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Atacamite
Chemical Formula	Cu2Cl(OH)3
Species	Halides
Crystal System	Orthorhombic
Mohs Scale	3
Specific Gravity	3.745-3.776
Color	Bright green, dark emerald-green to blackish green
Streak	Apple green
Luster	Adamantine, Vitreous
Refractive Index	n = 1.831 n = 1.861 n = 1.880
Diaphaneity	Transparent, Translucent
Cleavage	PerfectOn , fair on .
Fracture	Conchoidal
Crystal Habit：Slender prismatic crystals, fibrous, granular to compact, massive
Geological Setting：An oxidation product of other copper minerals, especially under arid, saline conditions; in fumarolic deposits; a weathering product of sulphides in submarine black smoker deposits; an alteration product of bronze and copper objects of antiquity.

It was first described for deposits in the Atacama Desert of Chile in 1801.

Atacamite is polymorphous with botallackite, clinoatacamite, and paratacamite. Atacamite is a comparatively rare mineral, formed from primary copper minerals in the oxidation or weathering zone of arid climates. It has also been reported from fumarole deposits, as sulfide alteration products in black smokers and as alteration of ancient bronze and copper artefacts. It occurs in association with cuprite, brochantite, linarite, caledonite, malachite, chrysocolla and its polymorphs.

It has been shown that atacamite is a component of the jaws of some Glycera species.