Find out what Blue John Stone actually is at a place it is mined. On the self guided audio tour (on your own Smartphone) of the cavern you will see the largest deposits of Blue John Stone in situ, and some of the finest stalactites in the Peak District. This is the only one of the Caverns at Castleton where you can have 'hands on' experience to work with the Blue John Stone, and make your own polished specimen of the rare mineral in our workshops with our craftspeople to help you.Take time to listen fully to the audio guide to learn about the geology of Treak Cliff Hill, why the mineral formed only here, and why it is so unique. Discover the 300 year old history of people mining and using Blue John Stone: see the collections and artefacts the owners have on display to tell their story. Browse the shop for unique Blue John Stone pieces produced on our site, direct from our mine.