新疆哈密绿松石的矿物学和光谱学特征研究

Study on Mineralogy and Spectroscopy of Turquoises from Hami,Xinjiang

最近在新疆哈密发现了可规模开采的宝石级绿松石矿床。采用X射线粉晶衍射仪、激光剥蚀电感耦合等离子体质谱仪、扫描电子显微镜、傅里叶变换红外光谱仪、拉曼光谱仪、紫外-可见光谱仪等测试方法,对该地绿松石的化学成分、矿物组成、表面微形貌、红外吸收光谱、拉曼散射光谱、紫外-可见吸收光谱等矿物学和光谱学特征进行了系统对比研究。新疆哈密绿松石的主要化学成分以富Cr(1 617ppm),V(435ppm),Ti(428ppm),贫Ba(99.9ppm)为特征,随着Fe_2O_3/CuO比值的递减,绿松石的色调由绿变蓝。由磷酸根、羟基和结晶水引起的特征峰出现在该地绿松石的拉曼光谱和红外吸收光谱,其中磷酸根的振动峰位于1 000~1 200和420~650cm^(-1),羟基的振动峰出现在3 400~3 600cm^(-1),而结晶水引起的振动峰位于3 000~3 300cm^(-1)。此外,该地绿松石的紫外-可见吸收光谱显示,在600~700和430nm处分别有由Cu^(2+)和Fe^(3+)引起的吸收峰,这两处的峰强与绿松石的蓝绿色调之间的关系,和新疆哈密绿松石成分中Fe_2O_3/CuO的比值与颜色之间的关系对应一致。

Recently,turquoise from Hami,Xinjiang Provence has been discovered with gemquality and large quantity.In this work,turquoise samples from Hami,Xinjiang were studied with X-ray diffractometer(XRD),laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS),scanning electronic microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy(Raman),and ultraviolet-visible spectroscopy(UV-Vis)to obtain the mineralogy andspectra characteristics.The chemical composition of turquoise from Hami was characterized by rich Cr(1 617 ppm),V(435 ppm),Ti(428 ppm)and poor Ba(99.9 ppm).And,the color of turquoise gradually changed from green to blue with the decrease of the rate of Fe 2O 3/CuO.The SEM results showed that the turquoise crystals were mainly needle,columnar and long plate shape with the size of 0.2~3μm.The infrared and Raman spectra of turquoise were induced by the vibration of phosphate group(located at 1 000~1 200 and 420~650 cm-1),hydroxy group(located at 3 400~3 600 cm-1)and crystal water(locatedat 3 000~3 300 cm-1).Besides,the UV-Vis spectra of the turquoise samples showed that the absorption peaks at 430 nm and 600~700 nm belonged to the electron transition of Fe 3+and Cu 2+,respectively.