四种绿色图章石的宝石学特征

以国内市场上采集的浙江山炮绿、四川绿、云南绿、贵州绿4个品种的绿色图章石作为研究对象,采用X射线粉末衍射仪、环境扫描电子显微镜及能谱仪、拉曼光谱仪等测试方法对4个品种图章石样品的主要矿物组成、化学成分及微观形貌等特征进行对比研究。研究发现,山炮绿和四川绿的主要矿物组成都为绢云母,云南绿的主要矿物组成为伊利石,而贵州绿的主要矿物组成为地开石,从主要矿物组成上可以将贵州绿和云南绿与其它品种绿色图章石相区别。但山炮绿和四川绿主要矿物组成都为绢云母,次要矿物特征也比较相似,都为地开石和石英,因此山炮绿和四川绿从矿物组合特征上难以进行区分。杂质离子的研究表明,绿色图章石的颜色与Cr、Fe离子的混入有关。

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 gem- mological 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 stones are different. The specific gravity of specific gravity of the four kinds of green figure GZL is the lowest and the value is 2.61. Thespecific gravity of SPL and SCL are similar, between 2.80 and 2.81, while that of YNL is 2. 85. The X-ray diffraction results show that major mineral components of SPI. 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 GZI. 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 ma- jor 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 col- our. 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.