伊朗Baghu绿松石及伴生矿物的矿物学和谱学特征

Mineralogical and Spectral Characteristics of Turquoise and Associated Minerals from Baghu,Iran

伊朗Baghu绿松石矿床位于Kuh-Zar地区,该矿床的绿松石品质较好但并未用于商业的开采。利用扫描电子显微镜、傅里叶变换红外光谱仪、拉曼光谱仪以及紫外-可见光光谱仪对伊朗Baghu矿区的4块蓝色-浅蓝色为主的绿松石矿样品进行矿物学和谱学特征研究。扫描电子显微镜显示,绿松石微晶大小约为1~5μm,呈长柱状、板状、鳞片状集合体;拉曼光谱和能谱的成分分析结果显示,伊朗Baghu绿松石伴生矿物有电气石、云母、石膏、假孔雀石、硅孔雀石、重晶石、黄铁矿、长石、石英、黄钾铁矾、明矾石及金红石,其中电气石呈放射状,石英自形程度好。根据伴生矿物共生组合,推断该绿松石成矿母岩为岩浆岩,该产地特有伴生矿物为电气石、孔雀石、硅孔雀石、假孔雀石,可作为判别产地的特征之一。拉曼光谱及红外光谱均显示出绿松石H_(2)O、OH^(-)、PO_(4)^(3-)基团的吸收谱峰,与其他产地的光谱特征较为一致。紫外-可见光谱显示的422、429 nm和650~670 nm处的谱峰分别是由Fe和Cu离子引起。

The Baghu turquoise deposit is located in the Kuh-Zar region,Iran.The turquoise from Baghu deposit is of high quality,which has not been used for commercial exploitation yet.4 pieces of light blue to blue turquoise samples were selected from Baghu deposit to investigate the mineralogy and spectroscopy of the turquoise there by scanning electron micrometer(SEM),Fourier transform infrared spectrometer(FTIR),Raman spectrometer and UV-Vis spectrometer.The SEM images showed that the turquoise microcrystals occurre as long columnar,plate and scale aggregates with the size ranging from 1 to 5μm.According to the test results of energy dispersive spectroscopy and Raman spectroscopy,the associated minerals are tourmaline,mica,gypsum,pseudomalachite,chrysocolla,barite,pyrite,quartz,jarosite,alingite and rutile.The tourmaline has an radial pattern and quartz is in good idiomorphology.According to the associated mineral association,it is inferred that the turquoise ore-forming mother rock is magmatic rock,and the associated minerals are tourmaline,malachite,chrysocolla and pseudomalachite,which can be used as one of the characteristics to distinguish the origin.Both Raman spectra and infrared spectra of turquoise showed the absorption peaks of H_(2)O,OH^(-)and PO_(4)^(3-) groups,which are consistent with the characteristics of turquoise from the other regions.The bands at 422,429 nm and 650~670 nm in UV-Vis spectra of turquoise are respectively attributed to Fe and Cu ions.