Iron Oxide Pigments
Iron oxide pigments have been used as colorants since early humans began painting on cave walls. The pigments can be derived naturally or synthetically. Natural pigments are made from several iron oxide minerals: Red pigments come from hematite. Yellow and brown pigments — ochres, sierras and umbers — are derived from limonite. Magnetite makes black iron oxide pigments.
Synthetic pigments are manufactured in such a way that that particle size, distribution and shape are homogeneous, resulting in good uniformity, color quality and chemical purity.
Iron oxide pigments are highly resistant to color changes from UV exposure. Also having good chemical resistance they are used in paints, coatings and construction materials such as in concrete products, mortar, paving stones and roofing tiles.