湖北神农架“梅花玉”的宝石学特征
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摘要
"梅花玉"是我国湖北神农架产出的一种红色天然矿石,通过常规宝石学测试、偏光显微镜、X射线粉末衍射仪(XRD)、拉曼光谱仪(LRM)、扫描电子显微镜(SEM)、X射线荧光能谱仪(EDS)对"梅花玉"的宝石学特征、矿物组成、化学成分、微形貌特征、颜色成因进行了测试分析。结果显示,该"梅花玉"具玻璃光泽—油脂光泽,不透明,密度为2.69~2.71g/cm~3,其主要矿物组成为方解石,次要矿物为白云石和石英;"血色"部分的矿物组成为赤铁矿;黑色脉状区域为隐晶质矿物,可能为黑云母等粘土矿物。在微形貌特征方面,"梅花玉"中白色方解石的结晶形态较好,结构紧凑,可见菱面体解理;红色部分自形晶少,赤铁矿呈细粒状或薄膜状充填在方解石裂隙和解理中而表现为红色,黑色矿物呈不规则条带状、脉状覆盖胶着在其它矿物表面。
"Meihua Jade"is a kind of red natural ore produced from Shennongjia,Hubei Province,China.The gemmological properties,mineral components,chemical compositions,micromorphology and cause of colour of"Meihua Jade"samples were investigated by using conventional gemmological methods,polarizing microscope,X-ray powder diffraction(XRD),laser Raman spectroscopy(LRM)and scanning electron microscope(SEM),energy dispersive spectrometer(EDS).The results showed that"Meihua Jade"is opaque,glassy to greasy luster,with density 2.69—2.71 g/cm~3.The main mineral component is calcite,and its minor mineral components are dolomite and quartz.The "blood"part of the stone is caused by hematite and the black veins are composed of cryptocrystalline minerals,which may be biotite or other clay minerals.In aspect of its micromorphology,the crystal form of white calcite is respectively better than the other parts and the structure is compact.The rhombohedral cleavage is visible.The red part is seldom self-shaped.Hematite is fine granular or thin film,which looks red when it fills in the cleavage and crack of calcite.Black minerals showed irreg-ular bands,and veins covered with glue on other mineral surfaces.
"Meihua Jade"is a kind of red natural ore produced from Shennongjia,Hubei Province,China.The gemmological properties,mineral components,chemical compositions,micromorphology and cause of colour of"Meihua Jade"samples were investigated by using conventional gemmological methods,polarizing microscope,X-ray powder diffraction(XRD),laser Raman spectroscopy(LRM)and scanning electron microscope(SEM),energy dispersive spectrometer(EDS).The results showed that"Meihua Jade"is opaque,glassy to greasy luster,with density 2.69—2.71 g/cm~3.The main mineral component is calcite,and its minor mineral components are dolomite and quartz.The "blood"part of the stone is caused by hematite and the black veins are composed of cryptocrystalline minerals,which may be biotite or other clay minerals.In aspect of its micromorphology,the crystal form of white calcite is respectively better than the other parts and the structure is compact.The rhombohedral cleavage is visible.The red part is seldom self-shaped.Hematite is fine granular or thin film,which looks red when it fills in the cleavage and crack of calcite.Black minerals showed irreg-ular bands,and veins covered with glue on other mineral surfaces.
引文
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[3]刘力,陈小龙,潘龙克,等.神农架隆起南缘石槽河组白云岩地球化学特征及其成因分析[J].资源环境与工程,2016,30(4):551-555.
[4]迟广成,肖刚,伍月,等.X射线粉晶衍射仪在大理岩鉴定与分类中的应用[J].岩矿测试,2014,33(5):698-705.
[5]陈涛,刘云贵,吴迪,等.福建寿山黑田与坑头黑的谱学与矿物学研究[J].光谱学与光谱分析,2016,36(11):3 693-3 697.
[6]杜广鹏,范建良.方解石族矿物的拉曼光谱特征[J].矿物岩石,2010,30(4):32-35.
[7]陈涛,鲁纬,唐亮亮,等.福建寿山高山桃花石的颜色成因研究[J].宝石和宝石学杂志,2008,10(3):1-4.
[8]韩孝朕,郭正也,康燕,等.拉曼光谱在鸡血石鉴定中的应用[J].光学学报,2015,35(1):446-453.
[9]王冠玉,陈涛.寿山红色月尾石与老岭石宝石学特征对比[J].宝石和宝石学杂志,2016,18(1):15-23.
[10]潘兆橹.结晶学与矿物学[M].北京:地质出版社,1994.