Related Clues:

• It could use some refinement
• Mineralogists' samples
• Groundbreaking discovery?
• It's raw
• Tram load
• Cinnabar, e.g.
• Rock bands?
• Hematite and galena
• Rock band?
• Salem's state: Abbr.
• Galena is one
• It's found underground
• Promising rock
• See 37 Across
• Unrefined find