The presence of carbonate within the Comet Geyser sample suggests that water, carbon dioxide, and chemical elements derived from rocks or sediments in and around ancient Jezero crater once reacted here to form carbonate. Carbonate minerals from Earth’s rock record are often used to reconstruct ancient climate–including conditions like temperature, precipitation, and aridity–and the history of life. Similarly, silica phases form when water interacts with rocks or sediments. The composition and crystallinity of silica can reveal the extent of the interaction with water, such as the intensity or duration of weathering and the pressure/temperature conditions during formation.