gangue: garnet, quartz, c a l c i t e , dolomite, e p i -dote, z o i s l t e , a c t i n o l i t e , c h l o r i t e , serpentine, plagioclase, and kaolin (?). A specimen of ore from the main p i t consists of pyrrhotite replaced by - 41 -chalcopyrlte that contains minute blebs and ve i n l e t s of tetrahedrite. The meta l l i c minerals replace granular quartz gangue as massive pods and small s t r i n g e r s . The specimen i s veined by l a t e c a l c i t e . Spectrograph!c analysis indicates the presence of gold i n pyrrhotite. Ore minerals also replace fine-grained garnet-epidote skarn, limestone, and limestone breccia as massive pods and fine-grained disseminations. This mineralization appears to be related to f a u l t s , the pods of massive ore occurring i n t h e i r footwalls. 2. Emma Mine Emma Mine i s one of the major mines of the Camp. I t i s near the contact of the main skarn zone with Emma quartz d i o r i t e at the junction of the old Phoenix-Eholt and B.C. Mine railway spurs. Access i s provided by these old grades. The workings consist of an i n c l i n e d shaft, four deep open stopes, w a t e r - f i l l e d underground workings on s i x l e v e l s , some trenches, and a prospect shaft (see 50 scale mine map). An old composite l e v e l plan indicates that the ore body was a nor t h - s t r i k i n g lens 600 feet long by 30. feet wide. The ore body dipped steeply to the east and raked north. Mineralization grades o f f to the north but apparently terminates abruptly to the south. I - k2 -(Unfortunately there are no surface exposures of t h i s end of the mineralized zone.) The attitude of the ore-body conforms to the bedding of limestone. Skarn contacts Lion Creek quartz d i o r i t e at the south end of the deposit (see 50 scale mine map). The lens of skarn l i e s against a steep contact of Emma quartz d i o r i t e . The skarn zone i s cut by pulas-k i t e and granodlorite dikes. Strongly metamorphosed Eholt p y r o c l a s t i c s outcrop on the footwall of the ore zone. The hangingwall of the oreshoot contains a d i f f u s e unmlneralized zone of c a l c i t e two to ten feet thick that p a r a l l e l s the f o l i a t i o n . A persistent one-foot thick layer of massive magnetite occurs ad-jacent to the c a l c i t e zone f o r a distance of 250 f e e t . In general, magnetite i s l o c a l i z e d along f o l i a t i o n planes, but sulphides commonly occur as i r r e g u l a r pads that are most numerous toward the footwall. In hand specimen, skarn ranges i n character from fine-grained light-coloured andradite rock to porphyroblastic replacements of marble by coarse-grained dark brown andradite, epidote, and diopside. In t h i n section, skarn proves to contain i n addition c a l c i t e , z o i s i t e , quartz, and minor scapolite and plagioclase. One specimen contains brecclated fragments of - 43 -andradite-diopslde skarn. Spaces between fragments have been f i l l e d with coarse-grained magnetite with some andradite and diopslde. The boundaries of the fragments are p a r t l y replaced by magnetite. Another specimen exhibits what are Interpreted as elongate brecciated. fragments i n an o r i g i n a l l y open fr a c t u r e . Some of these fragments are bordered by radiating c l i n o z o i s i t e c r y s t a l s , and the area between the en-crusted fragments i s occupied by magnetite with minor diopslde. Brecciated skarn was not found i n place. Although some magnetite appears to have f i l l e d f i s s u r e s , most has replaced country rock. The me t a l l i c minerals are magnetite, chal-copyrite, tetrahedrite, and a very few minute white Isotropic blebs of an un i d e n t i f i e d mineral. In most cases, magnetite replaces skarn along f o l i a t i o n planes and fractures. P y r i t e replaces.and cuts magnetite. Chalcopyrite replaces e a r l i e r metallic minerals and s i l i c a t e gangue as v e i n l e t s , and c a l c i t e as i r r e g u l a r bunches. Tetrahedrite and the unknown mineral occur i n chalcopyrite as minute blebs. Late c a l c i t e v e i n l e t s cut a l l e a r l i e r minerals. I t was observed i n the open stopes that copper mineralization i s strongest i n the footwall of the ore-body . - kk -3. Swallow Mine The term "Swallow Mine" i s used by the writer to denote a p i t on the Emma claim (see.index map). This p i t i s 800 feet south-west of Emma Mine proper, and l i e s within the main skarn zone i n l i n e with the north-east extension of i t (see 1 , 0 0 0 scale geological map). The Swallow p i t was reportedly worked i n con-junction with the Oro Denoro Mine. The workings con-s i s t of a w a t e r - f i l l e d p i t with two stopes or d r i f t s i n the north face and an i n c l i n e i n the south face (see 50 scale mine map). A steeply dipping lens of marble covers most of the north face of the p i t . Two f l a t - d i p p i n g sub-p a r a l l e l f a u l t s are exposed i n thi s face. Skarn i s cut by a set of joint s p a r a l l e l to these f a u l t s . At the norty-west corner of the p i t zones of magnetite occur along a breccia zone, and a large area of mag-ne t i t e i s exposed i n the east face. At the north-east end of the p i t , p y r i t e and c a l c i t e replace skarn along north-east s t r i k i n g steeply dipping f o l i a t i o n planes. The following observations regarding gangue and metallic minerals are based on examination of specimens col l e c t e d from the dump. Skarn consists of andradite, c l i n o z o i s i t e , a e t i n o l i t e , quartz, c a l c i t e , and sphene. Andradite i s partly altered to c h l o r i t e . - 45 -Skarn replaces very coarse-grained marble as coarse-to fine-grained aggregates. Residual c a l c i t e occurs i n i n t e r s t i c e s between s i l i c a t e c r