Mineralization occurs in vesicular basalt in a sequence of argillite, limestone and chert pebble conglomerate intruded by mafic sills and later cross-cut by dykes from a nearby granodioritic pluton. Mineralization in at least one locality consists of a lensoidal massive sulphide layer up to 20 centimetres thick, consisting of pyrrhotite, pyrite, malachite and azurite. Age of the sedimentary sequence is unknown although adjacent to exposures of Triassic age, lithologic constituents resemble nearby Siluro-Devonian rocks.