The Surprise Mountain area is underlain by rhythmically layered amygdaloidal, feldspar porphyritic and spherulitic basalt flows of the Upper Triassic Karmutsen Formation (Vancouver Group) overlain by a 15 metre thick subhorizontal unit of columnar jointed basalt. Mineralized quartz and quartz-carbonate veins with variable sulphide content, are associated with narrow, steeply dipping shear zones.

The Smuggler occurrence is underlain by amygdaloidal basalt of the Karmutsen Formation. A south-southwest trending silicified shear zone hosts minor chalcopyrite and pyrite mineralization.