Classification of Particles in Polished Sections of Chang’E-5 Lunar Soil Samples

Objectives After observing the backscattered electron images of lunar soil polished sections, some lunar soil particles are composed of a single mineral or multiple minerals. Since the number of particles in one lunar soil polished section is on the order of 10⁴, we develop a computer-based classification method of lunar soil particles.

Methods We determine the approximate range of different minerals in the particle by grayscale statistics, and then use the watershed algorithm to segment the minerals in the particle. Finally, these lunar soil particles are divided into three categories: single mineral particles, dual minerals particles, three and above minerals particles.

Results After counting all lunar soil particles with an area over 25 μm² in the three polished sections, the statistical results show that the percentages of single mineral, dual minerals, and three and above minerals are 15.3%, 19.2%, and 65.5%, and the percentages of mass are 59.1%, 31.1%, and 9.8%, respectively. The average diameters of three kinds of particles are 31.29 μm,19.09 μm,and 9.27 μm.

Conclusions The difference in size of three types of particles might be related to the particles composed of various minerals separating easily during space weathering.