Hackmanite is also known as the "chameleon" stone, due to a unique phenomenon known as tenebrescence.  
Tenebrescence is the property of certain minerals to temporarily change colour when exposed to ultraviolet (UV) light and then gradually return to their original colour when placed in darkness or exposed to visible light. This pinkish stone is part of the sodalite family. It is commonly found Canada, Greenland, Russia and Brazil.