Mineral, ZnS; sp. gr. 3.9–4.1; hardness 3.5–4.0; cubic; colour variable, but commonly yellow, brown, or black, and crystals can be transparent to translucent; brownish red to bright yellow or white streak; resinous to near-metallic lustre; crystals tetrahedral or dodecahedral, with curved faces, but also granular, fibrous, or botryoidal; conchoidal fracture; cleavage perfect {011}; the most common ore mineral for zinc metal, Zn–Pb is common in strata-bound veins and massive sulphide deposits, frequently associated with galena in hydrothermal veins, and in limestones where it occurs by replacement, commonly with pyrite, pyrrhotite, and magnetite; dissolves in concentrated nitric acid with the separation of sulphur.