Barstowite, formula Pb<sub>4</sub>[Cl<sub>6</sub>|CO<sub>3</sub>]â¢H<sub>2</sub>O, is a transparent to white mineral in the monoclinic system. It has a Mohs hardness of 3, a white streak and an adamantine lustre.
The type locality for Barstowite is Bounds Cliff, St Endellion, Cornwall in the United Kingdom. It is named after Richard W. Barstow (1947âÂÂ1982), a Cornish mineral collector.