Information (only German!) with stone to show the effect
Ulexite - the "Television Rock"
The crystalline structure of the ulexit leads to a special phenomenon. If the stone is cut transversely to the fibers and then polished and put over a text or a picture, both are projected to the surface. This is made possible by the light-conducting transparency of the mineral. This phenomenon gave the name "television stone" or "TV Rock" to the stone.
Origin: California, USA
The stones are approximately 2 - 3 cm in size and come packaged with an information card (german language only).