One of the main ore minerals for antimony, with the formula Sb₂S₃; sp. gr. 4.6; hardness 2.0–2.5; orthorhombic; normally lead-grey with a bluish tarnish; metallic lustre; crystals prismatic, columnar, acicular, and vertically striated; perfect lengthwise cleavage {010}, imperfect {100}, {110}; occurs mainly in hydrothermal deposits, at the low-temperature end, often forming sheet-like bodies, associated with fluorite, quartz, and barite, and with sulphides of lead, zinc, and other metals.