3D insights into the multiorigins of nanophase Fe<sup>0</sup> in the Moon surface.

Dai, Yiheng; Li, Zezhou; Jia, Tianyi; Xie, Zhiheng; Wang, Ruimin; Yin, Zongjun; Shen, Bing; Zhou, Jihan · Proc Natl Acad Sci U S A · 2026

basic_science · Level V

Where this comes from

Abstract

Nanophase metallic iron (npFe<sup>0</sup>) 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 npFe<sup>0</sup> have rarely been documented in lunar soil samples. Here, we reveal the unique 3D spatial multilayered distributions and morphologies of npFe<sup>0</sup> in the Chang'e-5 impact glass using a combination of electron tomography and spectroscopic techniques, demonstrating that npFe<sup>0</sup> 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 npFe<sup>0</sup>. This study quantifies the 3D abundance of npFe<sup>0</sup> in a piece of lunar impact glass, revealing localized Fe<sup>0</sup> accumulation up to 7.1 wt%. Our results provide 3D nanoscale analysis for multiple coexisting formation mechanisms of npFe<sup>0</sup>, elucidating the complex space weathering processes in the lunar surface.