DOI: http://dx.doi.org/10.21440/2307-2091-2017-4-52-56
Detection of beryllium in oxides and silicates by electron-probe microanalysis PDF
V. V. Khiller
The author developed the technique of electron-probe microanalysis for quantitative determination of beryllium content, providing the example of studying natural minerals (aluminosilicates and oxides). This technique allowed to obtain a quantitative content of beryllium (in combination with other elements) in the emeralds of the Mariinsky beryllium deposit and in zonal mariinskite-chrysoberyl from the chromitites of the Bazhenov ophiolite complex. All analyzes of minerals were performed on a CAMECA SX 100 electron probe microanalyzer with five wave spectrometers (IGG UB RAS). The pressure in the sample chamber was 2 × 10–4 Pa, in the electron gun region – 4 × 10–6 Pa, in wave spectrometers – 7 Pa. Accelerating voltage was 10 kV, the current of absorbed electrons on the Faraday cylinder (beam current) was 100–150 nA. Diameter of the electron beam focused on the sample was 2 μm, the angle of x-ray extraction was 40°. The spectra were obtained on wave spectrometers with TAP crystal analyzers (2d = 25.745 Å), LPET (2d = 8.75 Å), LiF (2d = 4.0226 Å), and PC3 (2d = 211.4 Å, a specialized crystal for determining the content of beryllium and boron); the author carried out all the elements measurements along the Kα-lines. To determine position of the analytical peak and the background from two sides with the minimum possible spectral overlap, the author preliminarily recorded spectra on wave spectrometers. The obtained microprobe analyzes of minerals with quantitative determination of beryllium converge well with the available theoretical compositions of beryl and chrysoberyl, which indicates the high efficiency of the developed technique. By using this technique, we can relatively quickly and reliably determine the quantitative content of beryllium in natural silicates and oxides, which is an acute need for geological researchers studying the mineralogy of beryllium deposits.
Keywords: beryllium; chrysoberyl; mariinskite; beryl; emerald; electron-probe microanalysis.
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