近期市场上出现了一种外形特殊的绿松石, 体色多呈现浓度不同的蓝绿色, 大部分表面都有大小不等的白色——浅蓝白色斑块和斑点, 斑块界限模糊, 部分品种表面有类似流纹的结构, 外表与压制绿松石极为相似, 这种绿松石原料主要产自于蒙古, 市场上俗称 “外蒙料”。 采用常规宝石学测试仪器, X射线荧光光谱、 红外吸收光谱、 激光拉曼光谱和X射线粉晶衍射等测试方法对这类“外蒙料”绿松石的宝石学性质、 化学成分及矿物组成等进行了较为详细的研究分析。 研究结果表明: “外蒙料”绿松石样品整体外观呈浅蓝绿至深蓝绿色, 颜色分布不均匀, 表面常见白色或浅蓝白色分布不均一的斑块或斑点, 内部常含有石英、 长石、 伊利石还有黄铁矿。 其折射率约为1.60~1.62, 相对密度约为2.43~2.76, 低于我国湖北和安徽的绿松石。 在长波紫外光下, 大部分样品可见较微弱的蓝白色荧光, 在短波紫外光下, 荧光为惰性。 “外蒙料”的主要化学成分均偏离绿松石理论化学成分值, w(Al2O3)在26.75%～30.30%之间, w(P2O5)在32.54%～36.40%之间, w(CuO)在6.99%～10.73%之间, w(FeO)在1.73%～4.39%之间, w(ZnO)在0.35%～2.93%之间, 属于绿松石——锌绿松石类质同像系列靠近绿松石的端元, 其中普遍含有一定量的SiO2, 质量分数可达2.38%～8.87%, 这一特点与国内其他产地绿松石几乎不含或含有极微量的SiO2不同。 X射线粉晶衍射及红外吸收光谱显示, “外蒙料”中不均匀分布的颜色斑块的主要组成矿物均为绿松石, 且整体未经优化处理, 为天然绿松石。 红外吸收光谱显示绿松石“外蒙料”的红外吸收光谱为结晶水、 羟基水及磷酸根基团的振动光谱, 与天然绿松石的红外吸收光谱特征一致。 “外蒙料”绿松石中不同透明度及颜色的杂质矿物的激光拉曼光谱测试分析表明该绿松石中所含有的白色不透明杂质矿物为钠长石, 白色半透明杂质矿物为石英, 黄铜色具有金属光泽的杂质矿物为黄铁矿。

Recently, one kind of turquoise with special appearance appears in the market. Their color is mostly pale blue and bluish green. Most of these materials are variegated with white or light blue-green plaques, whose boundaries are blurred. Some samples have similar flow structure on the surface, and their appearance is very similar to that of pressed turquoise. The raw material of the turquoise is mainly from Mongolia. The conventional gemological method, X-ray Fluorescence Spectrometer, Laser Raman Spectrometer and X-ray Power Diffraction were applied to the Mongolia turquoises in order to clarify their gemological properties, chemical and mineral composition in detail. The results show that the overall appearance of Mongolia turquoise is blue-green to deep blue-green with uneven distribution of color and uneven plaques on the surface. It often contains impurities such as quartz, pyrite, illite, feldspar and limonite etc. The refractive index of the turquoise in this area ranges from 1.60 to 1.62 (spot method), the relative density ranges from 2.43 to 2.76, and the relative density of the Mongolia turquoise is lower than that occurred in Hubei and Anhui. The samples fluoresce a weak ultraviolet to blue light glow under LWUV, with an inert reaction to SWUV. Weak ultraviolet light to blue fluorescence was observed in most samples under long-wavelength ultraviolet light, and fluorescence was inert under short-wavelength ultraviolet light. The main chemical composition of the Mongolia turquoise sample deviates from the theoretical chemical composition of turquoise, w (Al2O3) ranges from 26.75% to 30.30%, w (P2O5) ranges from 32.54% to 36.40%, w (CuO) ranges from 6.99% to 10.73%, w (FeO) ranges from 1.73% to 4.39%, w (ZnO) ranges from 0.35% to 2.93%. There is a certain amount of SiO2 in Mongolia turquoise samples, and the mass fraction can reach 2.38%~8.87%. This characteristic is different from that of other domestic turquoise areas, which contain nearly no or very trace SiO2. X-ray powder diffraction and infrared absorption spectra show that the main components of the uneven color plaques of Mongolia turquoise are turquoise, and they are natural and not optimised. Infrared absorption spectra show the vibrational spectra of crystal water, hydroxyl water and phosphate groups, which are consistent with those of natural turquoise. The laser Raman spectroscopy analysis of minerals with different transparency and color in Mongolia Turquoise show that the white opaque impurity minerals in the turquoise are sodium feldspar, white translucent impurity minerals are quartz, and brass with metallic lustre minerals are pyrite.