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Mineral Properties and Uses

Physical Properties of Prehnite

Chemical Classification silicate
Color white, green, gray, yellow
Streak white
Luster vitreous
Diaphaneity transparent to translucent
Cleavage basal
Mohs Hardness 6 to 6.5
Specific Gravity 2.8 to 3.0
Diagnostic Properties color, cleavage
Chemical Composition Ca2Al(AlSi3O10)(OH)2
Crystal System orthorhombic
Uses ornamental material, semiprecious gem

A cabochon of prehnite from Brazil. This gem is 3 carats, and approximately 10 millimeters by 8 millimeters.

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