Rosasite
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Rosasite | |
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Blue velvety mass lining a cavity
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General | |
Category | Mineral |
Chemical formula | (Cu,Zn)2(CO3)(OH)2 |
Identification | |
Color | Blue, bluish green, green |
Crystal habit | Radiating fibrous; botryoidal; mammillary; encrustations |
Crystal system | Monoclinic-prismatic |
Cleavage | Perfect in one direction |
Fracture | Splintery, fibrous |
Mohs Scale hardness | 4 |
Luster | Silky, vitreous to dull |
Refractive index | 1.672-1.83 |
Streak | Light blue or green |
Specific gravity | 4-4.2 |
Solubility | Effervesces in cold, dilute hydrochloric acid |
Major varieties | |
Nickeloan rosasite | Dark green |
Rosasite is a carbonate mineral with minor potential for use as a zinc and copper ore. Chemically, it is a copper zinc carbonate hydroxide with a copper to zinc ratio of 3:2, occurring in the secondary oxidation zone of copper-zinc deposits. It was originally discovered in 1908 in the Rosas mine in Sardinia, Italy, and is named after the location. Fibrous blue-green rosasite crystals are usually found in globular aggregates, often associated with red limonite and other colourful minerals. It is very similar to aurichalcite, but can be distinguished by its superior hardness.