mineral
Prehnite
Ca2Al(AlSi3O10)(OH)2
Hardness of 6-6.5 on the Mohs scale, pale green to white color, vitreous to pearly luster, orthorhombic crystal system, uneven fracture, specific gravity of 2.80-2.95.
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Physical properties
Hardness of 6-6.5 on the Mohs scale, pale green to white color, vitreous to pearly luster, orthorhombic crystal system, uneven fracture, specific gravity of 2.80-2.95.
Formation & geological history
Forms in hydrothermal veins and cavities of mafic igneous rocks, such as basalt, as well as in metamorphic environments. Often associated with zeolites.
Uses & applications
Used primarily as a gemstone, carved into ornamental objects, and collected by mineral enthusiasts.
Geological facts
Prehnite was the first mineral to be named after a person, specifically Colonel Hendrik von Prehn, who discovered it in South Africa in the late 18th century.
Field identification & locations
Identified by its characteristic apple-green color, botryoidal habits when raw, and association with basaltic rocks. Commonly found in South Africa, Australia, and the USA.
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