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 Tyhee occurrence is underlain by amygdaloidal basalt of the Karmutsen Formation cut by a shear structure striking 090 degrees and dipping 65 degrees south. Trenches and an adit explore the shear which is mineralized with massive pyrite and chalcopyrite with some malachite staining. The shear zone hosts brecciated, multiple phases of drusy quartz veining. Chip sampling of the shear within the adit assayed 9.19 grams per tonne gold, 0.39 per cent copper and 8.1 grams per tonne silver over 0.35 metres (Assessment Report 18672). A grab sample north of the adit assayed 1.03 per cent zinc and 0.28 per cent lead.

The dominant fault direction is northwest but mineralization is developed along conjugate shear zones.