An iron and nickel sulphide, with the formula (FeNi)9S8, and the main ore mineral for nickel; sp. gr. 4.5–5.0; hardness 3–4; cubic; light bronze-yellow; greenish-black streak; metallic lustre; very rarely found in well-formed crystals, usually occurring as irregular grains and inclusions; no cleavage, parting {111}; occurs with the other sulphide ores genetically associated with basic and ultrabasic rocks, together with pyrrhotite and chalcopyrite.