The Atan Copper showing is exposed in a tributary valley on the east side of Grayling Creek. The valley is underlain by Cambrian to Silurian platformal sequence of carbonates, quartzites and siltstones. Lower Cambrian Atan Group dolomites and quartzites, intruded by mafic dykes, are conformably overlain by Cambrian to Ordovician Kechika Group arenaceous dolomites and limestones and Silurian Nonda Formation siltstones.
A coarse crystalline chalcopyrite, malachite, and azurite vein is hosted within a dolomite, believed to belong to the lower Atan Group. A grab sample of this material graded 11.52 per cent copper and 27.8 grams per tonne silver (Assessment Report 21437).