Ulexite is a rare, lesser-known mineral that’s commonly colorless to white and popular among collectors. Another name for ulexite is “television stone” or “TV rock” — though it’s a mineral, not a rock — for its ability to reflect images underneath it onto its surface.
Is ulexite a gemstone? It can be used as a gemstone, particularly specimens that display chatoyancy (the “cat’s eye” effect). However, it’s too fragile for jewelry use.
In this guide, we’ll go over all of ulexite’s properties, history, benefits, and prices. Let’s crack in!
Ulexite is a semi-precious gemstone with many monikers. Besides “television stone,” some of ulexite’s nicknames include:
Hayesine / Hayesite
Natronborocalcite / Natroborocalcite
Composition: Selenite is a variety of the sulfate mineral gypsum, and ulexite is a borate mineral.
Hardness: Selenite has a Mohs hardness of 2, while ulexite has a hardness of 1 to 2.5.
Rarity: Selenite is a pretty common mineral, while ulexite is rare.
Density: Selenite has a higher density of 2.3-2.9 compared to ulexite’s density of 1.65-1.95.
One type of selenite called satin spar can actually display a “TV stone” effect similar to ulexite, but its fibers are so coarse that the image transmitted isn’t very sharp.
Industrially, what is the mineral ulexite used for?
Most of ulexite’s uses come from its boron content. Boron is quite rare but important to many industries. Some uses for boron or boron compounds extracted from ulexite include:
Heat-resistant borosilicate glass (e.g. Pyrex, headlights)
Soaps & detergents
Metal alloy production
Metal hardener in military vehicles
Pesticide / insecticide
Another benefit of ulexite is that it forms calcium carbonate (calcite) as a by-product after dissolving in a carbonate solution. This calcium carbonate by-product can be used in many ways, from coating printing paper to relieving heartburn as an antacid.
Image credit: Rock Currier | Creative Commons Attribution 3.0 Unported license
As a hydrated sodium and calcium borate, ulexite’s formula is NaCaB5O9 – 5H2O or NaCa[B5O6(OH)6] · 5H2O or NaCaB5O6(OH)6.5H2O. Ulexite’s “TV stone” quality is technically a fiber optic effect.
The reason for this fiber optic effect is because ulexite’s display something called total internal reflection. That means light travels along the length of each fiber. Slow rays are internally reflected and fast rays are refracted, polarizing the light.
As far as magnetism, ulexite is not magnetic. Ulexite is also not piezoelectric, unlike the borate mineral boracite.
Ulexite is usually found as masses that may be lens-like, nodular, or rounded. Small rounded ulexite masses that are loose are often called “cotton balls.” Some ulexite specimens even resemble clam shells, fittingly nicknamed “clam shell” ulexite.
Ulexite crystals are rarer but can form stunning arrays of needle-like fibers radiating from a central point or pointing in random directions. Distinct crystals are often elongated but even rarer.
Here are ulexite’s properties listed:
Mohs hardness: 1-2.5
Color: Colorless, white, gray
Crystal structure: Triclinic
Luster: Vitreous (glassy) or silky; May be vitreous on cleavage piece ends and silky on sides
Transparency: Transparent to translucent
Refractive index: 1.496-1.519
Cleavage: Perfect, 1-direction; Good, 1-direction; Poor, 1-direction
Luminescence: Fluorescence & phosphorescence sometimes present; Yellow, greenish-yellow, blue-green, cream, or white in SW-UV
Optical effects: Possible chatoyancy
Image credit: Anders Sandberg, Flickr
Unsurprisingly, ulexite’s spiritual meaning ties into its physical properties. Ulexite is a stone of visualization and imagery, whether that means inspiring imaginative ideas or inducing psychic visions of other dimensions.
It’s also said to help you interpret your dreams and understand your spiritual path.
The first person to make an accurate chemical analysis of ulexite is the stone’s namesake: 19th-century German chemist and politician Georg Ludwig (G.L.) Ulex. Ulex published his analysis in 1849, calling the mineral “boronatro-calcite.”
Mineralogists only became widely aware of ulexite in 1840. The original specimens of ulexite were found in the Iquique Province of Tarapacá, Chile.
