The Cosburn barite occurrence is located on a north-south–trending ridge, approximately 3.5 kilometres north-northwest of the southeast end of Redfern Lake.

The central portion of the Redfern Lake area is underlain by Middle Devonian Dunedin Formation carbonates conformably overlying Lower to Middle Devonian Stone Formation dolomites. To the east, this package is thrust over Devonian to Carboniferous Besa River Formation shales. To the west, a conformable package of Cambrian to Ordovician Kechika Group, Middle Ordovician Skoki Formation, an unnamed Upper Ordovician unit, Silurian Nonda Formation, Lower Devonian Muncho-McConnell Formation, Lower to Middle Devonian Stone Formation and Middle Devonian Dunedin Formation strata are thrust over the Dunedin Formation.

Locally, on Cosburn Ridge, north of Redfern Lake, a large body (400 by 60 metres) of massive barite is hosted within Dunedin Formation limestone breccia of the central thrust panel. The barite contains local concentrations of pink fluorite and minor galena. Approximately 250 metres to the south, a second body of barite crosscuts bedding in the limestone. Limestone breccia blocks occur within the flat-lying barite.

Work History

In 1972, Vestor Explorations Ltd. completed a program of geological mapping and soil sampling on the Redfern Lake area as the Chilly, Damn, Egg and Foo claims. Also at this time, Noranda Mining and Exploration Inc. completed a program of silt and soil sampling on the area as the BE claims of the Valley property.

In 1973, Rio Tinto Exploration Canada Inc. completed a program of geological mapping, minor rock sampling, a 36.2 line-kilometre induced polarization survey, a 30.5 line-kilometre ground magnetic survey and a photogeological study on the Foo, Egg, Chilly, Vista and Damn claim groups. In 1974, Rio Tinto Canadian Exploration Ltd. completed nine diamond drill holes, totalling 608.0 metres, on the Vestor property. The following year, a further program of geological mapping and soil sampling was completed on the property. In 1979, Teck Explorations Ltd. completed a program of geological mapping and geochemical (rock and soil) sampling on the Vestor property.