mineral

Prehnite

Prehnite (Ca2Al2Si3O10(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: Good in one direction; Specific gravity: 2.80-2.95.

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

Identified March 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral in hydrothermal veins and cavities of mafic volcanic rocks (like basalt). It typically occurs in low-grade metamorphic environments and is often associated with zeolites.

Uses & applications

Primarily used as a minor gemstone for jewelry (cabochons and beads) and as a popular specimen for mineral collectors. Some industrial interest as an indicator mineral for metamorphic facies.

Geological facts

It was the first mineral to be named after a person—Colonel Hendrik Von Prehn, who discovered it at the Cape of Good Hope in South Africa in 1788. It is sometimes referred to as 'Curaçao jade' or 'New Jade' despite having no relation to true jade.

Field identification & locations

Identify in the field by its distinctive 'chubby' or rounded globular (botryoidal) shape and its translucent, light-green color. Common locations include the Paterson, New Jersey (USA) basalt flows, the Karoo Basin (South Africa), and the Mali region.