The Telfer occurrence is located on a southeast facing slope west of Mark Creek, approximately 3.6 kilometres west of Sullivan Hill.

Regionally, the area is underlain by argillite, greywacke, wacke and turbidites of the middle Proterozoic Aldridge Formation (Purcell Supergroup). These have been intruded by gabbroic sills of the middle Proterozoic Moyie Intrusions. A full description of regional geology can be found in the Sullivan (MINFILE 082FNE052) occurrence.

Locally, as identified by diamond drilling, a 105.3- metre stratigraphic interval, from between 2481.6 and 2602.0 metres deep, is interpreted to consist of a package of turbidites thickened by deposition in a local sub-basin with gabbros, typical of Moyie intrusions, and a granophyre dike. The slumps and rapidly deposited sediments associated with sub-basin formation hosts re-sedimentation of unstable accumulations and exhalative sulphides. This package of sediments and intrusives is correlated with the stratigraphic sequence enclosing ore at the former Sullivan mine.

In 1988, a diamond drill hole (6464) intercepted 30 centimetres of deformed bedded sulphides with in a 0.9-metre zone containing 60 per cent sulphides, 40 per cent lithic material and a small amount of quartz veining. The sulphides are 85 per cent pyrrhotite and approximately 15 per cent sphalerite. Minor pyrrhotite and sphalerite mineralization occurring as disseminations to veined zones, up to 10 centimetres wide, were also reported within the 105.3 metre section. Samples of core assayed up to 0.10 per cent copper, 0.16 per cent lead, 4.1 per cent zinc and 11 grams per tonne silver (Assessment Report 18260).

Since the late 1800s, the area has been explored in conjunction with the nearby former Sullivan mine. In 1988, Cominco completed a program of geological mapping, a ground electromagnetic survey and six diamond drill holes, totalling 5107.5 metres, on the area.