blue John
nounUK /ˈbluː dʒɒn/
Etymology From blue + John.
2
A semiprecious mineral mined in Derbyshire, a form of fluorite with bands of a purple-blue or yellowish colour.
- Lee went up front to his icebox and brought back a jar of milk. The cream had been skimmed from it. I said, “This tastes like blue-john to me.”1968, Charles Portis, True Grit:
- Related terms
- sky blue