The Tats occurrence is north of Tats Lake within a gully of a south flowing creek. The creek flows into an east-west valley which is inferred to be the trace of the Tats fault. Rocks on the north side of the valley are amygdaloidal basalts and pillow basalts with local volcanic breccia, belonging to the Upper Triassic Middle Tats Complex. A massive chalcopyrite and pyrrhotite band up to 2 metres wide is exposed in the creek bed. A sample of massive sulphide contained 13.5 per cent copper, 0.12 per cent cobalt, 0.18 per cent zinc, 29 grams per tonne silver, and 0.3 grams per tonne gold. Immediately overlying the massive sulphide, pyritic flows contain bands of coarse-grained magnetite and pyrrhotite with minor chalco- pyrite. Quartz and calcite veins occur in the vicinity.