Tsavorite or tsavolite is a variety of the
garnet
Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives.
All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...
group species
grossular
Grossular is a calcium-aluminium species of the garnet group of minerals. It has the chemical formula of Ca3Al2(SiO4)3 but the calcium may, in part, be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from t ...
, a
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
-
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
garnet with the formula
Ca3 Al2 Si3 O12.
Gemological Institute of America
The Gemological Institute of America (GIA) is a nonprofit institute based in Carlsbad, California. It is dedicated to research and education in the field of gemology and the jewelry arts. Founded in 1931, GIA's mission is to protect buyers and se ...
, ''GIA Gem Reference Guide'' 1995, Trace amounts of
vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer ( pas ...
or
chromium
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Chromium metal is valued for its high corrosion resistance and hardne ...
provide the green color.
In 1967, British gem prospector and geologist
Campbell R. Bridges
Campbell R. Bridges (1937 – 11 August 2009) was a Scottish-born Kenyan gemologist.
Bridges, originally from Scotland, lived in Kenya with his family and regularly mined for rare gemstones with his son Bruce Bridges. The discovery of the green ...
discovered a deposit of green grossular in the mountains of
Simanjiro District
Simanjiro District is one of the six districts of the Manyara Region of Tanzania. It is bordered to the north by Arusha Region, to the north east by Kilimanjaro Region, to the south east by Tanga Region, to the south by Kiteto District
Kiteto ...
of
Manyara Region
Manyara Region (''Mkoa wa Manyara'' in Swahili) is one of Tanzania's 31 administrative regions. The regional capital is the town of Babati. According to the 2012 national census, the region had a population of 1,425,131, which was lower than th ...
of north-east
Tanzania
Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...
[Idar-Oberstein]
Tsavorite
International Colored Gemstone Association, accessed online January 24, 2007 in a place called Lemshuko, 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
)
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, capital = Nairobi
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, largest_city = Nairobi
, ...
, 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 known only to mineral specialists until 1974, when
Tiffany and Co
Tiffany & Co. (colloquially known as Tiffany's) is a high-end luxury jewelry and specialty retailer, headquartered on Fifth Avenue in Manhattan. It sells jewelry, sterling silver, porcelain, crystal, stationery, fragrances, water bottles, watc ...
launched a marketing campaign which brought broader recognition of the stone.
Bridges was murdered in 2009 when a mob attacked him and his son on their property in
Tsavo East National Park
Tsavo East National Park is one of the oldest and largest parks in Kenya at 13,747 square kilometres. Situated in a semi-arid area previously known as the Taru Desert it opened in April 1948, and is located near the town of Voi in the Taita- ...
. It is believed that the attack was connected to a three-year dispute over access and control of Bridges' gemstone mines.
[http://news.bbc.co.uk/2/hi/uk_news/8198630.stm BBC News 13 August 2009 Mob kills UK gems expert in Kenya]
The name ''tsavorite'' was proposed by Tiffany and Co president Henry Platt in honor of Tsavo East National Park in
Kenya
)
, national_anthem = "Ee Mungu Nguvu Yetu"()
, image_map =
, map_caption =
, image_map2 =
, capital = Nairobi
, coordinates =
, largest_city = Nairobi
, ...
.
Apart from the source locality and was first discovered in Manyara,
Tanzania
Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...
, it is also found in
Toliara
Toliara (also known as ''Toliary'', ; formerly ''Tuléar'') is a city in Madagascar.
It is the capital of the Atsimo-Andrefana region, located 936 km southwest of national capital Antananarivo.
The current spelling of the name was adopted ...
(Tuléar) Province,
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
. Small deposits of gem grade material have been found in Pakistan and Queen Maud Land, Antarctica. No other occurrences of gem material have yet been discovered.
[Tsavorite Garnet Value, Price, and Jewelry Information](_blank)
International Gem Society - Tsavorite Garnet Value, Price, and Jewelry Information - Accessed online February 18th, 2016
Rare in gem-quality over several
carats (1 carat = 200 mg), tsavorite has been found in larger sizes. In late 2006, a 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 oval mixed-cut gem was also uncovered in early 2006.
[Giant size top color clean tsavorite discovered in East Africa](_blank)
Multicolour Gems Ltd, - Giant size top color clean tsavorite discovered in East Africa - Accessed online December 7th, 2009
Tsavorite formed in a Neoproterozoic metamorphic event which involved extensive folding and refolding of rock. This resulted in a wide range of inclusions forming within most Tsavorite crystals. These inclusions are strong identifying features in Tsavorite.
[Common and Uncommon Inclusions Found in Tsavorite](_blank)
Lapigems Ltd, - Common and Uncommon Inclusions Found in Tsavorite - Accessed online November 2nd, 2016
References
External links
*https://web.archive.org/web/20080610182036/http://www.gemstone.org/gem-by-gem/english/tsavorite.html The ICA's tsavorite information page.
(Campbell R. Bridges)
- Daily Telegraph obituary
(Tsavorite Garnets Used in Celtic Jewelry)
{{Gemstone
Calcium minerals
Aluminium minerals
Garnet gemstones