The present study was carried out to estimate gamma radiation shielding properties of natural glass obsidian. For this purpose, linear attenuation coefficient, mass attenuation coefficient, mean free path, half-value layer, tenth-value layer, effective atomic number and effective electron number values of obsidian samples in black and brown colors were experimentally measured for 661.66, 1172.23 and 1332.48 keV gamma ray energies obtained from 137 Cs, and 60 Co radioactive sources. Measurements were performed at narrow-beam transmission geometry using a NaI(Tl) scintillation detector. In addition, all these parameters were theoretically calculated by using WinXCOM program in the energy region of 0.015 to 15 MeV. A good agreement was observed between theoretical and experimental values. Furthermore, energy absorption and exposure buildup factors (EABF and EBF) of obsidian specimens were determined in the energy range of 0.015 to 15 MeV using G-P fitting method. Finally, it can be concluded that these naturally occurring volcanic glasses can be used for radiation shielding applications.