A northwest trending belt of stratified Permian(?) or older metasediments and metavolcanics underlies the eastern part of Porcher Island. The metasediments, consisting of thinly laminated schists derived from argillites, are intruded by sills of metavolcanics derived from rhyolites and andesites. Granite of the Coast Plutonic Complex is noted to the south. Mineralized quartz veins, up to 0.6 metres wide, occur within the metavolcanics near the contact with the metasediments. Mineraliza- tion consists of molybdenite, pyrite and minor chalcopyrite. An average of 24 samples assayed 0.2 per cent MoS2 (Irwin, J.F., 1966).