Instead of being affected by temperature, however, these minerals magically transform when exposed to light.
The phenomenon, known astenebrescence, might be more familiar to people when they think of light-adaptive sunglasses.
Also known asreversible photochromism, this transformative ability was first discovered in Greenland in 1896.
These include spodumene, which darkens when exposed to high-energy radiation, and some light-colored varieties of tugtupite.
It is actually much more common than tenebrescence15% of minerals are able to fluoresce.
While some minerals fluoresce in their pure form, most show this ability when they contain impurities calledactivators.
Activators can include magnesium, lead, copper, and titanium.
No matter what the cause may be, fluorescence is one of the most thrilling parts of collecting minerals.
Once in hand, fluorescence can be manipulated to great effect.
