Related Clues:

• Lime and others
• Copper containers
• Waste gases, e.g.
• They're found in the ground
• Mined-over matter
• Raw material
• Cinnabar et al.
• Smeltery input
• Some binary compounds
• Some train cargoes
• They lack refinement
• Smelter's stuff
• Products of a 16-Across
• Metallurgists' studies
• Sourdough's find