Atacamite
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NameAtacamite
Chemical FormulaCu2Cl(OH)3
Mohs Hardness3
Crystal Systemorthorhombic
Lusteradamantine
Streak Colorapple-green
Cleavageperfect on {010}
Fractureconchoidal
Specific Gravity3.76
Colorsemerald green, dark green, blackish green
Transparencytransparent
Type LocalityLa Farola Mine, Cerro Pintado, Las Pintadas district, Tierra Amarilla, Atacama Region, Chile
Mineral GroupHalides
Usescollector's mineral, minor copper ore
Associated Mineralsgypsum, chrysocolla, brochantite, malachite
Rarityuncommon
Description
The specimen features a matrix richly covered with numerous dark emerald green, acicular to prismatic atacamite crystals, often forming radiating aggregates, alongside white to colorless gypsum crystals.
Geological Context
Atacamite is a secondary copper mineral typically found in the oxidized zones of copper deposits, particularly in arid regions. It forms from the alteration of primary copper sulfides in the presence of chloride-rich solutions.
