The Silbak Premier mine is located 22 kilometres north of Stewart covering an area of 5.3 square kilometres. Mineralization was initially discovered as a gossan zone in 1910 and production began about 1918 and continued with a few interruptions until 1968. Currently (1988), Westmin Resources Ltd., Pioneer Metals Corp. and Canacord Resources Inc. are constructing a 2000 tonne per day mill to extract the low grade, bulk tonnage ore, from an open pit in the "glory hole" area. Production is expected to begin in 1989.
The mine is located in the Intermontane Belt bounded on the west by the Coast Crystalline Complex and on the east by the Bowser Basin, in the volcanic arc assemblage of the Stikinia Terrane. The Premier deposit is hosted by Lower-Middle Jurassic andesitic to dacitic volcanic rocks, correlated with the Hazelton Group, Unuk River Formation. The Hazelton Group is a northwest trending belt of folded andesitic to dacitic metavolcanic rocks containing a thick sequence of argillites and siltstones infolded along a synclinal axis.
The orebody is hosted in aphanitic andesite, monolithic andesite breccia and lapilli tuff of the Unuk River Formation. The andesite, at least 750 metres thick, is intruded by Early Jurassic Texas Creek Plutonic Suite dacitic porphyry dykes and is unconformably overlain by volcaniclastic and epiclastic rocks. The mixed green and maroon heterolithic volcaniclastic rocks form the bulk of the Bear River ridge directly east of Silbak Premier.
There are three varieties of porphyritic dacite: 1) potassium feldspar porphyry, 2) hornblende-plagioclase porphyry and 3) maroon porphyry. They are hypabyssal members of the Texas Creek Plutonic Suite. These porphyries are characteristically blocky weathered and less foliated than the andesite or tuff.
The potassium feldspar porphyry, historically known as the "Premier Porphyry", is spatially associated with the ore. This association is believed to indicate a Lower Jurassic mineralization age.
Hornblende-plagioclase porphyry is texturally similar to potassium feldspar porphyry but contains few or no quartz or potassium feldspar phenocrysts.
Maroon porphyry, distinct with a maroon to purple groundmass, is higher structurally and all known mineralization lies stratigraphically and structurally below it.
The dominant structures at Silbak are pencil lineations, extensional white barren quartz veins and joints. Bedding attitudes are limited, an overall moderate northwest dipping section has been established based on drill results and sparse, controversial surface data. A pervasive northwest dipping phyllitic chlorite-sericite foliation is best developed in andesites. The ore is predominantly discordant but locally concordant with the moderately northwest dipping andesite flows, breccias and dacite flows. Narrow zones (less than 2 metres wide) of easterly striking, steeply dipping planar fabrics are exposed locally. Heterolithic epiclasts in a few outcrops are elongated and are colinear with the pencil lineations.
Hydrothermal alteration zones related to the mineralizing system are represented by a proximal silicification/quartz stockwork and potassium feldspar and/or sericite facies potassic alteration. Peripheral to mineralization is a propylitic alteration assemblage of carbonate, chlorite and pyrite. The variable intensity and type of alteration is partially controlled by fracture intensity and host lithology, and presumably, elevation in the hydrothermal system. The green weathering andesites are propylitically altered with ubiquitous disseminated pyrite, chlorite and sericite. The least altered samples contain small (less than 1 millimetre long) plagioclase and hornblende phenocrysts in an aphanitic groundmass. Rare amygdules are evident in drill core (P. Wodjak, personal communication, 1986). The most characteristic feature of the andesite package is the pervasive carbonate, chlorite and clay alteration around the deposit.
Mineralization occurs along two trends: 1) a steeply northwest dipping, Northeast or Main zone, (60 degrees near surface flattens to 30 degrees by the 6-level) and 2) a steep to vertical Northwest or West zone. These two zones have a combined en echelon strike of 1800 metres, a downdip extent of at least 500 metres and a width of about 10 metres. Most production came from an area within 500 metres of the intersection of these two zones. These trends are believed to represent structural controls to mineralization and emplacement of dacite porphyry intrusions. Similar showings occur in southeastern Alaska but no definite relationship has been established.
