Minerals and Metals in Ancient India v1.c14.s2.t2: Bronze
Minerals and Metals in Ancient India v1.c14.s2.t2
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Bronze
v1.c14.s2.t2.1
Not only copper, low-tin bronze was also used for making pins, mirrors, rods, chisels, flat axes, daggers and arrowheads; high-tin bronze was used for bangles and pins. The hardening property of lead was also known to the Lothal folk. They made use of this knowledge in hardening tools having sharp edges. Tin became a rare commodity in Sumer by 2700 BC until it could be had once again by 1500 BC. Sayce says that tablets from Kara Huyuk refer to tin which was a rare and precious metal in Babylon in c. 2500-2200 BC. It is perhaps during this period that bronze was being introduced in the Indus Valley and Kathiawar by the Harappan traders. Hence it had to be very sparingly used. Out of 71 copper objects from Lothal examined in four lots by Lal, the tin contents in two bangles were 11.20 per cent to 11.82 per cent. One grooved rod contained 9.02 per cent, a mirror 5.47 per cent, a pin 13.80 per cent, two chisels 9.02 to 9.62 per cent, an engraver 3.96 per cent, a spear 2.27 per cent. Thus only eight out of 71 objects may be said to have contained some appreciable quantity of tin. (Rao, 523)
v1.c14.s2.t2.2
Another important point which emerges from the analytical data is that although bronze, both low tin and high tin, was in use at Lothal, it is difficult to say whether the use of tin was intended to produce a metal harder than copper, which was to be used for the production of tools with keen cutting edges, or tin was used just to produce an alloy of a more pleasing colour and lustre. The examination of the two chisels show that whereas one contains a high proportion of tin viz. 9.62 per cent, the other is completely free from it. If the use of bronze for producing tools with a keen cutting edge was well understood, it is difficult to explain the presence of tin in one chisel and its total absence in the other. The same statement is true of the two bangles, one of which is made of copper and the other of tin (11.20 per cent) bronze. It seems that although the use of bronze was understood, it was not used in a systematic manner for the production of special types of artefacts requiring suitable hardness, durability and a sharp cutting edge; however, there is no doubt that both copper and bronze were in use. (Rao, 652)
v1.c14.s2.t2.3
From the above analytical work, it is concluded that artisans of Lothal were well conversant with the use of copper and bronze. It seems that for the objects of decorative and ornamental value, the use of bronze was considered essential. Its use was also considered essential for the strength and durability of the tools, and cutting edge in axes and chisels etc. (Rao, 652)
v1.c14.s2.t2.4
Most of the copper and bronze objects examined were evidently made of casting; shaping and finishing by hammering would also appear to have been practised. The mirror which is made of a low-tin bronze was probably heated and hammered after casting until it reached the atmospheric temperature; the same can be said of the celts, axes and chisels. The technique of forging was thus practised by the metal workers of Lothal.
v1.c14.s2.t2.5
The presence of such a high proportion of tin cannot be treated as accidental; it was used for producing a metal harder than copper; bronze-making and working reached a fairly high degree of technical excellence in those remote times. (Rao, 653)
v1.c14.s2.t2.6
It has been proved that the inhabitants of Lothal were acquainted with lead. A sleeved axe used for fashioning copper objects contained 2.51 per cent lead. An unidentified object contained 1.64 per cent lead. (Rao, 523)
v1.c14.s2.t2.7
Two specimens have been found to be made of lead; both of them are free from copper, iron, tin, zinc and silver. Nickel has been detected in traces in one lead specimen, whereas the other specimen shows 99.54 per cent of lead. It seems that lead of a high degree of purity was manufactured by the metal-workers of Lothal. (Rao, 655)