A Martian meteorite found in Mali in 2022 offers new evidence that Mars had a warm, wet environment billions of years ago. The rock, named Teghaza 001 (Teg 001), formed at least 4.1 billion years ago, making it the oldest Martian igneous rock ever found.
Researchers led by Yang Liu at NASA's Jet Propulsion Laboratory and Carl Agee at the University of New Mexico's Institute of Meteoritics analyzed the meteorite and published their findings in Science. They used uranium-lead dating of zircon crystals to determine Teg 001's age, conducting ten measurements across six shocked zircon grains.
The meteorite shows signs of interaction with water on Mars' ancient surface. Its oxygen isotope composition indicates exposure to surficial fluids, and the rock contains high levels of manganese oxide, a compound that rovers on Mars currently search for as an indicator of habitable environments. Pigeonite within the rock shows evidence of alteration by fluid reactions.
Agee noted the meteorite's distinctiveness. "It's the oldest Martian igneous rock ever found by a huge margin, but in addition to that, it seemed to have these clues in its composition that suggested it had been in an environment that had fluids and water coursing through it."
Unlike Black Beauty, the previous standard ancient Martian meteorite found in 2011, Teg 001 is a single unadulterated rock type rather than a conglomeration of different materials. Agee said: "This sample probably came from an environment on Mars that was more Earth-like."
The findings point to Mars' Pre-Noachian period, the planet's earliest epoch, when it may have been fundamentally different from the cold, dry desert it is today.