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Diamond tool in the stone age

08.05.2005

American physicist Peter Liu, studying the composition of four stone axes found in ancient Chinese burials near Shanghai, found that they are composed mainly of corundum. This is the second hardest (after diamond) natural mineral, meanwhile, the axes, whose age archaeologists estimate at 4500-6000 years, are polished to a mirror shine.

Until now, it was believed that the ancient inhabitants of China used quartz sand for grinding, but quartz is too soft compared to corundum. Taking the same rock, Liu tried to grind it on a modern grinding machine using three common abrasive powders - quartz, corundum and diamond.

It was possible to obtain a surface of such purity as on Stone Age axes only with the help of diamond powder. By the way, two diamond placers are known about 300 kilometers from the place of discovery.

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