It is a very recent stone with a coast of incomparable popularity, to such a point that in 2002, the AGTA (American Gem Trade Association) announces that Tanzanite also becomes the stone of December.
Discovered that in 1967 by Manuel Souza near Arusha in Tanzania, it aroused the admiration and the surprise until its arrival to the United States at the jeweler Of Tiffany and Co.
This blue stone, in the subtle reflection in intense of purple, is a part of the family of Zoïsites. Its capacity to present three different colors, blue, purple and pink, according to the angles under which we look at it, makes it exceptional. In gemology, we say that it is trichroïque.
90 % of Tanzanites are warmed at the exit of the mine, the brutes, even before being cut. The heating (400-500°C removes the yellowish brown tint that the stone can present to give way to an impeccable blue.
Tanzanite is a silicate which can be in granular, massive and fibrous aggregates. When it appears in different crystals, they are often streaked and have a prismatic or tabular aspect. The brightness of the mineral is glassy and its rather high(high enough) hardness (6 on the scale of Mohs) allows it a very good polishing.
It has an easy cleavage and an irregular fracture. This species is very often crystal clear and generally deprived of inclusions. However, in case they are present, they can be constituted by acicular crystals of trémolite, or by small empty or partially filled channels. We also meet fractures with liquid inclusions.
Sometimes, the arrangement of the trémolite gives rise to magnificent samples of brilliant Tanzanite, on the surfaces of whom we can observe strips of reflected and diffuse light
The unique deposit(, still exploited, is the one which was discovered in Tanzania at the end of the sixties, it is situated to approximately 60 km of Arusha, on the hills of Meralani, in the district of Lelatama. The rock in which is the mineral is constituted by veins pegmatiques. In such a deposit, Tanzanite can be so associated in quartz, pebbleweaves and feldspars. At present, we do not know other important localities of extraction.
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Legend
We tell that one day at the foot of the Kilimanjaro, flashes of lightning crossed the sky and came to strike the earth(ground), so activating(starting) a gigantic fire(light) destroying the territory of the big big cats. When the Massais were finally able to return, they found on this burned earth(ground), of strange blue and mauve crystals. According to these people of warriors, this stone will exist as long as the Big Animals will measure Earth of Tanzania.
Smithsonian Institution of Washington exposes Tanzanite faceted of 122,7 carats, in the shape of pillow, and an other, brilliant one, of 18,2 carats.
See the article on the site of the ICA. Cliquez
