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Black glass in new Martian meteorite

One of the largest Tissint meteorites (Morocco). An almost fully encrusted stone of 908 g on display at the Museum of Natural History of Vienna (Austria).
[Image NHM-Vienna, K. Kracher]

Last summer, a meteorite from Mars plunged into the Moroccan desert. A new study appearing in the October 12 issue of in the journal Science shows that the rock was ejected from the surface of Mars 700,000 years ago.

Hasnaa Chennaoui Aoudjehane at the University of Casablanca and colleagues found an abundance of black glass within the rock that may contain Martian soil. Tissint is the fifth Martian meteorite to be collected after a witnessed fall to earth.

Many other Martian meteorites have been collected, but these were not seen falling to Earth. They were found (often in Antarctica) long after their arrival on Earth and suffered more exposure to the terrestrial environment than the five observed meteorites.

The rock shows evidence of three distinct components derived from the interior, surface and atmosphere of Mars. To explain Tissint's composite nature, the authors propose that the rock was weathered by fluids derived from the red planet's surface, which leached elements from the Martian soil. These fluids were subsequently deposited into the rock's fissures and cracks.

Melting likely occurred in the rock's fractures during the impact of the asteroid or other body that crashed onto Mars and ejected the rock from its surface of the planet. This melting may have produced the black glass and retained in it chemical signatures characteristic of the Martian surface, the authors conclude.