The study of gamma—ray interactions with matter is increasingly important primarily due to new applications of gamma — emitting isotopes in agriculture, medicine and industry. Two igneous rocks, andesite and felsite, are investigated for radiation shields. The effects of particle size （grain diameter） ,d, mm and sample density ,ρ, on the linear μ, mass µ/ρ attenuation coefficients and side scattering coefficients ø,s, of compressed and natural rocks has been studied with gamma radiation energy ,E, ranging from 0.36 ,to, 1.33 MeV. Flux distribution in samples and the halfvalue layers ,X,1/2, were determined. The resuts showed an inverse proportionality between the linear at,¬, tenuation coefficient μ and bo,t,h ,d, and ,E., It was also found that μ has a direct proportionality with the sample density ,ρ., The side scattering coefficient ø,s, is directly proportional to both ,d, and ,E, but at the same time ø,s, has an inverse proportionality with the sample density ,ρ,.