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 settled just three miles from the area at Brough. It is likely that they were searching for deposits of lead ore and struck upon an outcrop of Blue John by chance. Being keen mineralogists, they would instantly have 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 principal colours are purple and white, disposed in undulating bands and usually separated by a third band, the two colours being mixed, assumed to the tint of the flame.