The Blue John Cavern is one of the four show caves in Castleton,

Derbyshire Derbyshire ( ) is a ceremonial county in the East Midlands, England. It includes much of the Peak District National Park, the southern end of the Pennine range of hills and part of the National Forest. It borders Greater Manchester to the nor ...

, 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 made locally into

jewellery Jewellery ( UK) or jewelry (U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a wester ...

. The deposit itself is about 250 million years old. The miners who work the remaining seams are also the guides for underground public tours. The eight working seams are known as Twelve Vein, Old Dining Room, Bull Beef, New Dining Room, Five Vein, Organ Room, New Cavern and Landscape. In 1865, Blue John Cavern was the site of the first use of

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

to light a photograph underground. It was taken by Manchester photographer Alfred Brothers.

Blue John

In the UK Blue John, or "Derbyshire Spar", is found only in Blue John Cavern and the nearby Treak Cliff Cavern. It is a type of banded

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

. The most common explanation for the name is that it derives from the French ''bleu-jaune'', meaning 'blue-yellow', but other derivations have been suggested.

In popular media

" The Terror of Blue John Gap", a short horror story by Sir Arthur Conan Doyle, was probably based on this cave. In the late 1950s, the cavern was photographed in 3D by Stanley Long of VistaScreen, for sale at the souvenir booth and through mail order. The cavern was featured on the 2005 TV programme ''

Seven Natural Wonders ''Seven Natural Wonders'' is a television series A television show – or simply TV show – is any content produced for viewing on a television set which can be broadcast via over-the-air, satellite, or cable, excluding breaking news, adv ...

'' as one of the wonders of the Midlands. The cave and jewellery production of Blue John was featured in the 2010 series of ''

How it's Made ''How It's Made'' (''Comment c'est fait'' in French) is a Canadian documentary television series that premiered on January 6, 2001, on the Discovery Channel in Canada and the Science Channel in the United States. The program is produced in th ...

''. Blue John Cavern is also visited by a couple in the 2013 film '' Sightseers''.

References

External links

* * {{Derbyshire Places of interest Caves of Derbyshire Show caves in the United Kingdom Tourist attractions in Derbyshire Tourist attractions of the Peak District Blue John (mineral) Fluorite mines