Chang’e-6 soil reveals metallic iron in lunar samples; it may preserve clues to Moon’s lost magnetic field

Representative Image (AI-generated) A study of soil brought back from the Moon’s far side by China’s Chang’e-6 mission has uncovered a form of metallic iron never before found in natural lunar samples. Researchers from the Chinese Academy of Sciences reported the discovery after examining tiny particles preserved inside impact glass collected by the mission. The material, known as face-centred cubic γ-Fe, has unusual magnetic properties that could make it useful for studying the Moon’s ancient magnetic environment. The finding, published in the Proceedings of the National Academy of Sciences, also offers clues about the extreme conditions created by impacts on the lunar surface.An unusual form of ironThe discovery centres on γ-Fe, also called gamma iron. Iron can exist in several different crystal structures, depending on temperature and pressure. γ-Fe normally forms under high-temperature conditions and is not expected to remain stable once temperatures fall. Yet researchers found nanoscale γ-Fe particles inside impact-glass grains from the Chang’e-6 samples. Their presence suggests that something unusual happened when the material formed and cooled.The researchers believe powerfu...