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Atacamite (Photo)

Year of discovery: 1802 (Atacama desert, Chile), 1967 (Japan)

Locality list: 19 localities of atacamite

• Cu₂Cl(OH)₃
• [Cu²⁺₂][(OH)₃|Cl]^4-

• Class: Chloride - Hydroxide
• Soluble in: HCl (very soluble), HNO₃, H₂SO₄
• Substitution pseudomorph: Replaced by Malachite.
• Substitution pseudomorph: Replaced by Chrysocolla.

• Polymorph: Anatacamite (Triclinic), Botallackite (Monoclinic), Clinoatacamite (Monoclinic)

• Cu₂ => MnCu: Iyoite

• Cu₄ => Cu₃(Cu,Zn): Paratacamite
• Cu₄ => Cu₃Zn: Herbertsmithite, Kapellasite
• Cu₄ => Cu₃Ni: Gillardite
• Cu₄ => Cu₃Mg: Haydeeite
• Cu₄ => Cu₃Mn: Misakiite

• Color: Green
• Streak: Green
• Luster: Adamantine
• Diaphaneity: Transparent-Translucent

• Habit: Acicular, Long prismatic
• Aggregate: Radial

• Cleavage: Perfect on {010} (1 plane), Good on {101} (1 plane)
• Hardness: 3-3.5
• Density: 3.8

• System: Orthorhombic
• Group: mmm, Pnma
• Lattice: a=6.0, b=9.1, c=6.9

Etymology: Atacama desert, Chile