Andradite Garnet
Andradite
A variety of Garnet Group
What is Andradite Garnet?
Andradite Garnet is a so-called "garnet" mineral - garnet is not a single mineral, but rather a group of several minerals with very similar physical properties and crystal forms. This popular gemstone has many varieties, but the most valuable is certainly Demantoid, an extremely rare, emerald-green, transparent gem. It's a birthstone for January, like all garnets.
Optical Properties
- Refractive Index
- 1.88-1.94
- Optical Character
- Isotropic
- Dispersion
- 0.057
Andradite Garnet Market Value Calculator
Estimate the market value of Andradite Garnet using size, quality, and finish. This preview calculator is for quick context and is not a formal appraisal.
Andradite Garnet Localities Map
See where Andradite Garnet is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Rock Types of Andradite Garnet
Andradite includes three varieties: Melanite: Black in color, referred to as "titanian andradite". Demantoid: Vivid green in color, one of the most valuable and rare stones in the gemological world. Topazolite: Yellow-green in color and sometimes of high enough quality to be cut into a faceted gemstone, it is rarer than demantoid.
Formation of Andradite Garnet
It occurs in skarns developed in contact metamorphosed impure limestones or calcic igneous rocks; in chlorite schists and serpentinites and in alkalic igneous rocks (typically titaniferous). Associated minerals include vesuvianite, chlorite, epidote, spinel, calcite, dolomite and magnetite. It is found in Italy, the Ural Mountains of Russia, Arizona and California and in Dnipropetrovsk Oblast in Ukraine. Like the other garnets, andradite crystallizes in the cubic space group [[Ia3d]], with unit-cell parameter of 12.051 Å at 100 K. The spin structure of andradite contains two mutually canted equivalent antiferromagnetic sublattices below the Néel temperature (TN=11 K).
Quick Facts
Physical Properties
- Color
- Yellow, greenish yellow to emerald-green, dark green, brown, brownish red, brownish yellow, grayish black, black
- Hardness (Mohs)
- 6.5 - 7
- Density
- 3.859 g/cm³
- Streak
- White
- Luster
- Resinous, Adamantine, Dull
- Crystal System
- Isometric
Chemical Properties
- Chemical Formula
- Ca3Fe3+2(SiO4)3
- Elements
- Ca, Fe, O, Si
Also Known As
Identify Andradite Garnet Instantly
- Snap a photo, get instant results
- 6,700+ rocks, minerals & crystals
- Discover collecting spots near you