Blue John: Remarkable fluorite from a limestone cavern
Steven Wade Veatch (USA) Blue John stone is the name given to banded fluorite found in the Castleton area of Derbyshire in England (Ollernshaw, 1964). It has been prized for centuries. Chemically, it is a calcium fluoride (CaF2) and occurs in distinct bands of different colours: blue, white, purple and … Read More