贵州罗甸和广西大化软玉的化学成分与光谱特征

Chemical Composition and Spectrum Characteristic of Nephrite from Luodian, Guizhou Province and Dahua, Guangxi Province

  • 摘要: 选取贵州罗甸县官固村及广西大化县岩滩镇产出的软玉作为研究对象,采用X射线荧光光谱仪、傅里叶变换红外光谱仪和激光拉曼光谱仪对样品的化学成分及振动光谱特征进行测试分析。结果表明,贵州罗甸和广西软玉的主要矿物组成为透闪石,并含有少量白云石。贵州罗甸软玉中FeOT平均质量分数为0.268%,低于广西软玉的1.757%,且白玉、青白玉、青玉的FeOT质量分数依次递增。随着晶体结构中Fe2+对Mg2+的类质同象替代作用增强,软玉红外光谱和拉曼光谱中M-OH振动谱带分裂程度逐渐提高。分裂程度最高者为广西青玉,其3 674、3 660、3 644 cm-1附近中红外吸收谱带由OH(Mg, Mg, Mg)、OH(Mg, Mg, Fe2+)、OH(Mg, Fe2+, Fe2+)基频振动所致,7 182、7 154 cm-1附近的近红外吸收谱带由OH(Mg, Mg, Mg)、OH(Mg, Mg, Fe 2+)的倍频振动所致, 3 672、3 658、3 642 cm-1的特征拉曼谱峰由M-OH伸缩振动所致。由于贵州软玉整体Fe质量分数比广西软玉低,故相关谱峰未出现分裂现象。

     

    Abstract: The nephrites from Guangu County, Guizhou Province and Yantan Town of Dahua County, Guangxi Province were selected as the research objects. The chemical composition and vibrational spectra of the samples were analyzed by X-ray fluorescence spectrometer, Fourier transform infrared spectrometer and laser Raman spectrometer. The test results show that the main mineral component of nephrites from Guizhou and Guangxi is tremolite, with a small amount of dolomite. The FeOT average mass fraction of Guizhou nephrites is 0.268%, which is lower than 1.757% that in Guangxi nephrites, and the FeOT mass fraction of white nephrites, green white nephrites and green nephrites increase in turn.With the enhancement of the isomorphism of Fe2+ to Mg2+ in the crystal structure, the degree of M-OH vibration band splitting in the infrared and Raman spectra of nephrite is gradually increased. The highest degree of division comes from green nephrite of Guangxi. The middle infrared absorption bands around 3 674, 3 660, 3 644 cm-1 are caused by the fundamental frequency vibration of OH(Mg, Mg, Mg), OH(Mg, Mg, Fe 2+) and OH(Mg, Fe2+, Fe 2+), and the near-infrared absorption bands around 7 182 cm-1and 7 154 cm-1 are caused by the double frequency vibration of OH(Mg, Mg, Mg) and OH(Mg, Mg, Fe 2+). The Raman peaks around 3 672, 3 658, 3 642 cm-1 are caused by M-OH stretching vibration. Since the overall Fe mass fraction of Guizhou nephrites is lower than that of Guangxi nephrites, there is no splitting phenomenon in the relevant peaks.

     

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