Atacamite
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Atacamite is a copper halide mineral: a copper(II) chloride hydroxide with formula Cu₂Cl(OH)₃. It was first described for deposits in the Atacama Desert of Chile in 1802 by Dmitri de Gallitzin. The Atacama Desert is also the namesake of the... Wikipedia
Color: Bright green, dark emerald-green to blackish green
Crystal class: Dipyramidal (mmm); H-M symbol: (2/m 2/m 2/m)
Crystal habit: Slender prismatic crystals, fibrous, granular to compact, massive
Crystal system: Orthorhombic
Formula (repeating unit): Cu2Cl(OH)3
Luster: Adamantine to vitreous
Mohs scale hardness: 3–3.5