In 1956, John Marmon observed that fibrous aggregates of ulexite project an image of an object on the opposite surface of the mineral. This optical property is common for synthetic fibers, but not in minerals, giving ulexite the nickname "TV rock". According to Baur et al. (1957), this optical property is due to the reflections along twinned fibers, the most prominent twinning plane being on (010). The light is internally reflected over and over within each of the fibers that are surrounded by a medium of a lower refractive index (Garlick, 1991). This optical effect is also the result of the large spaces formed by the sodium octahedral chains in the mineral structure. Synthetic fibers used for fiber optics transmit images along a bundle of threadlike crystals the same way naturally occurring ulexite reproduces images due to the existence of different indices of refractions between fibers. Additionally, if the object is colored, all of the colors are reproduced by ulexite. Parallel surfaces of ulexite cut perpendicular to the fibers produce the best image, as distortion in the size of the projected image will occur if the surface is not parallel to the mineral. Curiously, in situ samples of ulexite are capable of producing a decent, rough image. Satin spar gypsum also exhibits this optical effect; however, the fibers are too coarse to transmit a decent image. The thickness of the fibers is proportional to the sharpness of the projected image.
In 1956 John Marmon observed that fibrous aggregates of ulexite project an image of an object on the opposite surface of the mineral This optical property is common for synthetic fibers but not in minerals giving ulexite the nickname "TV rock" According to Baur et al (1957) this optical property is due to the reflections along twinned fibers the most prominent twinning plane being on (010) The light is internally reflected over and over within each of the fibers that are surrounded by a medium of a lower refractive index (Garlick 1991) This optical effect is also the result of the large spaces formed by the sodium octahedral chains in the mineral structure Synthetic fibers used for fiber optics transmit images along a bundle of threadlike crystals the same way naturally occurring ulexite reproduces images due to the existence of different indices of refractions between fibers Additionally if the object is colored all of the colors are reproduced by ulexite Parallel surfaces of ulexite cut perpendicular to the fibers produce the best image as distortion in the size of the projected image will occur if the surface is not parallel to the mineral Curiously in situ samples of ulexite are capable of producing a decent rough image Satin spar gypsum also exhibits this optical effect; however the fibers are too coarse to transmit a decent image The thickness of the fibers is proportional to the sharpness of the projected image