y s t a l s or as unre-placed zones. Magnetite replaces c a l c i t e and, to le s s e r extent, s i l i c a t e s . P y r i t e bears s i m i l a r r e l a t i o n s to gangue. Chalcopyrite, pyrrhotite, and a l i t t l e t e t r a -hedrite cut magnetite, p y r i t e and s i l i c a t e s and replace c a l c i t e extensively. Late c a l c i t e v e i n l e t s cut a l l other minerals. Some specimens of ore show a s t r i k i n g brec-ciated texture and features suggesting open-space f i l l i n g . Plate II;a i l l u s t r a t e s one of these speci-mens. Brecciatlon of f o l i a t e d andradite skarn Is proved by the d i s o r i e n t a t i o n of the f o l i a t i o n of angular fragments i n thi s specimen. These fragments were encrusted and s l i g h t l y replaced by coarse-grained magnetite and andradite. This stage was followed by deposition of andradite alone, then by deposition of epldote and radiating c r y s t a l s of a c t l n o l i t e . The f i n a l stage of open-space f i l l i n g was the deposition of c a l c i t e i n the remaining space. Replacement of e a r l i e r minerals by minor amounts of sulphides then occurred. Paragenesis i s si m i l a r to that described - 4 6 -above f o r other specimens of brecciated skarn. The main points i n favour of an open-space f i l l i n g o r i g i n of these textures are: (a) The established brecciated nature of the o r i g i n a l skarn. (b) The concentric nature of the mineral zones. (c) The cockade texture of a c t i n O l i t e . (d) The fact that a rough paragenesis holds for several specimens. The medium that deposited the encrusting minerals may have been f l u i d moving through an open jumble of skarn fragments. Jumbo Mine The Jumbo Mine i s a minor showing near the north end of the main skarn zone. I t l i e s i n meta-somatized Brooklyn limestone near i t s contact with Eholt volcanics. The showing was worked i n 1905, but has no recorded production. The workings consist of a shallow shaft, two open cuts, and three trenches (see 50 scale mine map). The showing can be reached from Emma Mine by a badly overgrown wagon road. The deposit i s In an apparently narrow zone of green andradite skarn that grades into s l i g h t l y metasomatized limestone breccia. F o l i a t i o n of skarn i s p a r a l l e l to the bedding of limestone. Minor shears occur at the north end of the main cut . The skarn - 4-7 -zone appears to end to the north between the northern open cut and the trenches. Skarn consists of f i n e - to medium-grained green andradite c r y s t a l s with inclusions and i n t e r s t i t i a l f i l l i n g s of c a l c i t e , quartz, and scapolite. The rock i s cut by ve i n l e t s of c a l c i t e and quartz, the quartz ve i n l e t s being p a r t l y replaced by magnetite and minor specularite. Chalcopyrite and magnetite occur as pods replacing c a l c i t e which i s i n t e r s t i t i a l to garnet c r y s t a l s (Plate I I I ; c ) . In a polished section of the ore, these pods are seen to be associated with a mag-netite-hematite v e i n l e t . Chalcopyrite contains a few blebs of tetrahedrite. P y r i t e cubes replace garnet. The "Pyrrhotlte Showing" This small prospect shaft i s i n Eholt green-stone on the h i l l north of the Emma Mine. A specimen of ore from the dump consists of euhedral p y r i t e c r y s t a l s and massive pyrrhotite cut and replaced by chalcopyrite containing blebs of tetrahedrite. The gangue i s andradite skarn. The deposit i s s i m i l a r to the minor showings i n Eholt rocks at the R.Bell Mine (described below) and may be related to a skarn zone i n underlying Brooklyn limestone. Oro Denoro Mine The Oro Denoro Mine i s i n the centre of the main skarn zone on the Phoenix-Eholt railway spur. - 48 -The v i s i b l e workings consist of a main a d i t , about 1,000 feet of d r i f t s on one l e v e l , f i v e open stopes, and a deep prospect shaft. The oreshoots occur i n a skarn zone that appears to be floored by a body of Emma d i o r i t e . The contact of the d i o r i t e dips to the north-west at a low angle. Country rocks are cut by the Lion Creek stock, which i s evident i n the open stopes (see 50 scale mine map). Skarn i s cut by narrow dikes of d i o r i t e , Lion Creek quartz d i o r i t e and pulaskite. The Lion Creek stock contains a roof pendant or sal i e n t of Tlimestone converted to mineralized skarn that com-prises the north h a l f of the Oro Denoro deposit, the south h a l f being part of the main skarn zone. Both roof pendant and main skarn zone contain disseminated metallic minerals within a few feet of the Lio n Creek contact, whereas ri c h e r zones occur along fractures further within the skarn bodies. Magnetite replaces skarn along f o l i a t i o n planes as at Emma Mine. In general, ore-controlling fractures are of two attitudes - roughly NE/V and NW/15w". M e t a l l i c minerals appear to be concentrated i n the lower crotches of the intersections of fractures as well as along the v e r t i c a l fractures. Skarn contains varying amounts of disseminated ore minerals and some c a l c i t e veins contain - 49 -massive bunches of sulphides. At l e a s t one wide c a l -c i t e vein containing brecciated fragments of skarn i s exposed i n the underground workings. In the under-ground workings a pulaskite dike i s not displaced by-f a u l t s which control mineralization. . Skarn consists mainly of andradite with minor amounts of diopoide, quartz, c a l c i t e , hematite, and c h l o r i t e . Epidote occurs i n places as i r r e g u l a r vein-l e t s and i s associated with chalcopyrite. Skarn i s medium- to fine-grained i n texture and i s i n places f o l i a t e d p a r a l l e l to o r i g i n a l bedding. Coarse-grained residual c a l c i t e and l a t e