Relaxation lengths of different types of rock were measured using gamma radiation from a 60CO source. Results show that limestone has the highest relaxation length of 20.000 cm, while sandstone has the least relaxation length of 8.850 cm. Half-thickness was determined for each rock sample. Results also show limestone with the highest value of half -thickness as 13.860 cm, while sandstone has the least half -thickness of 6.133 cm. Densities of rock were also measured.Mass attenuation coefficient was determined for each rock sample.With the proper choice of the thickness of rock sample fromtheoretical evaluation, it was observed that sandstone with thickness of 280 cmalmost completely attenuate gamma ray energy in the range 0.1Mev to 1.836Mev.