descloizite

descloizite, vanadate mineral containing lead, copper, and zinc that usually forms brownish red to blackish brown crusts of intergrown crystals or rounded fibrous masses; its physical appearance is varied, however, and specimens have been found in shades from orange-red to black and various greens. The chemical formula for descloizite is (Zn,Cu)PbVO₄(OH). Descloizite forms a solid-solution series with the similar mineral mottramite, in which copper replaces zinc in the crystal structure. These minerals occur with vanadinite...