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Nordstrandite in Bauxite Derived from Phonolite, Lages, Santa Catarina, Brazil
Bauxite Boehmite Gibbsite Nordstrandite Paraná Basin Phonolite Weathering
2011/12/5
Abstract: Nordstrandite from Lages represents the first occurrence of this mineral in an oxisoil that does not involve the influence of a calcareous substrate. This is also the first reported occurren...
Quantification and Characterization of Maghemite in Soils Derived from Volcanic Rocks in Southern Brazil
Aluminum Substitution Ferrimagnetic Maghemite Magnetic Susceptibility Magnetite Selective Dissolution
2011/12/7
Abstract: Many soils developed from volcanic rocks in southern Brazil exhibit spontaneous magnetization caused by the presence of fine-grained maghemite (γ-Fe2O3), but few attempts were made to quanti...
Hematite and Goethite from Duricrusts Developed by Lateritic Chemical Weathering of Precambrian Banded Iron Formations, Minas Gerais, Brazil
Hematite Goethite Laterite Mossbauer Spectrometry
2011/12/1
Abstract: The upper 15–20 m of a 200 m thick lateritic weathering profile on Precambrian itabirites of Capanema, Brazil, reveals a genetic pathway for the formation of hematitic and goethitic nodules ...
Crystal chemistry and petrologic significance of Fe3+-rich phlogopite from the Tapira carbonatite complex, Brazil
Crystal chemistry petrologic significance Fe3+-rich phlogopite Tapira carbonatite complex Brazil
2012/4/6
This contribution deals withthe crystal chemistry ofphlogopite and Fe3+-rich phlogo-pite from the Tapira alkaline-carbonatite complex (Brazil) to assess the petrological sig-nificance and genetic cond...
Channel occupancy in an alkali-poor beryl from Serra Branca (Goias, Brazil): Spectroscopic characterization
Channel occupancy alkali-poor beryl Serra Branca (Goias, Brazil) Spectroscopic characterization
2012/4/5
Spectroscopic (micro FfIR, Raman, MASNMR) and massspectroscopic techniques have been used to examine, on both single-crystal and powder samples, the behavior of H20 and C02 molecules in the structural...
Particle Morphological Evolution During the Conversion of I/S to Illite in Lower Cretaceous Shales from Sergipe-Alagoas Basin, Brazil
Illite Illite/smectite Morphology Shale TEM XRD
2011/12/1
Abstract: The illitic end of mixed-layer illite-smectite series (I/S) in shales from Lower Cretaceous Barra de Itiúba Formation, Sergipe-Alagoas basin, was examined with X-ray powder diffraction (XRD)...
Absence of Clay Diagenesis in Cretaceous-Tertiary Marine Shales, Campos Basin, Brazil
Diagenesis Illite Interstratified Nontronite Shale Smectite X-ray powder diffraction
2012/1/12
In Upper Cretaceous-Tertiary marine shales (Campos Formation) from the Campos basin, Brazil, mixed-layer illite/smectite (I/S) has remained randomly interstratified to depths of 3500 m and to temperat...
Hydroxy-Cu-Vermiculite Formed by the Weathering of Fe-Biotites at Salobo, Carajas, Brazil
Cation-exchange capacity Copper Intergrade Manganese oxide Supergene enrichment Vermiculite Weathering
2012/1/12
Weathering of a copper stratiform deposit (schist) at Salobo, Brazil, has produced two distinct Cu-bearing minerals from a biotite parent: vermiculite and a manganese oxide containing as much as 13% a...
Quartz Presence in Relationship to Gibbsite Stability in Some Highly Weathered Soils of Brazil
Quartz Presence Gibbsite Stability Highly Weathered Soils
2012/2/15
Determination of the mineralogical composition of six highly weathered soils of the Central Plateau of Brazil showed that the sand content (predominantly quartz) was not related to the relative amount...
A Golden-Colored, Ferri-Nickel Chloritic Mineral from Morro Do Niquel, Minas Gerais, Brazil
Golden-Colored Ferri-Nickel Chloritic Mineral Morro Do Niquel
2011/11/18
Abstract: A golden-colored, flaky mineral from Morro do Niquel, Minas Gerais, Brazil, gives an X-ray diffraction pattern of a IIb chlorite polytype, with basal spacing 14·21 【 0·02 ∈ and b = 9·23 ∈. T...
Nickeliferous Nontronite, a 15A Garnierite, at Niquelandia, Goias, Brazil
Nickeliferous Nontronite 15A Garnierite
2012/2/15
Garnierite from the Tocantins Complex at Niquelandia, Brazil, is a 15侌, dioctahedral clay mineral, nickeliferous nontronite. The principal octahedral cations are Fe3+, Al and Ni. The ferric state of t...