The Blue John Cavern in Derbyshire produces one of the scarcest minerals in the world and also offers a truly unique exploration experience.

Far from the dank and dingy caves usually associated with mining, these limestone caverns have been fitted with modern lighting and the sections of the caverns open to visitors have been neatly and cleanly paved. Visitors can wander the rippling stone formations and stalagmites, maybe even spotting the cavern’s titular rock.

In the winter months, miners enter the caverns to harvest deposits of the rare Derbyshire Blue John, which is a semi-precious stone consisting of vibrant yellow and blue crystalline bands. The mineral is remarkably only found in two caves in the entire world. Amateur spelunkers can also buy all manner of Blue John jewelry and other mineral accessories at the adjoining gift shop, taking home a souvenir that can only be found in this unique cave.