Mars boffins probe mysterious new mineral

Scientists have spotted on Mars what could be a previously unknown mineral linked to the kind of sulphaty gunk that clogs tailings ponds on Earth.

The unusual ferric hydroxysulphate, identified near the vast Valles Marineris canyon by a spacecraft in orbit, hints that the red planet’s surface is still chemically active. It offers a planetary cousin to the problematic waste minerals Earthlings grapple with in mine operations. Sulphates often build up in acidic drainage and coat tailings pond walls.

The finding, published Aug. 5 in Nature Communications by a team led by Janice Bishop of California’s SETI Institute, revealed a spectral signature unlike anything catalogued on Earth. Laboratory work suggests it formed in hot, oxygen-rich conditions and shed water as it crystallized – signals of volcanic activity that would have transformed the Martian surface.

“The material formed in these lab experiments is likely a new mineral due to its unique crystal structure and thermal stability,” Bishop, who is also at the NASA Ames Research Center near SETI, said in a news release from the Tuscon-based Planetary Science Institute. “However, scientists must also find it on Earth to officially recognize it as a new mineral.”

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The mineral’s chemistry matters because on Earth similar ferric sulphates often form in acidic mine tailings where bacteria thrive by driving redox reactions – the natural transfer of electrons that turns dissolved metals into solid minerals. On Mars, the same process hints at ancient pockets of oxygen and water, conditions that could once have sustained microbial life.

The mineral layers sit within deposits of polyhydrated and monohydrated sulfates long mapped in Valles Marineris, a canyon system stretching more than 4,000 km. The discovery builds on earlier reports, including one from Roger Wiens at Purdue University in Indiana. 

In March, Wiens directed NASA’s Perseverance rover to target some unusually pale rocks on the Martian surface with its laser. He and his team found that these rocks contain unusually high levels of aluminum linked to the mineral kaolinite.

It’s a clay that on Earth only forms in warm, wet conditions. Taken together, the work by Bishop and Wiens points to a Mars that was warmer, wetter and more complex than today’s dry husk, with echoes in the minerals Earthlings mine, manage and curse.