In the broader area of Pohorje Mts. (Eastern Alps), there are a number of pegmatite veins hosted by granodiorite, quartz monzogabbro, and metamorphic rocks. The research was aimed towards macroscopic and microscopic classification and geochemical characterization of beryl–bearing pegmatites from S–SE Pohorje. Our primary interest was focused on pegmatites trace element enrichment and to determine associated minerals. Furthermore, we evaluated Pohorje beryl–bearing pegmatites economic potential as a source of critical and rare–earth elements.
Pegmatites have mid– to coarse grained, in places very coarse grained uneven holocrystalline texture. Characteristic minerals of the pegmatites are plagioclase, microcline (microcline perthite) and quartz, accompanied by garnet, beryl, tourmaline and muscovite, accessory biotite, zircon, rutile, apatite, titanite and opaque minerals. Secondary are chlorite group minerals. By SEM/EDS analysis, uraninite, fluorapatite, monazite–(Ce), xenotime–(Y), tantalite–columbite, Fe–oxide/hydroxide, pyrite, bismite or busmutite and cassiterite were identified.
Depending on the degree of differentiation in the Sr-Ba-Rb diagram, three groups of pegmatites are distinguished. The first group is represented by three least differentiated samples from Cezlak, where the Ba is relatively more than Rb. In second, the more differentiated group are both pegmatites from Polskava, three from Cezlak and single from Bistrica Gorge. The third group contains Bistrica Gorge pegmatites, where feldspar contains significantly higher Rb concentration than Ba and Sr. Statistically significant pegmatites from three sites differ in the content of As, Ni, Sr, U and W content.
Beryl–bearing pegmatites from S–SE Pohorje Mts. are, based on their mineral assemblage and geochemical composition, corresponding with the group containing lithium, cesium, and tantalum (LCT). Pegmatites can be attributed to the class of muscovite pegmatites with REE (MSREL), MSREL–REE or REL–Li subclass, beryl–type and beryl–columbite sub–type. The content of the trace elements and gemstones in them are not economically interesting.
|
