Sorkheh Dizaj apatite - iron oxide deposit is located in southeast of Zanjan, within the Tarom subzone of Western Alborz - Azarbaijan structural zone. The oldest units in the area are Eocene trachyte, trachyandesite, olivine basalt and volcanoclastic brecciated tuff and lapilli tuff intruded by a quartz-monzonite, monzonite and granite subvolcanic pluton of Late Eocene - Early Oligocene age. The subvolcanic plutonic rocks show characteristics of I-type granites and the magmatism shows orogenic characteristics related to magmatic arcs. Mineralization in the area occurred in the form of vein that is located in the host subvolcanic pluton. Furthermore, mineralization in the volcanic rocks occurs as veins similar to those in the subvolcanic rock mineralization, but less abundant. Geometry of the ore bodies is of vein type and their textures are stockwork, massive, banded, brecciate and vein-veinlet. Magnetite (low Ti) and apatite are the most important minerals at Sorkheh Dizaj deposit accompanied by minor sulfide minerals such as chalcopyrite, bornite and pyrite. The supergene minerals like chalcocite, malachite, azurite, covellite, hematite and goethite have been formed due to weathering and supergene processes. The main alterations of this deposit are K-feldspar metasomatism, actinolitization, argillic, sericitization, silicification, tourmalinization, and chlorite-epidotic where silicification and argillic alterations are more abundant than other alterations. The most important characteristics of the Sorkheh Dizaj apatite - iron oxide deposit (including tectonic setting, host rock, mineralogy, hydrothermal alteration, structure and texture) indicate magmatic Fe-P-REE-rich fluids source for the mineralization. Comparison of the Sorkheh Dizaj deposit with various types of iron mineralization in the world suggests that the deposit shows the most similarity with the Kiruna type Iron Oxide - Apatite (IOA) deposits.