mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Hardness 6-6.5 on Mohs scale; Color: Pale green to yellow-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic (often occurs in botryoidal or globular habits); Cleavage: Distinct in one direction.
- Color
- Pale green to yellow-green
- Luster
- Vitreous to pearly
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Physical properties
Hardness 6-6.5 on Mohs scale; Color: Pale green to yellow-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic (often occurs in botryoidal or globular habits); Cleavage: Distinct in one direction.
Formation & geological history
Formed through hydrothermal activity in the cavities and veins of mafic volcanic rocks like basalt. It often occurs as a secondary mineral.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons and beads) and as a collector specimen. It is also sometimes used as a source of calcium and aluminum in specialized applications.
Geological facts
Prehnite was the first mineral to be named after a person—Colonel Hendrik Von Prehn, who discovered it in South Africa in 1788. It is sometimes called 'Cape Emerald' due to its color.
Field identification & locations
Identify by its characteristic 'grapes-like' botryoidal habit in the field and its distinct translucent apple-green color. Frequently found in South Africa, Australia, and the USA (New Jersey).
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Mineral
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