Mineralogical and XRD studies of graphite veins in the northeast of Alvand Mountain

The study area is located about 45 km southeast of Hamedan, northeast of Azandarian city and east of Alvand batholith. Graphite is seen in two forms in the region: 1) in the form of graphite veins with 5 to 10 cm thickness, in contact with smoky quartzite veins, 2) Scattered in spotted graphite schist, containing large crystals of muscovite, quartz, garnet, andalusite, kyanite and biotite. In this region, the most important impurities associated with graphite are ​​sersite and muscovite. In the X-ray diffraction pattern (XRD), graphite peaks with hexagonal crystallization system were observed in the samples. Thermometric studies show that there are 4 types of fluid inclusions in quartz veins:1) LCO2 + VCO2 + LH2O 2) LCO2 + VCO2, 3) VH2O + LH2O and 4) LCO2 + VH2O. Homogenization temperature for the fluids inclusions in all two-phase samples (range between 240-150) is 180 ° C in average, and calculated salinity is between 3 to 16.4% by weight equivalent of NaCl according to H2O-CO2-NaCl system. In addition, presence of CO2 in the fluids inclusions indicates the hydrothermal origin of available quartzite veins. The results of petrographic and physical properties studies of graphite mineral indicate, the formation of this mineral from the metamorphic transformation of organic matter from initial sediments to amphibolite facies. The mineralization of graphite in this deposit is directly related to formation of quartz hydrothermal vein of origin.