Blue John may refer to:
- Derbyshire Blue John, a form of fluorite mined in Derbyshire, England
- Blue John Cavern, a cavern in Castleton, Derbyshire where fluorite is mined
- Blue John Canyon, 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"
Famous quotes containing the word blue:
“The Reverend Samuel Peters ... exaggerated the Blue Laws, but they did include “Capital Lawes” providing a death penalty for any child over sixteen who was found guilty of cursing or striking his natural parents; a death penalty for an incorrigible son; a law forbidding smoking except in a room in a private house; another law declaring smoking illegal except on a journey five miles away from home,...”
—Administration for the State of Con, U.S. public relief program (1935-1943)