The one-of-a-kind blue color associated with the lava flows on Kawah Ijen volcano is not, as you might think, due to blue-colored lava. The scientific story is as fascinating as the images. (STÉPHANE DAMOUR / FLICKR)

This Erupting Volcano’s Lava Appears Blue, And Science Knows Why

Sometimes, chemistry can be more important for color than even physics.

All across the world, volcanic eruptions remind us of the destructive power residing beneath Earth’s surface.

You might be used to images of lava erupting from and flowing down active volcanoes, but that lava is normally dark, red, orange, or yellow. The blue that you see is unique to eastern Indonesia, and isn’t the color of the lava at all. (MICHAEL HEINIGER / FLICKR)

Molten rock, known as magma, erupts through fissures in Earth’s crust, becoming lava.

Lava erupts and flows from a Kilauea volcano fissure in Leilani Estates, on the Big Island, on May 23, 2018 in Pahoa, Hawai’i. (GETTY)

If that lava rises above 525 ˚C (977 ˚F), it glows red, with hotter lavas becoming orange or even yellow.

A slow shutter speed picture shows lava streaming down from Mount Anak Krakatau (Child of Krakatoa) during an eruption as seen from Rakata island on July 19, 2018 in Lampung, Indonesia. The orange-red color allows us to determine the temperature of the lava, which is hottest at the tip of the cinder cone and less hot as we view the lava flows farther down. (GETTY)

But one volcano, Indonesia’s Kawah Ijen, displays a spectacular blue color.

On many different parts of the mountains in the Ijen volcano complex, gas and liquid outflows can be seen. The blue color shown here is a true-color image, with an appearance unique among the known volcanoes of the world. (STÉPHANE DAMOUR / FLICKR)