The project aims to determine the distortion of the crystalline environment as a result of replacing the matrix ion with an impurity. This possibility is based on the relationship of the coordinates of the ions of the nearest oxygen environment and the parameters of the initial splitting of the ground state of the second rank obtained from experiments on electron paramagnetic resonance. In this work, rare-earth impurity S-ions in crystals of the structure of scheelite, garnet, and gallate of lanthanum are studied