mineral
Prehnite with Epidote and Quartz
Prehnite (Ca2Al(AlSi3O10)(OH)2)
AI-generated identification · may be incorrectMohs hardness of 6 to 6.5, pale green to yellow color, vitreous to pearly luster, often forms botryoidal (globular or grape-like) aggregates, specific gravity of 2.80 to 2.95, distinct cleavage on {001}.
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Physical properties
Mohs hardness of 6 to 6.5, pale green to yellow color, vitreous to pearly luster, often forms botryoidal (globular or grape-like) aggregates, specific gravity of 2.80 to 2.95, distinct cleavage on {001}.
Formation & geological history
Forms in low-grade metamorphic environments, typically in veins and cavities of mafic igneous rocks such as basalts, through hydrothermal alteration.
Uses & applications
Popular as a collector specimen, cut into cabochons, and used in distinctive artisan jewelry.
Geological facts
Prehnite was the first mineral to be named after a person, military commander Colonel Hendrik von Prehn, who discovered it in South Africa in the 18th century.
Field identification & locations
Easily recognized in the field by its characteristic pale green, botryoidal 'grape jelly' texture lining cavities within dark host basalt or diabase rocks.
