歙砚的宝石矿物学特征研究

Study on Gemmological and Mineralogical Characteristics of She Inkstone

以产自江西省婺源县的歙砚为研究对象,运用电子天平、显微硬度计、偏光显微镜以及X射线粉末衍射仪、环境扫描电子显微镜,对歙砚原石的宝石矿物学性质进行了较深入的研究,综合分析了歙砚的组成成分、质量分数及结构特征。测试结果表明:样品的平均摩氏硬度为4.45,平均密度为2.748 5 g/cm3;其主要矿物为绢云母,呈细小鳞片状结构,定向排列,还含有石英、绿泥石以及少量的锆石、正长石、高岭石和斑铜矿等。环境扫描电子显微镜及其能谱仪的测量结果显示,歙砚样品的主要矿物为多硅白云母,其单晶颗粒好,呈叶片状、定向排列,其集合体呈叠瓦状结构分布;其平均化学式为K0.59Na0.50{(Al2.86Mg0.50Fe03.7+5)4.11[(Al0.91Si7.09)8O20](OH)4}。

The gemmological and mineralogical characteristics of She inkstone samples from Wuyuan County,Jiangxi Province, are deeply studied by using electronic balance, micro sclerometer, polarizing microscope and X-ray powder diffraction（XRD）, environment scanning electron microscope（ESEM） with its X-ray energy-dispersive spectrometer（EDS）, including the geological survey, compositions, content and structure characteristics of She inkstone samples. The testing results show that the average Mobs hardness of the samples is up to 4.45 and the average density is up to 2. 748 5 g/cm^3, where the major mineral is sericite with small scaly structure and orientational arrangement,and the other minerals are quartz, chlorite and a small quantity of zircon, orthoclase, kaolinite and bornite,etc. Through environment scanning electron microscope and X-ray energy-dispersive spectrometer, the results indicate that the major mineral of the samples is Si-rich sericite, whose monocrystal is of being well, leaf-shaped and orientational arrangement, with its aggregate being imbricate characteristics. The average chemical formula of Si-rich sericite in the sample is K0.09 Na0.50 {（Al2.86 Mg0.50 Fe^3＋0.75）4.11 [（Al0.91Si7.09）8 O20-]（OH）4 }.