TV Stone Satin Spar Selenite Mineral Crystal Rock

TV Stone Satin Spar Selenite Mineral Crystal Rock Place a piece of television stone on an image. Unbelievably, the image will be transmitted up through the stone and appear on the surface, much like a television screen. Satin spar selenite is a type of gypsum, CaSO42H20, composed of parallel fibrous crystals that have the ability to transmit light. This phenomenon of light traveling through fibers is the same one used in fiber optics. When lake basin water containing calcium and sulfur evaporates, these minerals are deposited on the basin floor, sometimes in the form of satin spar selenite. Molar Mass- 172.17 Crystal Habit- Earthy - Dull, clay-like texture with no visible crystalline affinities Hardness: 2 Specific Gravity: 2.3 Optical Properties: Bi-axial 2V=58 Optical properties Bi-axial (-) 2V=58 Refractive index n=1.519-1.521, n=1.522-1.523, n=1.529-1.53 Quantity is one rock a little over 1 inch in length weighing about .8 ounces. Comes with info card about the rock. Ages 8 and up. Please note that this rock is a natural specimen and will have imperfections and fissures.