Blue lava is the color of sulfur fire—high-temperature burning of sulfur results in energizing flames. When sulfur burns, it produces "blue lava" flames, an electric blue fire. During sulfur combustion, a neon-blue flame forms. The term "blue lava" refers to the color of lava. These fires typically happen in places with high sulfur content, like Indonesia's Kawah Ijen volcano. These places include some mining sites. In some places, sulfur from the volcano's interior rises to the surface and catches fire, igniting blue flames. The sulfur melts, sometimes flowing down the face of the volcano carrying flames with it, which appear as if blue lava is flowing. Due to the blue color of the flames, they are only visible at nighttime.