Overview
- The minerals—micron-scale crystalline Fe2O3—were identified in South Pole–Aitken Basin soil returned in 2024, providing the first direct sample-based evidence of highly oxidized materials on the lunar surface.
- Electron microscopy, electron energy-loss spectroscopy and Raman spectroscopy verified the crystal structures and lunar origin of the grains, ruling out terrestrial contamination.
- The oxides occur primarily in impact-breccia materials and are observed alongside magnetite and maghemite, indicating a range of iron oxidation states tied to impact processes.
- Researchers propose formation during large impacts that vaporized material and produced transient high–oxygen-fugacity conditions that oxidized iron before vapor-phase deposition, a mechanism now under further testing.
- The results offer a plausible set of magnetic carrier minerals for unexplained lunar magnetic anomalies and reconcile earlier remote-sensing and Chang'e-5 hints of ferric phases with definitive sample evidence.