NASA’s Curiosity rover made a special discovery on the surface of Mars by accident. When the rover ran over some rocks, one of them cracked open. It turned out to contain yellow sulfur crystals never before seen on the Red Planet.

Since October of last year, the rover has been investigating a region of Mars where sulfates are abundant. Sulfur-containing minerals: a mixture of sulfur and other materials, have been regularly found. The rock found now is pure sulfur. NASA can’t yet say how the pure sulfur compares to other sulfur-containing minerals in the region.

Although we usually associate sulfur with the smell of rotten eggs, this pure sulfur is actually odorless. The yellow crystals can only form under specific conditions. Until now, scientists didn’t know that this was also possible at this location on Mars.

The discovery was made in what is called the Geddes Vallis Channel on Mars. You can see the surroundings of Curiosity in 360 degrees in this YouTube video from NASA:

There’s a lot of excitement at NASA. “Finding a field of pure sulfur rocks is like finding an oasis in the desert,” says project scientist Ashwin Vasavada. “It shouldn’t really happen there, so now we have to figure out how. Finding these strange, unexpected things is what makes planetary exploration so exciting.”

The yellow sulfur crystals certainly aren’t the first discovery Curiosity has made on Mars. Last year, new evidence of rippling lakes was found on the planet. And in 2022, a special “mineral flower” was discovered. According to NASA, the rock fragments formed billions of years ago when minerals from water bonded to the rock.

The Mars rover Curiosity landed on the red planet in 2012. Its main mission is to explore the climate and see if life could ever exist. The rover can analyze soil samples for signs of life. Since 2021, Perseverance has also been circling the planet to conduct soil research.