Is that triboluminescence in your pocket, or are you just happy to see us?
Forseriously though... Just rub our Flash Rocks together to see a totally natural piezoelectric rock show! They'll glow internally and emit a distinctive odor!
If you're lucky... someday soon you will be holding electric potential in your hands, so you can see for yourself. Flash rocks - aka quartz - are one of the few minerals with piezoelectric proprieties. So, when subjected to mechanical stress, these two little rocks generate an electrical charge.
Just place a rock in each hand, and forcefully rub the rocks together. To see the glowing electrical effect fully, you should do this in a darkened room. Also, note the distinctive odor given off by the frictions.
Made in the USA. Stone size varies. Card measures 3.5 inches wide x 6 inches long.