Related Clues:

• Undergrounddiscovery
• Some hard rock
• Mine car load
• Excavation yield
• ___-Ida (tater tots maker)
• Vein output
• 33rd st
• Contents of a vein pocket
• Source of slag
• Rock to be refined
• Subterranean resource
• It's found in lodes
• Prospector's target
• Rock for refining
• It's of miner interest?