Teghaza 001: Sahara Meteorite From Mars Is Over 4.1 Billion Years Old

A rare piece of early Martian crust

Teghaza 001 combines igneous minerals and textures that preserve evidence of a complex history. Its mineral makeup resembles materials seen in the southern highlands of Mars by NASA's Mars Reconnaissance Orbiter. Researchers cannot say exactly where it originated, but they have identified 13 possible source locations.

"It was only after we started looking closely that we realized this meteorite is really unique," said research leader Yang Liu of JPL. "One of the paper's reviewers called it a Rosetta Stone for Mars." Team member Lee Saper of NASA's Ames Research Center called it the first piece of Martian crust from a region never sampled before, one that records interactions of water and rock and possibly an imprint of the atmosphere as the planet lost water.

How the age was determined

Scientists first identified the rock as Martian from its oxygen isotopes. They then examined tiny zircon crystals and applied rubidium-strontium dating to individual mineral grains on its surface, which preserved the sample for future study.

The results show water altered the rock about 4.1 billion years ago, so the rock itself is older. The evidence points to a dynamic water cycle on early Mars, with liquid water interacting with the crust. It is the first time rubidium-strontium dating has been used on an ancient Martian meteorite, and the method could now be applied to other samples.

The findings were published on Thursday, Oct. 29, in the journal Science. A separate study of the meteorite's water content appeared on June 10 in Science Advances. "We've only scratched the surface," Liu said.