The photon linear attenuation coefficients (mu) have been calculated for four different igneous rocks which are widely used in industrial field using XCOM computer code and the results were compared with measured values. The relation between linear attenuation coefficients and some of the physical and mechanical properties of rocks has also been investigated by linear regression analysis. It has been found that with increasing linear attenuation coefficient, density, uniaxial compressive strength, bending strength, shore hardness and SiO2 percentage have also increased, however the other properties such as abrasion strength and porosity have decreased. (c) 2006 Elsevier Ltd. All rights reserved.