The Eureka (L.6473) occurrence is located on Grouse Mountain, north of Coppermine Lake and south west of North Lake.
Regionally, the area is underlain by a sequence of north west striking andesite flows and pyroclastics, with lesser rhyolite and basalts of the Lower Jurassic Telkwa Formation (Hazelton Group) and a north north-west trending sedimentary sequence comprised of marine black shale, argillite, siltstone and greywacke with intercalated tuffs and breccia of the Upper Jurassic Ashman Formation (Bowser Lake Group). The volcanic and sedimentary rocks are intruded by dikes and small stocks which strike north-northwest and dip west-southwest. These include feldspar porphyry, biotite feldspar porphyry, monzodioritic to gabbroic intrusives and aphanitic basic dikes of the Late Cretaceous Bulkley Plutonic Suite and Eocene Goosly Plutonic Suite. Alteration has affected mainly the feldspar and ferromagnesium minerals producing mica and clay minerals, chlorite, limonite, carbonates, and less commonly epidote.
The Eureka showing is a pyrite-chalcopyrite quartz vein system dipping 75 degrees northwest and striking 070 degrees subparallel to the central part of the north shore of Coppermine Lake. The host rocks are green tuffaceous sedimentary rocks which are crosscut by an aphanitic basic dike near the quartz vein network.
On surface, the vein is traceable for 91 metres following a line of old sloughed trenches. In 1914, a sample across a width of 1.5 metres assayed trace gold, 164.5 grams per tonne silver, and 6.2 per cent copper (Minister of Mines Annual Report 1914, page 228).
In 1984, drilling yielded intercepts of up to 3.1 and 4.05 per cent copper, 0.03 and 2.95 per cent zinc with 41.4 and 124.8 grams per tonne silver over 1.0 and 1.5 metres in holes 84-2 and 84-8, respectively (Assessment Report 14256). Also at this time, a 2.0 metre sample from a backhoe trench assayed 4.457 grams per tonne gold, 21.256 grams per tonne silver, 0.18 per cent copper, 0.01 per cent lead, and 0.17 per cent zinc. Another backhoe sample across 1.7 metres width assayed 1.029 grams per tonne gold, 66.855 grams per tonne silver, 1.93 per cent copper, 0.01 per cent lead, and 0.06 per cent zinc (Assessment Report 14256).
WORK HISTORY
The Eureka (Lot 6473), and Copper Crown, etc., claims were staked in 1914 by Samuel Bush, Joe Bussinger, and Louis Schorn. Later that same year the claims were optioned to Trim3le and Anderson, of Portland, Oregon, who formed the Cassiar Crown Copper Co., with head office in Tacopa, Washington. Work on the Eureka showings to 1920 included pits and trenches, and an adit of unknown length. The Eureka claim was Crown-granted to the company in 1920. The company was apparently re-organized in 1926 under the name Cassiar Crown Mining Co. and exploration work was resumed on the Copper Crown showings. Work was suspended in the summer of 1927; no work was reported on the Eureka.
The Crown-grants subsequently reverted to the Crown and were leased in about 1950 by A.B. Goodridge, Frank Cooke, and associates. Copper Ridge Silver Zinc Mines Limited was incorporated in February 1951 to explore the property. Diamond drilling totalling 93.3 metres in 3 holes was done on the Eureka claim during the year. The company suspended exploration work in August 1952. The company name was changed in 1962 to Copper Ridge Nines Ltd. An electromagnetic survey was carried out in 1965.
The 2007, Bard Ventures Ltd conducted IP work over the Copper Crown, Rainstorm, Eureka and possibly the North Lake zones.
Refer to Copper Crown (093L 026) for further information on work conducted on the Grouse Mountain property which included the Eureka showing.
