Minerals and Metals in Ancient India v1.c28.s7.t5.7

v1.c28.s7.t5.7

Bhardwaj (1979: 127-28) also examined the Gupta Period gold coins from Rājghāt analysing about 75 per cent gold and 25 per cent silver. The silver-content results in increased solubility of oxygen in molten gold; some of the pits and cavities revealed in the metallographic examination might be of this origin. The micro-structure shows equiaxed fine grains of dimensions around 20 µm. This indicates that the die-struck coins were either hot-worked or cold-worked followed by annealing above the recrystallisation temperature. The excellent details of embossing on both sides indicate that the die-striking techniques were well-developed in the Gupta Period; the die alignment was however not perfect, and this resulted in slight eccentricity of the striking on the reverse side.