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.