Fig. 7

OM photos and SEM–BSE images of the reddish purple glaze cross section: a, b the hole glaze, a □C linear patterns resembling earthworm-walking patterns, i.e. the area without corrosion; □E corrosion area; c, d corresponding to Fig. 1a □C; e, f corresponding to Fig. 1a □E, columnar pits and craters after crystals corrosion, large interconnecting craters from the surface to inner glaze (where white arrows pointing to)