Gemology and industrial minerals

Geochemistry and Origin of the Hamedan Chromium Reserve, Northwest Iran

Document Type : Original Article

Authors

Bizhan Etemadi 1
Zahra Gholami 2

1 Earth Sciences Department, Faculty of Sciences, Shiraz University, Iran

2 Earth Sciences Department, Faculty of Sciences, Shiraz University

10.22067/gemiran.2026.48063
Abstract
The mineral corundum (a type of blue sapphire) is found in the central section of composite aplite-pegmatite dikes (pegmatites with a combination of syenite), associated with the Elund plutonic suite in the Hamadan region. All aplite and pegmatite samples are highly aluminum-rich and are of type S granite. Chemical earth studies indicate an increase in Al2O3 and K2O with a decrease in SiO2 in corundum-bearing pegmatites. The increase in the Al2O3/TiO2 ratio indicates that element Al in the high-temperature fluid containing alkaline elements was extracted and enriched in the final metasomatic fluids by forming polymers such as Na-Al-Si-O from the melt. The chemical composition matching of corundum in the Hamadan region on the diagram separating types of primary corundum (FeO - Cr2O3 - MgO - V2O3) versus FeO + TiO2 + Ga2O3) confirms its metasomatic origin and direct crystallization from alkaline melt for the formation of this deposit.

Keywords

Corundum
Sapphire
Metasomatism
Composite dikes
Pegmatite
Sanandaj-Sirjan
Subjects

  • Receive Date 15 April 2026
  • Publish Date 21 March 2026

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