Brochantite
| Brochantite | |
|---|---|
 | |
| General | |
| Category | Sulfate minerals |
| Formula (repeating unit) | Cu4SO4(OH)6 |
| Strunz classification | 07.BB.25 |
| Identification | |
| Color | Green, emerald green, or black |
| Crystal habit | Prismatic crystals; acicular needle-like crystals; druse |
| Crystal system | Monoclinic |
| 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 |
| References | [1]<[2]<[3] |
Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is Cu4SO4(OH)6.[1][2][3] Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it was named by Armand Lévy for his fellow Frenchman, geologist and mineralogist A. J. M. Brochant de Villiers.[3]
Crystals of brochantite can range from emerald green to black-green to blue-green, and can be acicular or prismatic. Brochantite is often associated with minerals such as malachite, azurite, and chrysocolla, and may form pseudomorphs with these minerals.
The mineral is found in a number of locations around the world, notably the southwestern United States (especially Arizona), Serifos in Greece and Chile.
References
External links
 |
Wikisource has the text of the 1911 Encyclopædia Britannica article Brochantite. |