Zircon is a zirconium sillicate mineral with a chemical composition of ZrSiO4. Zircon occurs in a wide range of colors and has a brightness and fire that rivals those of diamond.
Zircon has been mined from stream gravels for over 2000 years. This early mining of zircon was mainly to obtain nice crystals for use as gemstones. Today, most zircon is produced by mining or dredging zircon-rich sediments. These sediments can be in beach, littoral, or alluvial deposits.
Zircon has a specific gravity of 4.6 to 4.7, which is much higher than the typical detrital sediment grain that is between 2.6 and 2.8. This specific gravity difference allows zircon grains to be recovered from the sediments by mechanical separation. Specific gravity separation methods make it possible to profitably recover zircon and other heavy minerals at an ore grade of just a few percent. Zircon is often a coproduct at mining/processing operations where ilmenite and rutile are being mined for titanium.
Industrial-grade zircon is mined from land – and marine – based deposits of alluvial origin in many parts of the world. Australia, South Africa, China, Indonesia, Mozambique, India, Ukraine, Sri Lanka, Madagascar, Brazil, Kenya and several other countries were important producers in 2014. These alluvial deposits contain mainly sub-millimeter grains of zircon derived from the weathering of granitic rocks.
Physical Properties of Zircon
Usually yellow, brown, or red. Also colorless, gray, blue, and green.
Colorless. Usually harder than the streak plate.
Vitreous to adamantine, sometimes oily.
Translucent to transparent
6 to 7.5
4.6 to 4.7
Hardness, luster, specific gravity
Ore of zirconium metal, ore of zirconium dioxide, whitening agents, white pigment, gemstones, radiometric dating.
Uses of Zircon
Zircon sand has a low expansion coefficient and is very stable at high temperatures. It is used as a refractory material in many foundry and casting applications. One of its most common uses is in the production of ceramics.
Zirconium dioxide (zirconia) is produced by heating rzircon sand to a high enough temperature to break down the zircon molecule. In powdered form, zirconium dioxide is bright white, highly reflective and thermally stable. It is used as an opacifier, whitening agent, and pigment in glazes and stains used on ceramics and pottery.