A freaky-lustrous, glassy and gemmy, penetration twin of deep purple fluorite, measuring 1.7 cm on a side, sits atop sphalerite-covered matrix here. The isolation is unusual and highlights the quality and form of the twin, which is among the most gemmy and well-developed we have seen. It has exceptional shallow surface features which make it interesting (and in fact a closeup is shown in "Classic Minerals of Northern England," page 86). The twin also fluoresces a rich, deep purple in daylight or UV lights. From the Frazer's Hush Mine, Weardale; and collected by miner Cliff Wilkie. Joe Budd photo, closeup.