BLUE JOHN - natural unpolished piece - Castleton, Derbyshire

'BLUE JOHN' FLUORITE

 Natural unpolished piece
 
Treak Cliff, Castleton, Derbyshire

A deep purple piece of solid fluorite, with some cubic crystals visible in cavities. It is almost entirely opaque purple fluorite.

Blue John is a variety of the mineral fluorite. It is only found in the vicinity of Treak Cliff, near Castleton in Derbyshire. It is typically banded with purple and white fluorite. Blue John has been mined for hundreds of years and made into jewelry, bowls, goblets, vases, and numerous other decorative items that are now prized throughout the world.

The origin of the name Blue John is not clear.  It is likely that it was a local name given to the stone by the Derbyshire lead miners who already knew the zinc mineral sphalerite by the nickname ‘Black Jack’. 

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