Iron oxides in two Oxisols from the Brazilian coastal plain |
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| Authors: | J. D. FABRIS M. RESENDE E. GALVAO DA SILVA J. M. D. COEY |
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| Affiliation: | Federal University of Viçosa, Viçosa, M. G., Brazil, Federal University of Minas Gerais, Belo Horizonte, M. G., Brazil &Trinity College, Dublin 2, Ireland |
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| Abstract: | Two Oxisols from the B2 horizon at similar locations 2 km apart on the Brazilian coastal plain with a udic, isohyperthermic regime were practically identical in chemical composition but differed markedly in colour; one was a dark reddish brown, the other a pale ochre. Mossbauer spectra at 295 K, 80 K and 4.2 K indicated a clear difference in iron oxide mineralogy. Iron was present as aluminous hematite and goethite, with Al substitutions of approximately 20% in the two phases. However, the relative proportion of iron present in hematite and goethite was 45:55 in the first sample and 12:88 in the second. Possible reasons for these differences are discussed. |
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