The area is underlain by the Weaver Lake Member of the Lower-Middle Jurassic Harrison Lake Formation which consists of a series of basaltic to rhyolitic flows, flow breccias and bedded tuffs. Strong regional faulting has resulted in intense local fracturing and shearing. Structural features appear to have controlled the locus of hydrothermal alteration and associated mineralization. Alteration in the flows consists mainly of epidote with local concentrations of chlorite, zeolite and potassium alteration. The Sakwi Creek fault cuts through the property.

The northwest part of the claim (old Mary J claims) is underlain by a distinctive intermediate flow, composed predominantly of rounded feldspar porphyry fragments in a matrix of the same composition. This rhyolite agglomerate is underlain by very fine grained lapilli tuffs.

Sulphide mineralization occurs in the altered rhyolite agglomerate. Alteration is associated with faulting with resultant alteration consisting of local silicification, clay alteration with minor epidote, chlorite and sericite. Black sphalerite, with minor chalcopyrite and galena, occurs with barite as fragment coatings and as veinlets and stringers in the rhyolite agglomerate.