mineral

Prehnite

Ca2Al(AlSi3O10)(OH)2

AI-generated identification · may be incorrect

Hardness: 6-6.5 on Mohs scale; Color: Pale green to yellow-green, sometimes white or colorless; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Cleavage: Good in one direction; Translucent to semi-transparent.

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

Identified July 5, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary or hydrothermal mineral in cavities and veins of mafic volcanic rocks (like basalt). It is typically found in low-grade metamorphic environments.

Uses & applications

Mostly used as a gemstone for jewelry (cabochons and beads) and as a collector's mineral specimen. In some cultures, it is used as a stone for meditation.

Geological facts

Prehnite was the first mineral to be named after a person (Colonel Hendrik von Prehn) in 1788. It is often found associated with minerals like zeolites, calcite, and epidote.

Field identification & locations

Identifiable by its characteristic 'milky' or 'oily' pale green color and its tendency to form radiating botryoidal (grape-like) clusters. Common locations include South Africa, Australia, Mali, and the USA (New Jersey).