NASA-funded scientists date Mars meteorite Teghaza 001 to more than 4.1 billion years

A rock weighing 800 grams and found in the Sahara Desert in 2022 came from Mars and formed more than 4.1 billion years ago, NASA-funded scientists said in an announcement on Oct. 29, 2026.

The meteorite is named Teghaza 001 after the salt plain in Mali where it was discovered, and prospectors found it in the Sahara Desert in September 2022. It is one of roughly 435 known meteorites from Mars and one of the three most ancient Martian meteorites found on Earth.

Researchers published an initial characterization of Teghaza 001 in Science on Thursday, Oct. 29, 2026. It marks only the second known Martian meteorite from the planet’s earliest crust; the other is Allan Hills 84001. Allan Hills 84001 is similar in age but composed almost entirely of one mineral, while Black Beauty, also known as NWA 7034, formed about 2.1 billion years ago and consists of small volcanic rock fragments.

The rock’s mix of igneous minerals records how Mars’ crust formed from cooling magma before subsurface water altered it. Its distinctive mineralogy matches observations by NASA’s Mars Reconnaissance Orbiter in the planet’s cratered southern highlands. No one will ever know exactly where Teghaza 001 originated on Mars, but the paper identifies potential locations matching its mineralogy and chemistry.

The age-dating work showed that Martian water altered Teghaza 001 around 4.1 billion years ago, meaning the rock itself formed even earlier. Clues within its oxygen isotopes, texture, and chemistry point to a much more dynamic water cycle on early Mars. A separate paper published in Science Advances in June detailed the meteorite’s water content and how water shaped the planet’s early surface.

Both Teghaza 001 and Allan Hills 84001 show Mars had more water early in its history and began losing it early as the magnetic field disappeared and the atmosphere thinned and cooled. Mars formed about 4.5 billion years ago, and the water loss seems to have come in the planet’s infancy because the meteorites are at least 4.1 billion years old. Clues about water loss come from hydrogen ratios; when Mars began losing water, the higher ratio of hydrogen to deuterium dropped.

Teghaza 001 reveals Mars had a crust like granite, which is surprising because the planet lacks plate tectonics. The meteorite is rich in zircons and silicon. Zircon contains uranium that decays to lead at a known rate for age dating. It contained a lot of silicon, hinting at granite-like rocks on ancient Mars.

Eva Scheller of Stanford University said Mars’s granite-like rock is strange because scientists do not expect that. Most of Mars’ crust is solid basalt, unlike Earth, where granite forms from cooling magma generated by tectonic plate movement. Impacts from meteorites have exposed some granite-like deposits on Mars. Scientists do not know yet how Mars produced granite-like deposits without plate tectonics, but evidence points to complex magma systems on early Mars.

The Perseverance rover found a rock outcrop called Plankeholmane containing quartz, a key component of granite, and a speckled white rock called Atoko Point containing pyroxene and feldspar, components of granite on Earth. Both rocks looked granite-like.

Researchers at the University of New Mexico had already identified Teghaza 001 as Martian based on its oxygen isotopes before Yang Liu examined it. Scientists verify a meteorite as Martian by matching its mineral and chemical components to data from NASA’s Mars missions, including the Viking landers and the Curiosity and Perseverance rovers. Teghaza 001 first appeared to be a shergottite, the most common class of meteorite from Mars. Martian meteorites found on Earth share a common history: an impact blasted them off Mars and placed them on a trajectory to Earth.

Liu and colleagues discovered zircon crystals in the meteorite, which record clues to a rock’s formation and can precisely age-date a sample. Zircon contains uranium that decays to lead at a known rate. Caltech coauthor Francois Tissot helped use a novel in-situ rubidium-strontium age-dating method, analyzing single mineral grains on the rock’s surface instead of dissolving the entire sample.

Tissot said his lab is among the few worldwide able to perform this age-dating and the first to date such an ancient Martian meteorite. He hopes to pave the way for dating more Martian meteorites or samples from other planets, moons, and asteroids. The method preserves rare samples because it analyzes single grains instead of dissolving the whole sample.

University of Maine professor Alicia Cruz-Uribe and colleagues measured isotopes at Caltech in summer 2025, showing Teghaza 001 is 4.1 billion years old. She developed a new laser ablation dating method as part of a multiyear project on Mars’ crust formation with colleagues from Caltech, UCLA, and the University of New Mexico. Her technique uses helium gas to carry laser-removed material into a mass spectrometer that separates elements by mass.

The method looks for rubidium and strontium, allowing dating of minerals other than uranium-and-lead-bearing minerals, which was crucial for dating feldspar in Teghaza 001. Cruz-Uribe and colleagues found the rubidium-strontium age matched the uranium-lead age for zircons from the rock. The mass spectrometer is in Francois Tissot’s Caltech lab, and a single laser spot takes less than one minute.

Samples used in the study are held at the Institute of Meteoritics at the University of New Mexico and total 22 grams of Teghaza 001. The primary mass, weighing 442 grams, is held by the Maine Mineral & Gem Museum in Bethel. The museum loaned an additional piece so work can continue at Caltech and UMaine. Cruz-Uribe analyzed an additional loaned sample in UMaine’s MicroAnalytical Geochemistry and Isotope Characterization Laboratory.

Yang Liu of NASA’s Jet Propulsion Laboratory is the lead author of the Science paper and said close study showed the meteorite is really unique. She almost passed on examining the rock but odd textures and unusual minerals she had not seen before drew her in. Lee Saper, the paper’s second author, worked at JPL as a postdoctoral scholar and is now at NASA’s Ames Research Center.

Saper said Teghaza 001 is the first piece of Martian crust from a part of Mars never sampled before. He said it records interactions of water and rock and maybe an imprint of the Martian atmosphere as it was losing water. A reviewer of the Science paper called Teghaza 001 a Rosetta Stone for Mars.

Lydia Hallis of the University of Glasgow said the discovery doubled the number of old meteorites available and many researchers want a piece. Christopher Herd of the University of Alberta said there is more of a story to Teghaza 001 than most other Martian meteorites. Lee Saper gave a talk at the Goldschmidt geochemistry conference in Montreal, Canada, on July 14 and said the meteorite will change the way scientists think about early Mars.

A Caltech-led team announced on July 16, 2026, that Teghaza 001 is over 4.1 billion years old. A not-yet peer-reviewed paper was available as a preprint on the ESS Open Archive on April 14, 2026.

Cruz-Uribe said adding a third sample with unique geochemistry lets scientists see a different part of Mars’s ancient history, including what the mantle looked like and different mantle sources on Mars. The new study in Science confirmed Teghaza 001’s age and that it dates back to the formation of Mars’ crust and mantle.