The Gemstone Zoisite

Ruby Zoisite Cabochon

Zoisite is a mineral that includes several gem varieties. The most important and well-known is Tanzanite, a sensational blue gemstone. The variety Thulite is used as a minor pink gemstone. A variety known as Ruby Zoisite, which is green Zoisite associated with opaque red Ruby (and often black amphibole streaks), is used as a carving gemstone as well as a minor gem. The term Zoisite is rarely used on its own in the gemstone trade.
Tanzanite and Thulite each have their own dedicated page.


? Blue, Red, Green, Pink, Purple


? 6 - 6.5

Chemical Formula

? Ca2Al3(SiO4)3(OH)

Mineral Class

? Zoisite

Additional Properties

Crystal System
? Orthorhombic
Refractive Index
? 1.69 - 1.70
Double Refraction
? .009
? Opaque. May be translucent in thin backlit sections.
? 3.2 - 3.4
? Vitreous
Cleavage ? 1,1

All About

Zoisite would not be of significant importance if not for the discovery of the transparent blue to purplish-blue variety that has been given the name Tanzanite. This form of Zoisite is the main gem variety and has become increasingly popular and mainstream ever since its recent discovery.

The pink to red variety, called Thulite, is an opaque compact Zoisite formed from densely interlocking crystals. The opaque green variety, which is often found in association with Ruby, was first discovered in Tanzania in 1954. This combination gemstone usually contains black amphibole inclusions or veins, and its frequent association with red opaque Ruby give it a unique color and contrast. This combination is known as Ruby Zoisite in the gem trade, and is occassionally also called Anyolite.


? Tanzanite is a very popular jewelry gemstone, faceted into all different gemstone cuts. Thulite is an inexpensive stone used for cabochons and beads. Green Zoisite and Ruby Zoisite are also used as cabochons and beads, and are popular material for ornamental figures such as animal carvings.



Treatments & Enhancements

? Tazanite is heat treated to achieve the blue color. The other forms of Zoisite are naturally colored and usually not enhanced.

Zoisite Sources

? The only source of Tanzanite is in the Merelani Hills of Arusha, Tanzania. Pink Thulite comes from Norway, Australia, and the U.S. (North Carolina). Green Zoisite and Ruby Zoisite come from Longido, Tanzania.

Similar Gemstones

? The purplish hue of Tanzanite makes it somewhat unique. It is bluer then Amethyst, though more purple then blue SapphireThulite can resemble Rhodonite. The green variety and Ruby Zoisite are unique.

Zoisite Photos

This page only lists photos of Green Zoisite and Ruby Zoisite. Images of Tanzanite are listed on the dedicated Tanzanite page, and we currently don't have any photos of Thulite.

Zoisite in the Rough Photos

This page only lists photos of Green Zoisite and Ruby Zoisite. Images of Tanzanite and Thulite are listed separately on their own dedicated pages.


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