The Saint Louis prospect is situated 200 to 800 metres east of the Similkameen River and 19 kilometres south of Princeton.

The area is underlain by the eastern facies of the Upper Triassic Nicola Group, comprising mafic augite and hornblende porphyritic pyroclastics and flows. These rocks are intruded by diorite and monzonite, locally pyroxenite and gabbro, of the Early Jurassic Copper Mountain and Lost Horse intrusions.

This prospect is hosted in a sequence of volcanic breccia, siltstone and sandstone, with minor andesitic and cherty tuff of the Nicola Group. These rocks were previously included with the Wolf Creek Formation (Geological Survey of Canada Memoir 171). The Copper Mountain stock (Copper Mountain Intrusions) lies 120 to 250 metres to the north.

The deposit consists of a 200 to 300-metre wide zone of pyrite-pyrrhotite mineralization extending eastward from the Reco prospect (092HSE114) for 600 metres. Total sulphides are in excess of 1 per cent, occurring as disseminations and fracture-fillings.

Two holes (75-1, 75-2), 260 metres apart, drilled near the east end of the deposit, encountered mostly pyrite and pyrrhotite, with minor chalcopyrite, in partially epidote and chlorite-altered volcanic breccia, and slightly bleached and albitized volcanic siltstone and sandstone (Assessment Report 5768). Pyrite occurs as stringers associated with chlorite, anhydrite and calcite, while pyrrhotite occurs in numerous fragments in volcanic breccia. Pyrrhotite and lesser chalcopyrite occur together as lenses, patches and disseminations in highly altered, anhydrite-rich zones 1 to 10 centimetres wide, in volcanic siltstone and sandstone. Individual zones are about 2 metres apart in drill core. Pyrrhotite generally fringes the chalcopyrite. Black, metamorphic spinel is associated with pyrrhotite.

A 6-metre section of drill core assayed 0.03 per cent copper, 0.001 per cent molybdenum, trace gold and 1.4 grams per tonne silver (Assessment Report 5768, Figure 2, hole 75-2). Ten other sections, 3 to 6 metres long, contained 0.01 to 0.02 per cent copper, 0.001 to 0.002 per cent molybdenum, 0.7 to 2 grams per tonne silver and trace to 0.07 gram per tonne gold (Assessment Report 5768, Figures 1 and 2).

The western portion of the deposit contains up to 10 per cent pyrite in fractures, shears and in mafic fragments in volcanic breccias. Eleven grab and chip samples from this area contained 0.003 to 0.039 per cent copper, nil gold and 0.1 to 0.4 gram per tonne silver (Assessment Report 15854, Appendix C).

This deposit was first assessed by Newmont Mining Corporation of Canada Ltd. in 1970 and 1971 by geological and geophysical surveying, and 424 metres of diamond and percussion drilling in 5 holes. Aquitaine Company of Canada Ltd. carried out geophysical and geochemical surveys, and 581 metres of diamond drilling in two holes in 1974 and 1975. Subsequent work by Kidd Creek Mines Ltd. and Targa Resources Inc. between 1982 and 1986 consisted of geophysical and geochemical surveys, with minor prospecting and sampling.