In the collection of minerals, stones and fossils, located in the Faculty of Natural Sciences and Engineering, Department of Geology, we selected 10 samples of natural stone belonging to the igneous rocks. They needed to be interpreted accurately and classified into specific groups. Samples were analyzed macroscopically and microscopically using optical microscopy. X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) were used for geochemical analysis. Samples were classified into separate groups using a TAS and QAP diagram. The emphasis was on the TAS classification.
By macroscopic and microscopic analysis, we observed that all samples were plutonic rocks, except samples 14707 and 14715, which were defined as migmatite. We determined their mineral composition and textural and structural characteristics. On the basis of all detailed geochemical analysis, the samples were divided into individual groups. Thus, samples marked 14708, 14709, 14711 and 14713 belong to the granite group, samples 14710 and 14712 to the gabbrodiorite group, sample 14714 to the gabbro group and sample 14716 to the group of monzonites. Classification was preformed on the basis of alkali and silica content. The samples that noticebly deviate from the majority are samples of the gabbrodiorite and gabbro groups, which have a lower content of both quartz and alkali compared to the others. The sample, which belongs to the group of monzonites, differs from the others due to the higher value of alkalis.
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