Spectacular Neon Blue Lava: Kawah Ijen Volcano (PHOTOS)

Blue lava, also known as Api Biru and sulfur fire, is a rare phenomenon occurring when sulfur burns. It produces an electric-blue flame due to the emission of excited sulfur atoms releasing energy as blue light.

While the term "blue lava" might sound like something out of science fiction, it's actually a real phenomenon that occurs when sulfur burns.

That's the surreal hue of Indonesia's Kawah Ijen Volcano, which glows with an otherworldly "blue lava" at night. The mountain contains large amounts of pure sulfur, which emits an icy violet color as it burns, turning the rocky slopes into a hot (at least 239 degrees Fahrenheit), highly toxic environment.

Miners carry between 176 and 220 pounds of sulfur chunks per trip and sell the pieces for around 2.5 cents per pound. Yahoo reports they average two loads every 24 hours, thereby doubling their salaries amid sulfurous flames that can reach 16 feet high.