The Point Astley prospect has been known since about 1900 (Spencer, 1906). It was intermittently explored by a succession of companies through 1984 (for details, see Spencer, 1906; Buddington, 1925; Herreid, 1962; Race, 1962; Kimble and others, 1984; Redman, 1988). There are two centers of mineralization separated by 700 feet, but much of the area is heavily vegetated and the continuity or extension of the known mineralization is uncertain. The prospect has been developed by 4, now-flooded shafts, one of which probably has a crosscut at depth, and 2 short adits. All of the workings date from before 1925. There has been no production but there was a test shipment to a smelter in about 1925.

The deposit consists of disseminated sulfides and small lenses of massive sulfides oriented along the foliation of the host rock. The massive sulfide lenses are no more than 3 feet long and 1 foot thick. The main sulfides are pyrite and sphalerite with minor galena and chalcopyrite. Locally in the richer portions of the deposit, bornite, chalcocite, covellite and digenite occur; native silver is reported. The host rock is green chloritic phyllite and black slaty phyllite, part of the Cretaceous greenschist unit of Brew and Grybeck (1984). Locally the sulfides have been remobilized and concentrated at the noses of small folds in the metamorphic rocks.

The northwest zone of mineralization has been explored by two shafts and a short the adit. Kimble and others (1984) sampled a 10-foot section of the mineralized rocks along the shoreline. A sample contained 0.48% copper, 0.11 percent lead, 1.65 percent zinc, and 0.2 ounces of silver per ton. A select sample from a lens of pyrite and sphalerite about 1.1 foot thick contained 0.44 per cent copper, 0.31 percent lead, 9.0 percent zinc, 0.17 ounce of gold per ton, and 1.45 ounces of silver per ton.