拉曼光谱分析在软玉颜色评价中的应用

APPLICATION OF RAMAN SPECTROSCOPIC TECHNIQUE TO INVESTIGATION OF NEPHRITE COLOR

应用拉曼光谱分析方法对新疆、青海、台湾等地的软玉进行研究,分析针对白玉、青白玉、青玉、黄玉、碧玉等不同颜色品种软玉晶体结构中M1,M3位置阳离子的占位情况。指纹区拉曼光谱显示软玉主要组成矿物为透闪石,杂质离子的取代导致不同颜色品种软玉化学成分上的细微差异;M—OH伸缩振动区内主要吸收峰对表征软玉化学组成及颜色分级别具有重要意义,即利用3 675cm-1,3 661cm-1,3 645cm-1的峰强比值法计算Mg2+/(Mg2++Fe2+)的比值及Fe的相对含量。利用能量色散荧光光谱仪测试样品中Fe元素的相对含量,并选择有针对性的样品用电子探针测试Fe,Mg元素的含量,以此进一步验证拉曼光谱仪的测试结果的可靠性,最终得出3 675cm-1,3 661cm-1,3 645cm-1的峰强比值法可作为评价软玉颜色的色调及饱和度的重要参考。

Nephrites from Xinjiang,Qinghai,Taiwan and so on were studied by using Raman spectroscopic.Specifically,a variety of nephrite with different colors,such as Baiyu,Qingyu,Huangyu and Biyu were investigated over their cations at M1 and M3sites.Raman spectra in the fingerprint region showed that the main composition of nephrite is tremolite.The replacement of impurity ions leads to some nuances in the chemical composition for a variety of nephrite with different colors.The peak of M—OH stretching vibration is important for recognizing the main chemical composition of nephrite as well as its color categorization.Ratio of Mg2＋/（Mg2＋＋Fe2＋）were calculated by using peak intensity ratio of 3 675cm-1,3 661cm-1,3 645cm-1,and the relative content of Fe,Mg element was tested by using X-ray fluorescence and electron probe.The reliability tested by using EDXRF and electron probe indicated that the method of peak intensity ratio of 3 675cm-1,3 661cm-1,3 645cm-1 can be used as a reference for evaluating nephrite whiteness.