Abstract

ALVES, Marcelo Eduardo; MASCARENHAS, Yvonne Primerano  and  VAZ, Carlos Manoel Pedro. Comparison of procedures for quantification of kaolinite and gibbsite in iron-free clay in Latosols. Rev. Bras. Ciênc. Solo [online]. 2008, vol.32, n.2, pp. 569-577. ISSN 0100-0683.  http://dx.doi.org/10.1590/S0100-06832008000200012.

The accurate determination of the clay component contents of Latosols can contribute for the improvement of both use and management of such soils. In this research, the kaolinite and gibbsite contents of iron-free clay in Latosols were determined by differential scanning calorimetry (DSC) and with the application of the Rietveld method to X-ray diffraction data for comparison with mineral contents calculated by the allocation method. It is likely that crystallographic differences between kaolinite and gibbsite used in the DSC calibrations and the kaolinites and gibbsites in the samples were responsible for the inaccuracy of the mineral contents evaluated by this thermal method. The Rietveld method determined gibbsite contents almost identical to those calculated by the allocation method and kaolinite contents with acceptable similarity to the ones calculated by the allocation of total SiO₂ iron-free clay contents.

Keywords : thermal analyses; X-ray diffraction; Rietveld method; disordered minerals.