The area of the occurrence is underlain primarily by pyro- clastics and flows of rhyolitic to andesitic composition belonging to the Telkwa Formation of the Jurassic Age Hazelton Group. A bleached argillic altered pyritic zone up to 30 metres wide is associated with a fault zone trending at 055 degrees and dipping vertically to steeply south. The fault marks the contact between Hazelton rocks and a dike or sill of Upper Cretaceous - Early Tertiary Age massive diorite - feldspar porphyry. The altered zone is in the volcanics which occur on the hanging wall side of the fault. Sporadic chal- copyrite mineralization occurs in the zone and quartz stringers, some containing minor sphalerite, are common.