Photo: Ollila et al., Geophys. Res. Lett., 2026
In 2025, NASA’s Perseverance rover used a laser to analyze light-colored rocks scattered around Jezero Crater. Researchers did not expect anything unusual, but the analysis revealed a surprising discovery, ScienceAlert reports.
Scientists found something never previously detected on Mars: a mineral that is considered a gemstone on Earth. The mineral is corundum, the crystalline form of aluminum oxide that makes up rubies and sapphires. The researchers also detected chromium inclusions, which give rubies their characteristic red color.
“Unexpectedly, analysis of three plagioclase-rich rock fragments at the crater rim using the SuperCam TRL instrument revealed clear evidence of chromium-bearing corundum,” a research team led by geochemist Ann Ollila of Los Alamos National Laboratory said.
The researchers subsequently conducted a detailed laboratory analysis and compared the Martian measurements with those from terrestrial rocks. The results showed striking similarities between the signals produced by the Martian samples and those of corundum found on Earth.
This is the first detection of corundum on Mars. The significance of the discovery is not that the mineral is considered a gemstone on Earth, but that the conditions required for its formation are difficult to find on the Red Planet.
“Corundum formation generally requires a bulk composition enriched in aluminum and depleted in silicon, and typically occurs either at high temperatures or in association with tectonic processes. Its detection in Martian rocks is therefore unexpected,” the researchers said.
Mars has no shortage of heat. The challenge lies in the planet’s chemistry. Corundum forms when aluminum oxide crystallizes, generally requiring abundant aluminum and limited silicon. When silicate minerals are present, they tend to bind the available aluminum into aluminosilicate minerals such as plagioclase feldspar.
All three samples in which Perseverance detected evidence of corundum were dominated by plagioclase. The issue is not that corundum and plagioclase cannot coexist, but that the geological conditions that would allow them to form together have not previously been observed on Mars.
All three samples were float rocks, meaning they were not attached to bedrock and were lying freely on the surface. This suggests they may have originated elsewhere and been transported to their current location. Such rocks are particularly valuable to researchers because they can provide information about Mars’ geology without requiring the rover to travel to another geological site.
The three samples showed two distinct luminescence peaks at wavelengths of 692.7 and 694.1 nanometers. These are characteristic signals produced by corundum when chromium atoms replace some of the aluminum atoms, as occurs in ruby.
In one sample — the only one for which this measurement was available — the luminescence lasted approximately three milliseconds, closely matching the range measured in terrestrial corundum.
Corundum can form through several processes, including crystallization from magma and interactions between rocks and hot fluids. However, the researchers believe the mineral in these Martian samples may have formed during the enormous impact that created Jezero Crater in the distant past.
Massive impacts expose rocks to extreme heat and pressure, creating conditions similar to those responsible for the formation of metamorphic minerals deep within Earth’s crust. Corundum has previously been found in impact-altered rocks on both the Moon and Earth.