hematitic vein c a l c i t e occur, i n places with brecciated Inclusions of skarn. In t h i n sections of vein c a l c i t e , crushed andradite may be seen i n a matrix of quartz and c a l c i t e . M e t a l l i c minerals replace s i l i c a t e s and c a l c i t e . Magnetite and minor specularite c r y s t a l l i z e d together. They replace gangue along fractures and f o l i a t i o n planes or form i r r e g u l a r patches i n skarn and marble. Py r l t e replaces magnetite and gangue, and l a t e chalco-p y r i t e with minute blebs of tetrahedrite replaces e a r l i e r minerals. In a few instances v e i n l e t s of magnetite cut p y r l t e , i n d i c a t i n g that deposition of the two minerals was to some extent contemporaneous. Chalcopyrite and p y r i t e occur most commonly as disseminated replacements of s i l i c a t e s or magnetite, - 50 -or as pods of massive ore. Disseminated p y r i t e and pods of chalcopyrite are found at the borders of c a l -c i t i c zones, and chalcopyrite occurs as pods i n some c a l c i t e bodies. Some f l o a t found i n the v i c i n i t y indicates that a stage of f i l l i n g of fissures by quartz occurred. The specimen co l l e c t e d has a two-inch wide unminerailzed vuggy quartz vein containing brecciated inclusions of skarn. The vein i s probably a post-mineralization feature related to l a t e calcite-quartz veins mentioned above. Mountain Rose Mine The Mountain Rose Mine Is 300 feet west of the highway at the north-east end of a narrow branch of the main skarn zone (see 1,000 scale map). The workings may be reached by wagon-road from the B.C. railway spur. The workings consist of a deep open stope from which ore was drawn into an adit (see 50 scale mine map). The deposit occurs i n a zone of skarn that exhibits a gradational contact with Brooklyn limestone. Skarn minerals replace limestone as scattered por-phyroblasts which become smaller and more numerous toward the completely metasomatized rock. Irregular pulaskite intrusives and a phonolite dike cut skarn and limestone. A prominent p a i r of pre-pulaskite - 51 -f a u l t s (NE/85SE) i s evident In the open stope. Gangue consists of fine-grained green garnet skarn. M e t a l l i c minerals are rare on the edges of the stope, and the stope f l o o r and walls are inaccess-i b l e , so the following observations are based on examination of specimens of oxidized ore c o l l e c t e d from the dump. Fine-grained magnetite c r y s t a l s replace garnet. Pyrite replaces and cuts garnet and magnetite. Late pyrrhotite and chalcopyrite replace e a r l i e r metal-l i c minerals, cut garnet, and replace residual c a l c i t e between garnet c r y s t a l s . Tetrahedrite occurs i n chalcopyrite as minute blebs. Because l i t t l e ore i s exposed i n the workings, i t i s probable that the Mountain Rose ore-body was completely mined out. 8. R. B e l l Mine The R. B e l l Mine i s one mile south of the B.C. Mine. The deposit l i e s i n Brooklyn limestone against the contact of one of the Eholt volcanic necks. The workings may be reached by good d i r t road from the highway. The workings consist of a main shaft, a caved ad i t , six prospect.shafts In Eholt volcanic breccia, and many trenches. Because there i s no outcrop of skarn or of the main zone of mineralization, specimens of ore and gangue were obtained from the dumps. High-grade - 53 -chalcopyrite occurs i n marble and fine-grained skarn. Coarse-grained andradite and pods of fine-grained c l i n o z o i s i t e replace r e c r y s t a l l i z e d c a l c i t e i n some specimens. In t h i n section gangue proves to be com-posed of zoned, p a r t l y anisotropic andradite and c a l -c i t e , quartz, p y r i t e , c l i n o z o i s i t e , diopside, specular-l t e , and c h l o r i t e . Euhedral andradite, radiating sprays of hematite, and c l i n o z o i s i t e - d r o p s i d e masses replace residual c a l c i t e . P y r l t e and pyrrhotite replace c a l -c i t e . Specularite v e i n l e t s cut garnet and p y r l t e and l a t e calclte-quartz-earthy hematite veins cut e a r l i e r minerals (Plate I I I ; a ) . Where skarn contacts Eholt volcanic breccia, there i s l o c a l replacement of breccia by andradite, c l i n o z o i s i t e , p y r l t e , and earthy hematite. The minor shafts and trenches of the B.Bell Mine are i n Eholt rocks that are strongly epidotized and p y r i t l z e d . Fractures i n the rock contain second-ary copper carbonates. In one trench a three-foot wide zone i s replaced by andradite and c a l c i t e , and mineralized by fine-grained manganoan magnetite, p y r i t e , pyrrhotite, and chalcopyrite that show no mutual r e l a -t i o n s . Rock i n t h i s trench i s heavily coated with manganese s t a i n due to weathering of the manganoan magnetite. - 5+ -Spectre-graphic analysis indicates the presence of gold i n the pyrite of the deposit. Because skarn containing much p y r i t e was stockpiled, gold content of the ore i s believed to have been appreciable but not recoverable. 9. Bluebell Mine The Bluebell Mine i s close to the B.C. Mine railway spur 2,000 feet west of the Mountain Rose Mine. The deposit i s i n metasomatized Brooklyn lime-stone near i t s contact with Eholt volca-nics. The work-ings consist of two w a t e r - f i l l e d shafts. Skarn outcrops as patchy replacements of limestone breccia by fine-grained brown andradite. A specimen of ore from the dump consists of euhedral coarse-grained p y r i t e replaced by magnetite. 