Iron oxide red is a generic name of a ferric oxide pigment of reddish colors. Multiple shades based on both anhydrous Fe
2O
3 and its hydrates were known to painters since prehistory. The pigments were originally obtained from natural sources, since the 20th century they are mostly synthetic. These substances form one of the most commercially important groups of pigments, and their names sometimes reflect the location of a natural source, later transferred to the synthetic analog. Well-known examples include the Persian Gulf Oxide with 75% Fe
2O
3 and 25% silica, Spanish red with 85% of oxide, Tuscan red. [1]