Blue John or Bluejohn may refer to: * Blue John, Kentucky, United States *

Blue John (mineral) Blue John (also known as Derbyshire Spar) is a semi-precious mineral, a rare form of fluorite with bands of a purple-blue or yellowish colour. In the UK it is found only at Blue John Cavern and Treak Cliff Cavern at Castleton in Derbyshire. Du ...

, a form of fluorite mined in Derbyshire, England *

Blue John Cavern The Blue John Cavern is one of the four show caves in Castleton, Derbyshire, England. Description The cavern takes its name from the semi-precious mineral Blue John, which is still mined in small amounts outside the tourist season and mad ...

, a cavern in Castleton, Derbyshire where fluorite is mined *

Bluejohn Canyon Bluejohn Canyon (often mistakenly referred to as "Blue John Canyon") is a slot canyon in eastern Wayne County, Utah, United States. It is on BLM land just south of the boundary of the Horseshoe Canyon Unit of Canyonlands National Park. Descr ...

, a canyon in Utah, United States, site of the Aron Ralston accident * ''Blue John'' (album), an album by organist John Patton * Lance-Constable Bluejohn, a character in the ''Discworld'' series, a member of Ankh-Morpork City Watch * Blue John Gap, a fictional location in Arthur Conan Doyle's short story ''

The Terror of Blue John Gap "The Terror of Blue John Gap" is a short story written by Arthur Conan Doyle, Sir Arthur Conan Doyle. It was first published in ''Strand Magazine'' in 1910. It is the subject of an ongoing study, The Terror of Blue John Gap Project, by Margie Deck ...

See also