Application of colorimetry for the study of rocks – the example of limestones from the Mokrá Quarry

The paper summarizes the results of colorimetric analyses of a large set of limestone samples from the Mokrá Quarry in the Moravian Karst (NE from Brno, Czech Republic). The examined samples belong to three lithologically different series of strata: Macocha, Líšeň, and Březina Formations. Limestones of these formations differ in the contents of non-carbonate component and, hence, in colour. The samples were prepared in four ways for colorimetric measurements: 1. unpolished bulk samples (cleavage planes were measured), 2. polished sections, 3. powder in a plastic bag, 4. simple uncovered powder. All of the four ways of sample preparation led to different results. The results were expressed using a CIE L*a*b* colour space. Based on the L* (specific lightness) value, the amounts of a non-carbonate component can be roughly judged. The specific lightness can be used for assigning a sample to a lithostratigraphic member and possibly also to correlation reasons in many cases.The paper summarizes the results of colorimetric analyses of a large set of limestone samples from the Mokrá Quarry in the Moravian Karst (NE from Brno, Czech Republic). The examined samples belong to three lithologically different series of strata: Macocha, Líšeň, and Březina Formations. Limestones of these formations differ in the contents of non-carbonate component and, hence, in colour. The samples were prepared in four ways for colorimetric measurements: 1. unpolished bulk samples (cleavage planes were measured), 2. polished sections, 3. powder in a plastic bag, 4. simple uncovered powder. All of the four ways of sample preparation led to different results. The results were expressed using a CIE L*a*b* colour space. Based on the L* (specific lightness) value, the amounts of a non-carbonate component can be roughly judged. The specific lightness can be used for assigning a sample to a lithostratigraphic member and possibly also to correlation reasons in many cases