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
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Andradite Garnet before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
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
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Andradite Garnet FAQs
How do I identify Andradite Garnet?
Andradite Garnet can be identified by its hardness of 6.5 - 7 on the Mohs scale, Yellow color, Resinous, Adamantine, Dull luster, Isometric crystal system. Look for these key characteristics when examining specimens.
What color is Andradite Garnet?
Andradite Garnet typically appears in Yellow, greenish yellow to emerald-green, dark green, brown, brownish red, brownish yellow, grayish black, black. Color can vary depending on impurities and formation conditions.
How hard is Andradite Garnet?
Andradite Garnet has a hardness of 6.5 - 7 on the Mohs scale. This gives it moderate hardness.
What is the rock types of andradite garnet 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.
What is the formation of andradite garnet 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).