Application of X-ray Fluorescence Spectroscopy in Identification and Classification of Marble

The identification and classification of marble depended mainly on the identification of rock slices and the semi-quantitative detection of minerals by X-ray Diffraction (XRD). It was found that the results of identification of rock slices were not always consistent with those of the semi-quantitative detection by XRD. Therefore, it is necessary to introduce other techniques to verify the results of thin section observation and XRD semi-quantitative analysis. 32 marble samples were analyzed by X-ray Fluorescence Spectrometer, the results and finding of which are reported in this paper. Based on the chemical composition of rock, rock impurity, magnesite, and calcareous coefficients are used to classify the marble. The results show that magnesite coefficients of calcite marble, dolomite marble, and magnesite marble are 0.01-0.13, 0.40-0.46 and 0.97-0.98, respectively. Calcareous coefficients are 0.78-0.84, 0.30-0.49 and 0.01-0.02, respectively. Different types of marble have various magnesia and calcareous coefficients, which can be used as the main basis for the division of marble types. Only the contents of SiO₂+Al₂O₃ in rocks are less than 30% (impurity coefficient less than 1.00), then can be classified as marbles. The establishment and application of impurity, magnesia and calcareous coefficients in marble can be used to correct the inconsistent results between thin section observation and X-ray Powder Diffraction mineral semi-quantitative analysis, making marble classification more accurate.