| Botallackite | |
|---|---|
| General | |
| Category | Halide minerals |
| Chemical formula | Cu2[(OH)3|Cl] |
| Strunz classification | 03.DA.10b |
| Crystal symmetry | Monoclinic prismatic 2/m |
| Unit cell | a = 5.717Å, b = 6.126Å, c = 5.636Å; β = 93.07°; Z = 2 |
| Identification | |
| Color | Shades of green |
| Crystal habit | Platy interlaced crystal crusts |
| Crystal system | Monoclinic |
| Cleavage | {100} Perfect |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 3.6 |
| Optical properties | Biaxial (+) |
| Refractive index | nα= 1.775, nβ= 1.800, nγ= 1.846 |
| Birefringence | δ = 0.071 |
| Pleochroism | Weak |
| Dispersion | r > v, strong |
| References | [1][2][3] |
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]
Botallackite crystallises in the monoclinic crystal system. It 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]