The Surprise Mountain area is underlain by rhythmically layered amygdaloidal, feldspar porphyritic and spherulitic basalt flows of the Upper Triassic Karmutsen Formation (Vancouver Group). Mineral- ized quartz and quartz-carbonate veins with variable sulphide content are associated with narrow, steeply dipping shear zones.

The Nancy Bell occurrence is underlain by Karmutsen Formation amygdaloidal basalt and a thin interbed of limestone. The rocks are cut by a shear structure striking 145 degrees and dipping 65 degrees southwest. The shear zone is locally silicified, strongly chloritic and 2 to 3 metres wide in places. The zone hosts quartz and quartz- calcite veining. En echelon bodies of silicified and mineralized volcanics indicate a component of right lateral shearing.

Mineralization consisting of pyrite, sphalerite, chalcopyrite and galena occurs on the footwall side of the veins. A composite grab sample of sulphide-rich material assayed 16.48 grams per tonne gold, 197.8 grams per tonne silver, 9.62 per cent copper, 2.9 per cent zinc and 0.09 per cent lead (Assessment Report 18672).

Past work includes a shaft developed on the shear zone, 240 metres northeast of the Silver Tip workings (092F 261).