Comparative microstructural and elemental analysis of iron artefacts from Kaveri valley archaeological sites

Iron has been one of the most critical technotraditions that had lasting impact on social formation throughout the Iron Age and historical period. Iron was used in warfare and subsistence economy. Our knowledge on ancient iron smelting and working have generally been derived from ethnography and ethnohistory, which is by all means, time, region, and raw material specific. Scientific analyses of ancient iron have contributed in understanding this heritage to a respectable extent, yet a comprehensive knowledge about the evolution of iron making through time and space in India eludes us. In this work, a comparative study of iron artefacts from two Iron Age/Megalithic-Early Historic sites of Tamil Nadu, south India, that is, Mangadu (burial site) and Ambal (habitation-cum-burial site) is carried out to understand the iron thermal-processing capabilities. The retrieved artefacts were examined using X-ray fluorescence (XRF) for elemental composition. The imaging of the artefacts was done using Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), and Optical Microscopy (OM). In addition, phase identification was performed using X-ray diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDS). Combination of these analyses illustrates that inhabitants of Mangadu and Ambal were aware of the iron alloy manufacturing/processing techniques such as forging and hammering.