The reporter learned from the Institute of Geochemistry of the Chinese Academy of Sciences on the 27th that the Li Yang research team of the Institute recently carried out in situ micro analysis of the sulfide particles in the lunar soil powder taken from the Chang'e 5 surface, and for the first time confirmed the existence of impact origin submicron magnetite in the lunar soil. Relevant achievements were published in the international journal Nature Communication. Magnetite usually involves important scientific issues such as ancient magnetic field and extraterrestrial life, so it has attracted much attention from scholars in the field of planetary science. The Chang'e 5 mission successfully brought back 1.731kg lunar soil material from the young lunar sea basalt unit. Although the sample analysis results showed that almost all lunar soil of Chang'e 5 was from local materials, a small part of lunar soil particles were still sputtered from the large impact crater, and the initial reaction information of the lunar surface impact process was probably retained in the lunar soil. Through scanning and transmission electron microscopy, the research team found spherical iron sulfide particles with a diameter of about 2 microns in the Chang'e 5 fine lunar soil, which is generally characterized by dissolved oxygen and contains a large number of submicron magnetite and pure metal iron particles. The iron oxide particles embedded in the spherical iron sulfide particles are determined to be submicron magnetite crystals. In addition, the typical characteristics of silicate gasification, oxygen dissolution and equilibrium precipitation of magnetite and metal iron particles suggest that the dissolved oxygen iron sulfide particles in Chang'e 5 lunar soil are the products of a large lunar impact event. The research shows that the sulfide on the moon surface will undergo complex gas-liquid reaction during the impact process, making the zero valent iron dissolved into the sulfide generate submicron magnetite and simple metal iron through eutectoid reaction. Since the era of Apollo spacecraft, people's understanding of ferromagnetic minerals on the moon has been dominated by metallic iron. On the basis of predecessors, this study provides another important ferromagnetic mineral on the lunar surface - magnetite, and effectively establishes the relationship between the formation of ferromagnetic minerals and the impact event, so it is of great significance. (Liu Xinshe)