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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  15-Jan-2004 by Robert H. Pinsent (RHP)

Summary Help Help

NMI
Name CHANCE Mining Division Revelstoke
BCGS Map 082K064
Status Prospect NTS Map 082K11W
Latitude 050º 37' 18'' UTM 11 (NAD 83)
Longitude 117º 20' 56'' Northing 5607812
Easting 475320
Commodities Silver, Gold, Lead, Zinc, Copper Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
Tectonic Belt Omineca Terrane Kootenay, Barkerville
Capsule Geology

The Chance prospect is on the east side of Silver Cup Ridge. It is at 2300 metres elevation "on the opposite side of the cirque" from the Morning Star [082KNW098] property and approximately 400 metres west of it. It is most likely immediately south of the Triune [082KNW026].

The Chance vein was found in the early 1900s and explored intermittently through to 1914. At that time, it was explored by two northwesterly trending adits. The upper adit, at 2305 metres elevation, was driven to provide 19.8 metres of crosscut and 50.3 metres of drift to the north and south. The lower adit, at 2294 metres elevation, enters the vein after 31 metres and drifts along it towards the north. In 1979, the Chance showings were covered by a claim cluster, known as the Silver Basin Group, owned by American Chromium Limited. Other prospects in the group included the Morning Star [082KNW098], I.X.L. [082KNW118], and Noble Five [082KNW153]. The ground was explored into the late 1980s. The Trout Lake area is underlain by a thick succession of sedimentary and volcanic rocks of the Badshot Formation and Lardeau Group near the northern end of the Kootenay arc, an arcuate, north to northwest trending belt of Paleozoic and Mesozoic strata that is now classified as a distinct, pericratonic, terrane. The arc rocks are bordered by Precambrian quartzite in the east and they young to the west, where they are bounded by Jurassic-age intrusive complexes. They were deformed during the Antler orogeny in Devonian-Mississippian time and were refolded and faulted during the Columbian orogeny, in the Middle Jurassic. A large panel, the "Selkirk allochthon", was later offset to the northeast by dip-slip motion along the Columbia River Fault.

The Badshot Formation is composed of a thick Cambrian limestone that is a distinctive marker horizon in the Trout Lake area. It is underlain by Hamill Group quartzite and it is overlain by a younger assemblage of limestone, calcareous, graphitic and siliceous argillite and siltstone, sandstone, quartzite and conglomerate, and also mafic volcanic flows, tuffs and breccias, all of which belong to the Lardeau Group. The rocks are isoclinally folded and intensely deformed, but only weakly metamorphosed. They occur as intercalated beds of marble, quartzite and grey, green and black phyllite and schist. Fyles and Eastwood (EMPR BULL 45) subdivided the group into six formations (Index, Triune, Ajax, Sharon Creek, Jowett and Broadview) of which the lowermost (Index) and uppermost (Broadview) are the most widespread. The Triune (siliceous argillite), Ajax (quartzite) and Sharon Creek (siliceous argillite) are restricted to the Trout Lake area. The Jowett is a mafic volcanic unit.

The Chance claim probably straddled the Cup Creek Fault. It was most likely underlain by black siliceous argillites of the Triune Formation and green phyllites and carbonates of the Index Formation. The rocks in the area are highly folded, deformed and schistose. The foliation displays the northwest strike and moderate to steep northeast dip found throughout the Silver Cup Ridge area.

The Chance vein is in carbonaceous phyllite that is separated from the limestone unit that hosts the nearby Morning Star [082KNW098] vein system by a diorite dyke. The vein strikes 115 degrees and dips at 72 degrees to the northeast. It is well defined, and consists of quartz and schist fragments, intermixed with galena and pyrite. In the upper adit, the sulphides occur as "bunches" of solid ore, and as layers that give the rock a banded appearance. Tetrahedrite and sphalerite occur sparingly. A well mineralized sample taken from across the face of the vein in the south drift assayed 2.74 grams per tonne gold, 3329 grams per tonne silver and 31 per cent lead over 0.46 metre and a composite sample, representative of an area 0.61 metre by 12.19 metres in the south drift, collected in 1979, assayed 5.14 grams per tonne gold 4975 grams per tonne silver and 16.5 per cent lead. However, a sparingly mineralized sample collected over 0.2 metre in the north drift assayed only a trace of gold and 75.4 grams per tonne silver. The high values found in the upper adit could not be duplicated in 1988. In 1914, there was reported to be a 0.1 metre wide vein containing galena and chalcopyrite in the face of the drift in the lower adit, but it had not yet reached the location of the main oreshoot. The adit had collapsed by 1988.

Bibliography
EMPR AR 1911-K154; *1914-K304
EMPR ASS RPT 7324, 9037, *17446
EMPR BULL 45 pp. 56,78
EMPR EXPL 1979-90
EMPR OF 1990-24
GSC MAP 235A
GSC MEM 161 pp. 45,56,115

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