Antimony Mineralization in Relation to AlvandGranitoids(Hamedan)

Antimony mineralization occured in Hamedan district (Faghireh) which is related to Alvand Granitoids. The mineralization occurcd as a series of veins. Thickness of veins are variable and reach up to 0.7m. The veins are emplaced along high angle faults. These faults acted as a pathway for migration of are nuids. Veins are composed of stibnite, pyrite, realgar and orpiment with quartz as a gangue. The textures of veins are open space filling, however brecciations also occured. Monzogranites, which formed the main part of Alvand pluton, is the host of quartz - stibnite veins. Monwgranites are composed of quartz, sodium plagioclase (oligoclase), orthoclase, biotite and sometimes muscovite. The veins arc composed of 30.5% antimony , 0.83 ppm gold and 498 ppm arsenic. Based on geochemical studies, Sb, Au, AS, Ag, Hg, Sn, Ni, Co and Cr contents of host rocks are much higher than the world chr('39')s average monwgraniets and have probably anomalies. Spiderdiagrams show an identical pattern for host rocks and veins, which strongly suggests that these veins are cogenetic with the intrusive rocks (monzogranite). 1n summary, with all geological evidences In the region, it can be concluded that the mineralization is probably occured in the epithermal type.