(named after the French 19th-century mineralogist A. J. M. Brochant de Villiers), a mineral of the class of sulfates. It has an insular-type structure made up of PO₄ tetrahedrons connected by Cu arranged in the center of the octahedron Cu[(OH)₅O]. Its chemical composition is Cu₄[SO₄](OH)₆. Brochantite crystallizes in a monoclinic system. It is found in the form of crystalline crusts with druses of small, needle-like dark-green crystals or in the form of powdery masses. The mineral’s hardness on the mineralogic scale measures 3.5-4.0; its density is 3,800-4,100 kg/m³. Brochantite is formed in the zones of oxidation of deposits of copper sulfide ores under the conditions of a hot, dry climate. Along with other minerals of the zones of oxidation of copper deposits, such as atacamite, chrysocolla, and azurite, it may serve as a copper ore.