The area is underlain by volcanic rocks of the Upper Triassic Vancouver Group, Karmutsen Formation which strike northwest and dip 10 to 25 degrees north.

The occurrence consists of minor chalcopyrite, bornite, pyrite and pyrrhotite, occurring as disseminations and in amygdules in Karmutsen flows and breccias. Narrow, better grade areas are associated with northwest and northeast trending fracture and fault zones. Bornite is confined to coarse-grained basalt. The overlying fine-grained basalt is not mineralized.

Open cuts on the Copper Island claim show a width of mineralization up to 1.5 metres in epidote-altered, coarse-grained basalt.

In 1929 the Demerara group consisted of the three claims, River, Eagle and Copper Island, owned, respectively, by Maisonville, S.A. Husen, and I.M. Stauffer. The main workings were open cuts done of the Copper Island claim. In 1972 the property consisting of the Sea 1 to 36 claims was held by W. Kuhn. Work done by El Paso Mining Company included surface geological mapping.