The historic Stump Lake mining camp is located on Mineral Hill within a north trending belt of Upper Triassic intermediate volcanics, volcaniclastics and sediments belonging to the Nicola Group. The Nicola Group greenstones consist of massive, chlorite- epidote altered andesite and basalt, augite porphyry, andesitic flow breccia and tuff, minor interbedded argillite, conglomerate, and limestone. Attitudes of tuff horizons and sedimentary bedding suggest that the north plunging axis of a syncline passes through the occurrence area. Both west and northeast of Stump Lake, the Nicola Group volcanics are intruded by Lower Jurassic granitic batholiths; scattered granodiorite outcrops have also been mapped. Secondary to the regional north-northeast trending Quilchena and Stump Lake faults, are numerous smaller faults which form a complex fracture pattern and appear to control alteration and mineralization. The volcanics are bleached, pervasively silicified, pyritic and brecciated. Mineralization occurs in veins and shear zones. Numerous north trending quartz, and less commonly calcite veins, generally less than 50 centimetres wide, are vertical to steeply eastward dipping and can be traced along strike for hundreds of metres.

The workings on the Don showing include three(?) shallow shafts and several open cuts. An inclined shaft 15 metres deep in the northern area follows a vein zone which strikes 350 degrees and dips 35 degrees east. This zone shows carbonate, limonitic, sericite and kaolinite alteration and contains quartz (and calcite) veins 45 centimetres to 1.5 metres wide. Sulphide mineralization is sparse and includes pyrite, chalcopyrite, galena and sphalerite. Small amounts of scheelite are disseminated in the quartz. Recent rock sampling of the quartz vein returned 1.47 grams per tonne gold and 75.4 grams per tonne silver over a true width of 1.5 metres (Assessment Report 18495).