Solum Diatomeae/Diatomaceous Earth/Terre De Diatomees is the INCI name for diatomaceous earth (DE), a naturally occurring, soft sedimentary rock that is easily crumbled into a fine white powder. Diatomaceous earth is mostly comprised of silica (80 to 90%), but also contains alumina (2 to 4%), and iron oxide (0.5 to 2%). 

In cosmetics and personal care products, diatomaceous earth functions as a natural, gentle abrasive due to its rich composition of silica. Products that contain diatomaceous earth as an abrasive will help to exfoliate the top layers of skin, removing makeup, excess oil, dirt, and other impurities that may have accumulated during the day. Diatomaceous earth is also used as an absorbent because of its ability to absorb excess moisture and oil from the surface of skin. Due to this property, diatomaceous earth can also be used as an anticaking agent. By absorbing liquids, it prevents powder products from clumping together (caking) and helps other ingredients to apply more smoothly. Lastly, as an opacifying agent, diatomaceous earth can be added to clear or transparent cosmetic formulations to render them more resistant to visible light.