In Jezero crater, 24 mineral species reveal the volcanic nature of the Martian surface and its interactions with water over time. The identified minerals in the crater reveal three types of fluid interactions, each with different implications for habitability. The presence of sepiolite in all of these units reveals a widespread episode of liquid water creating habitable conditions in Jezero crater and infilling sediments. “MIST not only informs Mars 2020 science and decision-making, but it is also creating a mineralogical archive of Jezero Crater that will be invaluable if samples are returned to Earth.”The results confirm that Jezero crater — once home to an ancient lake — experienced a complex and dynamic aqueous history. Multiple Episodes of Fluid Alteration in Jezero Crater Indicated by MIST Mineral Identifications in PIXL XRF Data From the First 1100 Sols of the Mars 2020 Mission.