Two ultramafic sills about 15 and 30 metres thick intrude Upper Paleozoic carbonates on the southwest slope of Nadahini Mountain. The sills strike southeast and dip about 60 degrees northeast. At one locality, known at the Nadahini Mountain occurrence, veinlets of cross-fibre chysotile up to 2.5 centimetres long, but of poor quality, occur in a zone of serpentinization.