Items Unit Index Chemical composition Al2O3 % 41.00-46.00 ZrO2 % 35.00-39.00 SiO2 % 16.50-20.0 Fe2O3 % 0.2max Bulk density g/ cm3 3.6min Apparent porosity % 3.00max Phase 3Al2O3.2SiO2 % 50-55 Indined ZrSiO4 % 30-33 Corundum % 5.00max Glass % 5.00max