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Gemstones 250x250

The Gemstone Andradite (Garnet)

Deep Green Demantoid Garnet

Andradite is the most  is the most lustrous of the Garnets and has several gemstone varieties. The term Garnet describes a group name for several closely related minerals that form important gemstones, and Andradite is an individual member mineral of the Garnet group. Andradite is a common mineral but is usually opaque and not fit for gemstone use; the transparent gemmy forms are rare and valued. The term Andradite is strictly a mineral term and is rarely used in the gem market. The gem forms of Andradite are known by their variety names of Demantoid, Topazolite, and Melanite.

Color

? Red, Green, Yellow, Orange, Brown, Pink, Gray, Black, Multicolored

Hardness

? 6.5 - 7.5

Chemical Formula

? Ca3Fe3+2Si3O12

Mineral Class

? Andradite (Garnet)

Additional Properties

Crystal System
? Isometric
Refractive Index
? 1.888 - 1.889
Double Refraction
? None
Transparency
? Transparent to opaque
SG
? 3.8 - 3.9
Luster
? Adamantine, submetallic
Cleavage ? None

All About

The green Demantoid variety is a rare and valuable form of Garnet. The original deposits of Demantoid were from Russia, and these types of Demantoid almost always contains inclusions of asbestos, which are known as horsetail inclusions. Large gemstones of Demantoid, which display a brilliant luster and fire are extremely rare and can be very valuable.

The yellow to orange-yellow variety of Andradite, Topazolite, seldom occurs in crystals large enough to be worth faceting, and is not commonly seen in jewelry. The black opaque variety Melanite has become a popular black gemstone, with a highly reflective submetallic luster. It is the most well-known black Garnet and is often simply known as "Black Garnet".

Uses

? Andradite Garnets are not commonly used as gemstones. Demantoid was more popular in the 19th century, but its popularity has decreased because of its lack of widespread availability and low hardness. Topazolite is also seldom used in jewelry and is mostly faceted for collectors. With an increased interest of black gemstones on the market, Melanite makes a very good and inexpensive black gemstone, and is used in bracelets, rings, earrings, pendants, and beads.

Varieties

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Treatments & Enhancements

? Andradite Garnet gemstones are naturally colored and not enhanced.

The Gemstone Andradite (Garnet) Sources

? The original historical deposits of Demantoid were in Russia. A new more extensive deposit of Demantoid is in Namibia, with other lesser-scale deposits in Madagascar, Afghanistan, Iran, and Italy.

Deposits of the other forms of Andradite, including Topazolite and Melanite, are in Russia, Azerbaijan, Italy, Mali, Mexico, and the U.S. (Arizona and California).

Similar Gemstones

? Demantoid: Similar to Peridot, Tsavorite, and Emerald.
Topazolite: Similar to Topaz, Citrine, Yellow Sapphire.
Melanite: Similar to Onyx, Schorl Tourmaline, Black Sapphire.

The Gemstone Andradite (Garnet) Photos

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The Gemstone Andradite (Garnet) in the Rough Photos

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