Brilha J.B., Sequeira Braga M.A.

Preented in the IV Congresso Nacional de Geologia - Porto
Memórias nº4 do Museu e Laboratório Mineralógico e Geológico da Fac. de Ciências da Univ. do Porto, 613-617, 1995

Abstract
The chemical and mineralogical characterization of clay minerals has been performed using several analytical techniques, in special x-ray diffraction (XRD). Nevertheless, when the studied sample is constituted by a mixture of clay minerals (and when separation procedures are not possible) the study of its mineralogical composition is disturbed by overlapping of the diverse mineral reflections. With the connection between an ordinary XRD apparatus and a microcomputer, it was possible to obtain a new set of data which allow the execution of new treatments (mathematical and/or graphical). In this work, the application of a specific software is referred, which allows spectra decomposition procedures, identifying overlapped reflections. Examples of standard clays (smectite and mixed-layer illite/smectite) and clays formed by hydrothermal alteration episodes of a basaltic rock from the Lisbon Volcanic Complex are presented.

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