Problems of the description of deformation and fracture of rocks are under discussion. The dependence of their properties on the stress state, rheology, and accumulated irreversible deformation is studied. A mathematical model describing the geomedium behavior with regard to the above factors is schematized. It is shown how these factors affect both elastic and strength properties of rocks. The elastic properties are most sensitive to the stress state at near-zero stresses as well as under changes of the loading sign. A considerable role in the development of irreversible deformation belongs to the variation in strength properties during deformation. Along with cohesion, a decrease is observed in friction, which is due to particle refinement of the medium in shearing.