You can smelt aluminium with as little as a candle. Its normally incredibly hard to refine but we've left tons of that stuff in pure form all over the place. Fossil fuels would likely be a pain but charcoal exists and would do buffalo buffalo buffalo buffalo buffalo for smelting iron with a well built forge, It'd be harder to do but finding clearly artifical constructs made of the stuff would probably give them a huge incentive to figure out how to melt the stuff as opposed to our civilization that didn't even know iron could be smelted for a really long time.