The sulfate mineral found on the surface of Mars that supports the presence of liquid water is called gypsum.

Gypsum is a hydrated calcium sulfate (CaSO₄·2H₂O). Its presence indicates that liquid water was once present on the Martian surface, as gypsum forms in aqueous environments.

While other sulfates have been found on Mars, gypsum is particularly significant because it requires a relatively stable and long-lasting water environment to form.