Related Clues:

• See 51-Across
• Comstock output
• A three or a five, for instance
• Band of gold?
• See 38-Across
• Bauxite or hematite
• Mesabi Range yield
• Change from a krone
• It lacks refinement
• See 5-Down
• Some can dig it
• Valuable rocks
• It's found in the ground
• Profitable extraction
• Lucky strike