Microstructural Corrosion Stratigraphy of Inland Excavated Iron Artifacts From Kotul, India: Evidence for β‐ FeOOH Formation Under Alluvial Burial Conditions

This study investigates corrosion behavior in seven iron artifacts excavated from the late medieval stratified floodplain site of Kotul, western India. Using x‐ray fluorescence (XRF), x‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy‐dispersive x‐ray spectroscopy (EDS) analyses, we identify chloride‐induced corrosion and the formation of akaganeite (β‐FeOOH), a phase typically associated with marine environments. Sample LOT‐27 exhibits significant co‐localization of Cl, Pb, and Sn, suggesting micro‐galvanic interactions that destabilize corrosion layers. The mineralogical and textural diversity observed—ranging from acicular and flower‐like forms to plate‐like structures—confirms complex corrosion stratigraphy influenced by episodic wet–dry cycles and soil chemistry. XRD reveals hematite, magnetite, quartz, and calcite as dominant phases, while field emission scanning electron microscopy coupled with energy‐dispersive x‐ray spectroscopy (FESEM‐EDS) highlights heterogeneous rust layering and environmental inclusions. The presence of akaganeite in inland contexts challenges conventional assumptions about its formation, emphasizing the need for targeted conservation protocols including chloride extraction and low‐humidity storage. These results contribute to a broader understanding of inland corrosion dynamics and preservation of archaeological iron.