Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. mineral
8. clay mineral

Additional parents:

1. top of the aat hierarchies
2. Materials Facet
3. Materials
4. materials
5. materials by form
6. materials by chemical form
7. compounds
8. silicates

Anotations

Scope note:

Mineral originally found on the Isle of Mull and used as refractory material for firebrick and furnace linings. It occurs naturally as fused argillaceous sediment inclusions in the mineral buchite, but this is rare, and as a result, it is produced artificially.