Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by form]
6. [materials by chemical form]
7. compounds (materials)

Anotations

Scope note:

Binary compound of oxygen and iron as occurs naturally, for example, in the mineral hematite. There are sixteen known iron oxides and oxyhydroxides. The corrosion product rust is a form of iron oxide. Iron oxides have many applications including chemical catalyst, pigment and colorant.