... 80% Physical Properties:Color RedShape Angular, edge sharpCrystal Form Alpha alumina trigonal systemSpecific Gravity 3.94Hardness 2090 Knoop scale, 9.0 ... Available (P):12, 16, 20, 24, 30, 36, 40, 50, 60, 80, 100, 120, 150, 180, 220 Microgrit Sizes Available (P ... fused aluminium oxide,fused brown corundum,corundum,brown fused alumina,brown aluminium oxide,fused alumina brown fused alumina FEPA P grit