Facts About Garnet

Red garnet, the birthstone for January, is a fiery and beautiful stone. In fact, red garnet has been mistaken for the more precious ruby for hundreds of years. While the red garnet is the one we most associate with the word "garnet," it is not the only color of this diverse family of minerals.

Description

All garnets are a variation on silica. Magnesium, calcium, iron, aluminum and chromium are present in various chemical compositions in the group of garnets. Garnets have hardness on the Mohs scale ranging from 6.5 to 7.5. They are relatively easy to work with, and the red color variety exists in plentiful quantities around the world.

Some of the most sought-after gemstones have classic "horsetail" inclusions. These are small, needle-like marks inside the gemstone. They are called horsetails because of their hair-like appearance.

Reddish Garnets

The color red is the most associated garnet color, but the garnet family is a diverse group. There are six known varieties of garnet with their own distinctive characteristics. Pyrope garnets, dark red in color, are rarely cut into faceted pieces of more than one carat in size. Almandine garnets are also dark red, and pyrope and almandine blend to make up the some of the most commonly seen garnets. Sessarite garnet in its purest form is light orange. When blended with almandine, sessarite garnets become orangish-red to reddish-brown in color.

Less Common Types

The highly sought after andradite garnet is also rare. The dematoid variety of andradite is green due to its chromium content. The dematoid rivals the diamond in its brilliance. Famed Russian jeweler Carl Fabergé used dematoids in many of his pieces. Grossular garnets come in every color but blue, and red coloration also occurs rarely in this variety. Hydrogrossular garnet varies from all other garnets in that it is opaque. Uvarovite is the rarest of the garnet family, and, thanks to its chromium content, is green.

Geography

Garnets are mined all over the word. Some of the most valuable dematoid garnets come from the Ural Mountains. Arizona and areas of Southern Africa have also proven to hold substantial mines of various garnet varieties, as have India and Sri Lanka. For each type, there are variations and subtypes that can be found in any number of places across the globe.

Uses

The most popular use for garnet is to cut facets into it and use it in jewelry; the red garnet is the most commonly used variety. Collectors of gemstones prize dematoid garnets for their brilliance and beautiful green shades. Some of the harder varieties of garnet are used as abrasives in sandpaper.

References

• Mineral and Gemstone Kingdom
• United States Geological Service
• Internation Colored Gemstone Association