Fluorite: Frazer’s Hush Mine, Rookhope, Stanhope, County Durham, England, UK

Description

Species: Fluorite

Locality: Frazer’s Hush Mine, Rookhope, Stanhope, County Durham, England, UK

Size: 21 x 19 x 5 cm.

Ex. Charlie Ruggles Collection

This superb large plate of lustrous, gemmy, penetration twinned fluorite crystals to nearly 4 cm was likely collected in 1990 by miner Cliff Wilkie from a special pocket which produced the best-ever Frazer’s Hush mine fluorite specimens including the famous ex. Lindsay Greenbank collection piece. Specimens from this pocket exhibit large, glassy, lustrous crystals which have a remarkable “daylight fluorescence”, probably the brightest and most intense of any fluorite from any worldwide locality- see the color change from indoor light to sunlight in these photos (note the images have been taken under a diffuse U.V source to simulate the intense color they exhibit in sunlight). The dramatic color change in most British fluorites from the North Pennines is due to trivalent rare earth elements (such as Europium and Ytterbium) substituting for Ca2+ in the fluorite crystal structure… these REE’s are well known phosphors and cause a dramatic fluorescent effect due to the U.V. component of sunlight. The source of these elements are likely A-type granites which underlie the limestone in the North Pennines and were responsible for bringing abundant fluorine into these MVT type mineral deposits. This is a gorgeous large Frazer’s Hush mine fluorite plate is in outstanding condition, very 3-dimensional, and covered in large glassy penetration twinned crystals to 3 cm on edge. Classic! Charlie purchased this specimen from dealer Mike Bergmann in the early 1990s in Denver. Mark Cross photos.