A vibrational spectroscopic study of the phosphate mineral rimkorolgite (Mg,Mn2+)5(Ba, Sr)(PO4)4·8H2O from Kovdor massif, Kola Peninsula, Russia

We have studied aspect of the molecular structure of the phosphate mineral rimkorolgite from Zheleznyi iron mine, Kovdor massif, Kola Peninsula, Russia, using SEM with EDX and vibrational spectroscopy. Qualitative chemical analysis shows a homogeneous phase, composed by P, Mg, Ba, Mn and Ca. Small amounts of Si were also observed. An intense Raman peak at 975 cm(-1) is assigned to the PO4(3-) ν1 symmetric stretching mode. The Raman band at 964 cm(-1) is attributed to the HPO4(2-) ν1 symmetric stretching vibration. Raman bands observed at 1016, 1035, 1052, 1073, 1105 and 1135 cm(-1) are attributed to the ν3 antisymmetric stretching vibrations of the HPO4(2-) and PO4(3-) units. Complexity in the spectra of the phosphate bending region is observed. The broad Raman band at 3272 cm(-1) is assigned to the water stretching vibration. Vibrational spectroscopy enables aspects on the molecular structure of rimkorolgite to be undertaken.