mineral

Prehnite

Prehnite - Ca2Al(AlSi3O10)(OH)2

Hardness: 6 to 6.5 on Mohs scale. Color: Pale green to yellow-green, translucent. Luster: Vitreous to pearly. Crystal Habits: Botryoidal (grape-like hemispherical clusters), mammillary, or massive. Cleavage: Good in one direction.

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

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Hydrothermal mineral formed in cavities, veins, and vesicles of basaltic and other igneous rocks, often as a secondary mineral replacing plagioclase feldspars. Common in altered mafic volcanic rocks.

Uses & applications

Popular as a gemstone for cabochons, beads, and ornamental carvings. highly prized as a collector specimen, especially when associated with minerals like epidote, stilbite, or apophyllite.

Geological facts

Prehnite was the first mineral to be named after an individual—Dutch colonel Hendrik Von Prehn, who brought specimens from the Cape of Good Hope to Europe in 1789.

Field identification & locations

Identified by its distinct pale apple-green to yellow-green color, characteristic rounded botryoidal (grape-like) growth habit, and Mohs hardness of 6-6.5. Commonly found in South Africa, Australia, Mali, Scotland, and the USA (New Jersey).