Zircon: Zircon, also known as zirconium silicate, is a mineral with a wide range of applications. The world’s largest deposits of zircon sands are found in Australia, Brazil, China, India, Russia, South Africa and the United States. Zircon sand is used for its physical properties including hardness, density and refractive index. It is also used as an opacifier in glazes and ceramic bodies. Other uses include foundry sand casting moulds, abrasives and refractory materials.