Teghaza 001, a meteorite found in the Sahara in September 2022, has been dated by a Caltech-led team to over 4.1 billion years, potentially making it the oldest known Martian fragment. Its silicon-rich chemistry suggests early Mars may have formed a chemically evolved, granite-like crust despite lacking plate tectonics. Hydrogen isotopes in the rock point to substantial early water even as Mars began losing its atmosphere; the study is a preprint and awaits peer review, with scientists cautioning that zircon ages can be reset by later melting or fluids.
Teghaza 001: A Possible 4.1+ Billion-Year-Old Mars Rock Suggests Early Drying and a Granite-Like Crust
Photo Credit: iStock
A meteorite recovered from the Sahara Desert is offering scientists a rare window into Mars' earliest history. Named Teghaza 001, the sample may be the oldest Martian fragment yet found on Earth and points to a planet that began drying earlier than many researchers expected while developing a more chemically evolved crust.
A Caltech-led team reported in a July 16, 2026 preprint that Teghaza 001 dates to more than 4.1 billion years ago. Prospectors discovered the rock in September 2022. Because Mars formed about 4.5 billion years ago, this specimen appears to come from the planet's infancy and—if confirmed—would join Allan Hills 84001 as one of only two known Martian crust samples from that ancient era.
How the Age Was Determined
Scientists dated Teghaza 001 using zircon minerals, which contain uranium that decays to lead on a predictable timetable (U–Pb dating). Zircon is a robust mineral for precise crystallization ages, but researchers caution that zircon "clocks" can be reset by later melting or fluid exposure, a factor that makes interpretation more complex.
Chemistry and What It Means
The meteorite is unexpectedly rich in silicon and shows chemistry that resembles granite-like rocks on Earth. On our planet, granite commonly forms in settings influenced by plate tectonics; Mars lacks clear evidence of plate tectonics, so the finding suggests alternative igneous processes—complex magmatic differentiation or prolonged crustal reworking—could produce chemically evolved crust on Mars.
Water, Atmosphere and Early Mars
Hydrogen isotopic ratios preserved in the meteorite provide evidence that substantial water was present early in Mars' history even as the planet began losing its atmosphere. That picture is consistent with other lines of evidence suggesting Mars' magnetic field weakened, its atmosphere thinned, and surface water largely disappeared over time.
"Teghaza 001 will revolutionize the way that we think about early Mars," said Lee Saper, a geochemist at NASA's Jet Propulsion Laboratory.
"It's very strange; we don't expect that," added Eva Scheller, a planetary scientist at Stanford University, referring to the granite-like chemical signal.
Next Steps and Cautions
Because the paper is currently a preprint, the results await formal peer review and follow-up studies. Researchers are comparing Teghaza 001 with other Martian evidence—including Allan Hills 84001 and observations made by rovers such as Perseverance, which has identified outcrops and mineral mixtures that can appear more evolved than previously thought.
Further analyses will test whether the zircon ages record the rock's original formation or later thermal or fluid events, and whether Martian crustal evolution routinely produced silica-rich rocks without Earth's style of plate tectonics. These questions bear on broader issues: how rocky planets retain water, how atmospheres evolve, and why Earth remained habitable for billions of years.
Help us improve.
