Grossular is a garnet species made of calcium, aluminum and silicon. It has perhaps the widest color range of any garnet species.
Properties
| Refractive index | 1.73 to 1.76 (usual); full range 1.720 to 1.800 (IGS) |
|---|---|
| Birefringence | None (singly refractive) |
| Optic character | Singly refractive |
| Dispersion | 0.028 |
| Specific gravity | 3.55 to 3.73 (gemdat), usually near 3.65 (IGS); full range 3.4 to 3.71 (IGS) |
| Hardness (Mohs) | 6.5 to 7.5 |
| Crystal system | Cubic |
| Pleochroism | None |
| Absorption spectrum | Orange stones may show this band, 407 nm; orange stones may show this band, 430 nm |
Published values. They change a little from stone to stone. Our tools do not model grossular yet. Sources: International Gem Society · Gemdat
In more detail
Tsavorite is the green variety of grossular, and vanadium produces its color. Hessonite ranges from orange and orangy red to brownish red. Hessonite often has a turbulent inner look, called the roiled effect. Tsavorite is one of the harder garnets.
Related terms
- Garnet: Garnet is a group of closely related mineral species. They share the same crystal structure but differ in chemical composition.
- Demantoid: Demantoid is the green variety of andradite, a garnet species of calcium, iron and silicon. Chromium causes its color.
- Spessartine: Spessartine is an orange garnet species made of manganese, aluminum and silicon. Its hues are warm: yellow, orange, red or brown.
- Gem variety: A variety is a subdivision of a gem species, usually by color. Ruby and sapphire are varieties of corundum, and emerald is a variety of beryl.