Atacamite Atacamite [ Cu2Cl (OH)3 ] is named after the Atacama Desert of northern Chile. It is a rare mineral formed through the oxidation of copper, especially in arid saline conditions. Atacamite crystals are generally bright to dark emerald, green growths of fibrous, prismatic crystals. When examined under a microscope, other copper-related minerals have been identified in association with atacamite, such as cuprite, malachite and chrysocolla. It develops as a secondary mineral through the interaction of chloride-rich fluids with primary copper sulfides. Its stability and occurrence provide key insights into fluid salinity and supergene alteration in copper deposits. Amazing Fact Atacamite is relatively unstable under prolonged freshwater exposure and is best preserved in saline, arid conditions. Source: Geological Survey of India