A Martian meteorite recovered from the Sahara Desert in Mali has been dated to at least 4.1 billion years ago, placing it among the rarest known samples of the Red Planet.
The Rarity of Ancient Martian Crust
Crater counts across Mars indicate that most of the planet’s surface formed more than three billion years ago. Yet the physical samples available to researchers on Earth tell a different story. The three primary classes of Martian meteorites—shergottites, nakhlites, and chassignites—are all 2.4 billion years old or younger.
Until this analysis, only two genuinely ancient Martian meteorites were known: Allan Hills 84001, recovered from Antarctica, and a jumbled rock from northwest Africa nicknamed Black Beauty. Teghaza 001 now joins this group.
Analysis of the Teghaza 001 Sample
The meteorite was found in Mali in 2022. Subsequent analysis led by Yang Liu, a planetary scientist at NASA’s Jet Propulsion Laboratory, established its formation age at a minimum of 4.1 billion years. As Liu noted, “It’s very old and similar to some of the oldest rocks on Earth.”
Planetary scientists have sought to understand why old Martian rocks are so rare on Earth. The journey itself acts as a natural filter. Launching a rock off the Martian surface requires a large impact.
That ejection process filters the material. If an impact hits into loose powder, it may not get cemented to become a rock and fly off Mars’ gravity. Consequently, weak rocks do not make it off Mars.
Implications for Planetary History
Because weak rocks do not make it off Mars, every Martian rock in our possession represents a survivor.
Teghaza 001 formed at least 4.1 billion years ago.
