ABSTRACT Ferrimagnetic Fe-oxides are important soil components, which are present in most of the agricultural soils of Brazil. Distinction, origin, and assessment of the influence of these minerals on magnetism and geochemistry is a challenge for mineralogists. This study aimed to characterize mineralogically Fe-rich Rhodic Oxisols ( Latossolos Vermelhos ) originating from several mafic rocks in Brazil, and assess the implications on their magnetic and geochemical properties. We present results on magnetic measurements, chemical dissolutions, X-ray diffractometry, Rietveld refinement, Raman, […]

ABSTRACT Despite the considerable amount of information on the mineralogical characteristics of pedogenic Fe oxides in Brazilian soils, there are few studies on Fe-rich soils developed from mafic rocks with taxonomic identities at lower categorical levels. This study evaluated the mineralogical characteristics of pedogenic Fe oxides in B horizons (Bw) of Fe-rich Oxisols developed from several mafic rocks in the state of Minas Gerais, Brazil. The Bw horizons were sampled at a 0.8-1.0 m depth in 13 Ferric and Perferric […]

The occupation and territorial dispersion of the first settlers in South America, especially in Brazil, are still little known and require continuous interdisciplinary studies involving anthropology, archeology, and soil science. Under natural limestone shelters, pre-Columbian populations lived for thousands of years, introducing and removing materials of different nature and from different origins, resulting in the development of very peculiar anthropogenic soils, which have been little investigated so far. To deepen the knowledge on this type of soil, we evaluated the […]

The ferrimagnetic minerals maghemite (γFe2O3) are closely related with metal availability and P adsorption capacity. Magnetization is spontaneous in a significant percentage of Brazilian soils. In the State of Paraná (Brazil) this area represents up to 50 %. The determination of the mass-specific magnetic susceptibility (ΧBF) is the simplest method of identification and quantification of ferrimagnetic minerals in soils. The ΧLF is a quick, cheap, non-destructive technique, with satisfactory reproducibility, and can be used as a criterion in pedogenetic studies […]

Tuffite-derived magnetic soils in the Alto Paranaíba region, State of Minas Gerais, Brazil, have a variable mineralogy and are assumed to contain iron oxides that are isoestructural to spinel, more specifically, (Mg,Ti)-rich magnetite and maghemite. In this study, magnetic portions (saturation magnetization, 34.4 < s/J T-1 kg-1 < 43.7) were separated from sand fractions of pedomaterials of a Brunizem (Chernosol) (samples labeled AP31CR; AP31B and AP31A) and of a leptic Chernosol (AP33CR e AP33A) developed from tuffite were collected near the city of Patos de Minas, […]

The iron oxide mineralogy of sand, silt and clay fractions was studied in five soil materials. Samples were collected from a pedon of a Red Nitossolo (Brazilian Soil Classification; related to an Alfisol in US Soil Taxonomy) developing on a tholeiitic basalt, near the town Tupaciguara (18 o 35 ‘ 33 ” S; 48 o 42 ‘ 18 ” W) in the region of Triângulo Mineiro, state of Minas Gerais, Brazil. Portions of sand and silt were analyzed by magnetic separation and selective chemical treatments with NaOH […]