Secondary lead mineral, PbSO4; sp. gr. 6.3–6.4; hardness 3; orthorhombic; normally colourless to white, but sometimes yellow, grey, or coloured by a bluish tinge; white streak; adamantine lustre; crystals tabular, prismatic, or pyramidal, or occurring as massive, granular, or compact aggregations; normally occurs in the oxidized zone of lead deposits, and often surrounds a core of galena.