10. Rathmullen Showings The Rathmullen Showings are 3,000 feet west of the B.C. Mine. The deposit l i e s i n metasomatized Brooklyn limestone within 100 feet of an Eholt v o l -canic pipe. Access to the showings was provided by a wagon-road up Rathmullen Creek, but t h i s route i s now impassable. A recently b u i l t logging road from the B.C. Mine passes close to the mine. Ore contained gold values ranging from $12 to $80, but there i s no recorded production f o r the mine. Ore found on the dump consists of py r i t e and - 55 -chalcopyrite i n fine-grained gamet-epidote skarn. 11. S a i l o r Boy Showing The S a i l o r Boy showing i s 1,000 feet north-east of the summit of the pass at the head of Lime Creek. The deposit i s i n metasomatized Brooklyn lime-stone. The workings consist of a w a t e r - f i l l e d shaft and a dump ind i c a t i n g that about 350 tons of rock were mined. There i s no sign that any ore was shipped, but some strongly p y r i t i z e d skarn was stockpiled. There i s no outcrop at the shaft, but f i n e -grained f o l i a t e d light-brown garnet skarn i s exposed 100 feet to the west. "Ore" consists of large euhedral c r y s t a l s of pyr i t e i n a gangue of skarn. Fragments of d i o r i t e found on the dump indicate that an i n t r u s -ive body was encountered in, mining. 12. Shickshock Showing The Shickshock Showing occurs on the summit of the h i l l north of the S a i l o r Boy Mine. Skarn or lime-stone do not outcrop i n the immediate area, Eholt greenstone being v i s i b l e on the surface and i n the shaft. The Brooklyn Formation probably l i e s just below the surface. The workings consist of a caved prospect shaft with a small dump. Old reports indicate that the showing was explored from 1899 to 1906, but no production i s recorded, nor i s there evidence that ore was transported from the s i t e . Specimens from the - 56 -dump consist of massive magnetite replaced and cut by chalcopyrite and c a l c i t e i n a gangue of fine-grained garnet skarn. B. PRECIOUS METAL VALUES Despite the fa c t that gold or s i l v e r minerals were not noted i n polished sections, both elements occur i n recoverable quantities i n the ores of the Camp. The presence of tetrahedrite, which commonly contains large amounts of s i l v e r i n s o l i d solution, may account f o r s i l v e r values. Tetrahedrite occurs only In chalcopyrite, and copper values can be very roughly correlated with s i l v e r values throughout the Camp. Spectrographs analysis of tetrahedrlte-bearing chalcopyrite from the B.C. Mine i n d i -cates the presence of s i l v e r . Gold may occur either In s o l i d s o l u t i o n or as submicroscopic blebs i n sulphides.(Edwards, 195^, p.112). Spectrographlc analyses indicate the presence of gold i n py r i t e and pyrrhotite but not i n chalcopyrite. Relations of copper to gold values throughout the area also indicate that chalcopyrite contains l i t t l e or no gold. C. SUMMARY OF CHARACTER OF THE SKARN Limestone i s the only rock strongly affected by skarn metasomatism. In the two places where the "marble l i n e " i s v i s i b l e strong r e c r y s t a l l i z a t i o n of c a l -c i t e i s evident. Replacement of c a l c i t e by andradite and diopslde i s porphyroblastlc and coarse-grained i n the outer - 57 -zones, becoming finer-grained toward completely metasomat-ized rock. This fine-grained character may be a t t r i b u t e d to competition f o r growing space among many cr y s t a l s i n the intensely metasomatized rock. The mineralogy of skarn i s f a i r l y uniform throughout the Camp. The rock consists mainly of garnet of composition g r o s s u l a r l t e 1 0 andradite^Q. The r e f r a c t i v e Indices of a l l garnets tested l i e above 1.8215 and the s p e c i f i c g r a v i t i e s of clean fragments range from 3«732 to 3*7+2. The colour of andradite ranges from l i g h t green to dark brown. The darkness of colour i s thought to vary with s l i g h t variations i n i r o n contejnt. Skarn contains l e s s e r amounts of quartz, diopside, z o i s i t e , c l i n o z o i s i t e , ac-t i n o l i t e , c h l o r i t e , sphene, c a l c i t e , and scapolite (marla-l i t e ? ) . T ypical skarn i s medium- to fine-grained i n texture and consists mainly of light-coloured andradite with i n t e r s t i t i a l c a l c i t e and quartz. Diopside, quartz, c l i n o -z o i s i t e , z o i s i t e , and scapolite occur as inclusions i n andradite or as independent c r y s t a l s . The skarn i s cut by l a t e v e i n l e t s of quartz and c a l c i t e , and i s replaced by metallic minerals. Purely thermal effects have r e s u l t -ed only i n r e c r y s t a l l i z a t i o n of c a l c i t e , even where the o r i g i n a l limestone was arenaceous. This indicates that the temperatures of skarn formation were below the tem-perature above which quartz and c a l c i t e cannot coexist. - 58 -However, i t i s possible that metasomatism may have o b l i -terated such contact metamorphic minerals as wollastonite. The o r i g i n a l bedding of limestone i s preserv-ed i n skarn i n many places-. There i s no evidence of open space deposition of skarn minerals. In a few places, skarn minerals have replaced rocks of the Eholt Formation to a s l i g h t extent. D . LOCALIZATION OF SKARN METASOMATISM The genetic r e l a t i o n between the Oro Denoro-Emma-Jumbo skarn zone and the Lio n Creek stock i s evident from f i e l d r e l a t i o n s . Skarn zones not obviously related to L i o n Creek contacts appear to be controlled by: 1. The presence of fractures or permeable beds:, i n lime-stone that acted as channelways f o r metasomatizing f l u i d s . 