Ulexite – Natural, Specimen, White

Ulexite has an unusual form of transparency. Due to its birefringence, you can see what's behind it. In addition, it projects that image onto the surface closest to you. Since this looks like the image on a screen, the stone has earned the nickname, "TV Rock." "Ulexite on flickr," photo by Dave Merrill. Licensed under CC By-SA 2.0.

Article: What is Gemstone Transparency?

Credit: Dave Merrill