Geological and Geochemical Analysis of Baba-Ali Index

Alamgholagh Mountain is located in NW of Hamedan city. It comprises diorite to syenite and quartiziferous syenite rocks near its climax. The Pre-Jurassic ignimbrite and rhyolite host Baba-Ali ore body. This ore body contains magnetite, hematite and trace amounts of pyrite and chalcopyrite. Textural studies with reflecting microscope show some primary and replacement textures. SEM studies reveal parallel thin plates in magnetite crystals and bacterial activity on pyrite crystals.Spider REE diagrams show noticeable different patterns for ore body amphiboles and country rocks. In the ore body, the concentration of elements fluctuates alternately, however, in the country rocks decrease from La to Lu and show a negative anomaly in Eu values. Some of the calculated REE ratios for the ore body and country rock are different and suggest a different genesis.