The fractions of various clusters and single chromium atoms were calculated for a series of La1-0.2xSr0.2xCrxGa1-1.2xMg0.2xO3-δ solid solutions (0.01 < x < 0.10) within the context of diluted solution and Heizenberg-Dirack-van Vleck models. An essential influence of both the nature and concentration of heterovalent diamagnetic substituent on the quantitative and qualitative composition of chromium atom clusters was shown. These clusters include also strontium, magnesium atoms, and oxygen vacancies.