The western portion of the Mag showing is underlain by fine- grained green and grey andesite flows and tuffs, minor pyroxene porphyritic basalts and black fine-grained biotitic volcanic rocks or sediments of the Upper Triassic Nicola Group. To the west, near the border of the property, Nicola Group rocks are intruded by quartz monzonite to granodiorite of the Lower Jurassic Nicola batholith. To the east, hornblende metadiorite outcrops.

Minor amounts of chalcopyrite and bornite occur as disseminations in the volcanic country rock, in epidote veinlets and in occasional narrow quartz veins.