The Dia occurrence is located near a small creek, approximately 250 metres south east Diane Lake.

North striking carbonates and calcareous sediments of the Quatsino and Parson Bay formations overlie Karmutsen Formation tholeiitic basalts, all of the Upper Triassic Vancouver Group. Lower Jurassic Bonanza Group andesitic to rhyodacitic lava, tuff, breccia and minor sediments are coeval with, or genetically related to granodiorite of the Nimpkish Batholith of the Jurassic Island Intrusions. Strong regional north to northwest trending faults, often defining intrusive and lithological contacts, traverse the area.

Locally, several small stringers of sphalerite with minor chalcopyrite occur in Quatsino Formation limestone.