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Pegmatitska provincija Borborema (BPP) nalazi se u E – SE dijelu pojasa borâ Seridó i tektonskog područja Rio Grande do Norte, u saveznim državama Paraíba i Rio Grande do Norte. Lokalitet na kojem su uzorkovane nodule granata, Serrote Redondo, nalazi se 9 km južno od Pedra Lavrade. Cilj ovog istraživanja jest kristalografska karakterizacija granata koji se nalazi unutar polimineralne nodule. Uz pomoć metoda fazne i elementne analize (optička istraživanja u prolaznoj svjetlosti, XRPD, FTIR, SEM-EDS, klasična kemijska analiza) analizirani su kristali granata i mineralna asocijacija samih nodulâ. Nakon sprovedenih analiza, može se zaključiti kako se radi o almandinu, koji se pojavljuje u vidu izomorfnih kristala centimetarskih dimenzija, a koji se nalazi unutar polimineralnog matriksa, uglavnom sastavljenog od feldspata, kvarca, sillimanita, opâkih minerala, te akcesornih mineralnih faza (npr. cirkon, monacit). The Borborema Pegmatite Province (BPP) is located in the E – SE part of the Borâ Seridó belt and the Rio Grande do Norte tectonic area, in the federal states of Paraíba and Rio Grande do Norte. The locality where the garnet nodules were sampled, Serrote Redondo, is located 9 km south of Pedro Lavrada. The main goal of this research is the crystallographic characterization of the garnet found inside the polymineral nodule. With the help of phase and elemental analysis methods (transmitted light optical research, XRPD, FTIR, SEM-EDS, classical chemical analysis), garnet crystals and the mineral association of the nodules themselves were analyzed. After conducting the analyses, it can be concluded that the garnet mineral in question is almandine, which appears in the form of isomorphous crystals of centimeter dimensions, and which is located within a polymineral matrix, mainly composed of feldspar, quartz, sillimanite, opaque minerals, and accessory mineral phases (e.g. zircon, monazite). |
