The Chalco Creek showing area is largely underlain by andesitic tuffs of the Lower to Middle Jurassic Hazelton Group and by felsic (rhyolitic) volcanics of the Eocene Ootsa Lake Group. Quartz dioritic stocks, dikes and plugs of the Late Cretaceous Bulkley Plutonic Suite and Eocene felsitic intrusive rocks intrude the volcanics.

The Chalco Creek showing occurs above a southwest flowing tributary to Cummins Creek where in excess of a dozen quartz veins up to 1.5 meters wide are exposed. These veins, trending northerly, contain pockets of chalcopyrite, galena, sphalerite and sulphosalt (possibly tetrahedrite) which assay up to 342.86 grams per tonne silver and low gold (Assessment Report 17654).

Refer to Cummins Creek Veins prospect (093E 100) for common details of area work history.