Silica is another name for the chemical compound composed of silicon and oxygen with the chemical formula SiO2, or silicon dioxide. There are many forms of silica. All silica forms are identical in chemical composition, but have different atom arrangements. Silica compounds can be divided into two groups, crystalline (or c-silica) and amorphous silica (a-silica or non-crystalline silica). c-Silica compounds have structures with repeating patterns of silicon and oxygen. a-Silica chemical structures are more randomly linked when compared to c-silica. All forms of silica are odorless solids composed of silicon and oxygen atoms. Silica particles become suspended in air and form non-explosive dusts. Silica may combine with other metallic elements and oxides to form silicates.
Solubility Insoluble (NIOSH, 2024)
Formula
O2Si
Mol. Weight
60.08
CAS #
7440-21-3
Form
Powder
State
Transparent to gray, odorless powder. Irritating to the skin and eyes on contact. Inhalation will cause irritation in the respiratory tract. [Note: Amorphous silica is the non-crystalline form of SiO2
See origin →
Functions
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Physical Exfoliant
Anti-Aging Benefits
Antioxidant Protection
Reduces Inflammation
Gently polishes surface
Traditional Use
Used historically as an absorbent and mattifying agent in mineral-based cosmetics and traditional powder formulations. Modern cosmetic-grade silica is produced synthetically and valued for its oil-absorbing, anti-caking, and texture-improving properties.