The O.G.M. 104 (Gillespie) occurrence is located near Granite Creek, approximately 1 kilometre southeast of its creek mouth on the Nitinat River

The area is underlain by extensively faulted rocks of the Upper Triassic Vancouver Group and the Lower Jurassic Bonanza Group. The basal Vancouver Group sequence is comprised of basalt flows, breccias and tuffs of the Karmutsen Formation overlain by Quatsino Formation limestone, which is in turn overlain by black argillites of the Parsons Bay Formation. The overlying Bonanza Group consists of a sequence of argillites, cherts, cherty tuffs, volcanic and/or sedimentary breccias, sandstones and basaltic to rhyolitic flows.

The entire package of rocks has been broadly to tightly folded with fold axes generally trending northwest, and has been intruded by granodioritic and feldspar porphyritic dikes.

Locally, magnetite-chalcopyrite skarn zones in limestone have been explored by two short tunnels. Assays up to 4 per cent copper over 1.5 metres are reported from a pit, while 30 metres to the east, in the river canyon, a trench assayed 4.6 per cent copper over 1.5 metres (Assessment Report 00642).

In 1964, Avallin Mines completed a program of soil sampling and geological mapping on the area as the O.G.M. claims. In 1969, Quintana Minerals completed a program of regional soil sampling and geological mapping.