To assess relationship between engineering characteristics and petrographic features, conglomerates samples related to Qom formation from Famenin region in northeast of Hamedan province were studied. Samples were tested in laboratory to determine the uniaxial compressive strength, point load strength index, modulus of elasticity, porosity, dry and saturation densities. For determining petrographic features, textural and mineralogical parameters, thin sections of the samples were prepared and studied. The results show that the effect of textural characteristics on the engineering properties of conglomerates supposed to be more important than mineralogical composition. It also was concluded that the packing proximity, packing density, grain shape and mean grain size, cement and matrix frequency are as textural features that have a significant effect on the physical and mechanical properties of the studied conglomerates. In this study, predictive statistical relationships were developed to estimate the physical and mechanical properties of the rocks based on the results of petrographic features. Furthermore, multivariate linear regression was used in four different steps comprising various combinations of petrographical characteristics for each engineering parameters. Finally, the best equations with specific arrangement were suggested to estimate engineering properties of the Qom formation conglomerates. Keywords Conglomerate Petrographic and engineering characteristics Multiple linear regression Qom formation Famenin Hamedan 1 Introduction Conglomerates are mostly composed of grains with the size of coarser than 2 mm originated from pre-existing rocks. It is well known that large variations in physical and mechanical properties of clastic rocks have been attributed to variations in textural characteristics (Bell 1978a; Howarth and Rowlands 1986; Shakoor and Bonelli 1991). Lithological and textural characteristics are particular importance in predicting phys
