George III urns of Derbyshire Blue John
Category
King JamesA collection of George III urns of Derbyshire Blue John.
Also known as Derbyshire Spar, Blue John is a semi-precious mineral,a rare form of Calcium Fluorite, with distinctive, purple, blue and golden banding which runs through the stone. In the UK it is only found at two caverns at Castleton in Derbyshire. In the 19th Century, it was mined for its ornamental value and some small-scale mining continues today.
