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Tanzanite, named for the country of its origin, is the transparent dark blue to blue-violet gem variety of the mineral zoisite. Because it is only found on one place on earth, it’s considered rarer than diamonds. Tanzanite is known for its strong pleochroism: Depending on the direction of the light, its color changes from amethyst to violet-blue to brown. Most tanzanite is heat-treated so that only the rich blue color--which comes from trace amounts of vanadium—remains. The finest tanzanite is mostly blue with violet accents. Officially “discovered” in 1967, tanzanite is considered one of the newest gemstones, yet because its source is so limited—a narrow piece of land near Kilimanjaro--some geologists estimate that the world’s supply of tanzanite could be depleted within 15 years.
Color: Sapphire-blue, amethyst, violet
Chemical composition: Ca2Al3 (O/OH/SiO4/SiO2) calcium aluminium silicate
Mohs’ hardness: 6 ½-7
Transparency: Transparent
Luster: Vitreous
Fracture: Uneven, brittle
Crystal system: Orthorhombic, multi-faceted prisms, mostly striated
Cleavage: Perfect
Specific gravity: 3.35
Refractive index: 1.691-1.700
Dispersion: 0.030
Pleochroism: Very strong; violet, blue, brown
Fluorescence: None
Occurrence: East Africa (Tanzania)
Astrology: recently designated a December birthstone
Chakra: 6th (third eye) and 7th (crown)
Tanzanite formed approximately 585 million years ago in the veins or fissures of gneiss and metamorphic rock in the volcanoes that surround Mount Kilimanjaro. The identity of the person who first “discovered” tanzanite remains the subject of heated debate, but the most widely known version of the story begins in July 1967 with a Masai herdsman finding some of the violet-blue crystal in the metamorphic rocks of the Merelani Hills, and bringing it to an amateur prospector named Manuel d’Souza. D’Souza, a tailor from Goan, India, who was living in Arusha at the time, thought the crystal might be sapphire and sent it to Dr. John Saul for identification. Saul, a Nairobi geologist and a gem dealer, had never seen anything like it. He sent it on to a lab in Germany, which identified it as zoisite. Saul then cut the first two tanzanite gem - large oval stones - and sent them to his father in New York, who happened to be the vice president of Saks 5th Avenue. Saks, at that time, was next door to the famed jeweler, Tiffany’s. Henry Platt, Tiffany’s director, immediately became interested, declaring this new variety of zoisite to be “the most beautiful blue stone discovered in over 2,000 years.” Platt, though, realized that the name zoisite sounded a little too similar to the noun suicide, and that marketing the stone would be far easier if it had a more evocative name. It was Platt who renamed the blue zoisite tanzanite and began to sell it in Tiffany’s in 1968. Yet despite Tiffany’s interest, the gem was almost impossible to get. A combination of factors - disputed mining stakes, politics, poor management of the mines, and the murder of d’Souza - resulted in tanzanite’s availability being highly erratic until 1997 when Mike Nunn, a South African entrepreneur, took over the mine. Strangely, tanzanite became popular with the film Titanic, when it was mistakenly identified as the Heart of Ocean “sapphire” that’s hurled into the sea. There were also reports in 2001 that linked tanzanite with al-Queda financing - American jewelers temporarily stopped selling the stone - but these reports were found to be false, and tanzanite is now taking its rightful place as a luminous and precious gem.
Metaphysically, tanzanite is considered a “stone of magic” that can connect the wearer with the spirits of the ancients. It’s also said to helpful in communicating psychic visions and in encounters with beings from other planes.
Often compared to sapphire because of its rich blue, tanzanite is actually quite a bit softer on Mohs’ scale – a 6 ½ vs. sapphire’s 9-- yet it’s surprisingly resistant to scratching. However, the stone is brittle and can chip, so if you use the beads in a bracelet, wear it with care.
Tanzanite beads are spectacular when paired with black opal. They’re also lovely with pearls, rubies, emeralds, rubellite, garnet, and peridot. |
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