Characterization of ferric hydroxysulfate on Mars and implications of the geochemical environment supporting its formation.

Sulfate minerals are significant components of the martian surface and provide clues about the martian geochemical environment. One unusual Fe-sulfate phase has been intriguing Mars scientists for over a decade due to its unique spectral bands that are distinct from any known minerals and its occurrence in layered sedimentary rocks. We describe here detection of ferric hydroxysulfate (FeSOOH) and its implications for the geochemical history of Mars.

Carbonates identified by the Curiosity rover indicate a carbon cycle operated on ancient Mars.

Ancient Mars had surface liquid water and a dense carbon dioxide (CO)-rich atmosphere. Such an atmosphere would interact with crustal rocks, potentially leaving a mineralogical record of its presence. We analyzed the composition of an 89-meter stratigraphic section of Gale crater, Mars, using data collected by the Curiosity rover.

2/ Postorthopyroxene γ-LiScGeO, a New Dense High-Pressure Polymorph and Its Direct Transformation from the Structure.

Orthorhombic β-LiScGeO single crystals were compressed hydrostatically up to 10.35 GPa using a diamond anvil cell and investigated in situ by means of X-ray diffraction and Raman spectroscopy. Crystal-structure investigations at ambient conditions and at high pressure show a structural transition from an orthopyroxene-type structure ( ≈ 18.