Revealing High‐Manganese Material on Mars at Microscale.

High‐manganese materials would provide valuable information about the history of a water‐rich and oxidizing environment on early Mars. However, the detailed texture and components of these high‐manganese materials are unknown. In martian breccia meteorite NWA 11220, one unique lithic clast enriched in high‐manganese material (~5 vol%) has been recognized. Here, we report the morphological, micro‐textural, mineralogical, and geochemical features of the martian high‐manganese material at the microscale for the first time. Our results show that (a) high‐manganese materials are characterized by micron‐sized grain (<50 μm), complex associated‐phase (i.e., apatite, enstatite, magnetite, ilmenite, and amorphous matrix), and chemical heterogeneity; (b) nano‐sized (<500 nm) amorphous manganese‐oxide veins or grains are the only manganese‐bearing phases in the high‐manganese materials. These new observations provide new evidence for revealing the geological processes related to the high‐manganese materials on Mars and provide important information for future in‐situ exploration and data interpretation of high‐manganese materials on Mars. Plain Language Summary: On Earth, the presence of high‐manganese concentrations is commonly thought to be an indicator of water‐rich and highly oxidizing conditions. Similarly, high‐manganese materials have also been detected on Mars at the Curiosity/Opportunity landing sites and within a martian breccia meteorite. Knowledge of the components of these high‐manganese materials would provide important information about the environments in which they formed on Mars. However, the detailed texture and components of these high‐manganese materials from Mars are still unclear. Based on a unique lithic clast enriched in high‐manganese material (~5 vol%) from martian breccia meteorite NWA 11220, the morphology, texture, mineralogy, and geochemistry of the martian high‐manganese material were revealed at the microscale for the first time. These supplementary data provide a series of new insights into the high‐manganese material on Mars, including (a) the new occurrence of manganese concentration in martian igneous rocks, (b) micro‐textural evidence of fluid precipitation of high‐manganese material, and (3) geological history recorded by high‐manganese materials on Mars. Key Points: One unique lithic clast enriched in high‐Mn material (~5 vol%) was identified in martian breccia meteorite NWA 11220The texture, geochemistry, and mineralogy of the high‐Mn material on Mars are reported at the microscaleNano‐sized (<500 nm) amorphous Mn‐bearing material veins or grains are the only Mn‐bearing phase in the high‐Mn material [ABSTRACT FROM AUTHOR]