Related Clues:

• Sought-after rock group?
• They're all mined
• They're mined for metal
• Metal refinery input
• Crops of the pick?
• Assayers assay them
• Stuff in the rough
• Mine loads
• Lodes' output
• Mine outputs
• Mineralogists' study
• Some raw materials
• Some extracts
• Veins' contents
• Unrefined deposits