Related Clues:

• Heap content
• Fuji outflow
• Basalt, once
• Hot flower?
• Etna ejecta
• Soap containing pumice
• Cotopaxi outflow
• Wood stove residue
• Tapped-off part
• Bonfire aftermath
• Igneous-rock source
• Sweep's heap
• It's grate stuff
• Volcano's outflow
• Bat making material