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University of Maine professor Alicia Cruz-Uribe and her colleagues were analyzing a box of rock samples from Mars when they made an unexpected discovery. They would confirm that one sample came from one of the oldest Martian meteorites ever found on Earth.
While examining samples to determine their age, the group selected one from Teghaza 001, an ancient Martian meteorite found by Sahrawi prospectors in the Sahara Desert in 2022. Until recently, little was known about the age and origins of the meteorite.
Most Martian meteorites found on Earth are no more than about 2 billion years old. But in a lab at the California Institute of Technology in summer 2025, Cruz-Uribe and her colleagues measured isotopes showing that Teghaza 001 is 4.1 billion years old.
Only two other known Martian meteorites are older than 4 billion years: Allan Hills 84001 and NWA 7034, also known as Black Beauty.
“I think we actually jumped up and down; full on dance party in the lab,” said Cruz-Uribe, Edward Sturgis Grew Professor of Petrology and Mineralogy.
In a new study published in Science, Cruz-Uribe and her colleagues confirmed not only Teghaza 001’s age but also that it dates back to the formation of Mars’ crust and mantle — offering a rare window into the planet’s geologic history.
“When you add a third sample, and its geochemistry is really unique compared to the other samples that we have, it lets us see a different part of Mars’s ancient history in terms of what the mantle looked like and what the different mantle sources were on Mars,” Cruz-Uribe said.
