Atacamite Mineral Specimen

ATACAMITE

HISTORY, NAME, LOCALITIES: Atacamite, pronounced aht-ah-CAHM-ite, was recognized as a mineral in the 1790s, after mineralogists studied specimens from northern Chile’s Atacama Desert.  It is named for the region of its discovery.  Atacamite is collected in arid desert regions of Australia, Chile, Namibia, China, and the United States (Arizona, Nevada, New Mexico, Utah).

MINERALOGY, PROPERTIES, OCCURRENCE: Atacamite [basic copper chloride, Cu₂Cl(OH)₃] crystallizes in the orthorhombic system as thin, striated, prismatic and tabular crystals, and also in granular and fibrous forms.  It has a distinctive, dark-emerald-green to blackish-green color, a Mohs hardness of 3.0-3.5, perfect cleavage in one direction, vitreous-to-adamantine luster, and a specific gravity of 3.7.  Atacamite is a rare, secondary mineral that forms in arid climates where copper-sulfide minerals are exposed to atmospheric oxygen in the presence of chlorine ions and limited amounts of water.  It occurs in association with other oxidized copper minerals such as malachite, chrysocolla, and brochantite.

METAPHYSICAL PROPERTIES, LORE, USES:  Metaphysical practitioners believe that atacamite facilitates self-motivation, enhances self-confidence and enthusiasm, helps attain independence, and removes energy blocks.  Ancient Egyptians used powdered atacamite as a green pigment in ceramics, glass, and cosmetics.  In medieval times, it served as a pigment in the green inks used to illuminate manuscripts.  Atacamite is not used in jewelry.  It was formerly a minor ore of copper.

COLLECTORS’ INFORMATION: Atacamite is collected for its rarity, unusual green color and crystal habits, and interesting associations with other colorful, oxidized copper minerals.