When we think of a volcano erupting, the colours that come to mind are generally a mix of molten orange-red-yellow, right? 

But, guess what, the island nation of Indonesia that is dominated by active volcanoes, has an eerily beautiful volcano that erupts blue fire. Fascinating, no?

Source: Photographed by Olivier Grunewald

Kawah Ijen volcano in Indonesia erupts electric-blue fire that can often be seen streaming down the mountain at night and the pictures are stunningly beautiful. 

However, Paris-based photographer, Olivier Grunewald, who has been documenting the Kawah Ijen volcano for several years says the blue glow isn't lava, it is actually the light from the combustion of sulfuric gases.

Source: Photographed by Olivier Grunewald

Basically, when the gases emerge from the cracks of the volcano and come in contact with the oxygen-rich atmospheric air, they ignite, giving rise to a blue flame.

Olivier Grunewald further explains that when some gases condense into liquid sulphur and continue to burn as it flows down the slopes, it gives us the illusion of lava flowing. 

Source: Photographed by Olivier Grunewald

Apparently, the blue hue is best seen at night, which is why, many tourists make their way to the crater to see this unusual phenomena after sunset. 

Grunewald took these captivating photos without using any filters on them so what you see right now, is natural beauty at its best. 

Source: Photographed by Olivier Grunewald

Situated within the crater, there also lies the world's largest known acidic crater lake which is filled with hydrochloric acid. In fact, its bluish-greenish colour comes from a high concentration of dissolved metals.

The gases from the volcano often react with the water resulting in a low pH of 0.5. But, when the gases cool down, they leave sulphur deposits around the lake as residue. 

Source: Photographed by Olivier Grunewald

Here are some more stunning photos of the blue volcano ligthing up the night skies in Indonesia. 

Source: www.dailymail.co.uk
Source: www.dailymail.co.uk
Source: www.dailymail.co.uk

So, if you are planning to visit this volcano, don't forget to pack a gas mask and a eye protective gear, for your own safety. 

Also, here's a video of the blue flame volcano. Check it out.