Newly discovered tetrataenite in Chang’E-6 lunar soil: a space weathering-induced magnetic carrier

The lunar surface—particularly around large impact craters on the farside—displays pronounced magnetic anomalies whose origins and evolution remain enigmatic. The Chang’E-6 (CE-6) mission offers a unique opportunity to investigate the magnetic characteristics of the South Pole–Aitken basin. Here, we report the first discovery of tetrataenite, a hard magnetic mineral, in CE-6 returned fine-grained, space-weathered soil. Integrating microscopic mineralogical evidence with the Moon’s complex impact-related geology, we infer that Ni-rich chondrites metal was accreted during impact events. Subsequent repetitive impacts heated troilite droplets coated with taenite, spalling them from the parent body and depositing them in the Apollo basin. During cooling, the taenite underwent a monotectoid reaction that ordered the face-centered cubic taenite into body-centered cubic tetrataenite and simultaneously precipitated sub-micron-sized metallic iron. The presence of tetrataenite indicates that space weathering has significantly modified the magnetic evolution of the lunar surface.