Description
A fine and colourful specimen as a cutted and polished slab with deep lilac Fluorite and a distinct amber coloured, slightly crystallized rim from the well known Blue John Mine of Derbyshire in England. These were natural caverns worked for ornamental Fluorite, "Blue John" from the 1770s. Production was limited to about 3 tons per year of the "Blue John Fluorite" (yellow Fluorite and Baryte were left in the mine). The material was treated with resin to stabilize carving material. (mindat)