Andradite
Description
A type of Garnet composed of a calcium iron silicate. The color of andradite may be yellow, red, green, brown or black. Bright green andradite, or demantoid, is also called the emerald of the Urals. Gemstone quality andradite is mined in the Ural Mountains, Italy, Switzerland, Norway, France, and in the United States (Arkansas and New Jersey).
Synonyms and Related Terms
garnet; demantoid (green, emerald of the Urals); topazolite (yellow); melanite (brown or black); andradita (Esp.); andradite (Port.); Andradit (Deut.); andradiet (Ned.)
Other Properties
Fracture = conchoidal Luster = vitreous to resinous. Streak = colorless. Birefringence = none. Dispersion = 0.057 Pleochroism = none. UV fluorescence = inert
| Composition | Ca3Fe2Si3O12 |
|---|---|
| Mohs Hardness | 6.5 - 7.0 |
| Density | 3.9 |
| Refractive Index | 1.887 |
Additional Information
Mineralogy Database: Andradite
Comparisons
Authority
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971
- Encyclopedia Britannica, http://www.britannica.com Comment: andradite [Accessed May 20, 2003].
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979