Rutile – TiO2 (m.p. 3452o F/1900o C) is an economical source of TiO2 when pure white is not required. It is used in clay bodies and glazes (typically 1-3%) to produce ivory through yellow to dark tans in oxidation, and purples and blues in reduction. Its most frequent use is to modify the action of other colorants and to produce special effects such as mottling and streaking. Such effects are particularly striking in Gerstley Borate glazes.