Derbyshire Blue John from Castleton in Derbyshire
Derbyshire Blue John is a rare variety of the mineral fluorite which comes exclusively from Castleton in Derbyshire, United Kingdom. It was first discovered whilst mining for lead.
Derbyshire Blue John is a calcium fluoride mineral whose colour comes from films of oil which fell on the crystals many millions of years ago.
This Derbyshire Blue John vase is on display in the Natural History Museum London. Photo; Stone Mania ©. Clicking the image redirects to the original full size photo.