Quality Magnetite Millscale

Quality Magnetite Millscale consists primarily of magnetite, Fe304, of characteristic blue-gray "steely" color. An extremely thin outer film of hematite, Fe203, is invisible to the naked eye. The inner portion of the magnetite contains fine metal grains and sometimes, residual black FeO, which contribute to the roughness of descaled metal. Mill scale is found on all hot-rolled steel products unless processed in a protective atmosphere or descaled (e.g., for galvanizing).