广西阳朔磷氯铅矿矿物学和振动光谱特征分析

MINERALOGY AND VIBRATION SPECTRUM ANALYSIS OF THE PYROMORPHITE FROM YANGSHUO OF GUANGXI ZHUANG AUTONOMOUS REGION

广西阳朔长期出产宝石级磷氯铅矿,迄今未见其矿物学和振动光谱的研究报道。采用能量色散X射线荧光光谱、X射线粉末晶体衍射、红外光谱和拉曼光谱分析了14颗阳朔磷氯铅矿。该矿物为半透明的黄绿色六方柱,相对密度为6.484~7.310,白色条痕,硬度为4,化学成分以铅、磷和氯为主。红外光谱在1060~920 cm^(-1)和580~540 cm^(-1)区域观察到属于PO_(4)^(3-)的伸缩和弯曲振动带,平行和垂直光轴的谱带差异明显;部分样品观察到AsO_(4)^(3-)振动弱带,说明结构中有少量PO_(4)^(3-)被替代。拉曼光谱观察到916/940 cm^(-1)属于PO_(4)^(3-)伸缩振动强带、位于390/414/542/572 cm^(-1)系列弯曲振动带和160~262 cm^(-1)晶格振动带。这些谱带随着测试方向不同而变化,反映出结构中的PO_(4)^(3-)四面体在不同方向的变化。此外,出现在815 cm^(-1)的拉曼弱带归属于AsO_(4)^(3-)对称伸缩振动,证实结构中少量PO_(4)^(3-)被AsO_(4)^(3-)类质同象替代。综合分析表明,阳朔磷氯铅矿属于砷铅矿-磷氯铅矿固溶体系列矿物中靠近磷端元的矿物。

So far,the mineralogy and vibration spectra of phosphlorophenite produced in Yangshuo,Guangxi have not been reported.To understand the properties of gem-grade phosphlorophenite,14 Yangshuo pyromorphite ore grains are analyzed by energy dispersive X-ray fluorescence spectroscopy,X-ray powder crystal diffraction,Infrared spectroscopy and Raman spectroscopy.The results show that the mineral is a semi-transparent yellow-green hexagonal column with a relative density of 6.484 to 7.310,with white streaks and a hardness of 4.The chemical composition is mainly lead,phosphorus and chlorine.Stretching and bending vibration bands of PO_(4)^(3-)are observed in the 1060 to 920 cm^(-1)and 580 to 540 cm^(-1)regions of the infrared spectrum,and the bands of parallel and vertical optical axes are significantly different.AsO_(4)^(3-)weak vibrational bands are observed in some samples,indicating that a small amount of PO_(4)^(3-)is substituted in the structure.Raman spectra analysis shows that 916/940 cm^(-1)belongs to the PO_(4)^(3-)stretching vibration band,located at the bending vibration band of 390/414/542/572 cm^(-1)series and the lattice vibration band of 160 to 262 cm^(-1).These bands vary with the test direction,reflecting the variation of PO_(4)^(3-)tetrahedron in different directions.In addition,the Raman weak band at 815 cm^(-1)is attributed to AsO_(4)^(3-)symmetric stretching vibration,confirming that a small amount of PO_(4)^(3-)in the structure is replaced by AsO_(4)^(3-)mass isogram.Based on the comprehensive analysis,the Yangshuo pyromorphite can be classified as the mineral close to the phosphorus end member in the solid solution series minerals of pyromorphite-mimetite.