Fluorite (fluorescent)
Boltsburn Mine, Weardale Co., Durham, England, UK
Small Cabinet, 9.3 x 8.3 x 7.3 cm

The very word "fluorescence" was coined from the effect miners saw in fluorites from this district when they were brought up from the mines into sunlight, and they glowed purple. Crystals of this size and aspect are old, probably from prior to 1850, and turn up only in the oldest European and classics collections. They are desirable for their large size and gemminess, obviously, with the fluorescence being a bonus. This is a very fine, large, twinned, lustrous and gemmy crystal showing interpenetration growth. There is also a 6 mm thick band of light purple color banding at the termination, characteristic of this old mine. For such a large specimen the display faces are almost pristine, though there is very small wear, and some damage in the bottom where it sits anyhow. The fluorescence is stunning!