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 Mountain Chief occurrence is underlain by amygdaloidal basalt of the Karmutsen Formation cut by an north-northwest trending shear structure that is subparallel to, or the same as the structure which hosts the Silver Tip occurrence (092F 261) 250 metres to the south.

The shear zone hosts quartz veins mineralized with pyrite, sphalerite, galena and chalcopyrite. A grab sample from a pit assayed 3.33 grams per tonne gold, 27.2 grams per tonne silver, 2.37 per cent lead, 2.84 per cent zinc and 0.07 per cent copper (Assessment Report 18672).