“蓝水料”翡翠的宝石矿物学特征

Gemmological and Mineralogical Characteristic of“Lanshui”Jadeite

对市场上搜集的3件危地马拉"蓝水料"翡翠成品和2件原料进行了无损测试与分析,包括常规宝石学特征、红外吸收光谱和紫外-可见吸收光谱等测试方法。对危地马拉"蓝水料"翡翠原料进行了有损测试分析,研究其岩石矿物学特征,包括岩石薄片观察、X射线粉末衍射和电子探针分析。结果表明,"蓝水料"翡翠的宝石学特征与传统翡翠一致,矿物组成以硬玉为主,含少量绿辉石,红外吸收光谱显示其主要吸收峰在1 080cm^(-1)处,紫外-可见吸收光谱可见437nm特征吸收峰。"蓝水料"翡翠的岩石矿物学和宝石学特征均符合传统翡翠的定义。

In order to investigate the charateristics of the“Lanshui”jadeite from Guatemala,we collected three finished samples and two rough material from the market for non-destructive analysis,including conventional gemmological methods,Fourier transfom infrared spectrometer(FTIR),ultraviolet-visible spectrometer(UV-Vis).Destructive analysis were used for rough materials,such as the thin section observation,XRD and EPMA.The“Lanshui”jadeite is blue to green,glassy luster.Some samples contain several white minerals.The result showed that a spot refractive index of the“Lanshui”jadeite is 1.66 and a hydrostatic specific gravity is 3.33 to 3.35,which are in accordance with the traditional jadeite.The microstructrure showed that the“Lanshui”jadeite is mainly composed of jadeite,with minor zircon and metallic minerals.The jadeite crystals are columnar,fibrous and xenomorphic granular.The EPMA result indicated that the main mineral component is jadeite,with some omphacite.The main component of the“Lanshui”jadeite sample is SiO 2,Al 2O 3 and Na 2O.The w(SiO 2)varies between 56.84%-68.81%,and the w(Al 2O 3)varies between 9.57%-24.16%,and the w(Na 2O)varies between 5.89%-13.71%.The sodic(including jadeite)and sodic-calcic proxenes(including omphacite)were classified by Q-J pyroxenes diagram,where Q=Ca+Mg+Fe 2+and J=2Na,0.20<J/(Q+J)<0.80 is sodic-calcic pyroxenes(including omphacite),J/(Q+J)>0.80 is sodic pyroxenes.Most J/(Q+J)values of the sample present 0.82-1.00,which belongs to the jadeite,while only a few points vary from 0.50~0.41,which belongs to the omphacite.The XRD result showed that the main mineral of the“Lanshui”jadeite is jadeite.The FTIR spectra of the samples showed the main reflectance band is situated around 1 080 cm-1 which is consistent with the“jadeite jade”in previous work.UV-Vis absorption spectra of the“Lanshui”jadeite showed the absorption bands around 380 nm and 437 nm were attributed to Fe 3+in octahedral coordination,which are in accordance with the traditional jadeite.All the results including conventional gemmological charaterstic,petrological and mineralogical charaterstic,suggest the“Lanshui”jadeite is consistent with the definition of the traditional jadite jadeite.