Ulexite - The "Official" Television Stone
These amazing mineral specimens of hydrated sodium calcium borate are composed of thousands of fibrous fragments which transmit light. When the polished bottom surface is placed upon a printed page, the words can be read on the top surface, giving the appearance of a television screen. Ulexite is a naturally occurring fiber-optic material -- a fantastic addition for your science table! Each specimen is about 1/2-inch thick with a surface area of approximately 2 inches. All naturally occurring Ulexite contains some impurities.
Selenite – “ The Other Television Stone”
Selenite is a form of clear crystalline gypsum, Hydrated Calcium Sulfate. It exhibits some of the same fibrous optical properties as Ulexite, but these properties are far more directional. Selenite also tends to be found in a purer state without all of the trapped foreign matter common to Ulexite. These specimens are about 2-3 cm thick with a mass of ca 60 g.
Click here for the Differences Between Ulexite and Selenite.