What Is White Tanzanite?

Chemical Structure

• Tanzanite is a type of zoisite, which is a calcium aluminium hydroxy sorosilicate. Its chemical formula is Ca2Al3(SiO4)(Si2O7)O(OH).

Origin

• White tanzanite was discovered relatively recently, in 1962. It was first found in the African country of Tanzania, from which it gets its name.

Treatment

• When white tanzanite is dug from the ground it is usually a reddish-brown color. It must be artificially heated to around 600 degrees Celsius before it assumes an appearance suitable for use in jewelry. Changes in treatment can produce slightly different colors.

Trichroism

• White tanzanite is popular for its trichroism, or its ability to appear to be slightly different colors from different angles. This effect is because its chemical structure causes the double refraction of light that passes through it.

Rarity

• White tanzanite is a fairly rare stone, not only because most tanzanite is a deep purple or blue, but also because it only comes from Tanzania. Political instability in that country has limited the world's access to this stone.