Raman microscopic study at 300 and 77 K of some pegmatite minerals from the Iveland-Evje area, Aust-Agder, Southern Norway

The Raman spectra at 300 and 77 K of beryl, columbite-tantalite and topaz single crystals from pegmatites in the Iveland-Evje area are described in detail. The beryl is shown to contain mainly water type I and less of type II in its channels, while CO2 is only a very minor channel constituent. Cooling to 77 K results in minor shifts towards higher wavenumbers for most bands. The Si-O vibrations at 1009 and 1066 cm(-1) show a doubling to four bands at 1015, 1072, 1087 and 1149 cm(-1) due to structural rearrangements in the hexameric rings forming the channels in the beryl crystal structure. In addition a new band becomes visible around 1155 cm(-1). The tantalite could not be analysed in detail due to strong fluorescence. The Raman spectrum of the yellow topaz from Sol?s is comparable to that of the colourless topaz from Topaz Mountain, Thomas Range, Utah. Upon cooling to 77 K, two OH-stretching bands become visible around 3644 and 3655 cm(-1), which were not observed at room temperature.