A Martian Meteorite Kept a 4.1-Billion-Year Water Record
Teghaza 001 is among the oldest known Martian meteorites. Its minerals record water altering ancient crust—but not where on Mars the rock began.
A Stone Older Than Most Martian Rocks We Can Hold
A meteorite found in the Sahara in 2022 now carries an unusually old record of Mars. NASA-funded researchers report that Teghaza 001, a roughly 800-gram rock named for a salt plain in Mali, formed more than 4.1 billion years ago. Their study appeared in Science on 29 October 2026. This is a newly described analysis of an existing find—not a fresh rock fall or a sample returned by a spacecraft.
The NASA/JPL report says the rock is one of the very oldest Martian meteorites identified on Earth. Its studied slice preserves a patchwork of volcanic minerals. That mixture matters because it records more stages of an early crust than a specimen dominated by a single mineral.
The Water Is in the Sequence
Scientists first identified its Martian origin by comparing oxygen isotopes with known Martian meteorites. They then examined mineral textures and zircon crystals, which help constrain a rock's history. The team used an in-situ rubidium–strontium technique on individual mineral grains in a piece smaller than a fingernail, preserving much of a rare specimen rather than dissolving it wholesale.
The age results indicate the rock was altered by water about 4.1 billion years ago. That means its original volcanic formation preceded the alteration. The evidence is a chemical and mineral record of water interacting with rock, not a photograph of an ocean or proof of life. A separate Science Advances paper published in June examined its water content; the October study adds a broader account of the rock's ancient crustal history.
- Found on Earth: the Sahara discovery dates to 2022.
- Origin: isotope and mineral evidence supports a Martian meteorite; its exact Martian launch site is unknown.
- Timing: formation predates water alteration around 4.1 billion years ago; the dates refer to different events.
What the Meteorite Cannot Tell Us Yet
NASA compares the meteorite's mineralogy with orbital observations of Mars's southern highlands and discusses possible source regions. None is a confirmed address. Future study may refine what the sample says about the planet's early water cycle; it cannot on its own map every ancient river or settle whether Mars hosted organisms.
One rock kept two chapters of early Mars.
The accompanying image is a NASA/JPL-Caltech photograph of a studied slice, with a one-millimetre scale bar. It shows the interior specimen under laboratory lighting, not the rose-coloured exterior pictured elsewhere in NASA's story, and not an image of Mars's surface. Credit: NASA/JPL-Caltech. NASA's media guidelines permit factual editorial reuse with acknowledgement, without implied endorsement.