The Peso occurrence is located south west of the Koksilah River, approximately 5.4 kilometres north west of Grant Lake.
The area is underlain by volcanics of the Lower Jurassic Bonanza Group, which are in fault contact to the north with the volcanics of the Upper Triassic Karmutsen Formation. The Bonanza volcanics consist of basaltic and rhyolitic tuffs, breccia and flows of silicified vesicular basalt. These rocks have been intruded along regional bedding planes by a shallow southeast dipping dioritic sill, about 25 metres thick. The main fault along the contact of the Karmutsen and Bonanza rocks is composed of several distinct shears, exposed in roadcuts over a width of about 50 metres.
Mineralization associated with these structures consists of finely disseminated pyrite in clay-altered, silicified gouge and fine to medium grained disseminations of euhedral pyrite, chalcopyrite and sphalerite in the well-fractured, oxidized basalts and basaltic breccias.
In 1978, Union Miniere Expl. & Mining Corp. Ltd. completed a program of soil geochemical sampling on the area as the Metal and Heavy Metal claims. In 1985, Imperial Metals Corp. completed a program of silt and stream sampling on the area as the Dunc 1-3 claims. This work identified anomalous gold in the north fork of the Koksilah River. In 1988, Abacom Resources completed a program of geochemical sampling, geological mapping and ground geophysical surveys on the area as the Bingo and Peso claims. A sample of light grey silicified basalt adjacent to a sheared contact between diorite and basalt assayed 2.5 grams per tonne gold and 10.3 grams per tonne silver (Assessment Report 18848).
In 1991 and 1992, Boston Industries completed programs of geological mapping and a ground electromagnetic survey on the area as the Koksilah claims.