Almandine is a garnet species made of iron, aluminum and silicon. It is typically brownish to purplish red.
Properties
| Refractive index | 1.75 to 1.83 (usually above 1.78) |
|---|---|
| Birefringence | None (singly refractive) |
| Optic character | Singly refractive |
| Dispersion | 0.027 |
| Specific gravity | 3.95 to 4.30 |
| Hardness (Mohs) | 7 to 7.5 |
| Crystal system | Cubic |
| Pleochroism | None |
| Absorption spectrum | Strong band about 20 nm wide, 576 nm (Fe); strong band, 526 nm (Fe); strong band, 505 nm (Fe); line may appear, 617 nm (Fe); line may appear, 426 nm (Fe) |
Published values. They change a little from stone to stone. Our tools do not model almandine yet. Sources: International Gem Society · Gemdat
In more detail
Almandine and pyrope range in color from purple to orangy red. These red garnets typically have no eye-visible inclusions. Almandine is one of the harder garnets, and garnets have fair to good toughness.
Related terms
- Garnet: Garnet is a group of closely related mineral species. They share the same crystal structure but differ in chemical composition.
- Pyrope: Pyrope is a garnet species made of magnesium, aluminum and silicon. It is usually pink to orange-red or brown.
- Spessartine: Spessartine is an orange garnet species made of manganese, aluminum and silicon. Its hues are warm: yellow, orange, red or brown.
- Hardness (Mohs): Hardness is a gem's resistance to scratching. Gemologists rank it on the Mohs scale, on which diamond is 10.