Magnesium aluminum silicate is a naturally occurring mineral derived from silicate ores of the montmorillonite group (a type of clay). It is refined to a powdery, dry-feeling, white solid for use in cosmetics and pharmaceutical applications. Due to the large size size of its molecules, magnesium aluminum silicate is unable to be absorbed into the skin. Magnesium aluminum silicate primarily functions as a thickening agent and filler in products such as deodorants, shaving creams, and thick lotions. Its thickening property allows products to achieve a more desirable, spreadable texture.

Magnesium aluminum silicate may also be used as an absorbent, anticaking agent, opacifying agent, viscosity-increasing agent, and suspending agent. By absorbing liquids, it prevents powder products from clumping together and helps other ingredients to apply more smoothly. As an opacifying agent, magnesium aluminum silicate can be added to clear or transparent cosmetic formulations to render them more resistant to visible light.