Some potential gemological patterns from west and central Anatolia and their geological setting

Prepared to Examine some gem Stones of Middle And West Anatolia this study focused on the gemologic and geologic formations of Eskisehir-Dereyalak Dendritic opal, Kütahya Simav Fire opal. Dendritic opal is located at the village of ?nönü named Dereyalak which is a province of Eskisehir city. Region opals are seen at the colour of yellow, honey yellow, grey, blue and green and their shapes are usually sphere and semi-sphere. Opal formations are located in the volcano-sedimentary part in the shape of tufa and tiny pieces. Surfaces of opals are observed being surrounded by a thin white coloured film. Sizes of opal formations change from few centimeters. to 20 centimeters. ?t is determined by SEM studies that Mn element gives dentritic character to opal and seems like tree branches. At region dentritic opal is not the only element it is found with other silisified elements like chalcedon and quartz. At opal samples SEM studies are made to determine micro formation. At the samples of dentritic opal the existence of capillary and round shaped pores are determined. At the temperature of 900 0C degrees some breakages and fractures at the micro structure of opal are observed. At the samples heated up to temperature of 1100 0C degrees silis spheres are observed by SEM photos and connected to this it is determined that opals are formated from gel forms with granular forms. At the temperature of 1300 0C degrees it is observed that opal pores shrink.KEYWORDS: ESKİŞEHİR DEREYALAK DENDRİTİC OPAL. KÜTAHYA SİMAV FİRE OPAL. GEMOLOGY. GEOLOGY. SEM