The Bridon chromite showings are located on a ridge crest at the head of Rock Creek, about 17.5 kilometres north of Bridesville. The showings and trenches follow a northwest-trending ridge at elevations between 1889 and 1981 metres. This ground is presently staked as the Ray 1-4 claims.
The showings were first staked in 1939 as the Don Nos. 1 to 8 claims and a small amount of hand trenching was done at that time. The property was further examined by Stevenson (1941) and the claims were apparently allowed to lapse. In 1957, the Belair Mining Corp. Ltd. restaked the ground as the Bridon Group. The company did extensive amounts of trenching, stripping, mapping, geophysical surveys and diamond drilled several holes totalling 487 metres of core (Assessment Reports 16172, 17109). Seven large chromitite lenses were uncovered but the claims were allowed to lapse. In 1986, Granges Exploration Ltd. optioned the Ray 1-4 claims which presently cover the showings. Again extensive geophysical surveys, geological mapping, sampling and 741 metres of diamond drilling in 16 holes were done. This work increased the number of known chromitite lenses and also tested for platinum, gold and palladium mineralization. Specific results have not been made public but the chromite values were considered good and the precious metals values were not encouraging (Assessment Reports 16172, 17109). In 1989, the claims were owned by A. Dupras and associates. Since 1987, no further work has been recorded.
The chromite is hosted in a long, thin serpentinite body emplaced in metasediments of the Carboniferous to Permian Anarchist Group near granodiorites of the Cretaceous to Tertiary Okanagan batholith. Locally the Anarchist Group rocks consist of hornblende schists, metaquartzites and limestones with zones of marble. Well developed, penetrative vertical foliation trends northwest in the metasediments and parallels the shearing and sharp boundaries of the serpentinite (Assessment Report 16172; Whittaker, 1983). Other similar serpentinite bodies have been mapped in the Greenwood area by J. Fyles. These are described as thrust slices of oceanic crust associated with the Cache Creek Terrane (J. Fyles, personal communication, 1989). Adjacent to the property, around the northern boundary, plagioclase porphyritic granodiorite of the Okanagan batholith truncates the metasediments of the Anarchist Group.
The serpentinite is a narrow body about 1000 metres long and 75 to 100 metres wide at surface. The protolith is dunite, not completely serpentinized, with only rare grains of olivine preserved. The serpentinite is sheared parallel to the regional northwest subvertical foliation. Chromite mineralization is restricted to the serpentinite and is found as short, disseminated stringers and long, narrow aggregates of crystals. The chromite is fine to medium grained and the lenses pinch and swell along their length. Extensive trenching by Belair Mining Corp. Ltd. in 1957 exposed 7 large lenses of chromite about 1 metre wide and ranging from 8 to 30 metres long. Some of the lenses have been openly folded leading to a structural thickening of chromite in the fold noses and thinning of the arms. An average grade across one lens is 20 per cent Cr2O3 (Stevenson, 1941) and higher grades of up to 29 per cent Cr2O3, with Cr:Fe ratios of 1.84 have been reported (Minister of Mines Annual Report 1957). A sample of cleaned, high-grade chromite yielded the following results in per cent (Stevenson, 1941):
------------- Cr2O3 48.90 Al2O3 10.30 CaO 0.40 MgO 11.90 MnO 0.34 TiO2 1.36 SiO2 1.38 FeO 22.00-------------
Sampling for platinum and palladium has yielded results of 3 to 100 parts per billion. Platinum values were generally a few tens of parts per billion and palladium values were consistently lower (Assessment Report 16172).