Blue John Cavern
{{Short description|Show cave in Derbyshire, England}}
{{Use dmy dates|date=December 2020}}
{{distinguish|Bluejohn Canyon}}
{{Infobox Cave
| name = Blue John Cavern
| photo = Blue John Veins in the Blue John Cavern.jpg
| photo_caption = Blue John seams in the cavern
| location = Castleton, Derbyshire, England
| depth =
| length =
| coords = {{Coord|53.3456|-1.8035|type:landmark_region:GB|display=inline, title}}
| discovery =
| geology = Blue John
| difficulty =
| entrance_count = 1
| access =
}}
The Blue John Cavern is one of the four show caves in Castleton, Derbyshire, England.{{cite web|url=http://www.castleton.co.uk/caverns/blue_john_cavern.aspx|title=Blue John Cavern|website=castleton.co.uk|publisher=Peak Hideaways|access-date=22 January 2017|archive-url=https://web.archive.org/web/20170121185136/http://www.castleton.co.uk/caverns/blue_john_cavern.aspx|archive-date=21 January 2017|url-status=dead}} The others are Peak Cavern, Treak Cliff Cavern and Speedwell Cavern.
Description
File:Blue John Cavern entrance.jpg
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. 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 to light a photograph underground. It was taken by Manchester photographer Alfred Brothers.{{cite news|url=https://books.google.com/books?id=yINSqbNUNM0C&pg=PA14|title=Art of Darkness|first=Chris |last=Howes|magazine=New Scientist |date=23 December 1989|access-date=5 July 2014}}
Blue John
{{main|Blue John (mineral)}}
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. 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.{{cite book | title=An Gerlyver Meur: Cornish–English, English–Cornish Dictionary | first=Ken | last=George | year=2009 | publisher=Cornish Language Board | isbn=978-1-902917-84-9}}
References
{{reflist|22em}}
External links
{{commons category|Blue John Cavern}}
- {{official|http://www.bluejohn-cavern.co.uk}}
- {{YouTube|id=FRvHNIL2Z_M|title=Blue John Cavern Castleton, Derbyshire}}
{{Derbyshire Places of interest}}
Category:Castleton, Derbyshire
Category:Show caves in the United Kingdom
Category:Tourist attractions in Derbyshire