The Blue John Cavern is one of the four show caves in Castleton, Derbyshire, England. Main article: Derbyshire Blue John. In the UK Categories: Caves of.
English. Wikipedia has an article on: Derbyshire Blue John Etymology[edit ]. From blue + John. A semiprecious mineral mined in Derbyshire, a form of fluorite with bands of a purple-blue or yellowish colour. [from 18th c.] Categories.
Media in category " Derbyshire Blue John - mineral". The following 26 files are in this category, out of 26 total. " Blue John " stone (a fluorspar) in.