Abstarct: Lajaneh iron ore is located in 40 Km of south eastern of Shahrood city. This region is a part of the northern margine of the central Iran zone. In this area, Permian dolomitic limestones and Cretaceous marly limestone have crops out. A numerous of plutons with compositional ranges from syenite to monzodiorite intruded into the sedimentary rocks and skarnization itʹs products. Results of electron microprobe analysis on some of the dioriteʹs minerals suggests that these rocks have plagioclase with andesine composition and pyroxene with augite composition. The chemical composition of pyroxene indicates thatʹs crystallization temperature from 1150 to 1200˚c and pressure from 8 to 10 kbar and thatʹs formation is in association with back arc zone. On the basis of biotite chemistry figure out calc-alkaline orogenic tectonical setting of diorite bodies.The Lajaneh intrusive bodies in the contact with ore have become to garnet, mextasomatic pyroxene, actinolite and Epidote index minerals. Clinopyroxene׳s composition is diopsidic in endoskarns. Field evidence, systematic sampling and thin section study suggest an mextasomatism zonation from intrusive body from inside (endoskarn) to its rim (exoskarn). On the basis of mineralogy, exoskarns are divided to phlogopite skarn, scapolite bearing skarn, garnet bearing skarn, banded calcite- magnetite skarn and garnetiferous skarn veins. Compositions of garnets is grandite and only have a small percentage of spessartite. Propylitic mextasomatism evidence are seen in subvolcanic diorite porphyry of the deposit. During this mextasomatism, low temperature and hydrothermal actinolite, epidote, chlorite, calcite, sericite, hematite and quartz minerals are formed for orthoclase, plagioclase, pyroxene, hornblende and biotite destruction. Phyllic mextasomatism accured in syenites and characterized with sericite- quartz- epidote and pyrite index minerals. Significant characteristic of this deposit that highlights it from other similar deposits is banded iron skarn existence. In this area mineralization include magnetite, hematite, pyrite, ilmenite, malachite, azurite, Sphalerite, goethite, limonite minerals that have massive, semi massive, veiny textures. baxsed on comparison between the Lajaneh iron deposit with different skarn deposits, the deposit show most similarities with calcic- magnesium type skarn deposits.