The Shag (C3) occurrence is located east of the Albert River, approximately 3.3 kilometres southeast of Miller Pass.

Regionally, the area is underlain by Middle Cambrian Cathedral Formation carbonates, laterally equivalent Chancellor Formation shales and limestones and Upper Cambrian McKay Group shales.

Locally, reddish-orange sphalerite is hosted by a granular or brecciated dolostone, overlain by dark, laminated limestone. The sulphide concentrations appear to be restricted to two horizons, although a number of megascopically similar horizons occur in the succession. The mineralization has been traced for 9 metres.

In 1977, five grab samples of talus, taken from immediately below the occurrence, yielded from 5 to 27 per cent zinc (Property File - C. Graf [1977-11-01]: Graf Lead-Zinc Reconnaissance - Southern Rocky Mountain - Volume I).

In 1977, Riocanex completed a regional program of geologic mapping, silt sampling and prospecting on the area as the Shag claims. In 1978, Rio Tinto Canadian Exploration Ltd. completed geological mapping, prospecting, diamond drilling and soil sampling on the claims. The following year, a program of geological mapping, prospecting, soil sampling and six diamond drill holes, totalling 460.6 metres, were completed. In 1981 and 1982, Esso Resources Canada Ltd. completed programs of geological mapping, geochemical sampling and diamond drilling. In 1988, Delta Geoscience Ltd. was contracted by Chris Graf of Ecstall Mining Corp. to conduct ground geophysical surveys. In 1990, Toklat Resources Inc. completed geochemical sampling and geophysical surveys. In 1991, Teck Corp. conducted soil sampling, geological mapping and limited prospecting. In 1998, Ecstall Mining Corp. completed a petrographic and chemical analysis of rock samples from the Shag claims.