Rock Identifier
Prehnite (Ca2Al(AlSi3O10)(OH)2) — mineral
mineral

Prehnite

Ca2Al(AlSi3O10)(OH)2

AI-generated identification · may be incorrect

Hardness of 6 on the Mohs scale, pale green to yellow-green color, vitreous to pearly luster, and orthorhombic crystal system with uneven fracture.

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Physical properties

Hardness of 6 on the Mohs scale, pale green to yellow-green color, vitreous to pearly luster, and orthorhombic crystal system with uneven fracture.

Formation & geological history

Forms primarily in veins and cavities of mafic igneous rocks through hydrothermal alteration at low temperatures.

Uses & applications

Widely used as a gemstone in jewelry, often cut into cabochons, and prized by mineral collectors.

Geological facts

Prehnite was the first mineral named after a military officer, Colonel Hendrik von Prehn, who discovered it in South Africa.

Field identification & locations

Identified by its characteristic pale green color, botryoidal habit, and white streak; commonly found in South Africa, Australia, and the USA.