Tanzanite

Tanzanite is the blue and violet variety of the mineral zoisite (a calcium aluminium hydroxyl sorosilicate), caused by small amounts of vanadium, belonging to the epidote group. Tanzanite is only found in Tanzania, in a very small mining area (approximately 7 km (4.3 mi) long and 2 km (1.2 mi) wide) near the Merelani Hills. Tanzanite is the blue and violet variety of the mineral zoisite (a calcium aluminium hydroxyl sorosilicate), caused by small amounts of vanadium, belonging to the epidote group. Tanzanite is only found in Tanzania, in a very small mining area (approximately 7 km (4.3 mi) long and 2 km (1.2 mi) wide) near the Merelani Hills. Tanzanite is noted for its remarkably strong trichroism, appearing alternately blue, violet and burgundy depending on crystal orientation. Tanzanite can also appear differently when viewed under different lighting conditions. The blues appear more evident when subjected to fluorescent light and the violet hues can be seen readily when viewed under incandescent illumination. In its rough state tanzanite is colored a reddish brown to clear, and it requires heat treatment to remove the brownish 'veil' and bring out the blue violet of the stone. The gemstone was given the name 'tanzanite' by Tiffany & Co. after Tanzania, the country in which it was discovered. The scientific name of 'blue-violet zoisite' was not thought to be consumer friendly enough by Tiffany's marketing department, who introduced it to the market in 1968. In 2002, the American Gem Trade Association chose tanzanite as a December birthstone, the first change to their birthstone list since 1912. Manuel de Souza, a Goan tailor and part-time gold prospector living in Arusha (Tanzania), found transparent fragments of blue and blue-purple gem crystals on a ridge near Merelani, some 40 km (25 mi) southeast of Arusha. He assumed that the mineral was olivine (peridot) but, after soon realizing it was not, he concluded it was 'dumortierite' (a blue non-gem mineral). Shortly thereafter, the stones were shown to John Saul, a Nairobi-based consulting geologist and gemstone wholesaler who was then mining aquamarine in the region around Mount Kenya. Saul, who later discovered the famous ruby deposits in the Tsavo area of Kenya, eliminated dumortierite and cordierite as possibilities, and sent samples to his father, Hyman Saul, vice president at Saks Fifth Avenue in New York. Hyman Saul brought the samples across the street to the Gemological Institute of America who correctly identified the new gem as a variety of the mineral zoisite. Correct identification was also made by mineralogists at Harvard University, the British Museum, and Heidelberg University, but the very first person to get the identification right was Ian McCloud, a Tanzanian government geologist based in Dodoma. Scientifically called 'blue zoisite', the gemstone was renamed as tanzanite by Tiffany & Co., who wanted to capitalize on the rarity and single location of the gem, and thought that 'blue zoisite' (which might be pronounced like 'blue suicide') would not sell well. Tiffany's original campaign advertised that tanzanite could now be found in two places: 'in Tanzania and at Tiffany's'. From 1967, an estimated two million carats of tanzanite were mined in Tanzania before the mines were nationalized by the Tanzanian government in 1971. In 1990, the Tanzanian government split the tanzanite mines into four sections: Blocks A, B, C and D. Blocks A and C were awarded to large operators, while Blocks B and D were reserved for the local miners. In 2005 the government renewed the lease of Block C mine to Tanzanite One, who paid 40 million dollars for their lease and mining license. In June 2003, the Tanzanian government introduced legislation banning the export of unprocessed tanzanite to India (like many gemstones, most tanzanite is cut in Jaipur). The ban has been rationalized as an attempt to spur development of local processing facilities, thereby boosting the economy and recouping profits. This ban was phased in over a two-year period, until which time only stones over 0.5 grams were affected. In 2010, the government of Tanzania banned the export of rough stones weighing more than one gram. Tanzanite One Mining Ltd is owned by Richland Resources, but a 2010 law in Tanzania required them to cede 50% ownership of their mining license to the Tanzanian State Mining Company (Stamico). Production in 2011 amounted to 2.4 million carats, earning them $24 million.