Wire reporting: (Reuters, via CNA)

A rose-colored rock found in Mali's Sahara in 2022 is a piece of Mars that records crust more than 4.1 billion years old, NASA-funded researchers reported in Science^1,3,4.

Named Teghaza 001 after the salt plain where it was found, the nearly 800-gram stone is among about 435 known Martian meteorites and one of three oldest identified on Earth^3,4.

University of New Mexico researchers first matched its oxygen isotopes to other Mars meteorites; it was initially classed as a shergottite before JPL planetary scientist Yang Liu's team found unusual minerals and zircon^1,4.

Liu said, "It was only after we started looking closely that we realized this meteorite is really unique"⁴.

Unlike Allan Hills 84001, which is nearly a single mineral, and NWA 7034 ("Black Beauty"), a 2.1-billion-year-old mix of fragments, Teghaza 001 is an intact igneous rock with mixed volcanic minerals^1,4.

Independent clocks — zircon, phosphates and in-situ rubidium-strontium dating of a fingernail-size chip, using a method from Caltech's Francois Tissot — cluster near 4.11 billion years^1,4.

That age marks water alteration; Liu told Ars Technica the crystallization age is older, and that the rock is "very old and similar to some of the oldest rocks on Earth"¹.

Chemistry matches Mars Reconnaissance Orbiter views of the cratered southern highlands; a likely source is northwest of Hellas, though the exact launch site is unknown^1,4.

Lee Saper, now at NASA Ames, said the sample is crust from a region not represented before and records water-rock interaction^3,4.

A June Science Advances paper addressed the rock's water content; Liu said further work has only begun^3,4.