Before Ulex’s analysis, other mineralogists like Augustus Allen (A.A.) Hayes and Johann Freidrich Ludwig (J.F.L.) Hausmann had also analyzed the mineral, calling it “hydrous borate of lime” or “hydroborocalcite,” respectively.
British-Canadian chemist and geologist Henry How discovered borate minerals in Canadian evaporate deposits in 1857, one of which was ulexite but How called it “natro-boro-calcite.”
The name “ulexite” didn’t catch on until around 1918.
The “TV stone” nickname didn’t come until 1956, when Australian sailor John Marmon noticed the optical property in fibrous ulexite aggregates. This characteristic is typically seen in synthetic fibers, not minerals.
The mechanisms behind this characteristic were first explained in 1963 by E.J. Weichel-Moore and R.J. Potter.
The crystallography of ulexite was first explored by American mineralogist Joseph Murdoch in 1940, re-examined by American geologists Joan R. Clark and Louis Christ in 1959, and finally described correctly in 1964 by Clark and Daniel E. Appleman.
In 1991, American geologist George Donald Garlick first noticed another interesting characteristic: ulexite’s ability to display concentric circles of light when held up to a bright light or shining a laser pointer at an oblique angle through the stone.
You can use ulexite as a healing stone. Its white color means it has the purifying and clarifying properties of white gemstones. It’s also a powerful third eye and crown chakra stone, the energy centers of spiritual awareness and ascension.
Physically, ulexite is said to treat or help with:
Nervous system function
Ulexite gemstone benefits emotionally are said to include boosting creativity, helping you think for yourself, and assisting in problem-solving. For students or those in highly intellectual jobs, ulexite is believed to help you process complex ideas and remember them.
Spiritually, ulexite is a stone for assisting in visualization and revelation. Crystal healers recommend it for clarifying and manifesting your desires.
Though ulexite gemstones are rare, they’re still graded on standard properties like color, cut, clarity, and carat weight.
Ulexite is only found in white, colorless, or gray hues. The best ulexite color is fully colorless and transparent or pearly white. Most ulexite stones are milky.
Ulexite is almost never faceted, given its softness, perfect cleavage, and rarity. Fibrous specimens that display chatoyancy, the “cat’s eye” effect, must be cut as cabochons. Many ulexite specimens are sold uncut.
Clarity describes the visible inclusions in a gemstone. Fewer inclusions mean higher value in ulexite, as they can affect the transparency and thus, the “TV stone” effect.
Larger ulexite stones of good quality can cost more, but you can find ulexite nodules weighing multiple pounds.
Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0
Borate minerals like ulexite are rare (since boron is rare) and usually only form in arid conditions (very dry with little rain), often areas where volcanism is common.
These minerals form when pyroclastic rocks leach solutions containing boron. The solutions run into basins and evaporation occurs, causing borate deposition in stratified layers.
Ulexite is usually found in evaporite deposits like salt playas and dry saline lakes. Playas are dry, flat areas at the bottom of undrained desert basins where water may briefly fill the area.
The mineral is usually found with borax, colemanite, and other borate minerals.
The primary source of ulexite is Boron, California. Other significance sources are:
Image credit: Cran Cowan, Flickr
Ulexite can be affordable, but its price varies by the form, size, and seller.
You can find small, clear ulexite crystals or slabs for under $10.
Large crystal specimens with attractive or rare habits (like radiating needle-like crystals) can cost upwards of $200.
Cat’s eye ulexite cabochons are usually $120 to $200 each or $25-$105 per carat.
Before we discuss gemstone care, is ulexite poisonous? Ulexite is considered non-hazardous with low acute oral and dermal toxicity. It’s not flammable, explosive, or combustible.
If you’re curious, ulexite doesn’t have a taste, unlike the alkaline flavor of similar borate minerals.
You’ll want to keep ulexite away from water and household chemicals. It will decompose slightly in cold water but quicker in hot water.
Don’t use ultrasonic cleaners on ulexite. Store it in dry conditions separately from other gems.
Image credit: Brandon Cripps, Flickr
Ulexite may not be a well-known gem, but its popularity has been increasing as of late. Collectors love its unique optical properties and gorgeous natural shapes, while crystal healers love its purported ability to help you understand and harness your true power.
Either way, ulexite doesn’t fail to impress!
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