Economic history.

I took this picture of the oldest blast furnace still operating in the UK around 1965. The date on the lintel supported by the two round pillars is 1711!!! It has now stopped operating.

The only reason it was still in operation in 1965 was that it was in a wooded area (Backbarrow, Cumbria) and used some mixture of wood or charcoal and coal as a fuel. This produced iron with some sort of special characteristic for which there was a small amount of demand.