Corsi Collection of Decorative Stones

view of stone 541

Corsi 541, approx. 145 x 73 x 40 mm, © Oxford University Museum of Natural History

OUMNH Number: 541  
Name and quarry location: Fluorite, Blue John, from Castleton, Derbyshire, England  
Geological description: Hydrothermal vein deposit of colour-zoned purple-blue/colourless fluorite, the variety known as Blue John. It has some yellow ferruginous staining.  
Comments: This specimen was given to Corsi by the 6th Duke of Devonshire following the Duke's visit to see Corsi's collection in 1824. It is a fine example of Blue John. This variety was first discovered at Castleton around 1700, and was mined as an ornamental stone from around 1750 onwards. It was employed with particularly fine effect in the manufacture of decorative ormolu by Matthew Boulton in Birmingham. Small amounts are still extracted today, mainly for jewellery and tourists' souvenirs. For a detailed account of the mining, history and use of Blue John, see Ford (2000). Note that China has produced purple banded fluorite in recent decades for use as a decorative stone, but this usually has some green banding present, a colour not seen in the Derbyshire material.  
References: Ford et al (1993); Ford (2000); Price (2007) 266; Webster (1994) 337-341  
Further information:

Corsi's classification: Class 2. Fluorspars  
Corsi's text: 133.4 Altro dello stesso luogo [Spato di Darbyshire]... trovato a Castelton  

Full entry in English

Enter some search terms
Show results as:

search tips

Searches the database for all stone records containing the words you enter. To search for a text string, put it between quotation marks. To search for stone records that don't contain a word, put a minus sign in front of it.

For example, entering: granite "coarse-grained" -Egypt will find all the coarse-grained granites that do not come from Egypt.

Terms of three characters or less have not been indexed.