Sahara meteorite Teghaza 001 samples Mars's primordial crust from at least 4.1 billion years ago

Teghaza 001, a meteorite found in the Sahara Desert in Mali four years ago, is a fragment of Mars's primordial crust that formed at least 4.1 billion years ago, according to Yang Liu and colleagues in a paper published online in Science on October 29, 2026.

It is a coarse-grained igneous rock, a plagioclase-rich gabbro, whose internal structure shows it cooled slowly, probably underground, the study authors write. Sci.News, covering that paper, reports a measured total mass of 798.5 g for the eight recovered fragments of Teghaza 001; among those fragments, the largest has a measured mass of 442 g and is roughly 10 cm across. Dr. Yang Liu, a researcher at NASA's Jet Propulsion Laboratory, told Sci.News that the rock's distinctiveness emerged only under close study. One of the paper's reviewers, Liu added, 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, according to that 2026 Sci.News account of the Science study. 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 whose crystallization age is about 4.1 billion years, and a group of fragment-filled rocks that includes Northwest Africa 7034, some of whose pieces in that assemblage are older than 4.3 billion years. The study authors say Teghaza 001 differs from both.

Using uranium-lead methods on zircon crystals in Teghaza 001, Liu and colleagues report a measured crystallization age of about 4.11 billion years. A separate rubidium-strontium analysis in the same study gave a consistent estimate of about 4.24 billion years. That 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 reading places formation no later than about 4.1 billion years ago, in Mars's earliest geological period.

Oxygen isotopes in Teghaza 001 are heavier than those of other Martian meteorites, which the authors attribute to interaction with fluids enriched in oxygen-18 in the crust or with the magma. Minerals in the rock were also chemically altered on Mars before an impact ejected it. Matching the chemistry to orbital data, the team points to the southern Martian highlands, especially northwest of the Hellas impact basin, as the most likely source region.

Dr. Carl Agee, director and curator at the University of New Mexico's Institute of Meteoritics, told Sci.News that parts of the Northwest Africa 7034 assemblage known as Black Beauty reach similar ages, but that meteorite is a mix of rock types. Teghaza 001, he said, is a single unadulterated lithology at 4.1 billion years or older, with compositional clues of fluids and water, and is the oldest Martian igneous rock yet found by a wide margin. Another match anytime soon is, in his estimate, very unlikely. A specimen with a conflicting crystallization age, or chemistry that failed to match the southern highlands, would break that neat reading of an intact early-crust sample.