The lunar soils evolution over time is mainly caused by space weathering that includes the impacts of varying-sized meteoroids and charged particles implantation of solar/cosmic winds as well.It has long been established that space weathering leads to the formation of outmost amorphous layers(50-200 nm in thickness)embedded nanophase iron(npFe0)around the mineral fragments,albeit the origin of the npFe0 remains controversial.The Chang'e-5(CE-5)mission returned samples feature the youngest mare basalt and the highest latitude sampling site,providing an opportunity to seek the critical clues for understanding the evolution of soils under space weathering.Here,we report the surface microstructures of the major minerals including olivine,pyroxene,anorthite,and glassy beads in the lunar soil of CE-5.Unlike the previous observations,only olivine in all crystals is surrounded by a thinner outmost amor-phous SiO2 layer(～10 nm thick)and embedded wustite nanoparticles FeO(np-FeO,3-12 nm in size)instead of npFe0.No foreign volatile elements deposition layer and solar flare tracks can be found on the surface or inside the olivine and other minerals.This unique rim structure has not been reported for any other lunar,terrestrial,Martian,or meteorite samples so far.The observation of wüistite FeO and the microstructures support the existence of an intermediate stage in space weathering for lunar minerals by thermal decomposition.

Jian-Gang Guo;Tianping Ying;Hanbin Gao;Xu Chen;Yanpeng Song;Ting Lin;Qinghua Zhang;Qiang Zheng;Chunlai Li;Yigang Xu;Xiaolong Chen

Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences(CAS),Beijing 100190,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;CAS Key Laboratory of Standardization and Measurement for Nanotechnology,CAS Center for Excellence in Nanoscience,National Centre for Nanoscience and Technology,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Lunar and Deep Space Exploration,National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,China;State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China

科学通报（英文版）

[1]Jian-Gang Guo;Tianping Ying;Hanbin Gao;Xu Chen;Yanpeng Song;Ting Lin;Qinghua Zhang;Qiang Zheng;Chunlai Li;Yigang Xu;Xiaolong Chen-.Surface microstructures of lunar soil returned by Chang'e-5 mission reveal an intermediate stage in space weathering process)[J].科学通报（英文版）,2022(16):1696-1701

meteoroids,outmost,nanophase,npFe0,wustite,istite

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