Fluorite

Of the numerous Fluorite producing mines throughout the Weardale Valley in County Durham, Boltsburn is probably the most sought-after locality because of its stunning mauve coloured crystals which have become famed across the world.  The Boltsburn mine is situated to the north of the village of Rookhope and specimens from here are highly prized, especially in collections of British minerals.  This specimen is an off matrix interpenetrant twin, comprising of a 2.8 x 2.3 x 2.1 cm crystal intersecting a part, larger crystal whose longest edge is 4.3 cm.  The back of this larger crystal is broken off from where the specimen was detached from in-situ.  Both crystals have an outer almost colourless zone within which is a beautiful warm mauve interior, ranging from transparent through differing degrees of translucent colour-zones.  Under LWUV the crystals fluoresce strong purple, with an especially bright zone embedded within the peripheral edges of each cubic prism.  A stunning Boltsburn Fluorite, the colour of which is instantly recognisable as from this locality.