Chemical Formula: Ca3Fe3+2Si3O12
Chemical Composition: Calcium iron silicate
Crystal System: Cubic (Isometeric)
Mineral Group: Garnet
Varieties of Andradite: Demantoid, Melanite, Topazolite
Hardness: 6 — 7
Density/Specific Gravity: 3.7 — 4.1
Refractive Index: 1.88 — 1.94
Double Refraction: None
Absorption Spectra: 701, 693, 640, 622, 443
Colour: Black, brown, yellow-brown, greenish yellow, lemon yellow
Transparency: Transparent, translucent, opaque
Lustre: Vitreous (glassy), adamantine (diamond like – non-metallic)
Countries: Deposits are widespread. China, France, Germany, Italy, Korea, Mexico, Norway, Romania, Russia, South Africa, Switzerland, USA, Zaire
Notes: Demantoid is the most valuable garnet and has a diamond like lustre. Deposits found in China, Korea, Russia, USA, and Zaire.
Melanite deposts are found in France, Germany, Italy, and Colorado.
Topazolite looks like topaz and is yellow to lemon yellow in colour. Deposits found in California, the Italian Alps, and Switzerland.