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Gemstone Crystal System Density Hardness Refractive index Treatments
Tanzanite orthorhombic 3.30 6.0-7.0 1.690-1.700 heat


tanzanite

Color:
Blue with violet modifier

Durability:
Care must be taken. Tanzanite cleaves easily.

Localities:
Meralani district of Tanzania

Governmental challenges, flooding, hand mining limitations, and tremendous popularity have now created a worldwide shortage of tanzanite. The finest material tends to be older stock, which is currently sold at a premium.

 


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Tanzanite

Ca2Al3(SiO4)3(OH)

Tanzanite, is a variety of zoisite, discovered in the Merelani district of Tanzania, near Mount Kilimanjaro in 1967. So far, all tanzanite discovery has been limited to a six kilometer strip in this area, which was divided into four blocks, labeled A, B, C and D. Block C is the only site still commercially producing rough tanzanite at this time.

All purple and blue varieties of the stone are the result of heat treatment. The stone is a yellowish-brown "bug juice" color when it is mined, but when heated to between 800-900 degrees Fahrenheit, it becomes that gorgeous violet blue that is used in jewelry. The stone has never been found in another locality, so it is indeed a depleting resource. It is somewhat soft (6-7 on Moh's scale of hardness), and has a direction of cleavage, along which it can be easily broken. It is desirable because of its' elegant and opulent color.

This gemstone is often confused with:

Iolite
Amethyst
Spinel
Tourmaline
Fancy Sapphire
Scapolite
Cortanite, Tanvolite, Tanzalike & other Lab Grown imitations
Glass
Plastic


tanzanite