Sulphide mineral, CuPbSbS3; sp. gr. 6; hardness 3; grey; sub-metallic lustre; massive or rarely as cogwheel aggregates, in which the twinning habit (see twin law) causes crystals to form a rough cross with pitted, deeply striated edges; occurs in hydrothermal veins associated with copper and lead mineralization. The mineral was first identified in 1804 by the French mineralogist and crystallographer Count Jacques Louis de Bournon (1751–1825).