Tugtupite

Tugtupite gets its unique name from the location of its discovery in southwest Greenland. This semi-transparent to opaque mineral species is usually pink to red and often mottled with white, gray or black. Nicknamed the "Reindeer Stone," tugtupite is tenebrescent; when stored in darkness, the gem's color will fade, but returns immediately upon exposure to daylight. Among collectors, tugtupite is also prized for its luminescent properties: strong fluorescence and less commonly, phosphorescence, when the gem continues to fluoresce even after the ultraviolet light source has been removed.