一种含赤铁矿包裹体绿柱石的谱学特征

Spectral Characteristic of Beryl Containing Hematite Inclusion

  • 摘要: 本文所研究的绿柱石是以定向赤铁矿为主要包裹体的一种市场罕见品种,利用LA-ICP-MS、拉曼光谱仪、红外光谱仪、显微紫外-可见-近红外光谱仪对该绿柱石进行详细谱学特征研究。该绿柱石样品除主量BeO,Al2O3,SiO2外,含一定量的Fe、Mn、Cs、Ti、V,碱金属总质量分数为0.48%,为贫碱型绿柱石; 经拉曼光谱仪测定了其核部主矿物平行c轴和垂直c轴的拉曼位移及赤铁矿包裹体拉曼位移; 红外光谱仪确定核部主矿物指纹区振动频率及结构水振动频率:Ⅰ型结构水位于3 699 cm-1处,Ⅱ型结构水位于3 661,3 596 cm-1处。显微紫外-可见-近红外光谱分析结果显示,E⊥c轴偏振方向可见Fe3+的371,427 nm处吸收,Fe2+的820 nm处吸收,Ⅰ型水位于1 402、1 835、1 956 nm处吸收和Ⅱ型水位于1 369、1 897 nm处吸收; E//c轴偏振方向可见Fe3+的427 nm处吸收,Ⅰ型水1 402、1 467 nm处吸收,Ⅱ型水1 152、897 nm处吸收。在平行c轴方向,Ⅱ型水强度较垂直c轴方向强。对该罕见以赤铁矿为主要包裹体的绿柱石样品成分、谱学的详细研究,丰富了该品种绿柱石的宝石学特征相关资料,为后人研究奠定基础。

     

    Abstract: The beryl studied in this paper is a rare kind of beryl with hematite as the main inclusion. The detail spectral characteristics study were carried out on the samples by using LA-ICP-MS, Raman spectroscopy, IR spectroscopy and UV-Vis-NIR microscopic spectrophotometer. The samples contain a certain amount of Fe, Mn, Cs, Ti and V except the main amounts of BeO, Al2O3 and SiO2, and the total amount of alkali elements is 0.48%, which belongs to alkali-poor beryl. Using the Raman spectrometer, we got the Raman shifts of I region sample parallel to c axis and vertical to c axis. Measurement of the infrared vibration frequency was performed using infrared spectrometer, acquiring the results of 3 699 cm-1 for type I water, 3 661 cm-1 and 3 596 cm-1 for type Ⅱ water. With the Jasco Msv-5200, the Micro-UV-Vis-NIR spectra shows that in E⊥c direction absorption peaks at 371, 427 nm were caused by Fe3+; 820 nm was caused by Fe2+, and the 1 402, 1 835, 1 956 nm were caused by type I water and 1 369, 1 897 nm were caused by type Ⅱ water. The polarization direction of E//c shows the absorption of Fe3+ at 427 nm, and the absorption of type I water at 1 402, 1 467 nm; type Ⅱ water at 1 152, 1 897 nm. The strength of type Ⅱ water is stronger in the direction parallel to the c axis than that in the direction perpendicular to the c axis. The study enriches the gemmological study of this kind of beryl and lays a foundation for future research.

     

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