The Sumpter occurrence is located near the north western shore of Upper Campbell Lake, approximately 1.2 kilometres south east of Bacon Lake.

The area is underlain by Upper Triassic Vancouver Group, Quatsino Formation limestone and the western contact of the Quinsam granodiorite of the Early to Middle Jurassic Island Plutonic Suite.

Locally, a shaft has been sunk for a depth of 5 metres on a showing of garnet and epidote containing a little bornite and chalcopyrite in grey limestone. A narrow fissure cutting across the shaft is mineralized with garnet and quartz and the same two sulphides. A sample from the bottom of the shaft assayed 96.00 grams per tonne silver, 3 per cent copper and a trace of gold (Minister of Mines Annual Report 1916).

A nearby open-cut exposes 2.4 metres of copper stained garnetite with a little magnetite in altered crystalline limestone. A pronounced fault wall on the north side of the mineralized zone strikes 040 degrees along a hill and similar mineralization occurs for about 23 metres.

In 1987, R. Tessolini prospected the area immediately north as the Bacon claims. In 1989 and 1991, M. Sawiuk completed programs of geological mapping, rock sampling and ground magnetometer surveys on the area immediately north. In 1997, IMA Resources Corporation completed a program of geochemical sampling and geological mapping on the area as the Bacon 1-4 claims. During 2009 through 2013, Western GateWay Minerals explored the area as apart of the Bacon Lake property.