engleski

57^Fe-Moessbauer spectroscopy on natural eosphorite-childrenite-ernstite samples

Samples of the eosphorite-childrenite [(Mn^2+, Fe^2+)AlPO_4(OH)2H_2O] series from Divino das Laranjeiras and Aracuai(Minas Gerais State) and Parelhas (Rio Grande do Norte State) pegmatites have been investigated by X-ray diffraction, microprobe analysis and Moessbauer spectroscopy at 295 and 77K. The Moessbauer spectra of ernstite [(Mn^2+, Fe^3+)AlPO_4(OH)_2-xO_x] showed the existance of ferric ions seem to be located in both sites, and no Fe^3+ could be detected. The interpretation of the Moessbauer 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.

eosphorite; childrenite; ernstite; pegmatite; Moessbauer spectra; Brazil

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