Due to the very few content of loveringite in glazes, it had little influence on the opacity and strength of the glaze surfaces. As a result, the presence of whitlockite and quartz were only considered. Fig. 4 shows the STEM/EDS elemental analysis of the etched glazes surface at different firing temperatures. Due to the acid treatment, some aggregate crystals were observed on the glaze surface at 1160 C, while they diffused at 1220 C and finally disappeared at 1280 C. Moreover, strong Ca and P signals were detected from the aggregate crystals, indicating that these crystals might be whitlockite rather than quartz.