应用FTIR-XRD-XRF分析测试技术研究新型仿制绿松石的矿物学特征

近年来绿松石及其仿制品的鉴定工作较多局限于应用傅里叶变换红外光谱对仿制品进行简单的筛选,前人报道的仿制绿松石的矿物组成主要为单一的矿物相(如异极矿、三水铝石、磷铝石、羟硅硼钙石、菱镁矿等)。本文应用傅里叶变换红外光谱(FTIR)、X射线粉晶衍射(XRD)与X射线荧光光谱(XRF)对当前珠宝市场上几种新型仿制绿松石进行了初步分类,并对不同类别的仿制绿松石的具体矿物组成、物相及晶型特征作了对比研究。结果表明,这些新型仿制绿松石可分为三大类:一类主要由硅酸盐(斜硅钙石)与碳酸盐(方解石)两种矿物组成;另一类为白云石与方解石两种碳酸盐矿物的混合相;第三类以硅酸盐类为主要矿物,并含有钡长石、辉石与石英。显然,新型仿制绿松石的矿物组成明显相异于传统仿制品,可见仿制绿松石的矿物组成日趋多样性、复杂化,该现状必然对新型仿制样品的物相鉴定提出了更高的要求。

Determination of Mineral Compositions of New Kinds of Imitated Turquoise by FTIR-XRD-XRF

Identification of turquoises and corresponding imitations is commonly determined by Fourier Transform Infrared (FTIR) Spectrometer. Previous studies have shown that imitation turquoise was mainly composed of a single mineral phase such as hemimorphite, gibbsite, variscite, hydroxyl datolite, or magnesite. Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD) and X-ray Fluorescence Spectroscopy (XRF) were used to investigate new kinds of imitation turquoises in order to classify them based on their mineral compositions and the method is described in this paper. Mineral compositions, crystal phases and crystalline appearance of different types of imitation turquoises were also compared. Results show that new kinds of imitation turquoises in this study can be mainly classified into three groups. The first group is mainly composed of silicate (larnite) and carbonate (calcite). The second group is composed of mixtures of calcite and dolomite. The third group consists of silicate, and minor barium feldspar, pyroxene and quartz. The mineral compositions of new kinds of imitation turquoises were significantly different from those of traditional imitations. In other words, the mineral compositions of imitation turquoises are becoming more and more diverse and complicated, which implies a higher demand for jewelry inspection agencies and researchers.