Related Clues:

• Bed rock?
• Deposit of a sort
• Rock for miners
• What to take the lead from
• Rock bands, possibly?
• Miner's goal
• Mine extraction
• Unrefined material
• Unbelievable, say
• Valuable stuff in a vein
• Seam valuable
• Certain extraction
• Millerite, e.g
• Silicon Forest loc
• Comstock Lode find