Abstarct: Zartul area is located in 10 Km of the north of Semnan city. Form structural units point of view, this region is a part of central Iran zone. In this area, volcanic, volcanosedimentary rocks and fossiliferous limestones have outcrops. The presence of limestone intercalations contain Nummulite, Discocycline, Aselina, Olveoline, … confirm this mentioned age range. A numerous pluton with compositional range from gabbro to granite intruded in this sequence. Emplacement of these plutons, accompanied with the action of compresstional tectonic regime has been provided suitable conditions for mextasomatism (skarnization, mineralization and alteration). Investigation of this area in the larger scale to west or east, indicate that large major structural elements such as Semnan and Attary faults have been the important role in producing the crushed tectonic zones for infiltration or injection ore forming fluids from gabbroic-granitic plutons (granodiorits have the most important role in skarnization or mextasomatism). They are differences evidence of magma fractionation (fractional crystallization) into host rocks that all this collections. Skarnization as a part of mextasomatism processes has been resulted to generate mineral assemblages contain Ca-Fe bearing garnets, clinopyroxenes, scapolites, …. Ca-Fe bearing garnets are the most frequent index mineral of contact mextamorphism. baxsed on microprobe analysis, their composition is from And60-80 and And30-100. Garnets have compositional and color zonation. Clinopyroxenes have salite composition but their frequency is very low compared with garntes. Scapolites were produce in the margin of alkali feldspar granitic plutons and their tuffaceous host rocks and scapolites are from sodium rich end members which famous to dipyre. Petrographical investigations indicate that there is a very close relationship between iron ore minerals assemblages (especially Ca-bearing garnets). Skarnization and mineralization have been took place in the nearly contemporaneous time. baxsed on geothermobarometery by using garnet – pyroxene and thermometry of chlorite and with consideration the presence of mextasomatism have been produce high temperature range of skarn has been generated in approximately 450-560°C and <2 Kb. Barite and calcite veins, Zartul skarns have been produce in a temperatural range from 250-400°C. Furthermore an intensive mineralization of iron ore has been took placed in this area. Mineralography of iron ore deposits indicate that they have vein or replacement structural forms. They dominantly contain magnetite, hematite and also with a few grains of pyrite and chalcopyrite.