Alumina

Alumina is the common name of the ingredient aluminum oxide. It is a naturally occurring mineral used as an abrasive, a thickener, and an absorbent in cosmetics.

Alumina is sometimes used as part a coating blend for nano-sized mineral UV filters such as titanium dioxide. This coating keeps the very fine power particles of the mineral sunscreen on skin’s surface since the coating materials are a larger molecular size. These coating blends also improve the aesthetics and even application of mineral sunscreen ingredients.

In skin care preparations, alumina is used in amounts up to 25%. It’s been determined safe as used in cosmetics by the independent Cosmetic Ingredient Review panel. It is also approved by the U.S. Food and Drug Administration as a color additive for use in certain over-the-counter drugs.

Alumina in its natural form is a white solid. It is the third hardest naturally occurring substance, and is the primary component of rubies, emeralds, and sapphires (their color is determined by small impurities found in heavy metals).