Characterization of a soil ilmenite developed from basalt

Goulart, A. T.; Filho, M. F. de Jesus; Fabris, José Domingos; Coey, J. M. D.

doi:10.1007/bf02064605

Cited by 11 publications

(7 citation statements)

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“…In a recent paper, Goulart et al (1994) reported the existence of a ferric ilmenite, (0.85)FeTiO3, (0.15)Fe203, in a soil developed from basalt. At that time, it was not clear whether the solid solution was directly inherited from the parent rock, dominantly, a tholeiitic basalt, or was somehow formed during pedogenesis.…”

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“…Reported hyperfine (Fe 3+ :b/Fe = 0.28 mm/s, h = 0.35 mm/s; Fe 3+ : ~/Fe = 1.03 mm/s, A = 0.66 mm/s) and lattice (a = 0.5082 + 0.0001 nm; c = 1.398 _ 0.001 nm) parameters for the soil-ilmenite characterized by Goulart et al (1994) are close to those found for the basalt-ilmenite in this work, indicating its relatively high stability during pedogenesis. On the other hand, magnetite seems to be rather unstable under weathering, in this lithology, as it was not detected in the transitional horizon C/R of the overlying soil (B.…”

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confidence: 99%

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Ilmenite and Magnetite of a Tholeiitic Basalt

Filho

Fabris

Goulart³

et al. 1995

Clays and clay miner.

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confidence: 99%

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confidence: 99%

Ilmenite and Magnetite of a Tholeiitic Basalt

Filho

Fabris

Goulart³

et al. 1995

Clays and clay miner.

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“…The hyperfine parameters of ilmenite, obtained with low velocity range in full scale (spectrum not shown), were fixed during fitting of magnetic spectra (Tables 3 and 4). Differently from ilmenite of mafic origin (Goulart et al, 1994;Doriguetto et al, 1998), no Fe 3+ was detected in this case.…”

Section: Resultsmentioning

confidence: 49%

Magnetita e sua transformação para hematita em um solo derivado de esteatito

Santana

Fabris

Goulart

et al. 2001

Rev. Bras. Ciênc. Solo

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SUMMARYThe main objective of this work was to characterize the magnetic minerals and to identify their pedogenic transformation on a steatite-forming soil of Minas Gerais, Brazil. The iron-rich spinel phase was characterized by chemical analysis, powder X-ray diffraction, Mössbauer spectroscopy, with and without an externally applied magnetic field of 6 tesla, and saturation magnetization measurements. Nearly stoichiometric and well-crystallized magnetite was the only magnetic mineral actually detected. The cubic unit cell parameter of the fresh rock magnetite was found to be a o = 0.8407(5) nm. Hematite (hexagonal cell; a = 0.5036(3) nm, c = 1.375(4) nm) was detected in the altered rock and in the sand-soil and silt-soil fractions. Magnetite is assumed to transform into hematite during pedogenesis through progressive oxidation of structural Fe 2+ to Fe 3+ . In partially oxidized magnetites, a relatively small proportion of Fe 3+ was interpreted as being uncoupled from the Fe 2+ -Fe 3+ charge transfer system, in octahedral sites of the spinel structure. Compositional formulae of magnetite with different degrees of non-stoichiometry are proposed. Ilmenite was found in minor proportions in the magnetically extracted portions from both rock and soil samples.Index terms: Iron-rich spinel, iron oxide, soapstone, magnetic soil, Mössbauer spectroscopy.(1) This work is part of the thesis of the first author, presented to the Departmento

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“…The magnetic experiments were carried out with bulk samples after HCl treatment followed by magnetic separation in order to remove all iron oxides except hemo-ilmenite. The chemical treatment includes boiling the sample in concentrated acid solution with a 19:1 ratio of HCl to H 2 SO 4 [19]. Moreover, for structural and chemical analysis hemo-ilmenite particles were separated from the soil matrix.…”

Section: Samples and Methodsmentioning

confidence: 99%