Refining metal ores is one of those things that’s really, really hard to do without emitting a huge amount of greenhouse gasses. The energy sources behind our material economies are not as easily substitutable with renewables, because what they often require is extreme heat, and sometimes the carbon itself (in the case of steelmaking and concrete). Researchers at MIT are looking at a way of directly refining molten iron oxide directly into pure iron electrolytically that results in very pure iron, and virtually no emissions, and it might work for other oxide refining processes as well.
A great series of photos looking at the coal industry worldwide from The Big Picture. Even ignoring coal’s irreversible long term damage to the atmosphere and climate, it’s a pretty desperate business for a lot of people, who are still scratching it out of the earth deep underground, by hand. Popular with the kids too — they can really get into those hard-to-reach places.