White amorphous powder, m.p. 1670℃, bulk density 1.1 kg/L, soluble in dilute HCl and HNO₃, slightly soluble in cold water; anhydrous with stable quality and free of carbonate. Used in ceramics and glass to raise whiteness, transparency and compressive strength, as opacifier in glaze and brightener in body; also for flame retardants, anti-caking and flow agents. 25 kg PE-lined woven bags; 26 t per 20' FCL unpalletised.