Gemmological Characteristics of Four Kinds of Green Figure Stones

In the research,four kinds of Chinese green figure stones are collected as samples,whose commercial names are "Shanpaolv"(SPL)from Zhejiang Province,"Sichuanlv"(SCL)from Sichuan Province,"Yunnanlv"(YNL)from Yunnan Province and "Guizhoulv"(GZL)from Guizhou Province.These four kinds of green figure stones look nearly the same and it is hard for the customers to differ one kind from the others.This study focuses on the gemmological characteristics of these four kinds of green figure stones.All the samples are bought from the figure stone market of Qingtian,Zhejiang Province.X-ray power diffraction spectrometer,environmental scanning electron microscope and Raman spectrometer are uesd to obtain the mineral components,chemical compositions and microscopic characteristics.The conventional test results show that the specific gravity of the four kinds of green figure stones are different.The specific gravity of GZL is the lowest and the value is 2.61.The specific gravity of SPL and SCL are similar,between 2.80and 2.81,while that of YNL is 2.85.The X-ray diffraction results show that major mineral components of SPL and SCL are sericite and minor mineral components are dickite and quartz.The major mineral of YNL is illite and minor mineral component is feldspar.The major mineral of GZL is pure dickite.Different mineral assemblage can help to distinguish different kinds of figure stones.Based on the environmental scanning electron microscope results,the authors find that the the major mineral components of different figure stone samples are similar in lepidoblastic texture,but the degree of crystallinity,mineral morphology and particle size are different.All the samples contain Fe and Cr as the microelements,which may be the reason for the green colour.Combined with thin section observation and Raman tests,the authors find that hematite as the minor mineral,which can lead to the yellow stripes in the green figure stones.