There are at least four styles of mineralization with textures ranging from stockwork and siliceous breccia to locally layered and massive sulphide-rich mineralization. Sulphide content varies, generally less than 5 per cent but can be as high as 75 per cent. Although it has not been extensively studied, there is evidence for mineral zonation. The gold content varies laterally and the silver content decreases vertically. Such ore diversity is an indication of the complex and episodic nature to ore deposition.
Ore minerals include pyrite, sphalerite, galena with minor tetrahedrite, chalcopyrite, arsenopyrite and local pyrrhotite. Bonanza ore contains native gold, electrum, pyrargyrite, polybasite, argentite and native silver. Gangue minerals are quartz, potassium feldspar, chlorite, carbonates and others.
A hybrid ore genesis model combining epigenetic vein and porphyry copper characteristics compare well with the features observed.
Production data includes ore from B.C. Silver (104B 155), Sebakwe (104B 153), Northern Lights (104B 053) and Pictou (104B 156).
In 1994, mining was from two main areas, the Northern Light and the Glory Hole zones; proven and probable reserves as of January 1, 1994 were estimated by the company at 151,200 tonnes grading 7.54 grams per tonne gold and 55.2 grams per tonne silver (Information Circular 1995-1, page 7).
Westmin Resources began operations at the Premier gold mine in late May 1989. Production was 550 tonnes per day in 1995, two-thirds from Glory Hole fill recovered via a decline from 515 bench in the open pit, and one-third from pillars and ore on 4-level (Information Circular 1996-1, page 7).
Westmin completed 6900 metres of drilling in 84 holes resulting in proven and probable reserves of 261,000 tonnes grading 7.9 grams per tonne gold and 35.3 grams per tonne silver; and possible reserves of 151,000 tonnes grading 8.6 grams per tonne gold and 30.9 grams per tonne silver (T. Schroeter, personal communication, 1996).
Production at the Westmin Resources Limited Premier gold mine during 1995 totalled 580 kilograms of gold and 6235 kilograms of silver from 179,500 tonnes of ore milled at a daily throughput of 490 tonnes. Reserves estimated by the company at January 1, 1996 were 260,000 tonnes grading 4.65 grams per tonne gold and 68.0 grams per tonne silver (Information Circular 1997-1, page 9). During 1996 millfeed came from the Glory Hole and other underground areas. Underground mining was suspended on April 12, 1996 due to poor grades in the developed zones and dwindling reserves. A compilation in early 1996 by the company identified a possible underground resource of approximately 1 million tonnes grading 7.9 grams per tonne gold. Metallurgical testing examined the feasibility of producing a zinc concentrate. Westmin also conducted an aggressive, two-phase exploration surface and underground diamond drilling program, estimated to total approximately 12,800 metres, testing for mineralization between the No. 4 and No. 6 levels of the mine and also for deeper mineralization in the Martha Ellen (104B 092) zone on the Big Missouri deposit to the north.
As of January 1, 1997 diluted proven/probable reserves were 350,140 tonnes grading 7.19 grams per tonne gold (cut), 37.7 grams per tonne silver (uncut) and 1.6 per cent zinc. Possible diluted reserves were 111,573 tonnes grading 8.57 grams per tonne gold (cut) and 27.42 grams per tonne silver (uncut) (George Cross News Letter No.26 (February 6), 1997).
After considering offers from Treminco, BYG, Canarc and Hunter Dickenson, Westmin placed the mine on a long term care and maintenance program on April 12, 1996, due primarily to the depressed gold price (T. Schroeter, personal communication, 1997).
In 2009, drilling by Ascot Resource found sulphide mineralization consisting of fine grained pyrite with occasional sphalerite/galena hosted in a quartz-vein breccia. Host rocks are andesites with Premier Porphyry (feldspar porphyry) in close proximity. Except for P09-005, all holes encountered gold-bearing quartz veins with individual results varying from 1.46 grams over 2.0 metres in P09-006 to 18.28 grams per tonne over 7.70 metres in P09-002 (Assessment Report 31489). Results showed continuity of the vein system both in length and grade.
