About Blue John
Discovered nearly 2 thousand years ago by the Romans, Blue John is a rare natural variety of calcium fluorite, highly distincive and prized because of its characteristic bands of coloured veins. The only known deposit of this unusual mineral occurs in a hill to the west of Castleton in Derbyshire, England, opposite the mountain known as Mam Tor "The shivering mountain".
The Romans had settled just 3 miles away in Brough. It is likely they where searching for deposits of lead ore and struck upon an outcrop of Blue John by chance. Being keen mineralologists, they would have instantly recognised the outstanding beauty of their find. At this time the technology must certainly have existed to enable the complicated process of turning and polishing the stone.
The mineral is essesially mined by hand. It occurs in thin veins and also in nodules. Blasting is considered too dangerous as the shock can disturb the delicate crystalline structure and even render the sample colourless. The distintive coulouration is caused by the displacement of calcium atoms within the colourless crystal lattice. The Blue colour is formed by the scattering and absorption of the light as it passes through the crystals of calcium fluorite. It is this delicate structure which makes the work of the lapidiarist so difficult when attempting to cut and turn the raw mineral.
Splendid specmens of the Blue John stone can be found in imported collections throughout the world. The mines are sadly now largely extinct. It is unlikely that pieces of Derbyshire spar of sufficient size will ever be mined again to produce the wondrous ornaments that have been held in such esteem for many centuries. However smaller veins and nodules of sufficient size for jewellery can still be found.
All jewellery on our online shop is available in a variety of different stones including Blue John. All designed and created in our onsite workshop in Castleton in the Peak District.
- Stone Type
- Blue John