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; Specific Gravity: 2.80-2.90.
- Hardness
- 6-6
- Color
- Pale green to yellow-green
- Luster
- Vitreous to pearly
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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; Specific Gravity: 2.80-2.90.
Formation & geological history
Formed via low-grade metamorphism in cavities of mafic volcanic rocks (basalt). It is a secondary mineral resulting from hydrothermal alteration of plagioclase feldspars.
Uses & applications
Commonly used as a gemstone for jewelry (cabochons and beads) and highly valued as a mineral specimen for collectors.
Geological facts
Named after Colonel Hendrik Von Prehn in 1788, it was the first mineral to be named after a person. It is often found associated with minerals like zeolites and epidote.
Field identification & locations
Identified by its signature 'apple green' color and translucent, botryoidal (grape-like) habit in raw form. Commonly found in South Africa, Australia, and the USA.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Biotite Schist (Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]) — metamorphic](https://media.rock.id/9ca564b5-bc87-402b-965a-69b21f9aa6bf-thumbnail.jpg)
Biotite Schist
Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]
metamorphic