The quantitative analysis of carbonate rich materials is tested with conventional and Rietveld methods. In the case of artificial mixtures of aragonite, calcite, Mg-calcite and quartz the Rietveld method provides reliable results with a maximum deviation of ±5 wt %. In the natural samples, however, the conventional methods give more reliable results in comparison to chemical and sedimentological measurements. This is caused by the peak overlap of calcite/Mg-calcite, peak roadening of the Mg-calcite, and the difficulties in the refinement of minor amounts of feldspar phases.
