Greenland produces some of the most tenebrescent sodalite found anywhere. These pieces darken when exposed to SW UV in seconds, and fade just as rapidly upon exposure to a bright white light. This process can be repeated over and over. They are also perhaps the most fluorescent of the sodalites found around the world - a bright yel/orange under LW and SW, but under SW as the tenebrescence sets it, the color darkens to a rusty orange. Photos show SW and LW, as well as the tenebrescence. The animation shows this color change before/after UVC.
