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.

Despite its name, this neon-blue glow isn’t actual lava but results from sulfuric gases combusting at temperatures up to 600°C (1,112°F). These gases, released from volcanic fissures, ignite upon contact with oxygen-rich air, producing electric-blue flames that can reach 5 meters (16 feet) high.

As the gases condense, molten sulfur burns with a blue-violet hue, flowing down the volcano’s slopes and creating the illusion of blue lava against the dark night. Visible only after dusk, this spectacle contrasts with the volcano’s red-orange basalt lava and its turquoise, highly acidic crater lake, the largest of its kind globally.

The phenomenon, locally called Api Biru (blue fire), draws tourists to the Ijen caldera, a 20-km-wide complex, despite the toxic sulfur dioxide fumes requiring gas masks for safe viewing.

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.