The results of gabbro-diabase and granites processing-mineralogical studies — main types of rocks used for crushed stone production, are presented. It is shown that a rock strength, caused by a combination of factors related to mineral composition, density, texture and structure, determines the rock behavior in crushing. Strength of crushed stone size fractions, produced in crushing of different structural types of rock, depends on arrangement of crushing circuit equipment and crushing process conditions and parameters.