Zircon
Zircon (from latin:silex (stone, granite) zirconis) is a mineral belonging to the group of silicates. Its chemical formula is ZrSiO4.
Zircon is a remarkable mineral, if only for its ubiquitous presence in the crust of the earth. It is found in magmatites (as primary crystallization products), in metamorphites (as recrystallized grains) and in sediments (as detrital grains). Large zircon crystals are seldom abundant. Their average size is about 1-3 x 10-7m, but they can also grow to sizes of several centimeters.
The pervasive occurence of zircon has become more important since the discovery of radiometric dating. Zircons contain amounts of uranium and thorium (from 10ppm up to 5wt%) and can be dated using modern analytical techniques. Since zircons have the capability to survive geologic processes like erosion, transport, even high-grade metamorphism, they are used as protolith indicators. The oldest minerals found so far are zircons from the Narryer Gneiss Terrane, Yilgarn Craton, Western Australia, with an age of 4.404 Ga (S.A. WILDE et al., Nature 409, 175-178 (2001)).
Commercially, zircons are used for isolation and abrasive materials, and lesser amounts are sold as gemstones.