The Gemstone Prehnite

Green Prehnite Cabochon

Prehnite gemstones are usually light green in color, with a whitish hue or yellowish tinge. Deep green gemstones are not common. Prehnite gemstones often appear cloudy or velvety, and rarely fully transparent. They may also contain colors zones of lighter and darker green.


? Green


? 6 - 6.5

Chemical Formula

? Ca2Al2Si3O12(OH)

Mineral Class

? Prehnite

Additional Properties

Crystal System
? Orthorhombic
Refractive Index
? 1.61 - 1.64
Double Refraction
? .030
? Translucent
? 2.8 - 3.0
? Vitreous, waxy
Cleavage ? 1,1;3,1

All About

Prehnite has always been a minor collectors gemstone, but relatively recent deposits discovered in Africa containing facetable Prehnite in large quantities has made this gemstone more available and popular.  Prehnite is very sensitive to heat and has perfect easily chips, so care must be exercised when cutting. Prehnite Cat's Eyes do exist from the Australian finds, but these are very rare.


? Prehnite is an inexpensive gemstone, and due its lack of full transparency it is usually cut into cabochons and beads. Other facets may be cut, but less commonly. Prehnite may also be carved into small ornamental objects such as flowers.

Treatments & Enhancements

? Prehnite gemstones are natural and not heated or artificially enhanced.

Prehnite Sources

? Prehnite sources include Mali, South Africa, Namibia, Australia, China, and the U.S. (New Jersey).

Similar Gemstones

? Peridot - Slightly harder and usually more transparent.
Jade - Usually deeper in color and less transparent.

Prehnite Photos


Prehnite in the Rough Photos



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