Science Fair Project Encyclopedia
Umber is a natural brown clay pigment which contains iron and manganese oxides. The color becomes more intense when calcined (heated), and the resulting pigment is called burnt umber. The name derives from Umbria, a mountainous region of central Italy, but it is found in many parts of the world. Some of the finest umber comes from Cyprus. It has been used as a pigment since prehistoric times.
Chemical formula: Fe2O3 + MnO2 + nH2O + Si + Al2O3
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