The topic of my research paper are calcite crystals from Peči in the Gorenjska region, east of Kropa. Calcite is one of the most important minerals in Slovenia. In the Lipnica Valley, four limestone quarries were active in the past, and only two are still active today. Calcite, which is the subject of my research, is located in small cracks or geodes in an approximately 60 m wide belt around a central crack that extends across all quarry floors. With mineral collector Davorin Preisinger, I obtained specimens from his collection and at the quarry for further research. The samples were examined macroscopically and crystallographically determined. Crystals have been formed over three or even four generations. Scalenohedral crystals were formed first and the second generation was characterized by a positive rhombohedral habitus. The third generation of crystals is characterized by a negative rhombohedron. The last were crystals of steep rhombohedron. Polished thin sections were made from the selected crystals and samples were prepared for stable isotope analyzes. Using the microscope, transitions between generations and tiny inclusions were analyzed. With stable oxygen isotopes, we found that the calcite crystals of the steep rhombohedral crystallized at a maximum average temperature of 554 ° C, followed by the crystals of the basic rhombohedron at 536 ° C, followed by the scalenohedral crystals at 519 ° C, and finally the crystals of the rhombohedron at 451 ° C.
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