The Cotter occurrence is located north of Cotter Creek, approximately 3.3 kilometres east of the creek mouth.

The south side of Cotter Creek is underlain by metasedimentary and metavolcanic rocks of the Sicker Group (Myra Formation?), while the north and southeast sides of the valley are underlain by Upper Triassic Karmutsen Formation (Vancouver Group) volcanics. In the Cowichan uplift, the primarily upper sedimentary package of the Myra Formation has been reassigned to the newly created Mississippian to Pennsylvanian Fourth Lake Formation of the Buttle Lake Group; the lower section is now known as the Upper Devonian McLaughlin Ridge Formation (Sicker Group).

Mineralization consists of pyrite with minor chalcopyrite and sphalerite which occur within quartz veins and surrounding sericitized and silicified Karmutsen andesites and basalts. Within the veins, the sulphides range in content from less than 1 per cent to approximately 3 per cent. Veins, ranging in width from 10 to 36 centimetres, occur within north trending sericitized shear zones.

The principle vein, averaging 23 centimetres in width, strikes due north and dips 75 degrees to the west. The vein has been exposed by trenching for 6.7 metres. One sample taken across 23 centimetres contained 6.31 grams per tonne gold. In 1988, a sample from a 10 centimetre quartz vein assayed 20.98 grams per tonne gold and 20.24 grams per tonne silver; with an average value of 2.57 grams per tonne gold over 0.56 metres, including the vein and letered host volcanics (Assessment Report 17732).

During 1984 through 1987, Consort Energy completed a program of prospecting, geological mapping and rock, silt and soil sampling on the area as the Lazeo-Klein and Herb claims. In 1988, Stoney Creek Mines completed a program of geological mapping, soil sampling, trenching and a ground electromagnetic survey on the area as the Cotter claims.