Andradite is a type of garnet.
In turn, it is divided into several sub-types:
colophonite (reddish-brown, resinous sheen);
gelletite (light green);
melanitis (black, contains TiO2).
Andradite does not find practical application (with the exception of the most expensive variety - demantoid, which is used in jewelry). However, we love collectors.
You can see andradite stone for sale and buy it in the Minerals of Russia online store.
|Crystal class||Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
|Unit cell||a = 12.056 Å; Z = 8|
|Color||Yellow, greenish yellow to emerald-green, dark green; brown, brownish red, brownish yellow; grayish black, black; may be sectored|
|Crystal habit||Commonly well-crystallized dodecahedra, trapezohedra, or combinations, also granular to massive|
|Fracture||conchoidal to uneven|
|Mohs scale hardness||6.5 to 7|
|Luster||Adamantine to resinous, dull|
|Diaphaneity||Transparent to translucent|
|Specific gravity||3.859 calculated; 3.8–3.9 measured|
|Optical properties||Isotropic, typically weakly anisotropic|
|Refractive index||n = 1.887|
|Absorption spectra||demantoid – 440nm band or complete absorption at 440nm and below, may also have lines at 618, 634, 685, 690nm |
|Demantoid||transparent light to dark green to yellow-green|
|Topazolite||transparent to translucent yellow, may show chatoyancy|