Impact‐Melt‐Crystallized Magnetite on the Moon

The continuous bombardment of lunar surfaces by asteroids and comets has modified the chemical, mineralogical, and physical properties of the lunar crust. Oxidizing agents from these impactors could alter the redox conditions on the Moon. However, no Fe 3+ ‐bearing phase crystallized from impact melt has been reported in the lunar regolith. In this study, a submicron‐sized magnetite grain was observed in lunar impact glass from the Chang'e‐5 regolith breccia. Our results demonstrate that this magnetite was directly crystallized from the lunar impact melt under oxidizing conditions (IW‒WM buffer). We propose that these impact events could play a role in altering the oxidizing conditions of the lunar crust. Furthermore, impact‐melt‐crystallized magnetite grains may contribute to some extent to lunar magnetic anomaly signatures, but they are likely a very minor component relative to Fe‐Ni alloys.