mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Hardness: 6-6.5 (Mohs scale); Color: Light green to yellow-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific gravity: 2.80-2.95
- Hardness
- 6-6
- Color
- Light green to yellow-green
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 (Mohs scale); Color: Light green to yellow-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific gravity: 2.80-2.95
Formation & geological history
Formed as a secondary mineral in hydrothermal veins and cavities of mafic volcanic rocks (like basalt). It often occurs alongside zeolites.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons and beads) and as a collector's mineral specimen.
Geological facts
Prehnite was the first mineral to be named after a person, Colonel Hendrik Von Prehn, who discovered it at the Cape of Good Hope in 1788.
Field identification & locations
Identify by its distinct 'sea-foam' green color and botryoidal (grape-like) habit. It is commonly found in Australia, South Africa, and the USA (New Jersey and Virginia).
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