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 '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.