Related Clues:

• Raw rocks
• Things tunnelers look for
• Tramcar contents
• Congeals
• Underground discoveries
• Contents of trams
• Miners' diggings
• Concert divisions
• 6-2, 3-6, 7-6, e.g.
• Mine yields
• Mathematical groups
• Mesabi loads
• Iron and manganese, e.g.
• Film designers' designs
• They could use refinement