2. The presence of a contact of limestone with rocks l e s s susceptible to metasomatism. The contact may have served as a channelway or "cap" for the metasomatizing f l u i d s . The example of the f i r s t type of control i s the long zone or series of zones that extends along the st r i k e of bedding of Brooklyn limestone and contains the Mountain Rose Mine. The remaining skarn zones of the area are believed to be controlled by contacts as outlined i n 2, above. The rocks against which the metasomatized zones l i e are i n most cases Eholt rocks. At.the R. B e l l Mine, - 59 -a l t e r a t i o n to epidote i n the Eholt volcanic pipe i s believed to be related to skarn metasomatism. The Emma skarn zone occurs against a footwall of Emma quartz d i o r i t e . The S a i l o r Boy deposit i s not cl o s e l y r e l a t e d to a contact of Brooklyn limestone with other rocks of pre-mineralization age. I t i s believed that the l o c a l i z a -t i o n of skarn metasomatism at the S a i l o r Boy was effected by the presence of a cap of Eholt rocks now removed by erosion. E. FORMATION OF SKARN AND' MINERALIZATION The theory that skarn metasomatism i s the result of in t r u s i o n of Lion Creek rocks i s indicated from f i e l d r e l a t i o n s . For example, where limestone i s i n con-tact with the Emma quartz d i o r i t e , there i s no skarn de-veloped. Inclusions of marble showing only s l i g h t replace-ment by garnet are present i n the Emma i n t r u s i v e . At the Oro Denoro Mine, Lion Creek rocks have gradational contacts with skarn, the Intrusive being c h l o r i t i z e d and epidotized. Many large limestone xenoliths or roof pendants occur i n L i o n Creek quartz d i o r i t e i n the v i c i n i t y . These xenoliths are completely converted to skarn. Microscopic examination of a specimen of Lion Creek rocks containing small inclusions of skarn showed the following s i g n i f i c a n t d e t a i l s : 1. Surrounding granodiorite contains plagioclase (An3o) more sodlc than the average (An^y) f o r the stock. - 60 -2 . Diopslde and ^ o i s l t e occur both i n skarn and i n grano-d i o r i t e . 3. Within f i v e millimeters of the contact the g r a n i t i c rock contains very l i t t l e free s i l i c a , but further from the contact contains 20 percent of quartz. 4. Accessory p y r i t e occurs i n granodiorite. Within ten millimeters of the skarn contact, pyrite i s much less abundant. 5. Garnet occurs i n granodiorite. These re l a t i o n s .indicate that Fe and S i were removed from granodiorite by skarn, and that Ca was added to granodiorite. The a s s i m i l a t i o n of Ca by granodiorite has not resulted i n formation of feldspathoids because of an abundant supply of free s i l i c a . The plagioclase of the g r a n i t i c rock might be expected to have become more c a l c i c than average due to addition of lime. The reverse i s true, however. The sodic nature of the plagioclase can be ex-plained by Shand's (1930) hypothesis that c a l c i c plagio-clase formed sinks due to i t s high s p e c i f i c gravity, i t s place being taken by les s dense sodic plagioclase. Thei presence of high soda plagioclase might a l t e r n a t i v e l y be explained by Daly's (1933) hypothesis that resurgent gases removed Ca — much C02 was available for the process. A case of sodic plagioclase occurring at the contacts of skarn xenolith i n andeslte i s mentioned by Brouwer (1928) . - 61 -Iii summary, i t i s strongly indicated that skarn metasomatism.In the area i s the r e s u l t of emanations and heat from the Lion Creek i n t r u s i o n during i t s s o l i d i f i -cation. Comparison of the compositions of skarn and limestone show that replacement involving the addition and removal of substantial amounts of material has occurred. The following c a l c u l a t i o n of the amounts of replacement are based on complete volume f o r volume replacement of one kilogram of s i l i c e o u s limestone by 1.2 kilograms of skarn. Reasonable estimations of; average compositions of skarn and limestone were chosen. I t i s emphasized that these calculations are based on assumed average rock compositions and hence have l i m i t e d quantitative value. Table III 1.2 kg. skarn - 85$ (by weight) grossularite^o andraditecpo, 5$ c l i n o z o i s i t e , 5$ diopside, 5$ quartz. S.G. (calculated) = 3 - 2 5 1. kg. limestone - 90$ c a l c i t e , 10$ quartz. S.G. (calculated) = 2 .70 S i OH 0 224.1, 2.4 462.3 46 .7 - 197.3 +117.k +2.4 +65.0 Fe A l Mg Ca CO3 Skarn 209.0 24.8 6 .7 267.2. Ls. - - 360.0 395 Addition to Ls. +209.O +24.8 +6.7 - 9 2 . 8 -395 - 62 -The r e s u l t i n g figures give a very rough e s t i -mate of the gains and losses involved i n metasomatism. Country rock gained large amounts of Fe"'* and s i l i c a and l o s t substantial amounts of Ca and CO3. Less important additions are A l , Mg, and OH. The rare occurrence of marialite (?) indicates addition of s l i g h t amounts of C l . Skarn metasomatism was overlapped and followed by deposition of magnetite. This process and the production of andradite involved introduction of F e + + + and Fe . Con-sidering the large addition of Ca to the Lion Creek rocks, Swanson's (1924) hypothesis of replacement of Fe"*""1" by Ca"1"** i n mafic constituents of intrusives seems tenable (diopside occurs i n g r a n i t i c rocks near skarn contacts). Ferrous ions l i b e r a t e d i n this way would be oxidized by C 0 2 around 500 degrees centigrade according to the formula: FeO + CO2 ^—7 Fe 2 0 3 t CO (Butler, 1 9 2 3 ) These processes would provide the f e r r i c i r o n of andradite, specularite, and magnetite. Deposition of magnetite was closely followed and overlapped by sulphide mineralization. Butler ( 1 9 2 3 ) considers t h i s to be the normal order of deposition i n skarn deposits and attri b u t e s the paragenesis to f a l l i n g temperature. The sulphide assemblage i s a mesothermal one. The usual order of deposition f o r the Summit Camp Is p y r i t e , pyrrhotite, chalcopyrite, followed by the sulphosalt tetrahedrite. - 63 -C a l c i t e deposition i n fractures i s evident throughout the sequence of