This Fiery Volcano Spews Electric Blue Lava Dubbed as ‘Devil’s Gold’ at Night

Climbing into the fiery mouth of Kawah Ijen volcano is like stepping inside Dante’s inferno, as one miner told the BBC. Looming 9,183 feet above sea level, this raging volcano has suffocated so many miners to death with its toxic flames and poisonous gases. But when night sets in, the volcano suddenly undergoes an almost disco-like transformation. Under the cover of twilight, electric blue-purple flames erupt from the acidic pit of the volcano and rise towards the peaks. On the surface, the surreal blue fire appears to be coming from a much simpler secret. Not sorcery, not magic, it’s just chemistry, per Live Science.

Sitting in the heart of eastern Java, Ijen is a hotbed of sulfur. Its abundance of sulfur is the reason why flocks of miners wake up each day to traverse the meandering trails of the surrounding mountains and climb into the fumaroles of toxic gases to mine out this abundance of sulfur to feed their starving children. Dubbed “Devil’s gold,” sulfur is used in everything from batteries to cosmetics, rubber tires, and sugar whitening.

Sulfur is a shapeshifting guy. During the day, it sits inside the volcano in its usual hardened yellow form, but the moment night sets in and the miners ignite the pit with flames, it burns. And when it burns, its color changes from yellow to blue. Every flame of this burning sulfur is precious, which is why many miners working in the region double up as firefighters. They can’t let even one swirl of this blue sulfur go to waste. One flame lost means one less rock in their basket. One less rock means one less euro. And only these workers know how precious this one euro is for them and their families, as BBC Earth Science shows in a documentary.

As a Reddit user described it, the electric blue flames of Ijen resemble a “dark energon erupting from the earth,” referring to a fictional character in the Transformers universe. Before scientists unravelled the mysterious chemistry of this volcano, it seemed astonishing to watch this blue fire flickering through the night, blue lava dribbling down the slopes of the mountains. But when some science-brained detectives ventured into the volcanic region to decipher the mystery, they let out a chuckle. Ijen’s glowing blue lava illustrates why chemistry is the ultimate magician. In this case, the chemistry of sulfur.

When the abundance of sulfur packed beneath this volcano encounters pressure from the underground, it escapes through the cracks and fissures and spills onto the mountain slopes, ultimately collecting in the acidic lake of the volcano. When it comes into contact with oxygen, it starts burning, resulting in this glowing neon fire. What spews out into the air appears as blue fire, while what remains in liquid form appears as blue lava.