Gazestan ore deposit is located at 78km of the eastern side of Bafq and at 10km of southeastern of Gazestan Village. Rock units of the area belong to Rizu Formation and include carbonate rocks, shale, tuff, sandstone and volcanic rocks. From structural point of view, Gazestan ore deposit belongs to Central Iran Zone, Bafq - Posht e Badam subzone. In addition to sedimentary and volcanic rocks, intrusive rocks like stocks and dikes composed of gabbro-diorite, gabbro and diabase are exposed in different parts. Acid-intermediate green rocks host iron and phosphate mineralization which indicate nearly-deep facies in some parts.
Alteration is more apparent in volcanic rocks and includes silicification, feldspathization, chloritization, sericitization and formation of mafic minerals like epidote, thermolite and actinolite. Minerlization host rocks show metasomatic alteration. Mineralization in Gazestan ore deposit contains different proportions of iron oxides and apatite associated with quartz and calcite and seen in green rocks and rhyolites. Five mineralization forms are identified in the area. The common apatite mineral in the area is flouroapatite in which CI is less than Esfordi apatite. P2O5 content in the samples varies between some tenths of one percent to 35 percent. Also, REE content is significant in apatites (average: 1.5-2%).
There are three groups of P2O5, low-grade (2.5-4%), medium-grade (4-8%) and high-grade (more than 8%). Using balanced section technique, reserves of low-grade, medium-grade and high-grade groups were estimated to be 14357266, 1033975 and 5355580 million tons respectively. Based on the detailed exploration studies, there are 3.5 million tons ores with 2% P2O5, 1.56 million tons with 3% P2O5, 645 thousand tons with 4% P2O5. The results of processing studies on the ores of the area show there is a potential for the production of a concentrate with 34% P2O5. CI and F contents in this product are 0.1% and 0.04% respectively. Field relations, structural and textural evidences, mineralization and isotopic forms, proportions and contents of REEs and types of the magmatism and alteration indicate the correlation of Gazestan ore deposit and magmatic activities. Probably, Gazestan ore deposit is the result of the separation process of silicate phases from Oxide-carbonate phases during nephelinite lava ascent.