ZrO2 in zircon brick is about 65% which is almost composed of zirconite crystals and contains only a very small amount of glass phase and free ZrO2. The ture density is about 4.55g/cm3 or so, and the maximum ture density can reach 4.62 g/cm3. The bulk density of zircon is between 3.6 g/cm3 and 3.8 g/cm3, and apparent pososity is above 13%.