Fig. 1

Microscopic images of four representative grains. a A0042, dark group. This feature is dominant in Ryugu returned samples. b C0094, glossy group. Especially, the bottom part of this image shows shiny and glossy reflection. c A0017, bright group. Most of the flat surface of this grain shows bright color excluding upper left region corresponding with the dark lithology. d C0041, white group. One-third of this grain exhibits white inclusions