The effect of mineralogical and petrographical properties in polishing of metamorphic originated marbles

In this study, polishing properties of metamorphic origin marble have been investigated to determine the effects of mineralogical-petrographic features and chemical compounds.To achieve this goal, six different marble samples commercially available in the market were studied. Mineralogical-petrographical properties were determined by polarizing microscope, scanning electron microscopy (SEM) and X-ray diffractometer (XRD) analysis. Geochemical characteristics of the samples that reveal major oxides, trace and rare earth element (REE) analysis and physico-mechanical tests were determined. Using a laboratory-scale polishing machine, polishing experiments were applied under constant band speed, abrasive head pressure and abrasive head rotation for samples having 60x30x2 cm dimension. Roughness and brightness measurements were carried out on pre-determined surfaces of the marble samples.Polishing experiments showed that, with a few exceptions, brightness increased with decreasing roughness. Marble types having low sphericity exhibited relatively high roughness values. It was also concluded that the amount of non-carbonate minerals present in the samples, as well as their distribution, greatly affected brightness and roughness properties of the tested marble varieties. The common non-carbonate minerals were mainly mica, chlorite, feldspar, epidote, hornblende and hematite. These minerals were usually observed along micro-cracks and their volumetric percentages were as follows: 40% Uşak Green, 15.30% Afyon Sugar, 10.33% Akşehir Black and 8.50% Afyon Kaplanpostu. Other parameters influencing the brightness and roughness values of the tested marbles were micro-fracture frequency and micro-structural properties of the calcite minerals. Finally, although it was not the main objective of the present study, the effects of physico-mechanical properties on roughness and brightness of the marble varietes were examined.