Tsavorite (Garnet)
Tsavorite is a variety of Grossular Garnet which is a member of the Garnet Group of minerals that includes Almandine, Andradite, Grossular, Pyrope, Spessartine and Uvarovite. All Garnets fall into these basic varieties and some Garnets are a combination of two. The Garnets are a complex family of minerals all with similar crystalline structures but varying greatly in chemical composition and properties. Tsavorite is from the Grossular variety and is colored deep green by vanadium. It was originally thought to be colored green by chromium, but this occurs only in trace amounts. It is now known to get its incredible deep green coloring from significant amounts of vanadium. Demantoid Garnet on the other hand, gets its green color from chromium. Tsavorite is found in only a few locations in the world: the Tsavo National Park near Lualenyi, Kenya; Turkana district, Rift Valley Province, Kenya; Gogogogo Commune, Ejeda, Tulear Province, Madagascar; Merelani Hills, Umba Valley, Arusha Region, Tanzania.
Tsavorite is named after the Tsavo National Park in Kenya where it is found. The name Grossular is from the Latin wordgrossularia, meaning gooseberry, because of the resemblance of the light green Grossular Garnet to the color of the gooseberry fruit. The name Garnet comes from the Latin word granatus meaning grain. This is from the comparison of garnet grains in rock looking like the dark red seeds of the Pomegranite fruit scattered on the ground.
| Category: | Garnet |
| Formula: | Ca3Al2Si3O12 |
| Crystallography: | Isometric – Hexoctahedral |
| Crystal Habit: | Commonly in dodecahedra or trapezohedra, up to 15 cm, with striated faces. Also granular, compact, and massive. |
| Twinning: | None |
| Cleavage: | None; Parting on [110] rarely observed |
| Fracture: | Irregular/Uneven, Conchoidal |
| Tenacity: | Brittle |
| Hardness (Mohs): | 6.5 – 7.0 |
| Density: | 3.594 – 3.650 (g/cm3) |
| Luminescence: | Usually none in UV. All massive material and many faceted gems glow orange in X-rays. |
| Radioactivity: | Not Radioactive |
| Color: | Emerald Green |
| Transparency: | Transparent, Translucent, Opaque |
| Luster: | Vitreous to Resinous |
| Refractive Index: | 1.743 Isotropic |
| Birefringence: | 0.00 Isotropic; weak strain birefringence |
| Dispersion: | Moderate; 0.027 |
| Pleochroism: | None |