skarn formation and mineraliza-t i o n . I t i s probable that the large excess of Ca and CO2 i n the introduced f l u i d s tended to combine and p r e c i p i t a t e wherever conditions were appropriate. Carbon dioxide and CO, which have high p a r t i a l pressures, could provide d r i v -ing force for replacing f l u i d s i n general. Fracture control of mineralization indicates that f r a c t u r i n g occurred during metasomatism, and that the breaks produced may have served as channelways f o r mineral-i z i n g f l u i d s . Locallzatlon..:of mineralization mainly within skarn zones despite adjacent limestone being a more sus-ceptible host rock may be explained i n the following way. Mineralizing f l u i d s reached country rocks through the same channelways as skarn forming emanations. Metals were pre-c i p i t a t e d i n skarn. Solutions that reached limestone with some metals s t i l l present l o s t these rapi d l y by replace-ment of c a l c i t e , permitting massive and disseminated deposits at the" marble line". Such deposits were observed at the B.C. Mine. The following i s a generalized sequence of skarh metasomatism and mineralization f o r the whole camp. - 64 -Table IV Calcite-quartz f i s s u r e f i l l i n g veins Fracturing Tetrahedrlte Chalcopyrite Sb Ag Pyrrhotite + Au Cu Pyrite + Au C a l c i t e and quartz veins Au S Fracturing Deposition magnetite (py, specular-i t e) as replacements or f i l l i n g s i n breccia zones, with minor gar-net, epidote, and a c t i n o l i t e Brecciation, f a u l t i n g , f r a c t u r i n g Replacement of limestone by skarn minerals Al,Mg Fe S i The mutual r e l a t i o n s of the m e t a l l i c minerals are shown i n Figure 2. RELATIONSHIP OF SKARN DEPOSITS AND PRECIOUS METAL DEPOSITS OF THE BOUNDARY DISTRICT The d i s t r i b u t i o n of the precious metal depo-s i t s of the Boundary D i s t r i c t i s shown i n Figure 1 . As may be seenfrom the diagram, these ore deposits are d i s -tributed i n country rock near the peripheries of g r a n i t i c bodies, or i n the g r a n i t i c rocks themselves. No deposits of t h i s type have been discovered i n the Summit Camp. The veins occur i n Eholt volcanics, Rawhide a r g i l l l t e , Knob H i l l rocks, or g r a n i t i c rocks. Precious metal deposits F I G . 2. PARAGENETIC D I A G R A M O F O R E DEPOSITION - 65 -are associated with limestone at only two places, and even here are not found i n limestone. The ve i n deposits d i f f e r from skarn deposits i n temperature of deposition, which was lower i n the veins. Fissure f i l l i n g rather than replacement i s the t y p i c a l mode of emplacement of the veins. Ore consists of chalcopyrite, galena, chal-cocite, sphalerite, p y r i t e , tetrahedrite, ruby s i l v e r , argentlte, gold, and t e l l u r i d e s i n a gangue of c a l c i t e and quartz. The production of the three main deposits i s given i n the following table. Table V Tons Shipped Au (oz.) Ag (oz.) Pb (lb.) Zn (lb.) Providence 11,451 5,867 1,361,433 400,288 258,100 No. 7 15,152 2,971 99,987 213,926 13,727 Dentonla 95,884 23,731 157,620 3 ^ , 8 5 6 403 I t i s evident that the veins were very r i c h , e s pecially i n s i l v e r . I t i s suggested that these deposits are re-lated to the f i n a l stages recorded i n skarn deposits -deposition of chalcopyrite-tetrahedrite and f i l l i n g of fissures and breccia zones by c a l c i t e and vuggy quartz veins. I t i s possible that the precious metal deposits represent a f i n a l low temperature stage of mineralization not strongly affected by a s s i m i l a t i o n of limestone by the - 66 -magma. Fissures were produced i n intru s i v e and country rocks, perhaps by cooling, and minerals were deposited i n the f i s s u r e s . The cl u s t e r i n g of veins about and i n g r a n i t i c bodies may indicate that loi^ temperatures of wall rocks and ore-bearing f l u i d s permitted only short transport of metals before deposition. A s s i m i l a t i o n of C0 2 by the int r u s i v e may have been the cause of the release of metals into skarn during an e a r l i e r stage of cooling of the rocks. Carbon dioxide may have acted as a fl u x that prevented early consolidation of the intru s i v e where i t contacts limestone, thereby allowing early entry of mineralizing f l u i d s . AGE OF THE SKARN DEPOSITS I t i s probable that the skarn deposits of the Summit Camp are due to the eff e c t s of g r a n i t i c i n t r u -sions. Although the age of these intrusions i s thought to be Mesozoic on the basis of c o r r e l a t i o n with s i m i l a r intrusions of known age that occur outside the Summit Camp, the g r a n i t i c rocks of the Boundary D i s t r i c t may be of early T e r t i a r y age. White (personal communication) and Brock (1902) suspect a Te r t i a r y age for the skarn 1ype of mineralization i n the Boundary D i s t r i c t . Their best e v i -dence i s the apparent l o c a l i z a t i o n of mineralization against pulaskite dikes. The writer f e e l s that the occurrence at the Oro Denoro Mine of ore-controlling f a u l t which i s cut by a pulaskite dike indicates a pre-pulaskite age for mineralization i n the Summit Camp. - 6? -RECOMMENDATIONS FOR FURTHER SEARCH FOR ORE The regional diagram (Figure 1) of the area shows that where bodies of limestone occur i n the Camp, there i s a p o s s i b i l i t y of fin d i n g ore. As yet, search for new orebodies buried beneath overburden has not been very successful. I t i s possible that b l i n d orebodies may l i e i n the Brooklyn Formation below Eholt rocks or pulas-k i t e flows. Close study of strongly p y r i t i z e d and f r a c -tured Eholt rocks might provide a clue to underlying mineralization. More de t a i l e d mapping of a l l outcrop i n