The Raman spectra of five [4]B-bearing tourmalines of different composition synthesized at 700 °C/4.0 GPa (including first-time synthesis of Na-Li-[4]B-tourmaline, Ca-Li-[4]B-tourmaline, and Ca-bearing ☐-[4]B-tourmaline) reveal a strong correlation between the tetrahedral boron content and the summed relative intensity of all OH-stretching bands between 3300–3430 cm–1. The band shift to low wavenumbers is explained by strong O3-H···O5 hydrogen bridge bonding. Applying the regression equation to natural [4]B-bearing tourmaline from the Koralpe (Austria) reproduces the EMPA-derived value perfectly [EMPA: 0.67(12) [4]B pfu vs. Raman: 0.66(13) [4]B pfu]. This demonstrates that Raman spectroscopy provides a fast and easy-to-use tool for the quantification of tetrahedral boron in tourma-line. The knowledge of the amount of tetrahedral boron in tourmaline has important implications for the better understanding and modeling of B-isotope fractionation between tourmaline and fluid/melt, widely used as a tracer of mass transfer processes.

中文翻译：

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合成富铝电气石中四面体硼的拉曼光谱定量

在 700 °C/4.0 GPa 下合成的五种不同成分的含 [4]B 电气石的拉曼光谱（包括首次合成 Na-Li-[4]B-电气石、Ca-Li-[4]B-电气石和含钙的 ☐-[4]B 电气石）揭示了四面体硼含量与 3300-3430 cm-1 之间所有 OH 拉伸带的总和相对强度之间的强相关性。带向低波数的移动是由强 O3-H···O5 氢桥键合来解释的。将回归方程应用于来自 Koralpe（奥地利）的天然 [4]B 碧玺完美再现了 EMPA 衍生值 [EMPA：0.67(12) [4]B pfu 与拉曼：0.66(13) [4]B pfu]。这表明拉曼光谱为电气石线中四面体硼的定量提供了一种快速且易于使用的工具。