Temperature‐Dependent Evolution of Iron Content and Valence Between Clinopyroxene and Glass on the Moon

Abstract Recent studies challenge the classical view of the Moon as lacking ferric iron (Fe 3+ ). Laboratory investigations and remote sensing data confirm the presence of Fe 3+ , but its evolutionary mechanisms are not fully understood. We propose a temperature‐dependent mechanism for the evolution of iron content and valence in the assembly of clinopyroxene‐glass from Chang'e 5 lunar regolith samples. In situ heating experiments using transmission electron microscopy coupled with electron energy loss spectroscopy showed that heating from 23°C to 1,000°C reduced clinopyroxene's Fe concentration from 7.73% to 5.59%, while its Fe 3+ /∑Fe (∑Fe = Fe 3+ + Fe 2+ ) ratio increased from 30.17% to 59.74%. Concurrently, the Fe content in adjacent glass decreased at higher temperatures, with a significant drop in its Fe 3+ /∑Fe ratio from 22.81% at 700°C to 3.93% at 900°C. These findings indicate a heating‐induced co‐evolution of iron in lunar glass and clinopyroxene, suggesting that the impact‐induced thermal evolution of Fe 3+ may influence the lunar surface's local redox state.