Color pure iron oxide pigments, a process for their preparation

Iron oxide red pigments comprise clusters of a plurality of pigment particles, preferably at least five intergrown spherical particles, are prepared by conducting nuclear formation of iron oxide yellow alpha -FeOOH in the presence of compounds of the elements, B, Al, Ga, Si, Ge, Sn or mixtures thereof in quantities of from 0.05 to 10% by weight, calculated as tri- or tetravalent oxides and based on the arithmetically calculated precipitated alpha -FeOOH nuclei, separating brine from the resulting yellow slurry to isolate an iron oxide yellow paste, drying and annealing the paste to form iron oxide red pigment and grinding the red pigment, which pigment is useful in coloring foodstuffs, lacquers, plastics and building materials.