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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Simply, we just found out how to cheaply make aluminium recently. During Napoleon III’banquest, aluminium cutlery was reserved for the most important/special guests, normal guests used gold ones.
Fun fact: Napoleons’ silverware was made of Aluminum because, at the time, it was more valuable than gold. Not because Aluminum was particularly rare in the earth’s crust, on the contrary; it’s more abundant than iron, but because it’s so difficult to refine.
As the first post mentioned, one basically needs a giant electric arc furnace churning out massive quantities of energy to split the bauxite ore back to its constituent components. In fact, the power requirements are so high that many aluminum smelters require the construction of a entire hydroelectric dam just to run the factory.
TLDR; Aluminum is not rare but finding it in a ‘pure’ form is virtually impossible. The technology to purify it at any sort of scale didn’t exist until electricity becomes a thing people did.
From a slightly different perspective, (as others noted) aluminum oxidizes extremely easily. On top of that, aluminum oxide is very chemically *stable*, meaning it takes a lot of work to get it back to pure aluminum form.
Think of it like you’re dying a piece of cloth. It’s super easy to just soak the cloth in liquid and dye. Now try to remove the dye. Much more difficult!
Funniest thing is when it was first isolated, it was so rare royalty used it as cutrelry, compared to now when its treated as trash.
The history of the chemical elements is wild. There were seven metals known to the ancients. The Latin names for them are where we get their atomic symbols. Aurum (gold), hence “Au”. Argentum (silver), getting “Ag” (another element got “Ar”). Cuprum (copper), hence “Cu”. Plumbum (lead), hence “Pb”. Stannum (tin), hence “Sn”. Hydrargyrum (mercury), hence “Hg”. Ferrum (iron), getting “Fe”.
The next element isolated and named was in the 1700s, and they came fast after that.
But they knew about compounds and extractions, isolates, and distillates thereof. As was mentioned, alum has been known and used since ancient times. The extract of alum used to get the metal in question is alumina. Electricity then isolates aluminum. Prior to easy production of electricity, artisans had to rely on chemical batteries and electrolysis (like the penny experiments one might have done in middle-school science classes).
In addition to the other examples given of how prized it was for its value and rarity early on, the Buckingham Palace Guards’ uniform buttons are aluminum, for the same reason as the other things — most precious metal in the Empire.
Which reminds me… Platinum was thought by the Spanish conquistadors to be “unripe gold” and was dumped overboard by the ton as worthless. I’m curious how much is still lying at the bottom of the Atlantic between the Caribbean and the Azores…
EDIT to fix spelling.
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.
https://medium.com/discourse/why-napoleon-iii-served-dinner-on-aluminum-instead-of-gold-782196a92ef0
An interesting read.
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