Yellow Ochre – Fe2O3H2O Limonite (m.p. 2415o F/1325o C) is common in earthenware clay sources (rarely used in glazes as a colorant) and is one of the primary yellow or buff colorants in raw clay. It contains iron and manganese. When fired, the molecular bound water evolves off and forms Red Iron Oxide (Fe2O3). It is a significant source of red color in earthenware clay bodies. Used in Engobes as a colorant to produce ochre yellow, tans, and browns. Naturally occurring Yellow Ochre is less expensive than manufactured Yellow Iron Oxide.