A Mars meteorite found in the Sahara formed at least 4.1 billion years ago

A rose-colored stone that desert prospectors picked up in the Sahara turns out to be a piece of Mars that formed more than four billion years ago, when the planet was still young enough to have water working through its rocks. The meteorite, named Teghaza 001, is a single, intact chunk of ancient Martian crust, and its chemistry does not match any Mars rock scientists have studied before.

That makes it something close to a field trip. Every Mars rover has explored a handful of landing sites, and almost every Martian meteorite on Earth comes from young volcanic rock. Teghaza 001 instead appears to come from the cratered southern highlands, the oldest terrain on the planet, a region no lander has ever touched.

“This is really our first piece of Martian crust from a part of Mars we’ve never had a sample of before,” said Lee Saper, the study’s second author, who did the work as a postdoctoral scholar at NASA’s Jet Propulsion Laboratory and is now a scientist at NASA’s Ames Research Center. The lead author, Yang Liu of JPL, says one of the paper’s reviewers called the rock “a Rosetta Stone for Mars.”

The findings, published in Science by a team from JPL, Caltech, UCLA, the University of New Mexico and the University of Maine, describe Teghaza 001 as a slowly cooled igneous rock, a gabbroic diorite, that crystallized from magma deep in the crust. Its mix of minerals, its texture and its chemistry all set it apart from the roughly 435 known meteorites from Mars.

How a speck of zircon dated a piece of Mars

The rock did not look special at first. Researchers at the University of New Mexico’s Institute of Meteoritics confirmed it was Martian from its oxygen isotopes, the chemical fingerprint that separates material from different planetary bodies. It looked like a shergottite, the most common class of Martian meteorite. Carl Agee, the institute’s director, noticed that its oxygen values resembled those of NWA 7034, the famous Martian meteorite nicknamed Black Beauty, and that some patches were rich in manganese oxide.

Liu almost passed on the sample. When she looked, she found odd textures and something that changed the project: zircon, a tough mineral that locks in uranium and lead when it crystallizes. Because uranium decays to lead at a known rate, zircon works as a natural clock. The team’s zircon measurements gave an age of about 4.11 billion years, with an uncertainty of only about 13 million years.

A second, independent clock came from Caltech. François Tissot’s lab, working with Alicia Cruz-Uribe of the University of Maine, used a laser beam about one sixth the width of a human hair to drill tiny pits into feldspar grains and measure rubidium and strontium directly inside a mass spectrometer. Each laser spot takes under a minute, and the analysis used a fragment smaller than a fingernail, so the rest of the rare rock survives for future work. That method gave about 4.24 billion years, with a wider error bar of roughly 200 million years, overlapping the zircon result.

“I think we actually jumped up and down; full on dance party in the lab,” Cruz-Uribe said of the moment the first results came back.

Only two other Mars rocks come close

Most Martian meteorites are geologically young, typically a few hundred million years old, which means they describe a planet that was already cold and dry. Only two others are older than four billion years. ALH84001, found in Antarctica in the 1980s, is about the same age but is made almost entirely of one mineral, which limits what it can reveal. Black Beauty holds fragments of similar age, but they are jumbled into a breccia, a rock assembled from broken pieces and reworked by heat and impacts over more than a billion years.

“Teghaza 001 is just one unadulterated rock type, and it’s 4.1 billion years or older, so that was a big surprise,” Agee said in a University of New Mexico statement.

For a sense of scale, Mars itself is about 4.5 billion years old, so this rock dates to its first few hundred million years. Liu points out that the stone is older than the oldest intact rocks on Earth, where plate tectonics has buried and recycled almost all of the planet’s original crust. Mars lost that kind of geological churn long ago, which is why its early history survives in pieces like this one.

To find where the rock might have come from, the team compared its mineralogy and chemistry with orbital data from NASA’s Mars Reconnaissance Orbiter. They identified 13 locations with a matching signature, most of them in the ancient southern highlands.

Water, and an atmosphere already leaking away

The rock also records contact with water. Some of its minerals were altered, and its oxygen isotopes show it reacted with fluids enriched in heavy oxygen before an impact blasted it off the planet. A companion paper by Saper, Liu and colleagues in Science Advances measured water and hydrogen isotopes in its phosphate minerals. Heavy hydrogen, deuterium, builds up when a planet loses light hydrogen to space. The team found the Martian water reservoir at that time already held at least about twice the deuterium-to-hydrogen ratio of Earth’s seawater.

In plain terms, Mars was already losing its atmosphere and water to space more than four billion years ago. “It records interactions of water and rock and maybe even an imprint of the Martian atmosphere as it was losing water,” Saper said.

The rock also helps with a deeper question. Its chemistry points to a mantle source unlike the one that fed the common shergottites, which suggests the interior of Mars was more varied than its meteorite collection implied.

What the rock cannot tell us yet

No one knows exactly where Teghaza 001 came from. The 13 candidate sites are matches by mineral signature, not a confirmed launch crater, and a meteorite carries no address. “Mars is a complex planet, and this meteorite is really cool, but we don’t know exactly where it came from, so this is really another example of why we need to bring back samples,” said Anya Udry, a planetary scientist at the University of Nevada, Las Vegas, who was not involved in the study.

The age is a minimum. The uranium-lead, lead-lead and rubidium-strontium clocks agree, but the team says they may all have been reset by a heating event about 4.1 billion years ago. In that case the rock originally crystallized even earlier.

Earth has also left its mark. The meteorite sat in the Sahara before anyone found it, and NASA notes that some of the fine-grained carbonate, sulfate and clay in the rock formed on Earth. Separating desert weathering from ancient Martian alteration is part of the analysis, and the manganese-rich patches Agee spotted are a clue to past environments, not evidence of life. It is also one rock. A single sample can open a window, but it cannot map a planet.

Common questions about Teghaza 001

How old is the Teghaza 001 meteorite?

Zircon crystals inside it give an age of about 4.11 billion years, and a separate rubidium-strontium measurement agrees within its error bars. Because a later heating event may have reset those clocks, the rock formed at least 4.1 billion years ago and possibly earlier.

How do scientists know a meteorite comes from Mars?

They measure its oxygen isotopes, which differ between planetary bodies, and compare its minerals and chemistry with data from Mars missions. Gas trapped in some Martian meteorites even matches the atmosphere measured by NASA’s Viking landers.

Is Teghaza 001 the oldest Martian meteorite?

It is one of only three Martian meteorites older than four billion years, with ALH84001 and Black Beauty. ALH84001 is close in age but made of almost a single mineral, and Black Beauty is a mix of fragments, so Teghaza 001 is the clearest intact sample of early crust found so far.

Does Teghaza 001 show there was life on Mars?

No. It shows that water altered rocks in the ancient crust and that Mars was already losing hydrogen to space. Those are conditions scientists study when they ask whether life was possible, but the rock contains no evidence of life.

What comes next

The meteorite was found in 2022 and named after the Teghaza salt plain in Mali. Its largest piece, 442 grams, belongs to the Maine Mineral & Gem Museum in Bethel, which has lent another fragment so work can continue at Caltech and the University of Maine. The age study appeared in Science on October 29, 2026, after the water study in Science Advances in June. Liu says her team has “only scratched the surface,” and the 13 candidate sites give future orbiters and landers a short list of places where the rest of this ancient crust may still be waiting.

Reference: Liu et al., “A Martian meteorite that formed ≳4.1 billion years ago samples Mars’ early crust and mantle,” Science, 2026. DOI: 10.1126/science.adz5646

Tags: astronomy, nasa, Mars, water on Mars, Martian meteorites, meteorites