OLIVINE

(Mg,Fe)2SiO4

The minerals compromising the Olivine group are chemically and physically similar, and it is very hard to distinguish one from the other. Therefore, these minerals are rarely called by their real name, but are just called "Olivine". Olivine is a very common mineral, but it rarely occurs in sizes larger than microscopic grains. For this reason, larger specimens are rare and sought after. Only few localities yield large examples of this mineral, although small grains are found worldwide. Olivine is also found in meteorites, and some large grains have been reported in many of them.

Olivine occurs worldwide, but only few places yield large crystals.

peridot from Arizona (to the left, smothered over its matrix of basalt)

Gem-quality specimens of the mineral olivine are called peridot by gemmologists. Peridot has an love-or bottle-green colour due to the presence of iron, and a distintive oily or greasy lustre. It is found on St John's Island (Egypt), in China, Burma, Brazil, Hawaii and Arizona, Australia, South Africa and Norway. The Crusaders brought peridot to Europe in the Middle Ages, transporting stones from St John's Island in the Red Sea, where it has been mined for over 3,500 years.

Hardness: 6 1/2 - 7

Other characteristics