What is "bayldonite"

n. (context mineral English) A monoclinic-prismatic mineral containing arsenic, copper, hydrogen, lead, oxygen, and zinc.

Bayldonite (BAIL-done-ite) is a rare secondary mineral with the chemical formula PbCu(AsO)(OH). It was first discovered in Penberthy Croft Mine, Cornwall, England, United Kingdom. It is named after its discoverer, John Bayldon (1837(8) – 1872). Specimens are also found in Tsumeb, Namibia, and Arizona, United States. It is sometimes used a gemstone.