At present, GIS technology plays a significant role in exploration studies of natural resources. GIS can not only organize the mineral potential-related information, but also integrate different datasets and produce quickly and precisely required mineral potential maps. It also supports the spatial decisionmaking process. Here, we use GIS to produce the mineral potential map, MPM of the Chahefirozeh porphyrtic copper prospect to determine sufficient drilling localities. The procedure consists of four steps as following: 1) preparing various data layers (e.g. rock type, alterations, structures, mineral anomalies etc). 2) Producing the mineral factor maps, MFMs, 3) assigning the reasonable weights to the MFMs, and 4) integrating the weighted MFMs in the Inference Network using the Fuzzy-logic and index-overlay operators. The later is introduced as new method which can eliminates those defects involved with previous methods. It can integrate factor maps with more flexibility. The resulted MPM of the study regions indicates that main potential areas show N-S trend and locate in the central part of the region. Eventually, the degree of correlation between MPMs and 24 drilled exploration boreholes have been estimated for two different classes, 72.73% and 74.42%. Regarding to the resulted MPM, some new promising drilling localities have been suggested. Comparison between the high potential points indicated by our MPMs with those previous drilled boreholes reveals about 60% miscorrelation. In other word, if the present proposed methodology had been performed before drilling operation, about 900,000$ could be saved in this stage.