c r i t i c a l areas might reveal the configuration of the Brooklyn-Eholt contact, which controls skarn formation i n many deposits. Areas covered by Te r t i a r y flows would not be so susceptible to geological i n t e r p r e t a t i o n of underlying structure, but deep-probing geophysical methods might allow evaluation of such t e r r a i n . APPENDIX - 68 -APPENDIX The appendix contains descriptions of c r i t i c a l or t y p i c a l t h i n and polished sections. In general, one or more t y p i c a l t h i n sections from each major formation, some representative t h i n sections of skarn, and three of the most t y p i c a l polished sections of ore are described. POLISHED SECTIONS Polished Section 334 - Oro Denoro Mine M e t a l l i c Minerals Magnetite Pyri t e Chalcopyrite Specularite Macroscoplcally the specimen l s seen to be made up mainly of magnetite with some blades of specular-i t e . Magnetite contains p y r i t e and remnants of garnet. Microscopically magnetite l s seen to be intergrown with specularite. Euhedral p y r l t e c r y s t a l s appear to replace gangue and magnetite. P y r i t e occurs also as replacement veins along fractures i n magnetite. Chalcopyrite occurs as parts of the same veins and as replacing blebs i n garnet. Py r i t e presents euhedral faces to chalcopyrite, suggesting that the pyrite may have been e a r l i e r . - 69 -Polished Section 371 - Mountain Rose M e t a l l i c Minerals P y r i t e Chalcopyrite Tetrahedrite Magnetite Pyrrhotite Macroscoplcally the section can be seen to be made up of p y r i t e cut by pyrrhotite v e i n l e t s i n a gangue of skarn. The sulphides are cut by minute v e i n l e t s of chalcopyrite. Chalcopyrite occurs also as dissemina-tions and blebs i n an area containing many ve i n l e t s of the same mineral. Under the microscope remnants of mag-ne t i t e can be seen i n p y r i t e . P y r i t e replaces a mineral i n t e r s t i t i a l to garnet as well as garnet i t s e l f . Chalco-p y r i t e mineralization i s related to an i r r e g u l a r f r a c t u r e . Minute blebs of tetrahedrite occur i n chalcopyrite. Polished Thin Section 276 - Oro Denoro M e t a l l i c Minerals Chalcopyrite Tetrahedrite Magnetite The section consists of fine-grained garnet skarn with some residual c a l c i t e . One-half the section i s taken up by chalcopyrite containing remnants of c a l c i t e . A few grains of magnetite occur near the skarn-chalcopyrlte - 70 -contact. Minute blebs of chalcopyrite occur i n fractures i n garnet. The main mass of chalcopyrite i s cut by minute f r a c t u r e - f i l l i n g s of tetrahedrite that contains inclusions of chalcopyrite which match the borders of the veins. M e t a l l i c minerals and skarn are cut by a quartz-calcite v e i n l e t . THIN SECTIONS Thin Section 370 - Limestone Breccia (Brooklyn Formation) In hand specimen the rock i s seen to consist of rounded to subangular limestone fragments i n a f i n e -grained c a l c i t e matrix. A t h i n s e c t i o n of the matrix shows that It Is made up of carbonate grains .02 to .1. millimeters i n diameter, and a few quartz, b i o t l t e , and c h l o r i t e grains. The section contains small rounded pebbles of banded chert and fine-grained limestone. A single large (two millimeters) c r y s t a l of carbonate occurs i n the section. Thin Section 265 - Tuff (Eholt Formation) Macroscoplcally t h i s rock simulates the appearance of a fine-grained massive shale or s i l t s t o n e with a few greenish patches and a few small angular frag-ments. The rock i s a c t u a l l y a fine-grained agglomeratic t u f f containing the following minerals: Quartz 20$ C a l c i t e 15$ Orthoclase 10$ - 71 -Clays 45$ Magnetite 1$ Angular aggregates of bladed clay minerals 10$ The matrix consists of a fine-grained f e l t e d mass of clay minerals with a fev; grains of orthoclase and magnetite. Angular fragments of quartzite up to four millimeters i n diameter and fragmental aggregates of bladed clay minerals occur i n the section. Clay minerals are stained by hematite. C a l c i t e replaces the rock as vein-l e t s and vaguely defined patches. Thin Section 208 - Agglomerate (Eholt Formation) In hand specimen the rock i s seen to contain rounded to angular quartzite fragments i n a tuffaceous matrix. In t h i n section the agglomeratic fragments (.1 to one centimeter diameter) are seen to have corroded borders and fracture f i l l i n g s of t u f f . The matrix Is composed of the following minerals: Plagioclase (+ r e l i e f ) 30$ Clinochlore 60$ Magnetite Quartz 10$ Quartz and plagioclase are corroded and altered to c l i n o c h l o r e . - 72 -Thin Section 251 - Quartz d i o r i t e (Emma Intrusive) Plagioclase - An^g 70$ Quartz 15$ B i o t i t e 15$ The texture i s p o r p h y r i t i c , the phenocrysts being of plagioclase. Plagioclase i s zoned i n an o s c i l -l a tory manner, and i s strongly altered to fine-grained p h y l l o s i l l c a t e s . The fine-grained matrix of the rock consists of quartz and plagioclase. Thin Section 210 - Quartz d i o r i t e (Lion Creek Intrusive) Quartz 20$ Plagioclase - An-^ 50$ B i o t i t e 10$ Hornblendec. 