... and alkali.SPECIFICATION: CHEMICAL ANALYSISCOLORSiO2Al2O3Fe2O3MnOMgOCaOGREY35-4018--200.9-1.00.5-2.00.2-1.42.2-3.9PHYSICAL CHARACTERISTICSBasic MineralSiO2,Al2O3ColourBrown ... . Free grinding and polishing5. Filter Medium6. Surface Preparation Available Sizes:24, 30, 36, 40, 46, 54, 60, 70, 80, 90, ... 100, 120, 15020/40,30/60 10/20,20/8012/24,20/60Other special size could be supplied as required. Garnet ...