Scientists have uncovered a beforehand unknown Martian rock containing a mineral by no means earlier than discovered on the Pink Planet.
In contrast to Earth, the place billions of years of plate tectonics, volcanism, and erosion have regularly reshaped the floor, Mars has preserved much of its ancient geological record. That makes every rare Martian rock a valuable archive of the planet’s earliest history.
Now, an international team of scientists has uncovered one of the most intriguing examples yet: a previously unknown Martian rock type containing garnet, the first time the mineral has ever been identified in a sample from the Red Planet.
The finding could reveal new details about the temperatures, pressures, and geological processes that shaped Mars more than four billion years ago, offering scientists another piece of the puzzle of how the once-active planet evolved into the cold, arid world seen today.
The international research team included James Darling, Professor of Earth and Planetary Science at the University of Portsmouth’s School of the Environment and Life Sciences.
Garnet opens a Martian archive
Although best known as a deep-red gemstone and January’s birthstone, garnet is one of geology’s most informative minerals. Because it forms under specific combinations of heat, pressure, and chemistry, it can preserve a detailed record of the conditions in which a rock formed, making it a powerful tool for reconstructing a planet’s geological past.
Its unexpected discovery in a Martian sample provides scientists with an entirely new type of geological record from Mars, one that could reveal how parts of the planet’s crust formed and changed during its earliest history.
Professor Darling said: “The findings add a striking new dimension to our understanding of the geology of Mars and open an exciting new window into the evolution of our planetary neighbor.”
The research was led by Tanya Kizovski, Assistant Professor of Earth Sciences, from Brock University in Canada.
She said: “This discovery is going to expand our knowledge of the geologic processes that are possible on this planet. This new garnet-bearing rock type could give us clues to how Mars has changed throughout its history and new insights into the ancient environments that could have formed the garnet and related minerals.”
A second look revealed garnet
Kizovski and colleagues at the Royal Ontario Museum (ROM) detected the garnet while analyzing a fragment of a Martian meteorite called NWA 8171, which is held in the ROM’s collections.
Kizovski was studying the fragment’s minerals and chemical makeup.
“This little section of the meteorite looked really interesting, and the chemistry was a bit odd,” she said. “At first, we assumed it was a mineral called pyroxene, which is very common, but then we decided to take a second look.”
With the University of Portsmouth Electron Microscopy and Microanalysis Unit and the ROM’s specialized laser equipment, the group, which also includes scientists from the Università di Trieste in Italy and the Open University in the UK, unexpectedly identified garnet. Until now, that mineral had never been found on Mars.
Mars origin remains uncertain
The group studied the fragment’s chemistry and mineralogy, then considered how the garnet might have formed.
Professor Kizovski said: “Garnet is a classic example of a mineral often found in metamorphic rocks on Earth. The process of metamorphism transforms igneous or sedimentary rocks into a new form through exposure to extreme heat, high pressure, or hot fluids.
“On Mars, the heat and pressure needed to produce garnet through metamorphism could have come from the impact of a meteorite hitting the surface of Mars, magma rising up into the Martian crust, or both.”
Kizovski cautions that the evidence does not yet prove whether the garnet-bearing rock formed on Mars or arrived on the Red Planet inside another meteorite and became incorporated into its surface. That leaves open the possibility of an “extra-Martian” origin.
Isotopes could settle the source
Scientists now need to examine the garnet’s isotopic signatures to determine whether it formed on Mars or came from another planetary body.
“Measuring oxygen isotopes from the garnet-bearing rock type itself would help to confirm if it is Martian in origin or from an exotic meteorite impactor,” Kizovski said. “Isotopes are a collection of atoms with equal numbers of protons and electrons, but different numbers of neutrons.”
That test, however, would require destroying part of the sample, “which was avoided thus far due to its rarity, as it may be the only garnet-bearing Martian rock we have for study,” she added.
ROM curator Kim Tait and Research Assistant Jessica Tomacic, together with Professor Darling, are continuing to examine the sample. “With their work and more comparisons to rover and orbital data, I’m hopeful that we will be able to learn more about the origin and history of garnet on Mars,” Kizovski said.
Reference: “Expanding Mars’ lithologic diversity: discovery of a garnet-bearing clast in NWA 8171” by T.V. Kizovski, L.F. White, A. Černok, K.T. Tait, V.E. Di Cecco, X. Chu, J.M. Tomacic, R.I. Nicklin and J.R. Darling, 16 June 2026, Geochemical Perspectives Letters.
DOI: 10.7185/geochemlet.2619
This research project is funded in part by the Government of Canada’s Natural Sciences and Engineering Research Council (NSERC) and the Killam Trusts Dorothy Killam fellowship, as well as Science and Technology Facilities Council (STFC) funding at Portsmouth.
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