Gemmological and Mineralogical Study on Qijiang Stones from Shoushan, Fujian Province

Larderite is a unique kind of carving stone in China with long history and great reputation.The authors study the gemmological and mineralogical characteristics of Qijiang stones(a kind of larderite)from Shoushan，Fujian Province，by means of conventional gemmological instruments，X－ray powder diffraction(XRD)，laser Raman spectroscopy(LRM)and environmental scanning electron microscope(ESEM).Those studies indicate that the samples of Qijiang stones all belong to kaolinite group larderite，and they also shows that most samples are mainly composed of dickite，though a few samples mainly are of kaolinite.The authors believe that the sizes of particle and degrees of crystallization of mineral are associated with the transparency of stones，and those samples with high transparency are usually large particles with high degree of order and crystallization.In addition，the yellow and red colours of those samples are caused by Fe cation，and the more Fe cation，the deeper colour of samples.