Related Clues:

• Tram cargo, perhaps
• Extraction candidate
• Underground-railroad cargo
• Mine content
• Eugene's state: Abbr.
• It may have a lead part
• Magnesium source
• Miner's discovery, perhaps
• It needs refining
• Klondike find, perhaps
• Mineral bearing rock
• Get a lode of it
• Underground treasure
• It's found in seams
• Galena, for instance