Thermomagnetization of a Basaltic Lunar Regolith Simulant Driven by Fe Redistribution and Magnetic Phase Formation

The magnetic properties of lunar regolith are controlled by the abundance, valence state, grain size, and mineralogical occurrence of Fe‐bearing phases. However, how weakly magnetic Fe 2+ hosted in silicates and glassy components responds to thermal processing requires further study. Here, we investigate the temperature‐dependent magnetic and mineralogical evolution of a basaltic lunar regolith simulant during controlled heating under low oxygen partial pressure. Vibrating sample magnetometry shows that the mass‐specific magnetization measured at 20 kOe increases from 0.551 emu g −1 for the control sample to 0.703 emu g −1 after heating at 800°C, corresponding to a 27.5% increase, but decreases markedly at higher temperatures. Mössbauer spectroscopy reveals that the control sample is dominated by Fe 2+ ‐bearing components, whereas heating at 800°C produces metallic Fe and a magnetically ordered ferric component. X‐ray diffraction and transmission electron microscopy further indicate the formation of a magnetite‐like Fe‐rich oxide phase. These results suggest that at approximately 800°C heating promotes Fe redistribution from olivine‐ and glass‐related environments into metallic Fe, magnetite‐like oxide, and pyroxene‐like hosts. At higher temperature, these magnetic phases are no longer retained, and Fe is redistributed back into predominantly Fe 2+ ‐bearing environments. This study provides a plausible mechanistic interpretation based on Fe redistribution and magnetic‐phase formation in basaltic lunar regolith simulants, with implications for the magnetic evolution and potential beneficiation of lunar surface materials.