The T-81 occurrence is located on the south side of Mosquito Creek, approximately 8 kilometres northeast of Port Renfrew.

The area is underlain by a slate-phyllite unit and calc-silicate unit, both of the Jurassic to Cretaceous Leech River Complex. In this vicinity the metasediments are intruded by aplite sills and dikes.

Mineralization in the calc-silicate unit consists of disseminated pyrite, pyrrhotite and magnetite. Mineralization in the aplite intrusives consists of disseminated grains and clusters of pyrrhotite, pyrite and arsenopyrite. Mineralization in the slate-phyllite consists of disseminated pyrite cubes in foliation surfaces and abundantly disseminated pyrite and pyrrhotite in siliceous lensoid laminae, quartz veins and cross-veins.

In 1980, BHP-Utah Mines completed a program of geological mapping, rock and soil geochemical sampling and a ground magnetic survey on the OX claim. A sample (T81-013) assayed 3.9 grams per tonne gold (Assessment Report 9807).

In 1981 through 1986, M. Tavela completed programs of geological mapping, rock and soil sampling and ground magnetic geophysical surveys were completed. In 1988, Sumatra Res. Inc. completed a program of soil sampling, geological mapping and ground geophysical surveys on the area as the Carol claims. In 1990 and 1991, Beau Pre Explorations completed programs of rock and silt geochemical sampling and geological mapping on the area as the Potosi 1-4 claims.