Discovery of crystalline Fe<sub>2</sub>O<sub>3</sub> in returned lunar soils.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41237240.
- Also identified by DOI 10.1126/sciadv.ady5169 and PMC identifier 12617526.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Lunar materials were believed to have formed and been preserved in a reducing environment, with only Fe<sup>2+</sup> and Fe<sup>0</sup> present. Native oxidized minerals, such as hematite, have not been validated in previously returned lunar samples. In this work, we report the discovery of micrometer-scale crystalline Fe<sub>2</sub>O<sub>3</sub> in the forms of hematite (α-Fe<sub>2</sub>O<sub>3</sub>) and maghemite (γ-Fe<sub>2</sub>O<sub>3</sub>) overgrowing troilite in the recently returned Chang'e-6 (CE6) lunar soils. It is possible that impact-induced oxygen release created localized micrometer-scale regions of elevated oxygen fugacity, facilitating the formation of Fe<sub>2</sub>O<sub>3</sub> at temperatures between ~700° and 1000°C. This finding provides credible evidence for the presence of Fe<sub>2</sub>O<sub>3</sub> on the lunar surface, challenging the traditional understanding of lunar surface redox states. In addition, the Fe<sub>2</sub>O<sub>3</sub> in the form of maghemite may be the mineralogical reason for the generation of the magnetic anomalies observed around the South Pole-Aitken basin.