Water, carbon dioxide, and elements from rocks or sediments in the ancient Jezero crater once combined to form carbonate, as indicated by the presence of carbonate minerals in the Comet Geyser sample. Carbonate minerals found in Earth’s rock record are often used to reconstruct past climate conditions, such as temperature, precipitation, and aridity. Similarly, silica phases are formed when water interacts with rocks or sediments. The composition and crystallinity of silica can inform about the intensity or duration of weathering, as well as the pressure and temperature conditions during its formation.