mineral

Prehnite

Prehnite, Ca2Al(AlSi3O10)(OH)2

Hardness: 6-6.5 on the Mohs scale. Color: Typically light green to yellow-green, but can be colorless or white. Luster: Vitreous to pearly. Crystal structure: Orthorhombic. Cleavage: Good in one direction. Specific gravity: 2.80 - 2.95.

Hardness: 6-6
Luster: Vitreous to pearly

Identified March 28, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed as a secondary or hydrothermal mineral in cavities of mafic volcanic rocks (like basalt). It can also form during low-grade metamorphism. Significant deposits range from the Triassic to Jurassic periods.

Uses & applications

Primarily used as a gemstone for jewelry (cabochons and beads) and as a collector’s mineral specimen. In the past, it was considered a rare collector's stone but is now widely used in decorative arts.

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 'New Jade' or 'Cape Chrysolite.'

Field identification & locations

Identify in the field by its characteristic pale green 'globular' or radiating botryoidal crystal habits and its association with zeolites in volcanic rock. Commonly found in South Africa, Australia, China, and the United States (New Jersey/Virginia).