重晶石、三水铝石及方解石混合物仿绿松石与天然绿松石的光谱特征及化学成分对比

Comparison of Spectral Characteristic and Chemical Compostion of Barite,Diaspore and Calcite Mixture Imitated Turquoise and Natural Turquoise

采用红外光谱仪、激光拉曼光谱仪、X射线荧光能谱仪、紫外-可见光分光光度计对目前市场上新出现的一类绿松石仿制品和天然绿松石进行了对比研究。结果表明,该类仿制品主要由重晶石、三水铝石、方解石及有机物胶结而成,外观和天然“铁线”绿松石十分相似,可根据以下几项鉴定依据区分:绿松石仿制品样品的拉曼光谱和红外光谱均显示三水铝石、重晶石、方解石及有机物特征峰,且黑色花纹部分不存在石英、石墨等天然矿物;其化学成分以BaO、Al_(2)O_(3)、SO_(2)、CaO为主,缺失天然绿松石的关键化学成分P_(2)O_(5);紫外-可见-近红外吸收光谱缺失427 nm处的吸收峰,显示675 nm位于可见光红光谱的吸收峰,缺失近红外光区的吸收。

By Fourier transform infrared spectroscopy(FTIR),Raman spectroscopy,X-ray fluorescence energy spectrometer and UV-Vis spectroscopy,a new kind of turquoise imitation and natural turquoise were studied comparatively.The results show that this kind of imitation is mainly made of mixtures of barite,gibbsite,calcite and organic matter.Its appearance are very similar to natural turquoise.The imitation and natural turquoise can be distinguished according to the following identification criteria:the Raman spectra and infrared spectra of the imitation show the characteristic peaks of barite,gibbsite,calcite and organic matter,and there are no natural minerals such as quartz and graphite in the imitation’s black patterns.The chemical compositions of the imitation are mainly BaO,Al_(2)O_(3),SO_(2)and CaO,without the key chemical composition P_(2)O_(5)of natural turquoise.The UV-Vis-NIR absorption spectra of the imitation show absorption of 675 nm,without absorption at 427 nm and absorption in the near-infrared light region.