Curiosity is currently located in the Gale Crater, and more specifically in the “Pahrump Hills” region at the bottom of Mount Sharp, from where it has sent back photos of two-tone mineral veins in the surrounding rock, writes Ian O’Neill for Discovery News.

NASA Curiosity Rover Discovers Mineral Veins On Mars

Mars: Minerals deposited by water passing through bedrock

Mars was a wet planet in ancient times, and the mineral veins formed during this period. They now protrude up to 6 centimeters above the surface of the surrounding rock. By comparing the geology of this area with others lower down Mount Sharp, scientists can begin to build a picture of Mars’ geological history.

“Some of (the mineral veins) look like ice-cream sandwiches: dark on both edges and white in the middle,” said Linda Kah, Curiosity science-team member at the University of Tennessee, Knoxville. “These materials tell us about secondary fluids that were transported through the region after the host rock formed.”

The veins were formed when water passed through cracks in the Martian bedrock, depositing minerals as they went, and similar formations have been observed elsewhere on Mars. This site is different because the darker material suggests that there was water early in Martian history, while lighter deposits date from later times.

“At least two secondary fluids have left evidence here,” continued Kah. “We want to understand the chemistry of the different fluids that were here and the sequence of events. How have later fluids affected the host rock?”

Studying Martian geological history

Curiosity has taken on the role of Martian geologist since it landed on the Red Planet in 2012. Its recent work has focused on areas of higher elevation than before, and there are obvious changes.

By studying the formations of the rock, scientists can see during which times there was water on the surface of Mars, as well as working out the geological history of the planet.

The fact that Curiosity has discovered evidence of two distinct periods in which water was present on the surface of Mars raises more interesting questions for researchers, and Curiosity remains hard at work trying to fill in the gaps in our knowledge.