mineral

Prehnite

Ca2Al(AlSi3O10)(OH)2 (Calcium Aluminum Silicate)

AI-generated identification · may be incorrect

Hardness: 6-6.5; Color: Pale green, yellowish-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific gravity: 2.80-2.95; Translucent to transparent with a unique waxy appearance.

Hardness: 6-6
Color: Pale green, yellowish-green
Luster: Vitreous to pearly

Identified July 9, 2026More mineral →

Explore Prehnite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed primarily in the cavities and veins of basaltic volcanic rocks through hydrothermal processes, often as a secondary mineral during the alteration of mafic rocks.

Uses & applications

Used primarily as a semi-precious gemstone in jewelry (cabochons and beads) and as a collector's specimen. It was formerly an unimportant gemstone but has gained popularity in the metaphysical market.

Geological facts

Prehnite was the first mineral to be named after a person (Colonel Hendrik Von Prehn) in 1788. It often forms globular or 'botryoidal' aggregates that resemble clusters of grapes.

Field identification & locations

Identified by its distinctive oily luster, pale 'apple green' color, and brittle nature. Commonly found in association with zeolites, epidote, and calcite. Major localities include South Africa, Australia, and the USA (New Jersey, Michigan).