Hierarchy classification:

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

Anotations

Scope note:

Waste material produced by the process of coal mining, that may include coal gangue found in mining heaps, the light gray, washed waste produced during coal preparation, the red-colored burnt coal gangue caused by pyrite oxidation, and a high percentage of coal itself.