Fluorite ("Blue John") - Treak Cliff Caverns, Castleton, England

We often do not see true European classic minerals deep here in Western Canada but once in a while we get lucky. "Blue John" is a term given to the colourful, banded fluorspar found at Treak Cliff hill, that has been prized as a carving material in England for centuries. Mining at Treak Cliff Caverns began as early as 1745, with operations of many different scales, continuing to this day (although now mostly as a tourist attraction). Unlike the typical banded and massive fluorite commonly found at Treak Cliff, our specimen shows well-defined cubes of deep purple colour, though partially covered in a brown-orange crust. Some of the cubes show some cleavage or dings. I appreciate this is not the most pretty fluorite on the market but does represent a chance to acquire a true classic from one of the very first fluorite mines at an entry-level price. This reference specimen would most certainly help complete a specialty fluorite collection. Ex Tom Collins collection. From: Treak Cliff Caverns, Castleton, England. 

Mineral: Fluorite (“Blue John”)
Locality: Treak Cliff Caverns, Castleton, Derbyshire, England
Crystal System: Cubic (Isometric)
Mineral Class: Halides
Provenance: Ex Tom Collins Collection
Dimensions: 7 × 10 cm