16.56: Prehnite
- Page ID
- 6281
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Prehnite | ||
---|---|---|
Chemical composition | Ca2Al2Si3O10(OH)2+Fe | |
Crystal system | Orthorhombic | |
Habit | Usually Fibrous Aggregate | |
Cleavage | Good:1 direction | |
Fracture | Uneven-Conchoidal | |
Hardness | 6-6.5 | |
Optic nature | Biaxial (+) Aggregate | |
Refractive index | 1.649-1.616 | |
Birefringence | .020-0.031 | |
Specific gravity | 2.90 | |
Lustre | Vitreous-Pearly |
Figure \(\PageIndex{1}\): Prehnite cabochon
Photo courtesy of Barbra Voltaire
Figure \(\PageIndex{2}\): Prehnite crystals
Photo courtesy of Barbra Voltaire