Mars is hiding a clutch of ruby-like crystals in its rocks, observations from the Perseverance rover suggest, and astronomers say other precious minerals, like sapphires, could exist across the Red Planet, too.

An international team of researchers presented the findings, based on observations from spring 2025, March 16 at the 57th Lunar and Planetary Science Conference in Texas. These findings are currently under peer review and will appear in the journal Geophysical Research Letters.

The story begins a short time ago on a planet not too far away, when a roving robot the size of a compact car climbed the side of a 4 billion-year-old impact crater and began exploring its rim. On that ancient and stony rim, NASA’s Perseverance rover found a curious scattering of pale-colored “float rocks” — out-of-place rocks that must have been transported there by impacts, geological activity or hydrological processes.

As scientists often do when faced with a curious specimen, they blasted it with a laser — specifically, the green laser from the Perseverance rover’s SuperCam, situated atop its mast. This laser excites minerals, causing them to emit light at specific wavelengths. And because every element and compound emits certain wavelengths of light, this reveals a sample’s chemical composition.

The analysis showed that three of the laser-blasted float rocks exhibited clear signatures of the mineral corundum, with inclusions of the element chromium — crystals that match the chemical description of rubies. However, because the crystals are too small to be seen by Perseverance’s imager, and their exact chemical composition is uncertain, the researchers aren’t sure whether they have truly found Martian rubies or perhaps some other type of corundum.

“The different types of corundum are based on the chemistry,” study co-author Valerie Payré, a planetary geologist at the University of Iowa, told Live Science via email. “Although corundum is Al2O3, there are minor elements like chromium, titanium, and iron that can be present.””These elements will provide the color to the mineral, and the name of it,” Payré added. “We cannot quantify the amount of chromium, and other elements like iron and titanium might be present too. It is thus difficult to conclude whether they are rubies or other types of corundum [like sapphires].”

The team ultimately classified the crystals as corundum and declined to guess about the variety without more chemical evidence. Corundum is a mineral made of aluminum and oxygen. It is one of the hardest known natural substances, approaching the toughness of diamonds. Pure corundum is colorless, but microscopic impurities imbue it with brilliant hues. Iron or titanium inclusions yield brilliant blue sapphires, while chromium produces even rarer, resplendent rubies.

However, anyone holding out hope for a future Martian-gemstone-studded necklace may be disappointed. The corundum crystals found within the float rocks are tiny — less than 0.2 millimeters (0.008 inches) in diameter.