 Color in this red or pink series is annealed in geological conditions above temperatures of around 400 °C.Zircon is mainly consumed as an opacifier, and has been known to be used in the decorative ceramics industry.It is also the principal precursor not only to metallic zirconium, although this application is small, but also to all compounds of zirconium including zirconium dioxide (ZrO2), one of the most refractory materials known.