Quartz with hyalite opal, Chihuahua, Mexico. A geode with fluorescing hyalite opal also has a few tiny quartz crystals. This one is about 3 mm high and is intergrown with hyalite-opal to the point where the crystal becomes deformed, bent and hardly recognizable. Quartz doesn't like to absorb uranyl ions in its structure. Hyalite, however, does so eagerly. Hence the green fluorescence in SW-UV. I call this one "the joystick", but I've heard other comments... If you havent seen the movie "Skin Deep" (Peter Sellers) you may have no idea what I'm talking about. Go here to get the idea.
Source: Fluorescent Minerals Workgroup MKA