The Barnacle (Extension 1, 3) occurrence lies north of the Zeballos gold camp, in an area underlain by Lower Jurassic Bonanza Group rhyolitic volcanic rocks and Upper Triassic Vancouver Group, Quatsino Formation limestone. Dioritic to granodioritic Jurassic plutons of the Zeballos intrusion phase of the Island Plutonic Suite have intruded the older rocks.

The occurrence consists of three different vein-shears located over an area of 50 metres, and explored by the Number 1, 2 and 3 adits. The shear zones are within a contact area of mixed Bonanza Group andesites and diorite of the Island Plutonic Suite, which is about 100 metres from the contact of andesite with Quatsino Formation limestone.

The Number 1 adit on Lot 2008 (Extension 1) consists of a lenti- cular quartz-vein that occupies a 1.2 metre wide north striking, 65-degree west dipping shear zone. The vein is up to 15 centimetres wide and has been traced on surface for 60 metres. The adit extends for 13 metres along its strike.

The Number 2 or Main adit on Lot 2010 (Extension 3) traces a 5.0 to 10 centimetre wide quartz-vein in a 60 centimetre shear zone lying in andesite that contains patches of diorite and brown garnet. The quartz is vuggy and contains earthy limonite, chalcopyrite, pyrrhotite and visible gold. The vein dips vertically and strikes north.

The Number 3 adit, also on Lot 2010, follows a 2.5 to 20 centimetre wide lenticular quartz vein that measures about 30 centimetres in width. The vein material is strongly oxidized, strikes north and dips 85 degrees west. The host rock is andesite with garnet patches. A high-grade shipment of 1.4 tonnes of ore averaging 107.3 grams per tonne is reported to have been back-packed down the mountain (Bulletin 27, page 129).