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. synthetic inorganic red pigment

Anotations

Scope note:

Permanent pigment that, depending on conditions, can range in hue from orange to deep red. It is an unstable crystalline form and turns black when mixed with lead pigments. It is used in paint and to color ruby glass. It was invented and patented by Murdock in Scotland in 1847, it was replaced by cadmium red in the 1920s.