Ceramic colorant from untreated iron ore residue

► Iron ore residue used as a colorant for glazed ceramics. ► Residue used without any kind of pretreatment. ► The color of the glaze changes due to the type of glaze and firing temperature. ► Color variation is a function of crystal phase modification during firing. ► The untreated iron ore residue can be used as a ceramic colorant for roof tiles. ► Stable color was achieved at intermediate temperatures (1100 °C).