Related Clues:

• Volcanologist's study
• Lamp type
• Hot issue
• Stromboli output
• Etna output
• ___ lamp
• It may be found in a cone
• It's hot stuff
• Kilauea output
• Hawaiian bubbly?
• Rock on the roll?
• Etna effluent
• Obsidian, before cooling
• Volcanic rock
• Cone material