Andesitic rock of the Jurassic Hazelton Group is intruded by aplite. A shear zone in the andesite is mineralized with pyrite and minor chalcopyrite. A sample assayed trace gold, 137.1 grams per tonne silver, and 7 per cent copper (Minister of Mines, Annual Report 1932). The aplite contains seams of solid pyrite several centimetres thick.