Meteorite Found in Sahara is Piece of Mars at Least 4.1 Billion Years Old | Sci.News

Teghaza 001, a meteorite found in the Sahara Desert in Mali four years ago, is a fragment of Mars’ primordial crust, formed at least 4.1 billion years ago, according to a new paper in the journal Science.

Teghaza 001 consists of eight fragments with a total mass of 798.5 g, the largest being 442 g and roughly 10 cm across.

“It was only after we started looking closely that we realized this meteorite is really unique,” said Dr. Yang Liu, a researcher at NASA’s Jet Propulsion Laboratory.

“One of the paper’s reviewers called it a Rosetta Stone for Mars.”

Nearly all of the roughly 300 known Martian meteorites are far younger than the planet’s surface, which is dominated by terrain more than 3 billion years old.

The three main classes, known as shergottites, nakhlites and chassignites, formed 2.4 billion years ago or later.

Only two older specimens had been identified: Allan Hills 84001, a rock that crystallized about 4.1 billion years ago, and a group of fragment-filled rocks, including Northwest Africa 7034, some of whose pieces are older than 4.3 billion years.

According to the study authors, Teghaza 001 is different from both. It is a coarse-grained igneous rock, a plagioclase-rich gabbro, whose internal structure shows it cooled slowly, probably underground.

The researchers dated its zircon crystals using uranium-lead methods and arrived at an age of about 4.11 billion years.

A separate rubidium-strontium analysis gave a consistent, though less precise, date of about 4.24 billion years.

The date may mark a period of hot, mineral-laden water circulating through the rock soon after it crystallized, rather than the moment it solidified.

Either way, it formed no later than about 4.1 billion years ago, during the earliest geological period of Mars.

“There are a few parts to Black Beauty that are around that age, but that whole meteorite itself is a conglomeration of many different rock types,” said Dr. Carl Agee, director and curator at the University of New Mexico’s Institute of Meteoritics.

“Teghaza 001 is just one unadulterated rock type, and it’s 4.1 billion years or older, so that was a big surprise.”

“It’s the oldest Martian igneous rock ever found by a huge margin, but in addition to that, it seemed to have these clues in its composition that suggested it had been in an environment that had fluids and water coursing through it.”

Teghaza 001 also carries evidence of water: its oxygen isotopes are heavier than those of other Martian meteorites, which the researchers attribute to interaction with fluids enriched in oxygen-18, either in the crust or directly with the magma.

Minerals in the rock were also chemically altered on Mars, well before an impact flung the rock into space.

Comparing the rock’s chemistry with orbital measurements, the scientists identify the southern Martian highlands, particularly the region northwest of the Hellas impact basin, as the most likely source area.

“It’s not like this is very common so not only is it ancient and samples a different type of environment in a different time on Mars, but we don’t have any other samples like it,” Dr. Agee said.

“Chances are very slim or next to impossible, that we’ll get another one, like this anytime soon.”

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Yang Liu et al. A Martian meteorite that formed ≳4.1 billion years ago samples Mars’ early crust and mantle. Science, published online October 29, 2026; doi: 10.1126/science.adz5646