There is an old lead mine in the Peak District National Park of central England, just outside of the town of Castleton. Known as the Odin Mine, it’s surrounded by the most exquisite pastoral landscapes. Nestled in the countryside near the mine’s entrance is this contraption, known as a crushing circle.
Although the mine itself may be as old as the Roman era (opinions on its age differ), the crushing circle wasn’t constructed until 1823. These systems were commonly used in metal mining at the time, a somewhat crude—yet very effective—method of facilitating the separation of the valuable metal ores to from the rest of the junk minerals (called gangue).
The way it worked was simple—a heavy stone was carved round, and bound in iron. It was then pulled around a ring of iron by a horse, as ore was fed under the stone. The ore was pulverized by the weight, and the pressing of iron against iron would separate the contituents of the raw material which would then be hand sorted or separated in water using differential settlement, allowing for the smelting of the metals.
The Odin Mine is quite deep, at one time extending nearly a third of a mile into the hillside. It hasn’t been active since the early 20th century, and what remains of the cavern is now unstable and prone to dangerous collapse. You can still see the entrance, but investigating further in is not advised.
Around the site you’ll also find a range of plants, called metallophytes, that have evolved to tolerate the lead and other heavy metals in the soil. Some metallophyes actually require the lead to flower. Talk about lemonade from lemons.