Related Clues:

• Makeup of some seams
• Foundry delivery
• Magnetite, e.g
• Cinnabar or galena
• Rocks with metal
• It's all in your mine
• Mine layer
• Fruit of a miner's labors
• Gold in them thar hills?
• Feldspar, e.g
• Underground resource
• Mineral in a wall, perhaps
• 10-Down source, e.g
• Forty-niner's pay dirt
• 4-Down contents