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Tsavorite Garnet: The Brilliant Green Grossular of East Africa
Tsavorite is a rare and sought-after gemstone characterized by its vivid green hues and exceptional brilliance. As a member of the garnet group, it is specifically classified as a green grossular mineral. Due to its luminosity and durability, it is often compared to classic gemstones such as diamonds, rubies, and sapphires.
Discovery and History
The history of tsavorite is relatively recent compared to other gemstones. It was discovered in 1967 by British geologist Campbell R. Bridges in the mountains of north-east Tanzania. Bridges encountered the gemstone inside strange, potato-like nodules of rock. Upon gemmological examination, these crystals were identified as green grossularite, a color that had not been previously found in this mineral.
The gemstone was named "tsavorite" (sometimes referred to as "tsavolite") in honor of the Tsavo National Park and the Tsavo River. This name was proposed by Campbell Bridges and Henry Platt, the former president of Tiffany & Co., who supported the development of the gemstone from its inception.
Geological Formation and Sources
Tsavorite is found in the East-African bushland, primarily along the border between Kenya and Tanzania. The mining environments are described as arid grasslands with bare, dry hills. Specific locations mentioned include the Taita Hills in Kenya. The landscape is noted for being a wild habitat, home to snakes and lions.
Gemological Properties
Tsavorite is distinguished by its high refractive index (1.734/44), which contributes to its great brilliance and luminosity. It is a durable stone that is less likely to crack or splinter compared to more sensitive gemstones like emerald, making it suitable for "invisible settings" where stones are placed closely together.
The color palette of tsavorite is diverse, ranging from a spring-like light green and an intense blue-green to a deep forest green. While raw crystals over 5 carats are rare, cut stones exceeding 2 carats are considered precious.
Comparison with Demantoid Garnet
Although both are green garnets, tsavorite and demantoid are different minerals: - Tsavorite: A green grossular garnet. - Demantoid: A green andradite garnet. While their colors may overlap, andradite (demantoid) is softer than grossular (tsavorite) but possesses a higher refractive index and higher dispersion.
Summary Table of Properties
| Property | Detail |
|---|---|
| Mineral Group | Garnet (Grossular) |
| Color Range | Light green, blue-green, deep forest green |
| Refractive Index | 1.734/44 |
| Primary Origins | Kenya (Taita Hills), Tanzania |
| Common Cuts | Pear, Cushion |
Market and Value
Tsavorite is valued for its transparency and vivid color. Because of the rarity of large raw crystals, the value increases significantly with size. For example, a 2.28 carat cushion-cut stone from the Taita Hills in Kenya with small inclusions has been valued at a retail price of €4,400.