Iron oxides in a soil developed from basalt.

dc.contributor.authorGoulart, Antonio Taranto
dc.contributor.authorFabris, José Domingos
dc.contributor.authorJesus Filho, Milton Francisco de
dc.contributor.authorCoey, John Michael David
dc.contributor.authorCosta, Geraldo Magela da
dc.contributor.authorGrave, Eddy De
dc.date.accessioned2017-05-30T14:52:21Z
dc.date.available2017-05-30T14:52:21Z
dc.date.issued1998
dc.description.abstractA dusky red Oxisol forming on a tholeiitic basalt is found to contain varying proportion of aluminous hematite (Hm) and titanoaluminous maghemite (Mh) in the different size fractions. Maghemite is the main iron oxide in the sand and silt fractions whereas Hm is dominant in the clay fraction, together with gibbsite (Gb), kaolinite (Ka), rutile (Rt) (and probably anatase, An) and Mh. Maghemite is also the major oxide mineral in the magnetic separates of soil fractions (sand, about 65% of the relative MiSssbauer spectral area; silt, 60%). Hematite (sand, 30%; silt, 15%) and ilmenite (Im) (sand, 5%; silt, 16%) are also significantly present in the magnetic extract. Accessory minerals are Rt and An. No magnetite (Mt) was detected in any soil fraction. Sand- and silt-size Mh have similar nature (a0 = 0.8319 - 0.0005 nm; about 8 mol% of A1 substitution; saturation magnetization of 49 J T -* kg '), and certainly a common origin. Lattice parameters of clay-Mh are more difficult to deduce, as magnetic separation was ineffective in removing nonmagnetic phases. A1 content in Hm varies from 14 mol% (clay and silt) to 20 mol% (sand). The proposed cation distribution on the spinel sites of the sand-size Mh is" [Fe0.gzA1008] { Fe, .43Ti0.~8170.39 } 0 4 ([7 = vacancy, [ ] = tetrahedral sites and { } = octahedral sites), with a corresponding molar mass of 208.8 g tool -1. The predicted magnetization based on this formula is tr ~ 68 J T ' kg ~, assuming collinear spin arrangement. The large discrepancy with the experimentally determined magnetization is discussed.pt_BR
dc.identifier.citationGOULART, A. T. et al. Iron oxides in a soil developed from basalt. Clays & Clay Minerals, v. 46, p. 369-378, 1998. Disponível em: <https://link.springer.com/article/10.1346/CCMN.1998.0460402>. Acesso em: 20 abr. 2017.pt_BR
dc.identifier.doihttps://doi.org/10.1346/CCMN.1998.0460402
dc.identifier.issn1552-8367
dc.identifier.urihttp://www.repositorio.ufop.br/handle/123456789/7819
dc.identifier.uri2https://link.springer.com/article/10.1346/CCMN.1998.0460402pt_BR
dc.language.isoen_USpt_BR
dc.rightsrestritopt_BR
dc.subjectHematitept_BR
dc.subjectIlmenitept_BR
dc.subjectMaghemitept_BR
dc.subjectMagnetic Fractionpt_BR
dc.titleIron oxides in a soil developed from basalt.pt_BR
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