Occurrence of Cr-bearing beryl in stream sediment from Eskisehir, NW Turkey


ERKOYUN H. , KADİR S.

EARTH SCIENCES RESEARCH JOURNAL, cilt.20, sa.3, 2016 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 20 Konu: 3
  • Basım Tarihi: 2016
  • Doi Numarası: 10.15446/esrj.v20n3.47677
  • Dergi Adı: EARTH SCIENCES RESEARCH JOURNAL

Özet

Beryl crystals are found within stream sediments transecting schists in the northeast of Eskisehir, western Anatolia. This paper studied the Eskisehir 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 bluishgreen aquamarine, with ideal sharp IR bands. Wet chemical analysis of Eskisehir beryl yielded 61.28% SiO2, 15.13% Al2O3, 12.34% BeO, 0.18% Cr2O3, 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)(Na-0.32)O-18. 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.