Related Clues:
- Unrefined rocks
- Objects of extraction
- Hidden treasures of a sort
- Mining discoveries
- Metallurgical specimens
- Smelter inputs
- Underground rock bands?
- Bauxite, haematite etc
- Miners' take
- Assay specimens
- Many "-ite" compounds
- Underground coal sources
- Some deposits
- They may have low overhead
- Bauxite and cinnabar