3D insights into the multiorigins of nanophase Fe⁰ in the Moon surface

Nanophase metallic iron (npFe⁰) in lunar soils is a key indicator for understanding the space weathering mechanisms of airless bodies. However, the detailed three-dimensional (3D) spatial topology and distribution of layered npFe⁰ have rarely been documented in lunar soil samples. Here, we reveal the unique 3D spatial multilayered distributions and morphologies of npFe⁰ in the Chang'e-5 impact glass using a combination of electron tomography and spectroscopic techniques, demonstrating that npFe⁰ originates from multiple effects including iron sulfide decomposition, Fe(II) disproportionation, and solar wind irradiation. We provide direct evidence for the decomposition of iron sulfide to produce irregularly shaped npFe⁰. This study quantifies the 3D abundance of npFe⁰ in a piece of lunar impact glass, revealing localized Fe⁰ accumulation up to 7.1 wt%. Our results provide 3D nanoscale analysis for multiple coexisting formation mechanisms of npFe⁰, elucidating the complex space weathering processes in the lunar surface.