Abstract: A comparative study on the mineralogical differences of Laos stone and Shoushan stone is conducted on the basis of their petrography. The electron microprobe and X-ray powder diffraction are used to analyze the types and contents of chemical elements in stone samples and mineral compositions respectively. The results show that the mineralogical differences mainly lie in colors and compositions. The colors of Laos stone are mainly red, white, pink, and rarely yellow; while those of Shoushan stone are greatly varied with red, white, pink, purple, yellow, green etc. for different varieties. The change of Fe content could account for the difference. The higher the Fe content is in the stone, the darker the color is. The major mineral compositions of both gemstones are roughly the same, mainly consisting of dickite, kaolinite and nacrite, yet slightly differ in mineral contents and types. The mineral compositions of different varieties of Shoushan stone have a little difference, for example, pyrite and pyrophyllite are occurred in Shoushan Hukou stone, which is not seen in Laos stone.