They had the Stone Age and the Iron Age and now they’re going to call it the Rearden Metal Age-because there’s no limit to what your Metal has made possible.
Instead of building new furnaces, thought Rearden, he was now running a losing race to keep the old ones going; instead of starting new ventures, new research, new experiments in the use of Rearden Metal, he was spending the whole of his energy on a quest for sources of iron ore: like the men at the dawn of the Iron Age-he thought-but with less hope.
There are no more uses of "Iron Age" in the book.
Show samples from other sources
If she tried, Mae could get to at least a few of these events, but just when she was arranging some sort of itinerary, she saw something that obliterated all else: the Funky Arse Whole Circus would be on campus, on the lawn next to the Iron Age, at seven.
Dave Eggers -- The Circle
Then I’d remember Herodotus didn’t have a smartphone, because he had been dead since the Iron Age.