Barstowite
Barstowite, formula Pb4•H2O, 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 (geology)|type locality] for Barstowite is Bounds Cliff, St Endellion, Cornwall in the United Kingdom. It is named after Richard W. Barstow, a Cornish mineral collector.