Why Mars is Red: Ferrihydrite’s Role in the Martian Dust Revealed

Image from NASA

A new mineral clue on Mars

A new study published in Nature Communications on February 25, 2025, posits that the reddish color of the dust on Mars is probably due to the water-rich iron mineral ferrihydrite, not dry hematite as had been assumed.

The study combined orbital spectral data with results from rovers and landers, supplemented by laboratory experiments using analogs, and demonstrated that ferrihydrite (Fe₅O₈H·nH₂O) is the main iron oxide constituent of Martian dust.

Why it matters

The finding shifts our understanding of Mars's past because ferrihydrite forms in cool, water-rich, oxidative conditions. This means Mars more likely experienced a cold and wet phase of its climate rather than solely a long dry erosion process. This would have implications for Mars's climate evolution, habitability, and resource utilization (materials, mining) for future exploration.

Materials science angle This is significant from a materials science perspective, which informs how iron-oxide minerals behave in extraterrestrial conditions for mining, regolith processing, and manufacturing in-space or on-planet. Knowing the mineralogy of the dust is also crucial for designing machinery, robotic components, coatings, and materials that will operate on Mars without undue wear, corrosion, or unexpected behavior. For someone interested in engineering for space, this may suggest new lines of work: regolith-derived materials, coatings adapted to Martian dust chemistry, or structural materials designed for Martian surface conditions.