Oxalate minerals on Mars?

D. M. Applin, M. R.M. Izawa, E. A. Cloutis, D. Goltz, J. R. Johnson

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Small amounts of unidentified organic compounds have only recently been inferred on Mars despite strong reasons to expect significant concentrations and decades of searching. Based on X-ray diffraction and reflectance spectroscopic analyses we show that solid oxalic acid and its most common mineral salts are stable under the pressure and ultraviolet irradiation environment of the surface of Mars, and could represent a heretofore largely overlooked reservoir of organic carbon in the martian near-surface. In addition to the delivery to Mars by carbonaceous chondrites, oxalate minerals are among the predicted breakdown products of meteoritic organic matter delivered to the martian surface, as well as any endogenic organic carbon reaching the martian surface from the interior. A reinterpretation of pyrolysis experiments from the Viking, Phoenix, and Mars Science Laboratory missions shows that all are consistent with the presence of significant concentrations of oxalate minerals. Oxalate minerals could be important in numerous martian geochemical processes, including acting as a possible nitrogen sink (as ammonium oxalate), and contributing to the formation of "organic" carbonates, methane, and hydroxyl radicals.

Original languageEnglish
Pages (from-to)127-139
Number of pages13
JournalEarth and Planetary Science Letters
Publication statusPublished - Jun 5 2015
Externally publishedYes


  • Carbonaceous chondrites
  • Mars
  • Organic compounds
  • Oxalates
  • Oxalic acid
  • Reflectance spectroscopy

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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