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The qualitative and quantitative mineral analyses are important for the characterization of the geochemical, geological and mechanical properties, e.g. of rocks, soils and clays. Several methods of quantitative mineral analysis exist. Microscopic methods succeed in coarse-grained samples, but fail in fine-grained. X-ray diffraction (XRD) is the most common method for qualitative and quantitative phase analysis. While the qualitative determination of minerals with XRD poses no major problems the quantitative analysis especially of clay minerals is difficult. They commonly contain structural disorder such as semi-random or turbostratic stacking and have various compositions. Other problems are associated with the platy crystallite shape and size (peak broadening and preferred orientation). Full-pattern-techniques as the Rietveld-method with fundamental-parameter-approach-programs offer new possibilities for the improvement of the quantitative analysis with XRD. In combination with several methods like FT-IR and thermal analysis a procedure for sample preparation and measurement should be developed providing enough data to allow mineral amounts to be calculated.
Authors:Plötze, Michael and Kahr, Günter
Index Terms:ClayGroup; XRD; Rietveld; Kahr, Gunter; Plotze, Michael
3rd place in the 2nd International Reynolds Cup Contest in Quantitative Mineral Analysis of Clay-bearing Rocks 2004 see http://www.dttg.ethz.ch/thereynoldscup.html