mineral
Prehnite with Epidote
Prehnite (Ca2Al(AlSi3O10)(OH)2) with Epidote inclusions (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))
Hardness: 6-6.5 (Prehnite) / 6-7 (Epidote); Color: Pale green to yellow-green (Prehnite) with dark green to black inclusions (Epidote); Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific Gravity: 2.8-3.0.
- Hardness
- 6-6
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 (Prehnite) / 6-7 (Epidote); Color: Pale green to yellow-green (Prehnite) with dark green to black inclusions (Epidote); Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific Gravity: 2.8-3.0.
Formation & geological history
Formed as a secondary mineral in veins and cavities of basaltic volcanic rocks, often through low-grade metamorphism or hydrothermal activity. It is common in amygdaloidal basalt and gabbro.
Uses & applications
Used primarily in jewelry as cabochons or beads, and highly valued as a decorative specimen for mineral collectors.
Geological facts
Prehnite was the first mineral to be named after a person (Colonel Hendrik Von Prehn). It is sometimes nicknamed 'Grape Jade' when found in globular or botryoidal forms.
Field identification & locations
Identified by its distinctive 'bottleglass' green color and the presence of dark, needle-like or mossy inclusions of epidote. Commonly found in South Africa, Australia, and the USA (New Jersey).
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Schist
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Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
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Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic