Toranagallu mound: Provenance of unusual glassy materials

Abstract

Slag-like material from a mound of uncertain origin near the town of Toranagallu in the Bellary District of Karnataka, was analysed with the purpose of determining its origin. The material exemplifies 'ash mounds' of Neolithic age, which are abundant in the Deccan plateau and surrounding areas of Peninsular India. The material is porous and glassy, with abundant diopside crystallites in a rather homogeneous glassy matrix. Bulk analyses by instrumental neutron activation analysis (INAA), XRF and ICP-based methods, including ICPMS of REE, plus in situ electron-probe microanalysis (EPM) of the glass and crystallites provide chemical and mineralogical constraints on possible origins. The analytical results suggest that the sample may represent residue from a glass-making operation. This result defines one use of the mound, but leaves open the possibility that a range of other activities may have contributed to the mound's development over a protracted time span.