Botallackite

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Botallackite
Category Category:Copper minerals, Category:Halide minerals
Chemical formula Cu2[(OH)3|Cl]
Identification
Color Shades of green
Crystal system Monoclinic
Cleavage One, distinct to good
Refractive index nα= 1.775, nβ= 1.800, nγ= 1.846
Birefringence δ = 0.071
Dispersion r > v, strong
Pleochroism Weak
Density 3.6
Diaphaneity Transparent to translucent

Botallackite, chemical formula Cu2[(OH)3|Cl] is a secondary copper mineral, named for its type locality at the Botallack mine, St Just in Penwith, Cornwall. It is polymorphous with Atacamite, Paratacamite and Clinoatacamite.[1]

In the monoclinic crystal system, Botallackite is mountain-green to green in colour, with one distinct to good cleavage.[1]

Botallackite forms in copper deposits exposed to weathering and salt water.[1]

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