Doping of the matrix of mineral or chemical compound of different elements, with a small amount of salt is known to bring about the aliovalency effect. In essence, it is supposed to introduce defect or propagate its effect in the host element or matrix. This property has been judiciously exploited in the processing of refractory minerals like ilmenite, barite and celestite. Finally, the reasons for the success or failure of this effect in certain cases have been clearly elucidated.