... %Free Carbon 0.17%Fe2O3 0.12%Physical Properties:Color GreenShape AngularCrystal Form Alpha silicon carbide in hexagonal systemSpecific Gravity 3.20Hardness ... (F or JIS):12, 14, 16, 20, 22, 24, 30, 36, 40, 46, 54, 60, 70, 80, 90, 100, 120, 150 ...