The Indus Civilization c8.6

c8.6

The finding of a considerable amount of copper ore in a brick-lined pit at Mohenjo-daro proves that this metal was smelted there, although no furnaces have been discovered in which it could have been reduced. A very simple method would have been to heat the ore mixed with charcoal in a hole in the ground by means of a blast. The shape of several copper ingots from the city, one of which weighs two and a half pounds, suggests that this was done, and that the metal when molten ran through a channel into an even, semi-circular depression in the ground; a projection on one side of some of these ingots shows how the moulds were filled. The flat upper surfaces of all the ingots are very puckered owing to unequal cooling.