mineral

Prehnite

Prehnite, Ca2Al(AlSi3O10)(OH)2

Hardness: 6-6.5 (Mohs scale); Color: Pale green to yellow-green; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic; 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 April 15, 2026More mineral →

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Physical properties

Hardness: 6-6.5 (Mohs scale); Color: Pale green to yellow-green; Luster: Vitreous to pearly; Crystal Structure: Orthorhombic; Cleavage: Good in one direction; Specific Gravity: 2.80 - 2.95

Formation & geological history

Formed in hydrothermal environments as secondary minerals in cavities and veins of basaltic lavas or gabbro; often found in association with zeolites.

Uses & applications

Primary use is in jewelry as cabochons or beads, used by collectors for mineral specimens, and sometimes used in crystal healing practices.

Geological facts

Prehnite was the first mineral ever named after a person (Colonel Hendrik Von Prehn) in 1788. It is often called 'Grape Jade' when found in globular or botryoidal forms.

Field identification & locations

Identify by its distinctive pale 'sea-foam' green color, pearly luster, and brittle nature. Found globally with high-quality deposits in South Africa, Australia, and the USA (New Jersey and Virginia).