Extensively Transported and Bonded Independent Iron‐Rich Particles on the Lunar Surface Revealed by Chang'e‐5 Glass Beads

Abstract Iron‐rich particles, including nanophase metal iron (npFe 0 ) and iron sulfide, are generated from multi‐process space weathering effects such as micrometeorite impact and solar wind. However, their post‐formation behaviors, especially preservation and transport during reworking, remain poorly constrained. This study presents the microstructures of iron‐rich particles on the surface and inside the glass beads in the Chang'e‐5 regolith sample. The surface and internal iron‐rich particles have similar morphology but significant differences in number density, indicating a consistent formation mechanism but not contemporaneous products. The major element data shows that glass beads containing iron‐rich particles generally have higher volatile elements, suggesting that these particles tend to form under the mild low‐energy impact, which causes melting without extensive volatilization. The proportion of glass beads records the information of source materials, which with iron‐rich particles gradually decreases from ancient mare units to young mare units and then to highlands. In this case, the main factors controlling the formation of iron‐rich particles are the FeO content in the material; however, impact intensity and exposure time could also play roles, especially under similar FeO content. The oxygen isotope analysis and calculation results show that the contribution of iron‐rich particles formed by thermal decomposition is smaller than that of the disproportionation reaction, but the total production exceeds the abundance obtained from the regolith sample. These observations suggest that pre‐existing independent iron‐rich particles in the regolith are necessary, which are generated from mare units and can be widely transported to highlands and bonded to the surface of glass beads.