Phyllosilicate
Prehnite
Pale apple-green to yellow-green, often with fibrous or needle inclusions
Green
Yellow-Green
Optical characteristics
- Ref. index
- 1.611 – 1.649
- Birefringence
- 0.021 – 0.033
- Luster
- Vitreous to waxy
- Pleochroism
- Weak Weak; slightly different shades of yellow-green depending on viewing direction.
- Fluorescence
- Weak yellowish under LW UV.
Source localities
South Africa
South Africa: Cullinan / Venetia
Significant
Historic and important diamond source; South Africa also produces high-quality prehnite.
Australia
Australia: New South Wales / Queensland fields
Significant
Commercial sapphire and opal source; also a noted prehnite producer.
China
China: Xinjiang / Yunnan / Hubei
Commercial
Known for jade, turquoise, quartz and multiple gem deposits.
Mali
Mali: garnet localities
Significant
Known for Mali garnet; prehnite is also found in Mali pegmatites.
United Kingdom
Scotland: smoky quartz localities
Commercial
Known historically for cairngorm smoky quartz; also produces prehnite in ancient lavas.
Inclusions & features
Crystals Crystal Inclusions
Under 10x loupe: solid, well-formed mineral crystals trapped inside the host gem. They may…
Clouds Pinpoint Clouds
Under 10x loupe: concentrations of extremely tiny bright dots that individually are too small…
Zoning Color Zoning
Under 10x loupe in immersion: bands or patches of deeper or lighter color arranged…