NASA’s Perseverance rover discovered chromium-bearing corundum, the mineral behind rubies and sapphires, inside three pale float rocks in Jezero Crater in 2025. According to research published in Geophysical Research Letters in 2026, the unexpected find challenges existing models of Martian geology.
When NASA’s Perseverance rover examined pale rocks scattered across Jezero Crater in 2025, scientists did not expect anything out of the ordinary. Instead, laser spectroscopy revealed something new to the Red Planet: corundum, the crystalline aluminum oxide that forms precious gemstones on Earth.
The discovery marks the first time corundum has been identified in a Martian setting. While the detection does not mean sparkling gemstones litter the landscape, the presence of chromium-bearing crystals trapped inside three separate rock samples has opened a new debate about ancient planetary processes.
Time-Resolved Luminescence Analysis on Martian Float Rocks
Perseverance made the detections in March, April, and July of 2025 by targeting three distinct float rocks named Hampden River, Coffee Cove, and Smiths Harbour. Because these rocks are unattached chunks resting on the surface rather than bedrock, they likely originated elsewhere on the planet, offering a window into broader regional geology.
Using the rover’s SuperCam instrument, researchers applied time-resolved luminescence (TRL) spectroscopy. The method involves firing a laser to excite atoms within minerals and measuring the characteristic light they emit as they return to their normal state. The resulting spectra displayed two prominent luminescence peaks at wavelengths of 692.7 and 694.1 nanometers.
“Very unexpectedly,” wrote a team led by geochemist Ann Ollila of Los Alamos National Laboratory in a conference abstract, “SuperCam’s TRL analysis of three plagioclase-rich float rocks in the crater rim were found to exhibit clear signatures of chromium-bearing corundum.”
Ann Ollila, Los Alamos National Laboratory
Laboratory comparisons conducted by the research team revealed striking similarities between these Martian signals and the spectra of terrestrial rubies, sapphires, and diaspore. In the Smiths Harbour sample, the luminescence lingered for approximately 3 milliseconds, matching measurements recorded for terrestrial corundum.
The Chemical Conundrum of Aluminum and Silicon on Mars
The significance of the discovery lies not in gemstone valuation, but in the strict chemical conditions required for corundum to form. The mineral is an aluminum oxide that typically demands an environment rich in aluminum and depleted in silicon.
Where silicate minerals are abundant, they tend to consume available aluminum to form silicate rocks such as plagioclase feldspar. Yet all three corundum-bearing rocks identified by Perseverance were dominated by plagioclase, creating a geological puzzle for researchers.
“Its formation generally requires bulk compositions enriched in aluminum and depleted in silicon and typically forms at either high temperatures or in association with tectonic processes,” Ollila and her colleagues write in their paper. “Hence, its detection in Martian rocks is surprising.”
Ann Ollila and research team
While Mars has an extensive volcanic history and plenty of igneous material, matching the required low-silicon, high-aluminum chemistry remains difficult. Researchers suggest the minerals could have formed through magma activity or interactions between rock and hot fluids.
Modeling the Isidis Impact and Deep Mantle Debris
Beyond surface chemistry, planetary scientists are also investigating whether ancient impacts could explain unusual mineral deposits within driving distance of the rover. A modeling study led by Alexander Trowbridge of the SETI Institute in Mountain View, California, examined the colossal impact that carved out the Isidis basin roughly 3.9 billion years ago.
The computer simulations tracked how planet-scale collisions excavate material from deep inside the planet. Debris squeezed to extreme shock pressures between roughly 6.5 and 8.7 million pounds per square inch (45 to 60 gigapascals) originated predominantly from the Martian mantle.
That extreme pressure leaves distinct structural deformation within crystals, offering scientists a reliable physical marker. If Perseverance encounters rocks bearing the scars of that specific pressure band during its journey across Jezero Crater, researchers can identify them as direct samples from the planet’s deep interior, adding vital context to the cache of core samples secured in titanium tubes for eventual return to Earth.
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