A study suggests Mars takes its red hue from a type of mineral that forms in cool water, which could reveal insights about whether Mars was ever able to support life.

For centuries, Mars has captivated scientists and the public alike with its striking red hue. Early astronomers speculated that the planet’s color came from iron-rich minerals, much like rust on Earth.

Results from a new study show that the water-rich iron mineral ferrihydrite may be the main pigment behind Mars’ reddish dust.