Tuesday, January 10, 2017

Zircon

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. (not to be confused with cubic zirconia - the manmade cubic crystalline form of zirconium dioxide (ZrO2))

Zircon has been known since the Middle Ages. The oldest known zircons are from Western Australia, with an age of about 4.4 billion years. The name probably comes from the Persian word "zargun" which means "gold-colored," although zircon comes in a wide range of different colors.

It is typically brown, reddish-brown, green or yellow. Since the 1920s virtually all zircon gemstones used in jewelry have been heat-treated to enhance their colors. Heating produces blue and golden zircons as well as some colorless stones.
Most gem zircons are found as water worn pebbles in gravel deposits in Thailand, Cambodia, Vietnam, and Sri Lanka. Gem quality zircon is also found in Burma, Madagascar, Brazil and Tanzania. Due to its high refractive index and strong dispersion, zircon has great brilliance and intensive fire. The luster is vitreous to a brilliant sheen.