Derbyshire Blue John
C W Sellors showcase an exceptional collection of jewellery pieces made from Blue John. The beautiful and unique mineral variety of fluorite or fluorspar is found within the limestone at Treak Cliff Cavern near the North Derbyshire village of Castleton. Characterised by strong bands of white and bluish purple, Blue John is made up of many microscopic cubic crystals aggregated together to give it a distinctive serrated appearance, a feature which differs from flourite itself which is a softer material that cleaves easily. The use of Blue John flourished in the 19th Century where it was mined on a large scale for ornamental purposes. Today Treak Cliff cavern which is the only location in the UK where Blue John can be found, is mined by hand on a much smaller scale due to the mineral’s fragility. Once the Blue John Stone has been mined, it is left to dry out for a year where it is then treated with resin to aid its durability.
Blue John’s fascinating qualities require the delicate and highly skilled handiwork of professionally trained jewellery craftsmen to shape the friable mineral into beautiful, lustrous works of art. Each lump of raw Blue John Stone has its own compelling story to tell, discovered in veins measuring three inches thick or in nodular forms which line the inner walls of the cavities of the carboniferous limestone within the Derbyshire Caverns.