Clay samples collected from soils of indian territories of the middle plateau in Rio Grande do Sul were analyzed with the aim to obtain characterization data and technical parameters for their potential use as raw material for ceramic products. The mineralogical study in samples by using the X-ray diffraction technique demonstrated that the predominant clay mineral is kaolinite. Others minerals as quartz and rutile also are present in small amounts. Chemical analysis shows low percentages for oxides of Mg, Mn, K, Na, Ca, Cu and Zn (overall percentages smaller than 0.97%). The samples also were analyzed with the 57Fe Mössbauer spectroscopy. The Mössbauer spectra at room temperature confirm the presence of the mineral kaolinite. At 77 K they reveal the existence of the minerals goethite and hematite as ultrafine magnetic particles in a superparamagnetic state. The physical tests performed in the samples show that these soils are very fine material and present appropriate granulometric characteristics and plasticity, which can be taken in advantage for the production of materials for construction or production of ornamental artifacts.
Raw clayey materials; clays; Mössbauer effect
