Index Specificatiom Crystalline Phase r-Al2O3 Sphere Size mm 7--14 Φ 3--5 Φ 4--6 Φ 5--7 Appearance White Sphere Bulk Density g/cm3 0.76--0.85 0.65--0.72 0.64--0.70 0.64--0.68 Crush Resistance N/sphere >45 >70 >80 >100 Surface Area m2/g 200--260 Pore Volume cm3/g 0.40--0.46 Coefficient Of Water Absorption % >52