This property is located at about the 300 metres elevation on the east side of Cascade Creek, 8 miles north-northwest of Stewart. The Premier orebody was found to extend northeastward through the adjoining B.C. Silver Mines property into the Bush Mines (Sebakwe) claims. A West ore-zone was found to occur some 183 metres to the west of the original B C Silver Mines workings, the lower part of the zone extending into the adjoining Premier Border property.
The original Premier group consisted of the Cascade Falls Nos. 4 & 8, Pictou, Simpson, Essington, Rupert, and Hazelton claims (Lots 3590-3593, 3596, 3597). These claims were located O.B. Bush, in October 1910 incorporated Salmon Bear River Mining Company, Limited to carryon the exploration Westmin Resources Limited work; several adits were driven during 1911-12. In 1914 New York interests, represented by H.R. Plate, optioned the property and-to February 1916 some 488 metres of underground work was done. The results were not encouraging and the option was dropped; the main Premier orebody had been missed by a few feet. The property was bonded by R.K. Neill, of Spokane, and the Trites, Wood, &Wilson interests of Fernie in 1917. Exploration work was resumed and a short crosscut from the former workings encountered the orebody. The original claims were Crown-granted to O.B. Bush in 1918; three adjacent claims, the Pat Fraction, Dalby (Lot 3595), and Trites Fraction were Crown-granted to R.K. Neill. In February 1919 the Premier Gold Mining Company, Limited was incorporated to take over the property; Messrs. Neill, Trites, Wood and Wilson acquired a controlling interest in the company. At this time the property was expanded to 17 claims and fractions with the purchase of the Cascade Forks group of 8 claims from the Bunting Brothers this ground, lying west of and adjoining the original Premier group, was originally staked as the Cascade Falls Nos. 2, 3, and 7, Mainland, and Rapid Transit claims by Bunting Brothers and Dillsworth, who in September 1911 incorporated Cascade Falls Mining Company, Limited. Intermittent exploration work was done until 1916; the company charter was surrendered in 1919. This ground was subsequently restaked by the Bunting Bros. as the Cascade Forks group and reportedly Crown-granted to them in 1921.
The American Smelting and Refining Company, by participating in the financing of the exploration work, acquired a controlling interest in the Premier Gold Mining Company, Limited in 1919. A 100 ton per day mill was put into operation in July 1921. Additional claims were Crown-granted to Woods, Trites, &Wilson in 1922, and to the Premier company in 1923. Development work was carried out on 5 adit levels and an intermediate level. The mill capacity was increased to 400 tons per day in 1926 and to 500 tons in 1931. In 1935, the Premier Gold Mining Company, Limited reached an agreement with Selukwe Gold Mining and Finance Company, of London, England, for the amalgamation of the Premier, B.C. Silver, and Sebakwe (Bush Mines) properties under a new company, Silbak Premier Mines, Limited which was incorporated in December of that year. Selukwe owned Sebakwe and District Mines, Limited and also owned the British Canadian Silver Corporation, Limited which held a controlling interest in B.C. Silver Mines, Limited.
After the success of the McNeill-Trites interests in locating a major orebody in 1917 a large number of claims were staked in the area. In November 1919 B.C. Silver Mines, Limited was incorporated by O.B. Bush to acquire two groups of claims adjoining the Premier, one to the north and the other to the south. These claims were Crown-granted to the company in 1921; at the same time, 3 claims adjoining the north group, the Oakville Fraction, Oakville No.2 Fraction, and Oakwood, were Crown-granted to C.H. Lake. The exploration and development work, carried on until May 1931, succeeded in locating and partially developing the northeasterly extension of the Premier ore zone. This work was in part financed by The British Canadian Silver Corporation, who by 1922 had acquired control of B.C. Silver Mines, Limited.
