Silica is a mineral found abundantly in sandstone, clay, and granite, as well as in parts of plants and animals. Silica can also be manufactured synthetically, with both forms routinely used as an absorbent powder and thickener in cosmetics. Certain forms of silica can improve uniform distribution of pigments in cosmetics and prevent them from settling in makeup, ensuring an even, even application.
Research has shown that silica nanoparticles can increase the absorption of other ingredients and serve as an effective delivery system for antioxidants (such as quercetin). Silica can also enhance the protective ability of the mineral sunscreen ingredient titanium dioxide.
The US Food and Drug Administration allows silica to be added directly to foods as an anti-caking agent, and it has been determined to be safe as used in a wide range of concentrations in cosmetics by the independent Cosmetic Ingredient Review Panel. https://www.paulaschoice.com/ingredient-dictionary/ingredient-silica.html?q=Silica&fdid=ingredients