Prehnite – Crystal Wiki
Gentle green tones and tranquil structures – popular as a collector's and decorative mineral
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Properties & Characteristics
Scientific Data
- Chemical Formula
- Ca2Al(AlSi3O10)(OH)2
- Crystal System
- Orthorhombic
- Mohs Hardness
- 6–6.5
- Density
- 2.8–2.95 g/cm3
Physical Properties
- Color
- Light green, yellowish-green, whitish
- Luster
- Vitreous to pearly
- Transparency
- Translucent to transparent
- Special Feature
- Often botryoidal or radially fibrous aggregates
What is Prehnite?
Prehnite is a calcium aluminum silicate with a calm, soft color effect and versatile appeal for collectors.
Formation
It usually forms in cavities of basic volcanics and in hydrothermally altered rocks, often with zeolites.
Deposits & Market
Important localities include South Africa, Australia, China, and Scotland.
Quality Characteristics
Essential factors are uniform color, aesthetic form, and surface luster.
Care & Handling
Clean gently and store protected from harder minerals.
Frequently Asked Questions
Is prehnite rare?
Good pieces are available, but particularly aesthetic qualities are significantly more sought after.
Can prehnite be used in jewelry?
Yes, with caution; its hardness and toughness are in the medium range.
What is prehnite often confused with?
Occasionally with jade or serpentine material in similar green hues.