Electron microscopy, electron microprobe analysis, and x-ray diffraction are used to determine the composition and microstructure of Chinese porcelain of the Yuan dynasty from Jingdezhen, as well as porcelain-stone and glaze-stone from the region. The original miner-alogical compositions of the porcelain bodies and glazes are estimated. The results indicate that the yingqing porcelain bodies were made using a kaolinized porcelain-stone; whereas, the underglaze blue porcelain bodies were prepared by the addition of kaolin to a kaolinitefree porcelain-stone. In both cases, the glazes were made by mixing glaze-ash with the porcelain stone.