Resumo

ERKOYUN, Hülya  e  KADIR, Selahattin. Occurrence of Cr-bearing beryl in stream sediment from Eskişehir, NW Turkey. Earth Sci. Res. J. [online]. 2016, vol.20, n.3, pp.A1-A10. ISSN 1794-6190.  https://doi.org/10.15446/esrj.v20n3.47677.

Beryl crystals are found within stream sediments transecting schists in the northeast of Eskişehir, western Anatolia. This paper studied the Eskişehir beryl crystals with optical microscopy, scanning electron microscopy (SEM-EDX), infrared spectroscopy (IR) and geochemical analyses. Beryl is accompanied by garnet, glaucophane, quartz, epidote, muscovite and chlorite in the stream sediments. The crystals are euhedral emerald (green gem beryl) and light bluish-green aquamarine, with ideal sharp IR bands. Wet chemical analysis of Eskişehir beryl yielded 61.28% SiO2, 15.13% AlO3, 12.34% BeO, 0.18% &2O3, 1.49% MgO, 1.69% Na2O, 0.98% Fe2O3, and 0.008% V2O3, resulting in the formula (Al1.75Cr0.01Mg0.22Fe0.08)(Be2.90Si6.00)(Na0.32)O18. Large Ion Lithophile Elements (LILE) (barium, strontium), some transition metals (cobalt, except nickel) and High Field Strength Elements (HFSE) (niobium, zirconium, and yttrium) in stream sediments that are associated with beryl exhibited low content about metamorphic rocks. Beryl formation appears to be controlled by upthrust faults and fractures that juxtaposed them with Cr-bearing ophiolitic units and a regime of metasomatic reactions. Such beryl crystals have also been found in detrital sediments that are derived from the schists.

Palavras-chave : Beryl; Kaymaz; schist; SEM-EDX; IR.

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