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Chemical Formula | NaCaB5O9 · 8H2O | ||||||||
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Composition | Hydrous sodium calcium borate | ||||||||
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Color | White to light gray | ||||||||
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Streak | White | ||||||||
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Hardness | 2½ | ||||||||
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Crystal Forms and Aggregates |
(Triclinic) Rarely occurs in noticeable crystals; usually occurs in groups of tiny crystals in rounded or lenticular aggregates. It is most commonly seen as compact, parallel, fibrous veins. Occasionally occurs encrusting and as radial compactions of thin crystals. | ||||||||
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Transparency | Transparent to translucent | ||||||||
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Specific Gravity | 1.6 - 1.9 | ||||||||
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Luster | Silky | ||||||||
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Cleavage | 1,1 - prismatic ; 2,1 - basal | ||||||||
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Fracture | Uneven to splintery | ||||||||
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Tenacity | Brittle | ||||||||
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Varieties |  Television Stone - Variety
from Boron, California occurring in thin, parallel,
sheet-like fibers.
When polished at the top and bottom, each tiny fiber
transmits light through the specimen, causing anything
under the specimen to appear as if it is at the top. |
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In Group | Borates ; Hydrous borates | ||||||||
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All About | The locality of Boron, California, produces
a most unusual form of Ulexite. Gigantic hunks of this
mineral are found in great amounts in the form of fibrous, compact veins.
When polished, these specimens become the famous "Television
Stone" sold to amateur collectors. The optical
effect exhibited by Television Stone is caused by each of
its individual fibers
acting as fiber-optic cables, transmitting light from one
surface to the other. Since all the fibers are parallel
and compacted together, any image at one surface is
transmitted through each fiber to the other surface.
Thus, any text or image at the bottom of a specimen
appears as if it is on top. For this effect to be seen,
the specimen must be polished, since its surfaces must be
smooth. Fibrous Ulexite bundles can be carved into cabochons that display a very strong chatoyancy. However, due to its low hardness, it is unsuitable for gem use. |
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Uses | Ulexite is an ore of boron and is studied in regard to its unique optical properties. "Television Stone" is polished and sold to amateur collectors by the thousands. | ||||||||
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Striking Features | Silky luster, low weight and hardness. | ||||||||
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Complex Tests | Slightly soluble in hot water (this effect is so weak it is almost unnoticeable) | ||||||||
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Popularity (1-4) | 2 | ||||||||
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Prevalence (1-3) | 1 | ||||||||
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Demand (1-3) | 1 | ||||||||
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Distinguishing Similar Minerals |
The crystal habits and mode of occurrence distinguish Ulexite from practically all other minerals. Fibrous Ulexite may resemble asbestos minerals, but it only occurs in specific localities where asbestos minerals don't exist. It may also resemble Kernite, but Kernite's noticeable taste can immediately differentiate between the two. | ||||||||
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Commonly Occurs With |
Halite, Colemanite, Kernite, Borax, Calcite, Gypsum, Glauberite | ||||||||
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Noteworthy Localities |
The most splendid locality is undisputedly Boron, Kern Co., California, where enormous veins of compact fibers are found by the ton. Other forms of Ulexite are also found there, but are rarer. Rounded, cotton-like masses occur in Death Valley, Inyo Co., California. Other Ulexite deposits exist throughout the Mojave Desert in California and parts of Nevada. Ulexite is also said to come from Hants Co., Nova Scotia, Canada. It also exists in the Atacama Desert of Chile and in Salinas Grandes, Argentina. | ||||||||
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Picture Icon Links |
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Picture Links | 1. Massive
hunk 2. Fibrous vein 3. Vein in rock |
