Eli5 why is aluminium not used as a material until relatively recently whilst others metals like gold, iron, bronze, tin are found throughout human history?
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Electricity.
Here’s how you make aluminum. Maybe you’ve seen the classic chemistry experiment called “electrolysis” where you run an electric current through water, splitting the H2O up into hydrogen and oxygen? To smelt aluminum, you do the same thing *to solid rock*. You melt an aluminum oxide mineral called alumina, and then run truly stupendous amounts of electricity through it, separating the aluminum from the oxygen.
It’s not that aluminum ores are rare (they’re super common) and it’s not that the temperatures needed are particularly high (only about half the temperature needed to smelt iron), it’s the fact that you need tons of electricity. A typical aluminum smelting plant uses as much electricity as a large city.
[Several percent](http://wordpress.mrreid.org/2011/07/15/electricity-consumption-in-the-production-of-aluminium/) of the world’s total electricity production is used to smelt aluminum. The countries that produce the most aluminum are not the places where the ore is found, but the places where electricity is cheap.
Electricity is necessary because aluminum oxide holds onto its oxygen atoms a lot more tightly than other minerals. If you heat up other metal oxides with carbon, you can convince the oxygens to leave the metal and form carbon dioxide, but that doesn’t work for aluminum.
Aluminum is basically electricity in solid form, and before electricity was widely used, creating aluminum was almost impossible.
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