Impurities play an important role in different spheres of our day-to-day life. For example, trace amounts of impurities present in crystalline solids have a profound influence on their mechanical, electrical, thermal and optical properties. Consequently, the performance of different types of devices based on these solids depends on the nature and concentration of impurities present in them. Trace amounts of impurities present in a growth medium also have a strong influence on the processes of nucleation of crystallizing phases of the same substance and the subsequent growth of the nucleated phase. Typical examples of such processes are: beneficial mineralization such as the formation of bone and tooth, and pathological mineralization such as formation of human kidney stones, scale formation in domestic appliances and industrial plants, and crystallization of saturated fatty acid methyl ester components of biodiesel during cold seasons, clogging fuel lines and filters of engines.