新疆“直闪石玉”的宝石学特征
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摘要
采用常规宝石学测试、X射线粉末衍射仪、傅里叶变换红外光谱仪、扫描电子显微镜,激光诱导离解光谱仪及紫外-可见分光光度计等测试方法,对具有代表性的两种颜色(青色、粉红色)的新疆"直闪石玉"样品的宝石学特征、矿物组成、微观形貌进行了深入研究,探讨了其颜色成因。结果表明,青色"直闪石玉"的矿物主要组成为透闪石,粉红色"直闪石玉"的矿物组成为直闪石,所以,商业上用颜色以及结构特征作为筛选"直闪石玉"的标准并不准确。扫描电子显微镜结果显示,青色"直闪石玉"样品具和田玉典型的毛毡状结构,部分显示平行排列的纤维状、细长柱状,外观局部呈现出细腻的丝绢光泽;粉红色直闪石玉样品呈现平行排列的较粗柱状、板状结构,且矿物颗粒较青色样品的更大,肉眼可见比青色"直闪石玉"样品明显的平行排列的粗纤维状结构。青色"直闪石玉"样品的灰绿色应该与Fe元素和微量的C元素有关;粉红色直闪石玉样品的粉红色可能与微量元素Mn元素有关。
The"anthophyllite jade"samples from Xinjiang,with two typical colour varieties(pink and dark green)were tested by conventional gemmological methods.X-ray powder diffraction spectrometer(XRD),Fourier infrared spectroscopy(FTIR),scanning electron microscope(SEM),laser induced breakdown spectroscopy(LIBS)and ultraviolet-visible spectrometry(UV-Vis)were used to analyze the chemical compositons,mineral components and microstructures and possible colour origins of the"anthophyllite jade"samples.The results showed that the pink"anthophyllite jade"samples from Xinjiang are composed of anthophyllite;while the dark green"anthophyllite jade"samples are tremolite.So it was incorrect to name"anthophyllite jade"by the standard of colour and structure features as Xinjiang's businessmen did.SEM result showed the dark green sample is typical nephrite felt structure and there were also parallel slender fibrous and columns,bringing out the part exquisite silk lus-ter.Pink anthophyllite jade samples presented paralleled arrangement of coarser columns and slab structure,with bigger crystal sizes,leading to the visible obvious paralleled arrangement of coarser fibrous structure.LIBS results suggested the dark green colour may be caused by Fe and trace element C;and pink colour may be associated with trace element Mn.
The"anthophyllite jade"samples from Xinjiang,with two typical colour varieties(pink and dark green)were tested by conventional gemmological methods.X-ray powder diffraction spectrometer(XRD),Fourier infrared spectroscopy(FTIR),scanning electron microscope(SEM),laser induced breakdown spectroscopy(LIBS)and ultraviolet-visible spectrometry(UV-Vis)were used to analyze the chemical compositons,mineral components and microstructures and possible colour origins of the"anthophyllite jade"samples.The results showed that the pink"anthophyllite jade"samples from Xinjiang are composed of anthophyllite;while the dark green"anthophyllite jade"samples are tremolite.So it was incorrect to name"anthophyllite jade"by the standard of colour and structure features as Xinjiang's businessmen did.SEM result showed the dark green sample is typical nephrite felt structure and there were also parallel slender fibrous and columns,bringing out the part exquisite silk lus-ter.Pink anthophyllite jade samples presented paralleled arrangement of coarser columns and slab structure,with bigger crystal sizes,leading to the visible obvious paralleled arrangement of coarser fibrous structure.LIBS results suggested the dark green colour may be caused by Fe and trace element C;and pink colour may be associated with trace element Mn.
引文
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[2]王立本,刘亚玲.和田玉、玛纳斯碧玉和岫岩老玉(透闪石玉)的X射线粉晶衍射特征[J].岩石矿物学杂志,2002,21(S1):62-67.
[3]赵珊茸,边秋娟,凌其聪.结晶学与矿物学[M].北京:高等教育出版社,2004.
[4]卢保奇,夏义本,亓利剑.软玉猫眼的红外吸收光谱及热相变机制研究[J].硅酸盐学报,2005,33(2):186-190.
[5]彭文世,刘高魁.矿物红外光谱图集[M].北京:科学出版社,1982:372.
[6]Nakamoto K.Infrared and Raman spectra of inorganic and coordination compounds[M].New York:Wiley-Interscience,1978.
[7]吴瑞华,李雯雯.新疆和田玉岩石学特征及其扫描电镜研究[J].岩石学报,1999,15(4):638-644.
[8]史淼,何明跃,郭颖.新疆和田碧玉的结构特征与组成矿物成分分析[A].玉石学国际学术研讨会[C].北京:地质出版社,2011.
[9]何伟,王以群,毛荐,等.紫色翡翠致色机理探讨[J].华东理工大学学报(自然科学报),2011,37(2):182-185.
[10]那宝成,冷莹莹,李祥虎.软玉致色元素的研究[J].超硬材料工程,2008,20(3):55-58.
[11]谢意红,王成云.不同颜色翡翠的微量元素及红外光谱特征[J].岩矿测试,2003,3(22):183-187.
[12]国家珠宝玉石质量监督检验中心.珠宝玉石国家标准释义[M].北京:地质出版社,1996:87.