Textural and Compositional Variations of Goethite Across Different Iron Ore Varieties from the Daitari Iron Ore Deposit, Singhbhum Craton, India

Abstract

The Daitari Iron Ore Deposit of the Singhbhum Craton, eastern India, hosts extensive goethite-bearing ores that exhibit significant variability in field relations, internal textures, and mineral associations. This study investiGAtes the modes of occurrence, microstructural characteristics, and micro-compositional features of goethite occurring both as a dominant ore-forming phase and as an accessory mineral within different primary and modified iron ore varieties. The evolution of goethite and its role in iron ore transformation across different ore types remain poorly constrained, particularly with respect to the relationship between texture and compositional variability. Field and petrographic observations reveal diverse megascopic and microscopic textures, including laminated, massive, botryoidal, colloform, radiating, and spongy forms, reflecting heterogeneous pathways of iron redistribution and mineral transformation. Reflected-light microscopy reveals transitional relationships between goethite and hematite, indicating progressive replacement, recrystallization, and localized dehydration. Electron Probe Micro-Analyzer (EPMA) data indicate that goethite associated with goethitic ores is chemically distinct from accessory goethite, exhibiting higher Fe₂O₃ contents and more compositionally evolved characteristics. These contrasts indicate that goethite formation at Daitari occurred during multiple stages of near-surface evolution, rather than through a single uniform process. Nevertheless, the absence of isotopic and trace-element constraints limits definitive interpretation of the processes governing goethite formation. The results highlight the importance of integrating textural and compositional characteristics in understanding iron ore evolution and provide a refined framework for evaluating goethite-rich iron ores in Archean cratonic terrains.