China's Chang'e-6 Mission Reveals New Lunar Discoveries

A joint research team from the Institute of Geochemistry of the Chinese Academy of Sciences and Shandong University has made groundbreaking discoveries from the lunar soil samples retrieved by China's Chang'e-6 mission.

They have identified crystalline hematite, or Fe2O3, and maghemite, or gamma-Fe2O3, for the first time on the Moon, specifically from the South Pole-Aitken Basin. This finding, published in Science Advances, offers direct sample-based evidence of highly oxidized materials on the lunar surface.

Redox reactions are crucial to planetary formation and evolution, yet prior studies suggested that the Moon's environment was primarily reduced, with iron predominantly in its ferrous and metallic states.

However, recent studies using remote sensing techniques indicated the presence of hematite in high-latitude regions of the Moon. The Chang'e-6 mission provides a unique opportunity to explore oxidation processes through samples from the SPA Basin, one of the largest and oldest impact basins in the solar system.

The research team successfully identified micron-sized hematite grains, utilizing micro-area electron microscopy, electron energy loss spectroscopy, and Raman spectroscopy, confirming these minerals as primary lunar components rather than contaminants from Earth.

The study posits that the formation of hematite is closely associated with major impact events in lunar history. High temperatures generated during these impacts would have created transient high-oxygen environments, leading to the oxidation of iron ions.

This process resulted in the formation of crystalline hematite, which coexists with magnetic magnetite and maghemite. These findings also shed light on the origin of magnetic anomalies observed on the lunar surface, particularly in the northwestern SPA Basin.

The correlation between oxidation processes and the formation of magnetic carrier minerals provides essential insights into the carriers and evolutionary history of these anomalies. This research challenges the long-held belief that the lunar surface is entirely reduced, offering vital clues to understanding lunar evolution and the mechanisms underlying large impact events.

The Chang'e-6 mission's findings significantly contribute to our understanding of lunar geology and the history of impacts on the Moon's surface, enhancing our knowledge of the Moon's formation and evolution.