The Horseshoe showing is located 3.0 kilometres south of Mount Theophilus, about 9.0 kilometres east-northeast of Alice Arm.

The region is underlain by an assemblage of volcanics and sediments comprising the Upper Triassic Stuhini Group, the Lower Jurassic Hazelton Group and the Middle Jurassic to Upper Cretaceous Bowser Lake Group. The sequence is situated on the eastern flank of the north-northwest trending Mount McGuire anticline.

The showing is hosted in Stuhini Group augite porphyritic basaltic flows and breccias, underlain to the west by argillite. The showing consists of quartz veins containing chalcocite. A sample taken across a 0.46 metre wide vein assayed 29.0 per cent copper and 137 grams per tonne silver (Minister of Mines Annual Report 1922, page 62).

Quartz and quartz-barite veins up to 4 metres wide, 500 metres long and striking approximately north are reported to be hosted in andesitic tuff. The veins carry up to 30 per cent disseminated pyrite associated with sericite, however, assay results have not produced significant values (Assessment Report 21060).

In 1990, Santa Marina Gold Ltd. conducted regional mapping, prospecting, rock and silt sampling during which a total of 61 rock samples and 5 silt samples were collected. In the same year, Canadian Cariboo Resources Ltd. conducted a reconnaissance rock, soil and stream silt geochemical survey and prospecting program on their Illiance property which covered the showing.