Related Clues:

• Pompeii was covered in it
• Volcanic effluent
• Gas-grill rock
• Hot flower
• Rock that rolls?
• Pumice source
• Fuji's flow
• Stromboli spillage
• Source of igneous rock
• Pompeii coverer
• Vesuvius output
• Pumice provider
• Vesuvian flow
• Krakatoa output
• Rolling rock