There are methods of mineral prospectivity mapping whereby, besides assignment of weights to classes of evidence in an evidential map, every evidential map is also given a weight based on expert opinion. In this regard, evaluating the relative importance of every evidential map derived from particular spatial data sets is a highly subjective exercise and the assignment of meaningful weights to evidential maps usually involves a trial-and-error procedure. In this paper, we used a prediction-area (P-A) plot and normalized density to estimate weights of every evidential map. The method of P-A plot is a data-driven way, rather than using expert opinion, to evaluate and weight evidential maps.