Scientists discover a new rock type on Mars and a mineral it shares with Earth

Scientists analysing the Martian meteorite NWA 8171 identified garnet in an unusual rock fragment. The find could reshape understanding of ancient geological processes on Mars.

In Short

• Researchers from Canada, the UK and Italy examined the fragment closely
• Electron microscopy and laser analysis revealed an unexpected mineral signature
• Garnet preserves clues about temperatures, pressures and rock formation chemistry

Scientists studying a meteorite from Mars have uncovered a geological surprise hidden inside the space rock: a completely new type of Martian rock and the first-ever discovery of the mineral garnet on the Red Planet.

The breakthrough, made by an international team of researchers from Canada, the UK and Italy, could help scientists reconstruct Mars's ancient geological history and better understand the processes that shaped the planet billions of years ago.

The discovery came from an unusual fragment inside a Martian meteorite known as NWA 8171. While examining the meteorite's chemistry and mineral composition, researchers noticed something unexpected.

"This little section of the meteorite looked really interesting, and the chemistry was a bit odd," said Tanya Kizovski, Assistant Professor of Earth Sciences at Brock University in Canada, who led the study. "At first, we assumed it was a mineral called pyroxene, which is very common, but then we decided to take a second look."

Using advanced electron microscopy at the University of Portsmouth and specialised laser-analysis equipment at the Royal Ontario Museum, the team discovered that the fragment contained garnet, a mineral never before identified in a Martian sample.

On Earth, garnet is best known as a deep-red gemstone used in jewellery and celebrated as January's birthstone. But for geologists, it is far more important. Garnet acts like a geological archive, preserving evidence of the temperatures, pressures and chemical conditions that existed when a rock formed.

Its presence on Mars suggests the planet may have experienced geological processes previously unknown to scientists.

"This discovery is going to expand our knowledge of the geologic processes that are possible on this planet," Kizovski said. "This new garnet-bearing rock type could give us clues to how Mars has changed throughout its history."

The researchers believe the garnet may have formed through metamorphism, a process in which existing rocks are transformed by intense heat, pressure or hot fluids. On Earth, metamorphic rocks are common in mountain belts and tectonic collision zones.

Mars lacks active plate tectonics today, but scientists say similar conditions could have been created by powerful meteorite impacts or by magma rising through the Martian crust billions of years ago.

The finding offers a rare glimpse into Mars's distant past, potentially revealing information about ancient volcanic activity, impact events and the evolution of the planet's interior.

However, one mystery remains unresolved: did the garnet actually form on Mars?

Researchers caution that the mineral could have arrived on the planet through an ancient meteorite impact. Determining its true origin will require studying its isotopic composition, a process that would involve destroying part of the extremely rare sample.

For now, scientists are reluctant to take that step.

"Measuring oxygen isotopes from the garnet-bearing rock type itself would help to confirm if it is Martian in origin or from an exotic meteorite impactor," Kizovski explained.

Published in Geochemical Perspectives Letters, the study opens a new chapter in the exploration of Mars.

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