mineral

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Hardness: 6-6.5 Mohs scale; Color: Pale green to yellow-green, or colorless; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic; Specific Gravity: 2.8-2.95

Hardness: 6-6
Color: Pale green to yellow-green, or colorless
Luster: Vitreous to pearly

Identified June 11, 2026More mineral →

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Physical properties

Hardness: 6-6.5 Mohs scale; Color: Pale green to yellow-green, or colorless; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic; Specific Gravity: 2.8-2.95

Formation & geological history

A secondary mineral formed in hydrothermal environments, typically found in cavities, veins, and fractures of basaltic volcanic rocks, often associated with 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, 1788). It is often called 'Green Grape' or 'Cape Chrysolite' when found in South Africa.

Field identification & locations

Identifiable by its distinct bottle-green color and 'bubbly' or botryoidal habit in raw form. Often found in basalt quarries or volcanic deposits in locations like South Africa, Australia, and the USA.