Revealing of fracture harbingers of dielectric materials, that are under mechanical stress, is an important practical and scientific problem. Local stresses, produced by mechanical impact, can exceed the local strength, and a stress-strain state changes. As the result of such impacts, microcracks appear and lead to fracture. During change of stress-strain state, mechanoelectric transformations occur, that generate electromagnetic emission. So we aimed to observe regularities in electromagnetic emission characteristics. Rock samples, collected from Tashtagol ore-mine of Kemerovo region of Russia, were used as dielectric materials for the research. For analysis of rock samples deformation and fracture, integral characteristics of time series of electromagnetic emission were used. Observed, that low-strength samples accumulate and relax elastic energy stepwise unlike to high-strength samples, that accumulate energy linearizely. Differences in dispersion characteristics of samples differing with strength are observed. The research showed usability of suggested algorithms.