Ulexite: The "TV Rock" That Can Project Images

Ulexite, also known as TV rock or television stone, is a mineral that has the unique property of being able to reflect light in such a way that it appears to be projected onto a screen. This is due to the fact that ulexite is composed of tiny fibers that are aligned in parallel. When light hits these fibers, it is refracted and reflected in all directions, creating the illusion of a projected image.

Ulexite is found in evaporite deposits, which are formed when water evaporates and leaves behind minerals. The most common evaporite deposits are found in desert environments, but ulexite can also be found in other types of deposits, such as hot springs and fumaroles.

The largest known ulexite deposit is located in Death Valley, California. This deposit is estimated to be over 100 million tons in size. Ulexite is also found in other parts of the world, including Chile, Argentina, Bolivia, Turkey, and Russia.

In addition to its unique optical properties, ulexite is also a valuable source of boron. Boron is a chemical element that is used in a wide variety of industrial applications, including glassmaking, ceramics, and fertilizers.

natural Ulexite specimens
Natural Ulexite
Photos: AmazingCrystals on Etsy

What is the reason why Ulexite is called "TV rock"?

Ulexite is called TV rock because it has the ability to transmit light through its fibers by internal reflection. This means that if you place an object on one side of a piece of ulexite, you can see a reversed image of the object on the other side. This property is similar to the way that light is transmitted through optical fibers, which are used in telecommunications and other applications.

The name "TV rock" came about because the first ulexite specimens that were brought to the United States in the early 1900s were thought to be synthetic fibers that were used in early television sets. However, it was later determined that these specimens were actually natural ulexite. 

Ulexite Uses & Applications:

Ulexite is used in a variety of applications, including:

  • Glassmaking: Ulexite is used as a flux in glassmaking. This means that it helps to melt the other ingredients in glass and prevents them from crystallizing.
  • Ceramics: Ulexite is used in ceramics to make them stronger and more heat-resistant.
  • Boron compounds: Ulexite is used to make boron compounds, which are used in a variety of industries, including agriculture, medicine, and manufacturing.
  • Novelty items: Ulexite is also used to make novelty items, such as figurines, jewelry, and paperweights.

Properties of Ulexite:

  •  Chemical Formula: NaCaB5O6(OH)6·5H2O
  • Color is white or gray to colorless.
  • Named after George Ludwig Ulex (8 October 1811, Neuhaus, Germany - 25 March 1883 Altona, German Empire), German chemist and politician, who first correctly analyzed the species.
  • Luster is silky.
  • Transparency crystals are transparent to translucent.
  • Crystal System is triclinic; bar 1
  • Crystal Habits include tufts of acicular crystals called "cotton balls". Also as vein-like masses of parallel fibrous crystals.
  • Cleavage is perfect in one direction.
  • Fracture is fibrous.
  • Hardness is 2.5 (softer than a fingernail)
  • Specific Gravity is approximately 1.97 (very low density)
  • Streak is white.
  • Associated Minerals are borax, colemanite, hydroboracite and other borate minerals.
  • Other Characteristics: similar borate minerals have an alkaline taste, while ulexite is tasteless.
  • Notable Occurrences include several localities in California and Nevada, USA; Tarapaca, Chile and Kazakhstan.
  • Best Field Indicators are crystal habit, associations, locality, density, unique optical property, and hardness.

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