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 words blue and/or john:
“The modern queer was invented by Tennessee Williams. Brando in blue jeans, sneakers, white T-shirt and leather jacket. When you saw that, you knew they were available.”
—Derek Jarman (b. 1942)
“A process of genocide is being carried out before the eyes of the world.”
—Pope John Paul II (b. 1920)