Andradite
Andradite is a calcium iron garnet belonging to the garnet mineral group. It is known for its high brilliance, strong dispersion, and attractive colors such as green, yellow, brown, and black. Some varieties like Demantoid are highly valuable gemstones.
About
Andradite
Andradite is a member of the garnet group and is scientifically classified as a calcium iron silicate with the chemical formula Ca₃Fe₂(SiO₄)₃. It crystallizes in the cubic (isometric) crystal system, which is typical of garnets, and often forms well-defined crystals. Andradite is especially valued for its high refractive index and strong dispersion, which give it exceptional brilliance and fire. This gemstone occurs in a variety of colors, including green, yellow, brown, black, and rarely colorless. The green variety, known as Demantoid garnet, is the most prized due to its diamond-like brilliance and high dispersion. Another variety, Topazolite, appears in yellow to golden shades, while Melanite is the black variety of Andradite.
Physical & Chemical Properties
| Name | Andradite |
|---|---|
| Scientific Name | Andradite (Garnet Group) |
| Mineral Group | Garnet (Nesosilicate) |
| Hardness (Mohs) | 6.5 – 7 |
| Color | Green, yellow, brown, black |
| Origin | Russia, Namibia, Madagascar, Italy, Mexico, USA |
| Chemical Formula | Ca₃Fe₂(SiO₄)₃ |
Quick Facts
| Crystal System | Cubic (Isometric) |
|---|---|
| Specific Gravity | 3.7 – 3.9 |
| Birthstone | January |
| Refractive Index | 1.88 – 1.94 |
| Optical Character | Isotropic |
| Dispersion | High (0.057) |
| Major Sources | Russia, Namibia, Madagascar, Italy, Mexico, USA |
| Treatments | untreated. |
| Price Range | $20 – $100 |
| Care Instructions | Clean with mild soap and water Avoid harsh chemicals Store separately to prevent damage |