Abstarct: The Madanjoo iron ore deposit is located in 18km north Sangan, 45km southeast Khaf, 300km southeast Mashhad, the Khorasan Razavi province in the northeast of Iran. This area is a part of the Khaf-Kashmar-Bardaskan or Khaf-Drouneh volcanic-plutonic belt in the Central Iran micro-continental zone and at the northeast of the Lut block. The Madanjoo iron is one of the eastern anomalies of the Sangan iron ore complex. The rock units of the area include Jurassic shaly sandstone, lime mudstone, and sandstone, Cretaceous shale, tuff, microsparite to sparite limestone and dolomitic limestone sequences, late Eocene (38-40 Ma) biotite monzogranite (a little outside the research area), late Eocene skarn rocks, and Quaternary sediments. Biotite monzogranite is classified in type I granites, high-potassium calc-alkaline magmas, mexta-alumina and slightly peraluminous, and continental arc granitoids. The Jurassic and Cretaceous rock units are mextamorphosed into contact with Eocene intrusive and transformed to the skarn rocks, and away from the skarn zone, Jurassic clastic rocks transformed into slate facies and Cretaceous carbonate rocks have been recrystallized and marmarized. The mineralogical zonation in the Madanjoo skarn includes: pyroxene; pyroxene+garnet; Garnet;pyroxene+wollastonite+magnetite;magnetite;pyroxene+garnet+phlogopite;phlogopite;tremolite+actinolite+phlogopite; and muscovite+sericite+calcite+epidote+magnetite zones. The influence of hydrothermal fluids, the rock units has been affected by the argillic, chloritic, epidotic, sericitic, silicic and carbonate alterations. In the Madanjoo area, progressive skarn consists of anhydrous minerals i.e., Ca-rich garnet and clinopyroxene, In the late stages of the progressive phase, as a result of mixing of hypogenic hydrothermal fluids with meteoric waters and reducing of fluid pressure, the oxygen fugacity increases and form magnetite, pyrrhotite, hematite and oligiste, respectively. In the early stages of retrograde phase was formed magnetite, pyrite and chalcopyrite. The minerals such as hematite, goethite and limonite formed during the supergene surface erosion and oxidation. The main structures of mineralization are massive, disseminated, vein-veinlets, plat-shape, lens-shape, and open-space filling. Minimum and maximum contents of Fe in the Madanjoo ores are 11.50% and 43.22%, and Cu, S, and P amounts vary from 11 to 806 ppm, 0.16 to 33.63%, and 0.01 to 0.03, respectively. Iron have positive correlation with V, Cu, and S, and negative correlation with Ir, Mn, P, and Cr. The study of minerals chemistry illustrate that magnetite composition from the Madanjoo ore deposit is the same with that of hydrothermal and skarn origin. Olivine (forsterite), garnets (andradite and minor grossular) and pyroxenes (diopside and minor hedenbergite) are important minerals in the Madanjoo skarn. The thermo-barometric study baxsed on pyroxene chemistry display that the formation temperature of clinopyroxenes in the skarn zone between 458 and 689°C and a pressure of 2.21 kbar. Fluid inclusion microthermomery studies on garnet, pyroxene, tremolite-actinolite, and calcite minerals demonstrate that homogenization temperature vary from 95°C to 410°C, salinity from 2.01 to 57.57 wt.%NaCl, fluid density about 1 to 1.1 g/cm3, and vapor pressure from 10 to 400 bars. Progressive, retrograde and supergene ore mineralization in the Madanjoo skarn occurred at depths of 1400 m to 100 m, and mixing of hypogene hydrothermal fluids with meteoric waters have an important role in magnetite deposition. Finally, the Madanjoo iron occurrence is introduced as calcium-magnesium exoskarn-type ore deposit.