Just as fossils contain the history of past animals and plants, minerals can record the history of past planetary events and climates. One particularly good mineral for studying past climates is hematite. This reddish iron oxide mineral can form in watery environments, and in a review paper led by Zhaoxia Jiang, researchers start to break down what the different characteristics of this mineral mean and which do and don’t require water.

Basically, they want to see if we can use hematite to understand the past climate of Mars. It’s a common mineral on the surface and has been found in spectral data taken of Mount Sharp in Gale Crater, where Curiosity is currently wandering around. Those regions where hematite is found on Mars could be the key to searching for potential past biologic life on the red planet. Perhaps we could determine if there were even monsoons, not just water in general.

Published in Reviews of Geophysics, this paper builds on prior work using magnetic studies of hematite that analyzed archeological finds as well. Hematite affects the behavior of phosphorous in the soil, which is necessary for crop fertilization and not the easiest element to obtain.

So with one common mineral, we can learn more about both our own Earth and about Mars. Pretty good for a bunch of red rocks.

More Information

Expanded knowledge of a mineral that helps decipher past climates (EurekAlert)

“The Magnetic and Color Reflectance Properties of Hematite: From Earth to Mars,” Zhaoxia Jiang et al., 2021 November 29, Reviews of Geophysics

“Innovative ochre processing and tool use in China 40,000 years ago,” Fa-Gang Wang et al., 2022 March 2, Nature