The Eureka occurrence is located at approximately 1394 metres elevation on the southeast slopes of Baldy Mountain, 1.25 kilometres west-northwest of the Cariboo-Amelia occurrence (082ESW020). Bridesville, British Columbia lies 9.5 kilometres to the south-southeast.
The Eureka occurrence lies in a complex sequence of volcanic and metasedimentary rocks of the Carboniferous to Permian Anarchist Group. To the north are Cretaceous granitic and granodioritic rocks of the Okanagan batholith. Middle Jurassic granitic rocks of the Nelson intrusions occur to the southwest. Eocene Penticton Group volcanic and sedimentary rocks overlie locally sheared amphibolite and serpentinite bodies of the Anarchist Group to the east. For a more detailed description of the regional geology of the McKinney camp refer to the Cariboo-Amelia occurrence (082ESW020).
Two shafts exist on what is known as the Eureka vein on the Eureka claim. The first main shaft was sunk in 1899, to a depth of 49 metres with a 34-metre drift at 26 metres depth. The second shaft is 30 metres east of the main shaft and is 5 metres deep. On the west side of the claim the quartz vein is up to 2.74 metres wide, striking 110 degrees and dipping 82 degrees south. Flat faults have displaced the lower sections of the vein to the south. Opencuts and a 6.1-metre deep shaft have traced the vein 76 metres along a strike of 112 degrees. In the northwest section of these workings the vein is 1.2 to 1.8 metres wide while in the southeast section, it is 30 to 91 centimetres wide. The vein is hosted predominantly in greenstone. Wallrocks consist of argillic quartzites and greenstone. Carbonate alteration occurs within a few centimetres of this vein.
Mineralization in the vein is reported to consist of pyrite, chalcopyrite, galena and mariposite. The dump from the main shaft consists of quartz with pyrite and minor chalcopyrite. The dump is estimated to contain 1814 tonnes of variably mineralized quartz. Nine samples from this dump were assayed in 1986 yielding values ranging from 0.03 to 12.31 grams per tonne gold and an average of 4.59 grams per tonne gold (Assessment Report 16168). The smaller shaft dump is reported to yield 9.05 grams per tonne gold (Assessment Report 16168).
Development work on the Eureka Fraction consisted of several trenches and shafts. The deepest shaft is reported to be 4.6 metres deep.
On the Eureka Fraction the vein is 1.2 to 1.8 metres wide and strikes 280 degrees. The vein can be traced for 46 metres on surface and consists of pyrite and chalcopyrite containing gold and silver in a quartz gangue.
While physical evidence indicates the removal of a considerable amount of vein material from the Eureka occurrence, there are no known production records. It is uncertain whether this vein represents the western continuation of the Maple Leaf and Cariboo/McKinney veins.
The Lou claim, located in 1982 by J. Craney, covers the Eureka and Eureka Fraction. In 1987, it was optioned to Wapiti Exploration Inc., who conducted magnetometer and VLF-EM surveys. Big Blackfoot Resources optioned the claim in the mid-1990s as part of a larger grouping. Apparently, no work was done on the Lou claim between 1987 and 2004. In 2004, one inclined NQ diamond-drill hole was completed, to a depth of 107.59 metres, to test the Eureka vein downdip, between the Eureka and the Little Eureka shafts.
