Sahrawi prospectors found a rosy-coloured stone in the Sahara Desert in 2022. The rock, later divided into eight fragments weighing just under 800 grams, would prove to be Teghaza 001, the oldest known Martian meteorite ever found.
The meteorite entered the desert meteorite trade and was bought by a private collector, who sent a piece to the University of New Mexico. There, researchers identified it as Martian from its oxygen isotopes.
Yang Liu, a planetary scientist at the Jet Propulsion Laboratory at the California Institute of Technology, received a sample from the University of New Mexico team and led the subsequent work. The findings, published in Science, date Teghaza 001 to about 4.11 billion years and establish it as the oldest known Martian meteorite.
“We're holding a piece of a rock that's dated even before the oldest Earth rock—a piece of Mars that's so ancient, it existed when life had just started on Earth,” Liu said.
The name Teghaza 001 comes from the salt plain in Mali where it was discovered. It is a piece of Martian crust, an igneous rock formed as magma cooled slowly.
The stone is largely feldspar, threaded with darker pyroxene crystals that can reach a millimeter across. Its zircon crystals allowed researchers to use uranium-lead analysis for the age measurement.
Carl Agee, director and curator of the University of New Mexico’s Institute of Meteoritics, co-analysed the meteorite. “It's the oldest Martian igneous rock ever found by a huge margin,” he said.
Karen Ziegler, a planetary scientist at the University of New Mexico, measured the oxygen isotopes that confirmed the stone’s Martian origin.
Alicia Cruz-Uribe of the University of Maine and her colleagues tested the result with an independent rubidium-strontium dating technique. Working at the California Institute of Technology in summer 2025, they used a laser beam one-sixth the width of a human hair to drill into the sample, confirming the zircon age.
Lee Saper, the paper’s second author, is now a scientist at NASA’s Ames Research Center in Silicon Valley.
The rock records conditions deep inside early Mars. The magma from which it formed rose from more than 160 kilometers within the Martian mantle, at a depth where garnet is stable.
Some of its minerals were altered by water, evidence that liquid water once moved through the planet’s ancient mantle and crust. Hydrogen left within the meteorite also indicates that Mars was already well on its way to losing most of its atmosphere when the rock formed more than 4.1 billion years ago.
Composition and alteration patterns placed the meteorite in Mars’s southern highlands, northwest of the Hellas impact basin. The closest chemical matches were found in that rugged, crater-pocked terrain.
The main 442-gram mass is held by the Maine Mineral & Gem Museum in Bethel. The University of New Mexico’s Institute of Meteoritics holds 22 grams.
Only Allan Hills 84001 and Black Beauty (NWA 7034) are among the other known Martian meteorites older than 4 billion years. Researchers know of roughly 435 meteorites from Mars, though most reveal conditions from only the most recent 600 million years or so of the planet’s 4.5-billion-year history.
Teghaza 001 therefore gives researchers a rare sample from an earlier part of Martian history, preserving evidence of crust formation, water interaction and atmospheric loss from the planet’s first billion years.
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