Zirconia (ZrO2), the main oxide of zirconium, is an odourless white crystalline material that is almost insoluble in water, hydrochloric acid and dilute sulphuric acid (acid- and alkali-resistant) and chemically inert. Its high melting point, high electrical resistivity, high refractive index and low thermal expansion make it an important refractory, heat-resistant material in manufacturing.
