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Iron oxides in two Oxisols from the Brazilian coastal plain
Author(s) -
FABRIS J. D.,
RESENDE M.,
SILVA E. GALVAO,
COEY J. M. D.
Publication year - 1985
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1985.tb00357.x
Subject(s) - hematite , goethite , oxisol , udic moisture regime , iron oxide , mineralogy , chemical composition , monoclinic crystal system , chemistry , geology , materials science , metallurgy , crystallography , soil water , soil science , crystal structure , organic chemistry , adsorption , loam
SUMMARY 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.