Green grossular had been rare until 1967, when British gem prospector and geologist Campbell R. Bridges came across a deposit of the mineral in the mountains of north-east Tanzania[4] in a place called Lemshuko, 15 km away from Komolo, the first village. The specimens he found were of very intense color and of high transparency. The find interested the gem trade, and attempts were made to export the stones, but the Tanzanian government did not provide permits.
Believing that the deposit was a part of a larger geological structure extending possibly into Kenya, Bridges began prospecting in that nation. He was successful a second time in 1971, when he found the mineral variety there, and was granted a permit to mine the deposit. The gemstone was only known to mineral specialists Until 1974, when Tiffany and Co launched a marketing campaign which brought broader recognition of the stone.[4] Bridges was murdered in 2009 when a mob attacked him and his son on their property in Tsavo National Park. It is believed that the attack was connected to a three-year dispute over access and control of Bridges' gemstone mines.[5]
The name tsavorite was proposed by Tiffany and Co president Sir Henry Platt in honor of Tsavo National Park in Kenya.[4] Apart from the source locality in Tanzania it is also found in Toliara (Tuléar) Province, Madagascar, but so far, no other occurrences of gem material have been discovered.
Rare in gem-quality over several carats (1 carat = 200 mg) in weight, tsavorite has been found in larger sizes. In late 2006 a 925-carat crystal was discovered. It yielded an oval mixed-cut 325 carat (65 g) stone, one of the largest, if not the largest faceted tsavorites in the world. A crystal that yielded a 120.68-carat oval mixed-cut gem was also uncovered in early 2006.[6]
The hardness (Mohs scale) : 7.0 - 7.5
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Tsavorite or green garnet is the rare and expensive gemstone.
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