Brochantite - a secondary mineral of copper, formed in oxidation zones in hot and dry climates. It occurs in the form of small needle (sometimes tabular) crystals or fibrous streaks. Discovered in the Urals in 1824.
You can see brochantite stone for sale and buy it in the Minerals of Russia online store.
General | |
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Category | Sulfate minerals |
Formula (repeating unit) |
Cu4SO4(OH)6 |
IMA symbol | Bct |
Strunz classification | 7.BB.25 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/a |
Identification | |
Color | Green, emerald green, or black |
Crystal habit | Prismatic crystals; acicular needle-like crystals; druse |
Cleavage | Perfect [100] |
Fracture | Conchoidal - brittle |
Mohs scale hardness | 3.5 - 4.0 |
Luster | Vitreous - pearly |
Streak | Pale green |
Diaphaneity | Transparent to translucent |
Specific gravity | 3.97 |
Optical properties | Biaxial (-), 2V measured: 72° |
Refractive index | nα = 1.728 nβ = 1.771 nγ = 1.800 |
Birefringence | δ = 0.072 |
Pleochroism | Weak |