For a while it was the only place where burning coal to power an (early, inefficient) engine made any economic sense. There was an ACOUP piece linked on here r

For a while it was the only place where burning coal to power an (early, inefficient) engine made any economic sense. There was an ACOUP piece linked on here recently that did a pretty convincing job of explaining that you needed the twin circumstances of (relatively) deep coal mining (which means you need existing substantial demand for coal unrelated to powering engines) and a lot of effort already being spent on developing pressure vessels (say… a long-running arms race for better and more-powerful cannon) to both get the Industrial Revolution at all, and to see it develop so remarkably fast as it did. Absent the former, it just doesn’t happen, and absent the latter, it’s a lot slower to get going.