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Aluminum sure, but iron rusts. In tens of millions of years you could have oxides of iron from a civilization, but no workable steel or iron. Aluminum might sur
by scottie_m 9y ago
Aluminum sure, but iron rusts. In tens of millions of years you could have oxides of iron from a civilization, but no workable steel or iron. Aluminum might survive, gold and platinum would be fine, but not iron. It doesn’t matter though, we’d have gone through many cycles of subduction and renewal in such a long time, so we’d have new surface deposits. Coal and oil would even have started to form over such a long time scale.
- PeterisP 9y agoWhat do you mean by "workable steel or iron" ? We're not mining for steel, and it's not like iron age started with finding some magic store of "workable iron" instead of iron oxides - the surface iron and mined iron deposits e.g. hematite, magnetite, etc are oxides of iron. The fully oxidized remains of a scrapyard would form pretty much perfect iron ore. Our iron (and other metal) mining is not "using iron up", it's just bringing the iron closer to the surface and transforming it in ways that will be undone by millions of years. Fossil fuels are a different case, though.
- scottie_m 9y agoThe majority is hematite, but iron exposed to air will not form hematite, or even magnetite, but hydrated oxides. That iron will also be spread out over large areas in low concentrations, not richly concentrated ores of oxides. It would be economically and energetically unfeasible to gather hydrated oxides from rusted metal and then try to make workable iron from it. It’s certainly possible, but it would be a kind of insane process with low yields. The other problem is that you need to use coke as a reducing agent, so we’re back to fossile fuels.
- FreeFull 9y agoCharcoal also work as a reducing agent. The problem with using charcoal is that you're going to be using up a lot of wood to make it.