20$ Magnetite 1$ Chlorite The t h i n section contains not only Lion Creek quartz d i o r i t e but also part of an i n c l u s i o n of Emma d i o r i t e (see Plate I I ; b ) . The quartz d i o r i t e i s coarse-grained and equigranular i n texture. Hornblende and plagioclase are euhedral, whereas quartz i s i n t e r -s t i t i a l . Plagioclase c r y s t a l s are zoned i n an o s c i l l a t o r y manner, and are s l i g h t l y a l t e r e d to p h y l l o s i l l c a t e s . - 73 -Thin Section 212 - Pulaskite A l b i t e 15$ Riebeckite 2% Aegerinaugite 2% Cryptoperthlte 70% B i o t l t e 5% Chlorite 2% Nepheline 5% Magnetite 2% The texture i s p o r p h y r i t i c , feldspars forming phenocrysts. The matrix i s medium-grained. Phenocrysts, aegerinaugite, and riebeckite are euhedral. Feldspars are i n part altered to p h y l l o s i l i c a t e s . Magnetite occurs as anhedral grains i n the groundmass. Polished Thin Section 306 - Skarn (R. B e l l Mine) The specimen i s of coarse-grained marble re-placed by large euhedral.crystals of garnet and p y r l t e . Under the microscope the following minerals are evident: Garnet 40$ P y r i t e 20$ Carbonate 30$ Quartz 5$ Chlorite 5$ The green garnet c r y s t a l s are anisotropic and concentrically zoned at t h e i r outer edges. Chlorite replaces garnet along fractures. P y r i t e appears to - 7^ -replace the coarse-grained carbonate, but conforms to the boundaries of garnet c r y s t a l s . P y r i t e c r y s t a l s are sur-rounded by granular quartz. Veinlets of granular quartz and c a l c i t e cut garnet (Plate I I I ; a ) . Thin Section 332 - Skarn (Jumbo Mine) The hand specimen i s of medium-grained green garnet skarn with patches of carbonate. Disseminated grains of magnetite and chalcopyrite occur, most commonly near c a l c i t e . Thin, i r r e g u l a r hematite v e i n l e t s cut skarn. Minerals evident i n t h i n section are.": Quartz 2$ Garnet 85$ Carbonate 10$ Magnetite Chalcopyrite Hematite AntIgorite Muscovite Epidote Garnet occurs as euhedral c r y s t a l s replacing carbonate. Quartz occurs as rounded grains i n residual carbonate and with l a t e carbonate i n v e i n l e t s and patches that replace garnet. A few grains of an epidote replace carbonate. Antlgorlte occurs as rounded aggregates of radiating c r y s t a l s near garnet i n quartz, c a l c i t e , and to - 75 -a l e s s e r extent i n garnet. Fine-grained magnetite i s associated with antig.orite. Opaque minerals replace carbonate but conform to the borders of quartz and garnet. - % BIBLIOGRAPHY. Brock, H.W., "Preliminary report on the Boundary Creek Dis-t r i c t " , Geol. Surv. Can. Summary Reports f o r 1902. pp. 90-14-7. Brouwer, H.A., "Production of Trachyte and Phonollte from Pyroxene Andesitic Magma Associated with Limestone";, Jour. Geol. v o l . 36, no. 6 , (Aug.-Sept., 1928), pp. 5^5-5^8 . Butler, B.S., "!A Suggested Explanation of the High F e r r i c Oxide Content of Limestone Contact Deposits", Ec. Geol. v o l . 18, no. 4 , (June-July, 1923) , .pp. 398-404-. Daly, R.A., Geology of the North American C o r d i l l e r a at the  Forty-Ninth P a r a l l e l . Geol. Surv. Can. Mem. 38. 1912 Daly, R.A., Igneous Rocks and the Depths of the Earth.,New York and London, McGraw-Hill Book Co., 1933. Edwards. A.B., Textures of Ore Minerals and Their Significance. Melbourne, Aust. Inst. Min. Met., 1954. Eskola, P., On the Petrology of the Orl.larvl Region i n South-western Finland. Comm. Flnlande B u l l . 30 f 1-914. Holser, W.T., "Metamorphism and Associated M i n e r a l i z a t i o n i n the Philipsburg Region, Montana", B u l l . Geol. Soc. America, v o l . 6 1 , no. 10, (Oct., 1950), pp. 1050-1090. Le Roy, O.E., Geology and Ore Deposits of Phoenix. B.C.. Geol.  Surv. Can. Mem. 21 . 1912. McNaughton, D.A... Greenwood-Phoenix Area. Geol. Surv. Can. Paper 4 5 - 2 0 f 1945. Seraphim, R.H., "Geology and Copper Deposits of the Boundary D i s t r i c t , B.C."', Can. Min. Met. B u l l . , v o l . 4 9 , no. 534, (Oct., 1956), pp. 684 -694 . Shand, S.J., "Limestone and the Ori g i n of Feldspathoidal Rocks: An Aftermath of the Geological Congress", Geol. Mag.. v o l . 67, no. 8 , (Aug., 1930), pp. 416-426 . Spurr, J.E., Geology of the Aspen Mining D i s t r i c t . Colo.. U.S. Geol. Surv. Monograph 3%r I 8 9 8 - 77 -BIBLIOGRAPHY (cont'd) Swanson, C. 0 . , "Genesis of the Texada Island Magnetite De-posits", Geol. Surv. Can. Summary Reports f o r 1924. part A, pp. 106-144. White, W.H. and A l l e n , T.M., "Copper S o i l Anomalies i n the Boundary D i s t r i c t of B r i t i s h Columbia", Mining Engineering, v o l . 6 , no. 1, (Jan., 1954), pp. 49 -56 . , Williams, H., Turner, F.J., and G i l b e r t , CM., Petrography f San Francisco, W.H. Freeman and Son, 195^« Umpleby, J.B., Geology and Ore Deposits of the McKay Region. Idaho. U.S. Geol. Surv. Prof. Paper 97. 1.917. Annual Reports of the Minister of Mines. B.C. Dept. Mines, 1895-1937. Index No. 3 . B.C. Dept. of Mines. I.956, Table I - Recorded Lode-Metal Production. PLATE I (a) Limestone breccia at Phoenix (b) Limestone breccia from Lime Creek (c) x 1/3 - Chert breccia (d) x 1/2 - Chert conglomerate with s i l i c a overgrowth c ELATE II (a) x 1/5 - Brecciated skarn fragments encrusted with magnetite, a c t i n o l i t e , and c a l c i t e - Swallow p i t . sk - skarn; mag - magnetite; act - a c t i n o l i t e ; calc - c a l c i t e . (b) x 1/2 - Rounded Inclusions of Emma quartz d i o r i t e i n Lion Creek quartz d i o r i t e . (c) x 1/3 - Upper: Eholt agglomerate Lower: Eholt water-lain agglomerate and t u f f . (d) x 1/2 -Pulaskite extrusive. - 79 -PLATE H c d PLATE III (a) x 13 - Photomicrograph; plane-polarized l i g h t : p y r i t i z e d skarn from E. B e l l Mine, showing cross cutting c a l -c i t e v e i n l e t s . Black - p y r i t e ; grey - garnet;. white - c a l c i t e . (b) x 12 - Photomicrograph; plane-polarized l i g h t : magnetite ore from Emma Mine, showing unreplaced c r y s t a l s of garnet and remnants of the c a l c i t e that magnetite has replaced. Black - magnetite; grey - garnet; white - c a l c i t e . (c) x 11 - Photomicrograph, plane-polarized l i g h t : chert con-glomerate (same as shown on Plate I; d). Chert pebbles i n a c a l c i t e matrix. (d) x 15 - Photomicrograph; X-nicols: Lion Creek quartz d i o r i t e . - 80 -PLATE HI 

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