The area is underlain by Upper Triassic Karmutsen Formation volcanics of the Vancouver Group. These are interbedded with, and overlain to the northeast by a northwest trending belt of Quatsino Formation limestone (Vancouver Group) known historically as the "lime-belt". The Vancouver Group rocks are in fault and/or intrusive contact to the northeast with intrusive rocks of the Coast Plutonic Complex.

On the Triangle showing a few grains of chalcopyrite, galena, arsenopyrite and pyrite are scattered along a narrow zone of shearing where it traverses crystalline limestone. The presence of small black needle-like crystals of tourmaline arranged in sheaf-like aggregates were observed along joint planes in the limestone.