The yellow-brown mineral, called jarosite was found in Antarctica.
They require both water and acidic conditions to form, according to NASA — conditions that are hard to find now on the Red Planet..
On Earth, jarosite is a rare mineral that crops up in mining waste exposed to air and rain, Science reported. It can also form near the vents of volcanoes, according to NASA. Bacolod and his colleagues never expected to find the mineral in Antarctica, he told Science; but when the team pulled a roughly mile-long (1,620 meters) ice core from the ground, they found trace particles of jarosite, smaller than grains of sand, buried in the deepest layers of the ice.
After examining the particles with an electron microscope, the team deduced that the jarosite had formed in pockets within the ice. This finding hints that the mineral formed in the same way on Mars, although on the Red Planet, jarosite appears in "meters-thick deposits," not as a few sparse grains, Megan Elwood Madden, a geochemist at The University of Oklahoma who was not involved with the research, told Science.
These ultra-thick slabs of jarosite may have formed on Mars because the Red Planet is far dustier than Antarctica, providing more raw material to form jarosite, Baccolo noted. "This is just the first step in linking deep Antarctic ice with the Martian environment," he said.