'Tsavorite' or 'tsavolite' is a variety of the
garnet group species
grossular, a
calcium-
aluminium garnet with the formula Ca
3Al
2Si
3O
12)
[2] Trace amounts of
vanadium or
chromium provide the green color.
Green grossular had been rare until 1967, when a British gem prospector and geologist
Campbell R. Bridges came across a deposit of the mineral in the mountains of north-east
Tanzania.
[3] 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 gelogoical 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. He was granted permit registration to mine the deposit. Until 1974, the gemstone was only known to mineral specialists. In that year
Tiffany and Co launched a marketing campaign which brought broader recognition of the stone.
The name ''tsavorite'' was proposed by Tiffany and Co president
Henry Platt in honor of
Tsavo National Park in
Kenya.
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 clean gems over 1
carat (200 mg) in weight, tsavorite has been found in sizes yielding up to 15 carat (3 g) stones.
Recently, a gem quality tsavorite likely to be the largest ever discovered, over 325 carats (65 g), became available in Thailand (see "Multicolour.com" external link below).
References
1. Bancroft, Peter Tsavorite online reprint from Peter Bancroft’s classic book, Gem and Crystal Treasures (1984) Western Enterprises/Mineralogical Record, Fallbrook, CA, 488 pp., accessed online January 24, 2007
2. Gemological Institute of America, ''GIA Gem Reference Guide'' 1995, ISBN:0-87311-019-6
3. Idar-Oberstein, Tsavorite International Colored Gemstone Association, accessed online January 24, 2007
External links
★
Giant tsavorite
★
Mindat.org