Vibrational spectroscopy of the borate mineral chambersite MnB7O13Cl - implications for the molecular structure.

Abstract

Chambersite is a manganese borate mineral with formula: MnB7O13Cl and occurs as colorless crystals in the monoclinic pyramidal crystal system. Raman bands at 902, 920, 942 and 963 cm^-1 are assigned to the BO stretching vibration of the B7O13 units. Raman bands at 1027, 1045, 1056, 1075 and 1091 cm^-1 are attributed to the BCl in-plane bending modes. The intense infrared band at 866 cm^-1 is assigned to the trigonal borate stretching modes. The Raman band at 660 cm^-1 together with bands at 597, 642 679, 705 and 721 cm^-1 are assigned to the trigonal and tetrahedral borate bending modes. The molecular structure of a natural chambersite has been assessed using vibrational spectroscopy.