When NASA's 899-kilogram Curiosity rover passed over the rock on May 30, it broke. Scientists were surprised to notice yellow sulfur crystals in its interior. Although sulfates are quite common on the Red Planet, this is the first time sulfur has been found there in its pure elemental form.

When we think of sulfur, we usually think of the smell of rotten eggs. But this smell comes from hydrogen sulphide gas. Elemental sulfur is odorless and forms under very limited conditions. So the scientists were amazed when they took a closer look at the surrounding area, the Gediz Vallis channel, and noticed many light-colored rocks that resembled those pressed by the rover.

Experts believed that there should be no rocks composed of pure sulfur on the Red Planet.

"Finding a field of pure sulfur rocks is like discovering an oasis in the desert. They weren't supposed to be there, so now we have to explain it," said scientist Ashwin Vasavada at NASA's Jet Propulsion Laboratory.

Sulfates are salts that form when sulfur, usually in compound form, combines with other minerals in water. When the water evaporates, the minerals dry out, leaving sulfates behind. Pure sulfur, on the other hand, forms only under specific and limited conditions.

Deposits of elemental sulfur created by the reduction or bacterial decomposition of sulfate can be found in many places on Earth, mainly in the US along the Gulf of Mexico coast, but experts did not expect to find it on the Red Planet.

Of course, there are still many unknowns about the geological history of Mars. Now we need to understand how elemental sulfur ended up on the surface of Mars. In the meantime, the Curiosity rover will continue to collect data and samples for analysis to further our understanding of the Red Planet's geology.

The Gediz Vallis channel is a very interesting area through which an ancient river flowed billions of years ago, and scientists were waiting for an opportunity to take a sample of rocks from the channel. They achieved this on June 18. Although they weren't able to sample the sulfur-bearing rock, it was too small and brittle for the drill, they spotted large boulders nearby that were perfect for sampling.

It took some time for the engineers to find the optimal location for the drill. It wasn't until the 41st hole that they were able to get a sample of the powder. After this mission, the rover continued along the channel, ready for possible surprises already on the next rock.