Chinese researchers have identified magnetic gamma-iron nanoparticles in Chang’e-6 lunar samples, a discovery that could preserve evidence of the Moon’s ancient magnetic field.
The particles were found inside impact glass collected from the Moon’s far-side South Pole–Aitken Basin and represent the first confirmed detection of natural lunar γ-Fe, or gamma iron. Gamma iron normally forms at high temperatures and is expected to transform into another iron structure as it cools. The researchers propose that rapid cooling during meteorite impacts, trace stabilizing elements and the surrounding glass allowed the unusual phase to survive on the lunar surface.
Using electron microscopy and chemical analysis, the team identified nanoscale iron particles in two impact-glass samples. Electron holography showed that relatively large particles could form stable magnetic vortex states and maintain a consistent response to an external magnetic field. That behavior suggests the particles may act as microscopic recorders of magnetic conditions during past impacts or periods when the Moon’s core generated a dynamo.
Scientists caution that further work is needed to determine exactly how reliably γ-Fe preserves ancient magnetic signals, but the finding broadens the range of minerals available for reconstructing lunar history.