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Title: Vibrational spectroscopy of the sulphate mineral sturmanite from Kuruman manganese deposits, South Africa.
Authors: Frost, Ray Leslie
Cipriano, Ricardo Augusto Scholz
López, Andrés
Xi, Yunfei
Lana, Cristiano de Carvalho
Keywords: Sturmanite
Issue Date: 2014
Citation: FROST, RAY L. et al. Vibrational spectroscopy of the sulphate mineral sturmanite from Kuruman manganese deposits, South Africa. Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy. v. 130, p. 122-133, 2014. Disponível em: <>. Acesso em: 04 de set. 2014.
Abstract: The mineral sturmanite is a hydrated calcium iron aluminium manganese sulphate tetrahydroxoborate hydroxide of formula Ca6(Fe, Al, Mn)2(SO4)2(B(OH)4)(OH)12.26H2O. We have studied the mineral sturmanite using a number of techniques, including SEM with EPMA and vibrational spectroscopy. Chemical analysis shows a homogeneous phase, composed by Ca, Fe, Mn, S, Al and Si. B is not determined in this EPMA technique. An intense Raman band at 990 cm^-1 is assigned to the SO4^2- symmetric stretching mode. Raman spectroscopy identifies multiple sulphate symmetric stretching modes in line with the three sulphate crystallographically different sites. Raman spectroscopy also identifies a band at 1069 cm^-1 which may be attributed to a carbonate symmetric stretching mode, indicating the presence of thaumasite. Infrared spectra display two bands at 1080 and 1107 cm^-1 assigned to the SO4^2- antisymmetric stretching modes. The observation of multiple bands in this m4 spectral region offers evidence for the reduction in symmetry of the sulphate anion from Td to C2v or even lower symmetry. The Raman band at 3622 cm^-1 is assigned to the OH unit stretching vibration and the broad feature at around 3479 cm^-1 to water stretching bands. Infrared spectroscopy shows a set of broad overlapping bands in the OH stretching region. Vibrational spectroscopy enables an assessment of the molecular structure of sturmanite to be made.
ISSN: 1386-1425
metadata.dc.rights.license: O periódico Spectrochimica Acta Part A: Molecular and Biomolecular concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3466020807513.
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