Gemmological and Mineralogical Characteristics of Three Seal Stones that Imitate Shoushan“Kengtoudong”

Shoushan“Kengtoudong”is a typical stone of Shoushan puddle stone which is rare and expensive.By XRD，FTIR，ICP－MS，SEM and other instruments，mineral component，chemical composition，microstructure of“Qinghaibai”“Dandongbai”and“Yanmenjing”are investigated systematically when they appear on the market recently as the imitation of Shoushan“Kengtoudong”.The results show that“Kengtoudong”is mainly composed of dickite，observed with typical“Luobosiwen”，and a higher percentage of Fe in chemical composition might result from its pyrite inclusions.“Qinghaibai”is mainly composed of gypsum，which is of lower hardness.“Dandongbai”is mainly composed of clinochlore，and dark green speckle impurities lead to dusky appearance.“Yanmenjing”is mainly composed of dickite and higher V and Cr might be the reason that the stone show limegreen tones.SEM observation shows that Shoushan“Kengtoudong”samples have a high degree of crystallization with false hexagonal flake structure.The crystals plate of“Qinghaibai”is of large granularity，thickness and loose accumulation，thus it can be easily distinguished from others.The lamellar crystal of clinochlore of“Dandongbai”is thin and piled up closely，flex developed，thus it is smooth to the touch.The microscopical features of“Yanmenjing”are much like Shoushan“Kengtoudong”，but its crystal degree is a little lower.The stones mentioned above are different in colour，luster，weighting and inclusions，due to their different mineral components and chemical compositions.