The Lesley group of 6 claims, located north of and adjoining B.C. Silver, was owned by G. Mahood in 1916. The claims were subsequently acquired by O.B. Bush who incorporated Bush Mines, Limited in November 1918. Three adits were driven in the initial exploration but little mineralization was found and work ceased in 1919. Additional claims were acquired to a total of 16, all of which were Crown-granted to the company in 1921. Control of the company was sold by O.B.Bush to National Silver Mines t Limited in about 1923. Sebakwe &District Mines, Limited registered in British Columbia in February 1926, acquired the property from National Silver and underground exploration was resumed. Mineralization was located along the northeast extension of the Premier ore zone in 1927 and development work was continued into 1930.
Exploration, development, and production by Si1bak Premier from 1935 was confined mainly to the newly acquired ground. In 1940 an agreement was reached with he Premier Border Gold Mining Company, Limited for the exploration and development of the lower part of the newly discovered West ore-zone which extends into the Northern Light No.1 claim. The Northern Light group of 8 claims and fractions, owned by the Bunting Bros. from about 1917, was Crown-granted in 1922. The claims adjoin the B.C. Silver property on the west. Northern Light Mines, Limited was incorporated in January 1928 to purchase the claims. This company was absorbed on a share for share basis by Premier Border Gold Mining Company, Limited which was incorporated in February 1928. Exploration and development work by the company was suspended in June 1930.
The combined Silbak Premier workings were described (1947) in terms of the names of the former mines. The original Premier mine was developed by six main levels, five of which were adits, located at elevations of 609, 536, 474, 410, 326, and 240 metres. The levels were numbered in sequence downward. The lowest, No.6, is now known as the 790 level. No.4, now known as 1,350 level, was the main hau1age-adit. Levels above No. 4 were served by two internal shafts, and a third internal shaft, known as 601, provided service and ore-hoisting facilities to levels below No.4. The B.C. Silver mine, immediately north of the Premier workings, had five levels between elevations of 631 and 411 metres, and two internal shafts, one of which extended down to 1350 level. The Sebakwe mine, which adjoined the B.C. Silver on the northeast, had three levels between elevations of 508 and 411 metres and one internal shaft extending down to 1,350 level. The main haulage-level, 1350, finally attained a length of about 2133 metres. Prior to 1930 the Premier Border property had been developed by an exploration crosscut adit at the 344 metres level and some short lateral workings. The adit was driven about 550 metres in an easterly direction towards the B.C. Silver Mines property, the face of the adit stopping about 91 metres from the B.C. Silver.
The Granby Mining Company Limited optioned the property in December 1969. Work during 1970 included geological and induced polarization surveys. An anomaly outlined on the Bell and Loser claims was tested in 1971 by drilling in 10 holes. In addition drilling was done in the hanging wall of the main Premier replacement zone in 3 holes; the 1971 drilling totalled 1877 metres in 18 holes. The option was subsequently given up.
The company name (Silbak Premier) was changed in January 1977 to British Silbak Premier Mines Limited. From the work done in 1963, there were also indicated 6,350,000 tonnes grading 1.03 grams per tonne gold per ton and 25.89 grams per tonne silver (Norther Miner, July 10, 1980).
Local operators under the name Spring Investments Ltd. held a lease during 1978-79 and shipped 94 tonnes of clean up lead concentrate and 256 tonnes of hand-sorted ore from the floor of the old glory hole (No.1 level).
British Si1bak during 1980-81 carried out surface exploration, underground rehabilitation, cross-cutting and diamond drilling. In September 1981 the company signed a letter of intent to option a 50 per cent interest to Westmin Resources Limited; the agreement was finalized in March 1983; in the meantime the controlling interest in British Silbak was acquired from Mining Investment Corporation, of London, England by a Canadian group represented by the H.J. Block interests.
Exploration drilling in 1986 and early 1987, funded by Canacord Resources Inc., earned that company an 18.75 per cent interest in the interest held by Westmin. In 1986, 1737 etres in 10 holes were drilled. Exploration concentrated on the Simcoe-Pictou (SP) zone, a 700 metres long poorly exposed target on trend and south of the Glory Hole zone.
