Hackmanite is a variety of Sodalite that is a deeply coloured pinky purple when it is first mined, but upon exposure to sunlight fades to a much paler shade of white. When placed in a dark space, they revert back to their original colour. This effect is known as tenebrescence, and can be repeated many times, unless the crystal is heated. Some Hackmanite from Afghanistan and Burma actually do the reverse - they start off white, and upon exposure to sunlight they turn a shade of purple red. Hackmanite will also fluoresce orange under UV light.