Arsenical Copper Mask

This cast of a Mesopotamian ruler dating from 2300-2000 BCE is a fine example of the artistic skill of some of the world’s earliest metallurgists. Usually we think of the Bronze Age, when people first started metalworking, as marked by the mixture of copper with tin — a classic combination which produced a pliable, hard, and durable product. But this head is just an example of the copper alloys which proceeded the tin-and-copper metal — and it was made with arsenic.

In fact, arsenical copper metalwork dates back to the fifth millennium BCE in the Iranian plateau. Only later was copper mixed with tin. Both alloys are harder and more durable than copper alone — so why was arsenic the original metal worked into bronze? After all, the fumes from arsenic would have been toxic.

Part of the reason is that copper and tin mines usually don’t exist nearby each other (exception: Cornwall in the UK), whereas arsenic is often found in combination with copper. Historical metallurgists Lechtman and Klein have argued that if the copper and arsenic were smelted with other ores like malachite and arsenopyrite together, the fumes given off by the arsenic wouldn’t have been very toxic.

On the other hand, some historians have argued that the use of arsenic in early metalwork would have had horrifying effects on the workers. In fact, the Ancient Greek myths about the God of metallurgy, Hephaestus/Vulcans, describe the deity as someone with a limp — destruction of nerve endings is a common outcome of arsenic poisoning.