Glossary
An overview of iron oxides (Fe2O3, Fe3O4, FeO), the mineral-based pigments that provide red, yellow, and black colors in cosmetics, sunscreens, and natural skincare products. Iron oxides are among the most widely used and safest cosmetic colorants, with the added benefit of providing visible light protection.
Three iron oxides provide the color range for virtually all mineral makeup: red iron oxide (CI 77491, warm reds and pinks), yellow iron oxide (CI 77492, yellows and golds), and black iron oxide (CI 77499, blacks and grays). Blending these three pigments in varying ratios creates every skin-tone shade used in foundations, concealers, and tinted products.
In tinted sunscreens, iron oxides serve a dual function: they provide a cosmetically appealing tint that eliminates the white cast of mineral sunscreens, and they provide additional protection against visible light (particularly blue light), which mineral UV filters alone do not fully block.
Cosmetic-grade iron oxides are synthetic (produced under controlled conditions to ensure purity and consistency) rather than mined from natural deposits, which may contain heavy metal contaminants. Synthetic iron oxides have an excellent safety record spanning decades of cosmetic use.
Iron oxides are FDA-approved for cosmetic use, including use around the eyes. They are non-comedogenic, non-irritating, and suitable for sensitive skin. They are one of the few cosmetic colorants that virtually all dermatologists and clean beauty advocates agree upon.
Iron oxides occur naturally in minerals (rust is iron oxide). However, cosmetic iron oxides are synthetically produced to ensure purity, consistent color, and absence of heavy metal contaminants. They are chemically identical to natural iron oxides but cleaner.
Iron oxides absorb visible light, particularly high-energy blue light (HEV light) that contributes to hyperpigmentation and photoaging. They complement zinc oxide and titanium dioxide (which block UV) by extending protection into the visible light spectrum. Tinted sunscreens with iron oxides provide more comprehensive protection than un-tinted mineral sunscreens.
Iron oxides can leave temporary color on skin, which is their intended function in makeup. They are easily removed with standard cleansing. They do not permanently stain skin.
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