57Fe-Mössbauer spectroscopy on natural eosphorite-childrenite-ernstite samples

Samples of the eosphorite-childrenite [(Mn2+, Fe2+)AlPO4(OH)2H2O] series from Divino das Laranjeiras and Araçuaí (Minas Gerais State) and Parelhas (Rio Grande do Norte State) pegmatites have been investigated by X-ray diffraction, microprobe analysis and Mössbauer spectroscopy at 295 and 77 K. The M...

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Bibliographic Details
Published in:Physics and chemistry of minerals 2005-02, Vol.31 (10), p.714-720
Main Authors: Geraldo Magela da Costa, Scholz, Ricardo, Karfunkel, Joachim, Bermanec, Vladimir, Mário Luiz de Sá Carneiro Chaves
Format: Article
Language:English
Subjects:
Aluminum phosphate
Ferric ions
Ferrous ions
Ions
Iron 57
Mossbauer spectroscopy
Oxidation
Spectroscopy
Spectrum analysis
X-ray diffraction
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Summary:Samples of the eosphorite-childrenite [(Mn2+, Fe2+)AlPO4(OH)2H2O] series from Divino das Laranjeiras and Araçuaí (Minas Gerais State) and Parelhas (Rio Grande do Norte State) pegmatites have been investigated by X-ray diffraction, microprobe analysis and Mössbauer spectroscopy at 295 and 77 K. The Mössbauer spectra of ernstite [(Mn2+, Fe3+)AlPO4(OH)2-xOx] showed the existence of ferric ions in both A and B sites, whereas ferrous ions seem to be located exclusively in the A site. Nonoxidised samples show ferrous ions located in both sites, and no Fe3+ could be detected. The interpretation of the Mössbauer spectra of both, oxidised and nonoxidised samples, is difficult because the hyperfine parameters of these minerals are rather similar, rendering it difficult to make proper site assignments.
ISSN:0342-1791
1432-2021
DOI:10.1007/s00269-004-0434-7