Campania Island is underlain by granitic rocks of the Jurassic to Tertiary Coast Plutonic Complex. In the vicinity of the silica occurrence the rocks are comprised mainly of medium to coarse-grained granites and quartz diorites that are generally well-jointed in an east-west direction.

Three showings comprise the silica occurrence. The central and main outcrop is referred to as the Quartz Dome. It measures approx- imately 105 by 35 metres and consists of a vein of coarse anhedral milky white quartz. Impurities consist of minor muscovite and very local rusty stains along fractures. Two chip samples from the vein, collected in 1982 by the Geological Survey Branch, assayed 99.73 and 99.84 per cent silica (Open File 1987-15, page 33). Three outcrops aligned north-south occur 160 metres east of the Quartz Dome. The two northern outcrops contain only narrow quartz-stockwork veining, but a quartz vein with an outcrop area of 10 by 31 metres cuts the southern outcrop. The third showing lies 70 metres west of the Quartz Dome and consists of an outcrop cut by quartz stockwork vein- ing. Open-pit reserves of the Quartz Dome were estimated in 1975 at more than 270,000 tonnes at about 98 per cent silica (Open File 1987-15, page 33).