When a nearly 2-pound (800-gram), rose-colored meteorite was picked up in the Sahara Desert in 2022, no one knew its age or origin. NASA-funded scientists eventually confirmed it as a piece of Mars that formed more than 4.1 billion years ago.

Named Teghaza 001 after the salt plain in Mali where it was found, it joins roughly 435 Martian meteorites identified on Earth, and NASA describes it as one of the three most ancient ever recovered.

Researchers first suspected it was a common shergottite based on its oxygen isotopes, but closer study revealed odd textures and unusual minerals that set it apart. One reviewer of the paper, according to NASA's Jet Propulsion Laboratory, called it "a Rosetta Stone for Mars."

Teghaza 001 stands apart from its ancient peers, ALH84001 and "Black Beauty," because of its complex mix of igneous, or volcanic, minerals.

ALH84001 is composed almost entirely of a single mineral, while Black Beauty, which formed about 2.1 billion years ago, is made of small volcanic rock fragments. Teghaza 001 instead tells a story of how Mars' crust formed from cooling magma and was later altered by subsurface water.

Lead author Yang Liu of JPL said it was only after looking closely that the team realized the meteorite was unique. Co-author Lee Saper, now at NASA's Ames Research Center, told NASA that it is "our first piece of Martian crust from a part of Mars we've never had a sample of before."

The team found zircon crystals in the meteorite, minerals that record a rock's formation history and allow precise age-dating. Caltech coauthor Francois Tissot helped apply a novel in-situ rubidium-strontium dating method, analyzing single mineral grains on a piece smaller than a fingernail.

Unlike bulk techniques that dissolve an entire sample, this method preserves rare Martian material for future studies, CBS News reports. The results showed the rock had been altered by Martian water around 4.1 billion years ago, suggesting it formed even earlier.

Tissot said his lab is among very few worldwide able to perform this kind of dating and the first to date such an ancient Martian meteorite, hoping to pave the way for dating returned samples from other planets, moons, and asteroids.

The chemical signatures in Teghaza 001 point to a much more dynamic water cycle on early Mars than scientists had believed.

According to NASA, the meteorite's distinctive mineralogy matches what the Mars Reconnaissance Orbiter has observed in the planet's cratered southern highlands, and researchers identified 13 locations on Mars that match its mineralogy and chemistry.

Saper said the rock "records interactions of water and rock and maybe even an imprint of the Martian atmosphere as it was losing water."

A separate paper published in Science Advances in June detailed the meteorite's water content and how water may have shaped the early planet's surface, giving researchers two complementary views of the same ancient stone.

The findings carry weight beyond geology, touching on whether Mars could once have hosted life.

According to Labroots, co-author Dr. Carl Agee of the University of New Mexico said the sample's anomalous oxygen isotopes and high manganese levels were consistent with an environment on Mars that was "more Earth-like" than the dry desert the planet later became, noting that manganese oxide can indicate biological activity.

Labroots also describes hypotheses of a habitable early Mars with rivers, lakes, and seas before the planet's interior cooled, it lost its magnetic field, and volcanic activity ceased. These remain hypotheses, but Teghaza 001 offers physical evidence from the very beginning of Martian history.

The initial characterization, published Thursday in the journal Science, is only the opening act. Liu and her co-authors say they are eager to see what the wider scientific community learns from the meteorite, with Liu telling NASA that "we've only scratched the surface."

The rock's origin point on Mars will never be known exactly, but the 13 candidate locations in the southern highlands give future researchers concrete targets to compare against orbiter data.

Tissot's team hopes the new dating technique will now be applied to more Martian meteorites and, eventually, to samples returned from other planets, their moons, and asteroids — turning a lucky Saharan find into a template for studying rare planetary material without destroying it.