Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by function]
6. colorant (material)
7. pigments
8. [pigment by color]
9. red pigment
10. inorganic red pigment

Anotations

Scope note:

A permanent, reddish brown pigment that was originally prepared from a natural red ocher, but since the 18th century has been manufactured by calcining ferrous sulfate (copperas) with lime or calcium carbonate in a ratio of around 15-40% ferric oxide and 60-80% calcium sulfate. It is used in oil paints, house paints, and as a paper colorant.