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The distribution of chromophores and the composition of chromium-bearing spinels in Uralian emeralds and alexandrites were studied for the first time. It was prooved the main source of chromium for the coloring of emeralds and alexandrates from the Mariinsky deposit was chromium-bearing spinels of the Bazhenov ophiolite complex. The rare mineral zincochromite was described for the first time as an...
Summary The infrared absorption spectrum of amethyst in the region of stretching vibrations of X–OH groups reveals several bands that have been used for the separation of natural from synthetic amethyst. The intensity and shape of these bands have been measured as a function of crystallographic orientation. Using a resolution of 0.5 cm−1 the 3595 cm−1 band is present in all infrared spectra of natural...
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