The Crofton occurrence is located east of McNab Creek, approximately 1.3 kilometres north of the creek mouth on Thornbrough Channel, Howe Sound.

The area is underlain by granodiorite of the Cenozoic-Mesozoic Coast Plutonic Complex, which contains a small pendant of Lower Cretaceous Gambier Group metavolcanic rocks.

Mineralization occurs at the sheared, well-defined, northwest trending contact between the pendant and intrusive rocks. Pyrite, chalcopyrite, sphalerite and galena occur as irregular lenses filling fissures in the sheared volcanic rocks, and as disseminations in the volcanics.

A grab sample taken from an outcrop near a shaft assayed 7.8 per cent copper, 11 per cent zinc, 5 per cent lead and 116.5 grams per tonne silver (Minister of Mines Annual Report 1924).

Historic workings include a shallow shaft and open cuts. In 1979, Tri-Con Mining, on behalf of Silverado Mines, completed a program of silt and soil sampling on the area as the Adriana 1-9 claims.