The investigation of luminescence properties of banded and black obsidian

Obsidian which is formed by natural ways is a type of volcanic glass. It occurs when lava cools quickly. It is usually located in edge regions which cools quickly of felsic lava flows. There are two factors to become glass of obsidian: the cooling rate and amount of SiO2 in the composition. Although obsidian has especially black color, it has different colors like green obsidian (Nemrut Mountain-Tatvan) and red obsidian (İkizdere-Rize).In this study, physical and structural properties of banded (Kars-Sarıkamış) and black obsidian (Niğde ? Çiftlik- Bor) minerals were compared by using luminescence and other techniques. For this purpose, The elements constituent of obsidian are determined with XRD and ICP analyses. Thermoluminescence (TL) spectra have taken in the temperature range of 50-400oC. In addition, optical absorption spectra were examined to investigate the optical behaviors in the range from the visible region to the near infrared region (200-800 nm) of the electromagnetic spectrum.The samples exposed to different doses of X-ray and beta radiation are taken TL spectra in the range of 50-400 oC temperature. While thermoluminescence spectra of banded and black obsidyen was recorded after being exposed to X-ray, it wasn?t obtained any TL spectrum of black obsidian after beta irradiation. In the TL spectra recorded using different heating rates (2 0C/s, 4 0C/s, 6 0C/s, 8 0C/s, 100C/s), there are two and a few peaks for respectively banded and black obsidian In the optical absorption spectra of the banded and black obsidian, broad absorption band is observed.