Tags: Chemical Substance, Mineral.
Lyonsite (Cu3Fe+34(VO4)6) is a rare black vanadate mineral that is opaque with a metallic lustre. It crystallizes in the orthorhombic crystal system. Lyonsite often occurs as small tabular typically well formed crystals. Lyonsite has a good cleavage and a dark gray streak.Lyonsite occurs as a sublimate in volcanic fumaroles. It is often associated with howardevansite and thenardite. It was first described in 1987 for an occurrence on the Izalco volcano El Salvador.