Elemental composition and microstructure analysis of archaeological copper from central Ganga valley, India

Abstract

Copper alloys from an early-historic period site Kausambi, Uttar Pradesh, India were studied to understand the manufacturing technology and alloying practices through elemental analysis and microstructural examination. Most of the analysed samples were tin bronzes, and microstructure examination demonstrated casting, forging and annealing procedures adopted in manufacturing. Arsenic was absent in most of the samples, which may be due to recycling of the metal and awareness regarding the health hazards of this element among artisans. It is suggested that arsenic was not intentionally mixed in archaeological copper. On the other hand, tin was added in different quantities to meet the desired physical properties of the end-products. It is reported that copper metallurgy was developed in due course of time as a specialized craft in the Central Gangetic Valley, India and artisans of this region had mastered the copper-alloy technology since the early historic period