Rosasite

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Rosasite

Blue velvety mass lining a cavity
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.

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