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

Anotations

Scope note:

A rare brown or black mineral resembling brookite occurring in volcanic rocks as tabular crystals. It has been identified as an element in the yellow slip of Gallo-Roman marbled ware excavated in Graufensenque, France.