Finely disseminated graphite occurs in schists at the northeast end of Mussel Inlet.

The schists occur within a metasedimentary belt about 8 kilometres wide that extends northwest from Cascade Inlet to the head of Mussel Inlet and farther north into the Douglas Channel area. Typically, this Upper Paleozoic(?) package is comprised of biotite-hornblende schist, quartzite and limestone.