Submicroscopic Magnetite May Be Ubiquitous in the Lunar Regolith of the High-Ti Region

Magnetite is rare on the Moon. The ubiquitous presence of magnetite in lunar soil has been hypothesized in previous Apollo Mössbauer spectroscopy and electron spin resonance studies, but there is currently no mineralogical evidence to prove it. Here, we report a large number of submicroscopic magnetite particles embedded within iron-sulfide on the surface of Chang'e-5 glass, with a close positive correlation between magnetite content and the TiO content of the surrounding glass. The morphology and mineralogy of the iron-sulfide grains suggest that these magnetite particles formed via an impact process between iron-sulfide droplets and silicate glass melt, and ilmenite is necessary for magnetite formation. Magnetite in lunar glass is a potential candidate for the "magnetite-like" phase detected in the Apollo era and suggests that impact-induced submicroscopic magnetite may be ubiquitous in high-Ti regions of the Moon. Moreover, these impact-induced magnetite particles may be crucial for understanding the lunar magnetic anomalies and mineral components of the deep Moon.