mottramite

Mottramite is a rare mineral that belongs to the adelite-descloizite subgroup of the adelite group. Its chemical formula is PbCu(VO4)OH. It is characterized by its dark color, often appearing black, dark brown, or greenish-black. Mottramite typically forms in the oxidized zones of lead- and copper-bearing vanadium deposits. Crystals are usually acicular, radiating, or in small granular aggregates. The mineral has a vitreous to greasy luster and a hardness of around 3 to 3.5 on the Mohs scale. Its specific gravity is relatively high, ranging from 4.8 to 5.3. Mottramite was first discovered in Mottram St. Andrew, Cheshire, England, and was named after the locality. Other notable occurrences include Broken Hill in Australia and various sites in the United States. Its rarity and specific chemical composition make it of interest to mineral collectors and geologists studying secondary ore formations. It is not a significant ore mineral but is important for understanding the complex mineralogy of oxidized ore bodies.