The finding released Tuesday is the latest step in trying to better understand whether the environment could have been hospitable to microbial life.
Curiosity recently ingested its first soil sample and used one of its instruments to tease out the minerals present. An analysis revealed it contained feldspar and olivine, minerals typically associated with volcanic eruptions. Mission scientists say the Martian soil is similar to volcanic soil on the flanks of Mauna Kea.
Curiosity landed near the Martian equator in August on a two-year mission. It'll be another month before it drills into its first rock. Then it's expected to head toward a mountain by year's end.