The ancient Pan-African Tectonothermal Event produced blue zoisite known as tanzanite in Merilani in Tanzania. The mines are the largest and most productive of all types of gem mines in the country. Not only do the mines produce fine blue zoisite (tanzanite) they also produce pink, yellow and green zoisites as well as a host of other minerals including chrome diopside, tsavorite garnet, blue apatite, green tremolite and axinite. The mint green form of grossularite garnet known as “merilani mint garnet” has become a favorite of gem collectors.
The mines which are the only producers of gem quality tanzanite in the World are nearby to Arusha the gateway to the game parks of the Serengeti Plains. Located in the Merilani hills on the Western slope of the Lelatema Mountains the mines are approximately 2 kilometers wide and 4 kilometers long. Mount Kilomanjaro,the highest mountain in Africa is visible about 60 kilometers to the south west. The mines are 16 kilometers due south of Kilomanjaro Airport.
The story goes that lightning struck causing the grassland to start on fire which turned the brown zoisite crystals on the surface to blue where the Maasai tribesmen found the gem now known as tanzanite. Credit is given to a local Indian tailor named Manuel de Sousa for discovery of tanzanite but it was actually the unknown tribesmen who made the initial discovery but to them it had no value. Manuel was shown the location of the crystals by the maasai herders and he staked the first mining claim in 1967. Although Manuel de Sousa often gets credit for the discovery of tanzanite in 1967, in the U.S. Gemological Survey records it lists an identification of a blue zoisite crystal by Dr. William Pecora in 1959.
In the early 1970s Henry Platt, then President of Tiffany’s, was shown blue zoisite. Feeling the name zoisite would not be appealing to women he christened blue zoisite with the name Tanzanite after the country of origin. Henry Platt rightfully declared tanzanite to be “the most beautiful blue gemstone to be discovered in 2000 years.”
Many claims were filed after de Sousas initial claim in 1967 but all were revoked in 1971 when the mines were nationalized. At that time the mines were broken up in to four separate blocks, A block the farthest to the southwest is the smallest producer and is operated by Kilomajaro Mines Limited owned by a local businessman. B and D blocks are native blocks operated by artisanal miners. These are highly productive with D block being well known for producing many of the finest gems. Block B has had two major flooding disasters, one in 1998 killing as many as 200 miners and one in 2008 killing 74 miners. Block C is a highly organized and mechanized mine run by TanzaniteOne Group a publicly traded mining firm based in South Africa. Tanzanite one produces the most significant quantity of the World’s tanzanite and also buys from the artisanal miners. Tanzanite one has also been involved in the promotion of tanzanite through the Tanzanite foundation.org and through a system of site holders similar to the De Beers distribution of Diamond.
The Future of Tanzanite
The future of tanzanite is good with supply expected to last at least another 20 years. TanzaniteOne will attempt to control the market which will lead to stable but higher prices. We at tanzanitejewelrydesigns.com will continue our quest to find and cut the finest tanzanite and create unique designs for the “most beautiful blue gem to be discovered in 2000 years.”