Related Clues:

• Claim valuables
• Underground treasures
• Pitchblende and cassiterite, for two
• Metal-bearing minerals
• Underground sources of income
• Smeltery needs
• Mineral sources
• Tram loads, often
• Prospectors' prizes
• Tram contents
• Bauxite and galena
• Metal-filled rocks
• They're mined and refined
• Smeltery material
• Refinery rocks