Brochantite
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Brochantite
General
Category	Sulfate mineral
Chemical formula	Cu4SO4(OH)6
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
Refractive index	nα = 1.728 nβ = 1.771 nγ = 1.800
Optical Properties	Biaxial (-), 2V measured: 72°
Birefringence	δ = 0.072
Pleochroism	Weak
Streak	Pale green
Specific gravity	3.97
Diaphaneity	Transparent to translucent
References	[1][2][3]

Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is CuSO₄·3Cu(OH)₂. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it is named for its discoverer, the French geologist and mineralogist, A. J. M. Brochant de Villiers (1772-1840).

The mineral is found in a number of locations around the world, notably the southwestern United States (especially Arizona) and Chile.

References

1. ^ http://webmineral.com/data/Brochantite.shtml Webmineral
2. ^ http://rruff.geo.arizona.edu/doclib/hom/brochantite.pdf Mineral Handbook
3. ^ http://www.mindat.org/min-779.html Mindat

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