The article is devoted to determining regularities of occurrence and development of seismoacoustic oscillations in rocks under loading to the moment of their destruction. Investigations conducted by the authors enable ascertaining dependences of occurrence and development of such oscillations for crystalline rocks of different hardness that are typical of iron ore deposits of Kryvyi Rih basin. A mathematical model based on the obtained dependences makes it possible to determine the moment of the instable stress state onset – the indication of rock destruction – using characteristics of seismoacoustic waves. This model is essential for forecasting the moment of hazard occurrence based on geomechanical conditions of mining iron ore deposits.