Related Clues:

• Deposit worth digging up
• Rock to refine
• Chalcopyrite, e.g.
• Miner's rock
• Part of the underground economy?
• Foundry need
• Flin Flon commodity
• Refinery stuff
• Assay sample
• Rush igniter
• Rich find
• Dig this, and mine your business
• Natural minerals
• Metal-bearing rock
• Rock from which metal is extracted