Summary
A NASA-funded study dates the formation of Teghaza 001 to more than 4.1 billion years ago. Its minerals preserve evidence of ancient Martian crust and alteration by water.
A NASA-funded study has dated the formation of Teghaza 001 to more than 4.1 billion years ago, making it one of the oldest known Martian meteorites. The nearly 2-pound (800-gram) rock, found in the Sahara in 2022, contains a mix of minerals that records the formation of ancient Martian crust and its later alteration by water. The researchers’ initial characterization was published in Science, NASA’s Jet Propulsion Laboratory reported on Oct. 29, 2026.
A rare sample of ancient Martian crust
Teghaza 001 is one of roughly 435 meteorites identified as coming from Mars. It ranks among the three most ancient Martian meteorites found on Earth. One of the others, ALH84001, is of similar age but is composed almost entirely of a single mineral. “Black Beauty” formed about 2.1 billion years ago and consists of small fragments of volcanic rock.
Teghaza 001 offers a different geological record. Its varied igneous minerals—minerals formed from cooled magma—provide evidence about how the Martian crust developed and was subsequently changed by water beneath the surface. The JPL account says its mineralogy matches observations of Mars’ cratered southern highlands made by the Mars Reconnaissance Orbiter.
Researchers identified 13 locations on Mars whose mineralogy and chemistry could match the meteorite. Those matches help narrow the possibilities, but the exact place where the rock originated is not known.
Dating the rock and its water alteration
Researchers first identified Teghaza 001 as Martian by comparing its oxygen isotopes with those in other Martian meteorites. Oxygen isotopes act as geochemical fingerprints that can help distinguish material from different planetary bodies.
The team also found zircon crystals, which can preserve clues about a rock’s formation and be used for precise age dating. To analyse the rare sample, the researchers used an in-situ rubidium-strontium method developed by a team at Caltech. Unlike bulk analysis, which dissolves an entire sample, this approach examined individual mineral grains at the surface using a piece smaller than a fingernail. That allowed the researchers to study the meteorite while preserving more of it for future work.
The reported dating indicates that water altered Teghaza 001 around 4.1 billion years ago, suggesting the rock itself formed earlier. That distinction matters: the alteration date records when water changed the rock, rather than giving the precise date when its original material formed.
The meteorite’s textures, chemistry and oxygen isotopes also point to a more dynamic water cycle on early Mars, according to the researchers. The JPL report describes the paper as an initial characterization; further study of the sample may help scientists investigate how water and rock interacted as the planet’s early crust developed.