一颗钙柱石的宝石学特征测试分析

Gemmological Analysis on A Meionite

通过常规和大型宝玉石检测仪器对排查中出现的1颗无色样品的宝石学及谱学特征进行测试分析,结果表明:该粒样品的折射率值为1.550~1.588,双折射率为0.038,密度值是2.89±0.02 g/cm3,放大观察可见大量定向排列针状包裹体及垂直方向排列的短柱状晶体;X射线能谱仪测试显示样品主要化学元素属于方柱石族系列,Ma平均值为10.14%;红外光谱和拉曼光谱分析显示,其特征谱峰主要是由CO2-3和Si-O、Al-O、O-H基团所致,其中拉曼光谱在448、1090、1327 cm^-1处具有谱峰,红外光谱在指纹区峰位1404、1516、1007、853、609、544、459、413 cm^-1处具有谱峰;官能团区2939,2496、2612、3391 cm^-1处具有谱峰。紫外-可见吸收光谱显示,样品在可见光区基本无明显吸收峰,在312 nm处出现的吸收峰可能与Fe3+离子和Fe3+-Fe3+离子对的d-d电子跃迁有关,光致发光光谱测试其主要发光光谱带位于608 nm中心,并伴随558、569、588、629、650、678、698 nm的肩峰,综合结果显示该粒样品为较为少见的钙柱石。

In this paper,the gemmological and spectroscopic characteristics of a colourless sample in the routine testing process were analyzed by using the gemstone laboratory testing instruments and modern testing equipments.The results show that the refractive index of the sample is 1.550-1.588,the birefringence is 0.038,and the relative density is 2.89±0.02 g/cm3.A large number of directionally arranged acicular crystals can be seen through magnification observation,and short columnar crystals can be seen perpendicular to the acicular direction.The results of EDS show that the main chemical elements of the sample belong to the scapolite family,and the average Ma value is 10.14%.According to the infrared spectra and Raman spectra,the generation of spectral characteristic peaks is mainly due to the vibration mode and frequency of CO2-3,Si-O,Al-O and O-H groups,among which the Raman characteristic absorption peaks are at 448,1090 cm^-1 and 1327 cm^-1.The absorption peaks of infrared fingerprint location feature are at 1404,1516,1007,853,609,544,459,413 cm^-1.The characteristic absorption peaks of infrared functional groups are at 2939,2496,2612,3391 cm^-1.There is no obvious absorption peak in the visible region of UV-Vis absorption spectrum.The absorption peak at 312 nm may be related to the d-d electronic transition of Fe3+and Fe3+-Fe3+ion pairs.The main photoluminescence band is located in the center of 608 nm,with 558,569,588,629,650,678,698 nm shoulder peaks.According to the evidence provided above,the sample is a meionitea which is a rare gem variety.