Alteration history of Stah formation rocks inferred by PIXL x-ray fluorescence, x-ray diffraction, and multispectral imaging on Mars. Academic Article uri icon


  • Collocated crystal sizes and mineral identities are critical for interpreting textural relationships in rocks and testing geological hypotheses, but it has been previously impossible to unambiguously constrain these properties using in situ instruments on Mars rovers. Here, we demonstrate that diffracted and fluoresced x-rays detected by the PIXL instrument (an x-ray fluorescence microscope on the Perseverance rover) provide information about the presence or absence of coherent crystalline domains in various minerals. X-ray analysis and multispectral imaging of rocks from the Stah formation on the floor of Jezero crater shows that they were emplaced as coarsely crystalline igneous phases. Olivine grains were then partially dissolved and filled by finely crystalline or amorphous secondary silicate, carbonate, sulfate, and chloride/oxychlorine minerals. These results support the hypothesis that Stah formation rocks represent olivine cumulates altered by fluids far from chemical equilibrium at low water-rock ratios.

published proceedings

  • Sci Adv

altmetric score

  • 206.58

author list (cited authors)

  • Tice, M. M., Hurowitz, J. A., Allwood, A. C., Jones, M., Orenstein, B. J., Davidoff, S., ... PIXL Team.

citation count

  • 13

complete list of authors

  • Tice, Michael M||Hurowitz, Joel A||Allwood, Abigail C||Jones, Michael WM||Orenstein, Brendan J||Davidoff, Scott||Wright, Austin P||Pedersen, David AK||Henneke, Jesper||Tosca, Nicholas J||Moore, Kelsey R||Clark, Benton C||McLennan, Scott M||Flannery, David T||Steele, Andrew||Brown, Adrian J||Zorzano, Maria-Paz||Hickman-Lewis, Keyron||Liu, Yang||VanBommel, Scott J||Schmidt, Mariek E||Kizovski, Tanya V||Treiman, Allan H||O'Neil, Lauren||Fairén, Alberto G||Shuster, David L||Gupta, Sanjeev

publication date

  • November 2022