PESQUISA TEXTURAL DE MINÉRIO HEMATÍTICO DA JAZIDA DE ÁGUAS CLARAS (MG) PELO MÉTODO DE DIFRAÇÃO DE NÊUTRONS

Resumo

Natural haematite samples are always polycrystalline. In the samples the orientation of the single haematite crystallites, that means the "texture", is more or less pronounced. Beside the universal stage method for texture measurements only for transparent minerals, nowadays the X-ray and neutrons diffractions, is more and more used. With this method it is possible to measure not only transparent minerals but also opaque ones, and the measurements are more rapid and more exact because computer-controlled. Such texture analysis of banded haematite iron ore types from the Águas Claras Mine near Belo Horizonte/Minas Gerais by X-ray diffraction and neutron diffraction show a strong orientation of the (0001)-basal planes of the haematite crystallites parallel to the principal plane of schistosity (axial plane cleavage s₂). This is an effect of twin-gliding parallel to the (1011) - planes during the main deformation act. From this it may be concluded that the process of secondary iron enrichment giving rise to the formation of rich ore types in the Águas Claras Mine has taken place not later than this deformation.