The Blue Flames Aren’t Lava—They’re Burning Sulfur At Kawah Ijen in Indonesia, rivers of glowing electric blue light flow down the volcano at night. Despite appearances, this isn’t molten rock—it’s liquid sulfur burning at about 1,110°F (600°C) as it ignites on contact with air. The rare phenomenon occurs where sulfur-rich gases escape and condense into liquid before igniting. Important Details: • Known as “blue lava” phenomenon • Actually burning liquid sulfur • Temperature around 1,110°F • Vis