Related Clues:

• 49-Across source
• Assayer's stuff
• Bonanza yield
• It may be found in a pocket
• Smelter fodder
• Smelting material
• Seamy matter?
• Tramcar fill
• Miner's delight
• Cuprite, e.g.
• Smithsonite, e.g.
• '–ite' compound, often
• Lode deposit
• It's of miner concern?
• Comstock load