Pioneer Metals Corporation in mid 1987 purchased from John Block and associated companies the controlling interest in British Silbak; the latter name was changed in July 1987 to Silbak Premier Mines Ltd.; in May 1988, the company was amalgamated with Pioneer Metals Corporation under the latter name.
A feasibility study was carried out in 1987. Reserves at Silbak Premier were reported as open pit mineable 5,890,000 at 2.16 grams per tonne gold, 80.23 grams per tonne silver (Westmin Resources Limited, 1987 Annual Report). Westmin, as operator in 1988 unitized the Silbak Premier, Big Missouri and Martha Ellen properties under the name "Premier Gold Project". Interest in the project was Westmin 50.1 per cent, Pioneer Metals 40.0 per cent, Canacord Resources 9.9 per cent, with Tournigan Mining Explorations Ltd. holding a 5 per cent net profits interest. Stripping of the initial open pit and construction of a 2000 ton per day mill at the Silbak Premier property began in April 1988 ,and it was put into operation in May 1989.
In 1991, a 760 Airborne geophysical survey was conducted from the Premier area North to the Yellowstone (104b 032).
During the summer of 1992 a geological field mapping project was completed by Westmin in
order to test whether a major break occurred in the stratigraphy somewhere north
of Lesley Creek and, if so, where. Mapping in 1992 was successful in locating the break, now known as the North Fault, which is occupied by an intrusion of Premier Porphyry.
In 1993 a program of diamond drilling was carried out by Westmin (on the Climax claim) conisting of 3 holes. Three holes totalling 1,752.1 metres were drilled, all of which intersected the favourable stratigraphic package, and all of which contained alteration and sulphide mineralization in the target interval. None of the mineralization contains
commercial values of precious or base metals.
Ascot Resources Ltd conducted exploration on the Dilworth Property in 2007 and 2008 and subsequently acquired the Premier Gold Property from Boliden Ltd under the terms of a June 12, 2009 option agreement. During 2009 all exploration activity was conducted on the Premier and Big Missouri Properties.
The 2008 exploration program of Ascot Resources Ltd conducted on the Dilworth property included diamond drilling, surface rock sampling, geological mapping, a 428.2 kilometre airborne Mag/EM survey and airborne radiometric survey, geochemical sampling including contour sampling, a soil grid and stream sediment sampling of all streams on the west and east sides of the property (Assessment Report 31000). Diamond-drilling in 2008 totalled 10885.1 metres in 63 holes. Only the airborne survey extended off the Dilworth property to the south covering parts of the Big Missouri (104B 046) and further south to the Premier (104B 054). During 2009 (Assessment Report 31489) and 2010 (Assessment Report 32357) all exploration activity by Ascot was conducted on the Premier and Big Missouri Properties. In 2009 a total of 7465.3 metres were drilled in 48 holes into multiple zone including 3rd, Premier, Power, Hope, Loui's, S1, Northstar, Province, Martha Ellen, Montana, Rambler, Silver Tip, Unicorn, Golden Crown and Mudstones.
In 2009, Ascot drilled 7 of its 48 holes on the on the Premier Pit. Eleven holes (P09-001 to 011) were drilled from five pads constructed along the access ramp at the bottom of the Premier Pit. Targets were designed to confirm the previous results of Westmin Resources, and to test for the possible extension of additional resources below the existing pit.
In 2010 a total of 21,742 metres in 68 holes were drilled into a number of zones from the combined Dilworth and Premier properties of Ascot including: Unicorn, A-Vein, S1, Creek, Calcite Cuts, Province, Day, Martha Ellen, Sparky, Bee, Forty Nine and Gerrys zones.
See also Yellowstone (104B 039) and Big Missouri (104B 046) for related details of the Dilworth and Premier properties that were held as a single entity along with the Premier Silbak property in the 2000s by Boliden Ltd and Ascot Resources.