Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt.
A 1742 (OTTO) Aluminium oxide, 99.995% - used as an abrasive, dosimeter, filler of choice for plastic. Aluminium oxide flakes are also used in paint for providing reflective decorative effects. In laboratories it is widely used as a medium for chromatographic purifications.