Brochantite is a copper sulphate with chemical formula CuSO4?Cu(OH)2, one among many different cupric sulphates. It has the monoclinic crystal system with crystals usually having an acicular (needle form) habitat. Brochantite is green to very dark green and is found in oxidizing copper sulphide deposits. It is often associated with other copper minerals such as malachite, azurite, and chrysocolla, and may form pseudomorphs with these minerals. This sample is from the since long abandoned Tsumeb mines in Namibia, actual width 95 mm.