Scientists identify 4.1-billion-year-old Martian meteorite in Sahara

NASA-funded scientists have determined that an 800-gram meteorite recovered from the Teghaza salt plain in Mali in 2022 is more than 4.1 billion years old, making it one of the oldest known Martian rocks on Earth. The stone, named Teghaza 001, is among roughly 435 Martian meteorites identified so far and joins ALH84001 and a sample nicknamed Black Beauty as the three most ancient specimens.

The findings were presented in a paper published in Science on Oct. 29, with a complementary study on the meteorite’s water content appearing in Science Advances in June. Researchers highlighted the rock’s unusual mineral mix, including igneous minerals and zircon crystals, which together record the formation of Mars’ early crust and subsequent alteration by underground water.

"It was only after we started looking closely that we realized this meteorite is really unique," said lead author Yang Liu of NASA’s Jet Propulsion Laboratory. A reviewer described the sample as a "Rosetta Stone for Mars."

Co-author Lee Saper, now at NASA’s Ames Research Center, added that the meteorite provides the first direct sample of a portion of the Martian crust not previously represented in Earth-based collections, and may preserve evidence of early atmospheric loss.

Initial identification relied on oxygen-isotope signatures that distinguish Martian material, followed by detailed texture and mineral analyses. Age dating employed an in-situ rubidium-strontium technique developed by a Caltech team, allowing precise dating of individual mineral grains without destroying the sample.

The research suggests that water altered the rock around 4.1 billion years ago, implying that the meteorite itself formed even earlier. Scientists anticipate that further study will refine understanding of Mars’ early geological evolution, water cycles, and atmospheric changes.