The BJ occurrence consists of two small trenches located near the south shore of Shamrock Lake at an elevation of 2320 metres above sea level in the Golden Mining Division.

Regionally, the area is underlain by Proterozoic clastic sedimentary rocks of the Purcell and Windermere supergroups and by lower Paleozoic strata of the Beaverfoot and Mount Forster formations (Geoscience Map 1995-1).

The Purcell Supergroup strata include the Aldridge, Creston, Kitchener, Dutch Creek and Mount Nelson formations. The Windermere Supergroup unconformably overlies the Purcell Supergroup rocks and includes the Toby Formation and Horsethief Creek Group (Paper 1990-1).

In the vicinity of the occurrence, rocks of the Kitchener and Dutch Creek formations have been further subdivided and assigned to the Van Creek and Gateway formations. The Van Creek Formation correlates with the Lower Kitchener Formation while the Gateway Formation is equivalent to the lower portion of the Dutch Creek Formation. The Mount Nelson Formation has been subdivided into seven discrete members, a lower quartzite, a lower dolomite, a middle dolomite, a purple dolomite, an upper middle dolomite, an upper quartzite, and an upper dolomite (Open File 1990-26).

Rocks of the Horsethief Creek Group, Beaverfoot and Mount Forster formations are folded and overthrusted by rocks of the upper portion of the Dutch Creek Formation and the lower members of the Mount Nelson Formation. The sedimentary rocks have undergone regional metamorphism to at least greenschist facies.

Mineralization on the BJ showing is of two types. The first type consists of galena, sphalerite and tetrahedrite in fractures and quartz-carbonate veins. Smithsonite occurs in minor amounts as fracture coating. The second type of mineralization consists of only galena and tetrahedrite occurring in subvertical quartz veins. Both types of mineralization are within dolomite of the Monk Formation of the Horsethief Creek Group associated with tensional fractures near a fold axis.

A 0.5 metre rock channel sample collected across a 0.1 metre wide galena-tetrahedrite vein assayed 88 grams per tonne silver, 8.95 per cent lead, 4.36 per cent zinc and 0.05 per cent copper (Assessment Report 8514).