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Rosasite

Rosasite
Blue velvety mass lining a cavity
General
Category	Mineral
Chemical formula	(Cu,Zn)₂(C O₃)(O H)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.