Mineral Magnetic Characterization of Archeological Potsherds:An Example from the Deccan Province, Western Maharashtra, India

Abstract

The ancient (archaeological) and modern potsherds sourced from Deccan basaltic soils and sediments at selected sites in the Bhima and Godavari river basins of the western Maharashtra, India, show characteris-tic mineral magnetic properties. High magnetic sus-ceptibilities (χ lf ) for the Deccan-sourced sherds enable their distinction from other sources in the region. The modern pottery sourced from Deccan soils shows sig-nificant lower χ lf than ancient pottery in the region, which further shows lower χ lf than the associated soils (/sediments) due to successive removal of detrital grains as a function of improvement in the pre-processing techniques. The ancient and modern pot-teries show higher superparamagnetic content that is otherwise absent in the source, suggesting its neo-formation during firing. High hematite content in modern pottery relative to ancient pottery further in-dicates higher oxidative firing in the former. Based on close examination of Isothermal Remanence Magneti-zation (IRM) acquisition rates, we suggest the ratios: IRM 1.8 mT /IRM 0.3–0.025 mT and HIRM/Soft IRM along with other routine mineral magnetic parameters to esti-mate the relative degree of oxidative heating, source discrimination and the levels of pre-processing of raw material amongst the Deccan-sourced pottery. The present approach being rapid and economic, a large quantitative database can be generated from the pot-sherds for detailed characterization of these archaeo-logical materials.