In recent years, scientists are learning that Mars is more complex a planet geologically than they had previously believed. New research published in the scientific journal Nature Geoscience suggests that granite may actually exist on the planet, when previous theories had proved that idea doubtful.

“We’re providing the most compelling evidence to date that Mars has granitic rocks,” said study author James Wray, an assistant professor of earth and atmospheric sciences at the Georgia Institute of Technology.

The majority of Mars’ surface is made up of basalt, a dark-colored mineral also found on Earth throughout Hawaii. The research team examined an inactive volcano on Mars and found feldspar, which is a mineral found in granite. The location of the feldspar suggests that there may have been huge granite deposits.

This discovery puzzled the scientists. The discovery had been made by the Mars Curiosity rover in its previous mission in 2012. The soils had a composition similar to granite, which had a light color. No one knew what to make of this discovery because it was found only in a certain area on the red planet.

“Using the kind of infrared spectroscopic technique we were using, you shouldn’t really be able to detect feldspar minerals, unless there’s really, really a lot of feldspar and very little of the dark minerals that you get in basalt,” Wray said.

“We think some of the volcanoes on Mars were sporadically active for billions of years,” Wray added. “It seems plausible that in a volcano you could get enough iterations of that reprocessing that you could form something like granite.”

Granite deposits are generally found in tectonically active regions on Earth, like Hawaii. While the idea seems unlikely on Mars, the team of scientists has been able to conclude that granite could form under prolonged magmatic activity.

“We’re providing the most compelling evidence to date that Mars has granitic rocks,” said James Wray, an assistant professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology and the study’s lead author.

Scientists were able to theorize that the granite formed on Mars through a process called igneous distillation. As the subsurface magma would cool slowly, dense crystals and low-density melt would separate, cycling over and over again until granite formed (basalt is light; granite is dense). This process is possible in a volcano that is active over eons, which scientists believe some of the volcanoes were on Mars.