Rogerley Fluorite is a world-renowned and highly coveted mineral specimen sourced from the Rogerley Mine, located in the Rogerley Quarry near Stanhope, Weardale, County Durham, England . This mine holds the distinction of being the only mine in the United Kingdom operated commercially specifically for recovering mineral specimens . First discovered in the early 1970s by collectors Lindsay Greenbank and Mike Sutcliffe in an abandoned 19th-century limestone quarry, the mine has changed hands over the decades but continues to produce exceptional fluorite specimens prized by collectors worldwide . The fluorite from this locality is celebrated for its sharp, lustrous, often interpenetrant twinned cubic crystals that display a rich emerald-green to deep bluish-green color indoors . However, its most famous and distinctive characteristic is its remarkable daylight fluorescence, appearing to change to a purplish hue when exposed to sunlight and glowing a bright bluish-white or purple under long-wave ultraviolet light . This extraordinary optical effect is attributed to elevated levels of rare-earth elements (REEs) such as cerium, lanthanum, and yttrium within the crystal structure . Mined from specific pocket zones like the Bluebirds Pocket and the Jewel Box Pocket, these fluorites are found associated with other minerals like galena and quartz on a limestone matrix, making each specimen a unique piece of geological history from this historic English mining district .