Metals from the Ages #1: Copper Age

Tomas Pueyo wrote this excellent post on how metals shaped human civilization. A “mix of history, geography, physics, geology, and chemistry”, as he calls it. The first 3 metals used by humans were… he points to the Periodic Table! 

Gold, silver and copper. Why those three? Because, to recap chemistry, same column (group) = similar chemical properties. The similar property of relevance here is that they can all be found in “native” form, i.e., pure form.

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When rocks erode, the heavier and inert gold gets left behind, which is why we found gold first. Gold was valuable because it is rare, malleable, doesn’t oxidize, found in nuggets, and yes, shiny. All those characteristics meant it became a store of value. But it was too heavy, too malleable, so it was of no use to make tools.

 

Silver is more common than gold. But it tarnishes (it reacts with other things). Which is why it is harder to find in native form. Again, not of much practical use.

 

Copper is even more reactive than silver, so it is even harder to find in native form. But it is far more abundant than gold or silver.

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It was the creation of kilns that got us kickstarted in the use of metals.

“(Kilns are) big ovens that could reach high temperatures to turn clay into pottery, tiles, and bricks.”

Kilns used wood or coal as fuel, both of which have carbon. The carbon would react with the elements of the ore (unintentional and accidental) and the native metal was sometimes a byproduct. Copper, as we saw above is not all that rare, so it was native copper that was the most common byproduct of kilns. This was a groundbreaking event of enormous consequence to human history:

“For the first time, humans could make metal.”

 

Copper is hard and thus began to be used to make useful tools – hoes and sickles at first, knives and simple swords later:

“The discovery of copper dramatically improved agriculture, cooking, and violence, which led to a population boom and the ability to wage war.”

Copper was also reasonably stable, so it also began to be used as money. That in turn enabled more trade and a way to track wealth, both of which increased prosperity and yes, became the trigger for wars.

 

Since it was such an enormously consequential metal in human history, it is not surprising that the entire era is called the Copper Age.