Gigantic crystal formations of Ulexite occur in the form of fibrous , compact vein s.... More
Gigantic crystal formations of Ulexite occur in the form of fibrous, compact veins. When polished, these specimens become the well-known "Television Stone" or "TV Stone" sold to amateur collectors. The optical effect exhibited by Television Stone is caused by each of its individual crystal 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 below is transmitted through each crystal fiber to the top surface. For this effect to be seen, specimens are polished with smooth surfaces.
Fibrous Ulexite bundles can also be carved into cabochons that display strong chatoyancy. However, due to its low hardness, it is unsuitable for gem use. Hide
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Uraninite is the most important radioactive mineral, and was once thought to be worth... More
Uraninite is the most important radioactive mineral, and was once thought to be worthless. When the discovery of its useful uranium content was unveiled, it became extremely significant. It is the most common and widespread uranium mineral, making it the best known uranium ore. Many collectors refrain from collecting uranium minerals such as Uraninite because of their hazards and fragility. Uranium minerals should be kept out of light, preferably in a tight container, and unnecessary handling should be avoided. Hands should be washed after contact with any uranium mineral, and these minerals should not be stored in a room where one eats or sleeps on a regular basis. Hide
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Uvarovite is a rare member of the Garnet group that is consistently deep green in col... More
Uvarovite is a rare member of the Garnet group that is consistently deep green in color. Its most widespread habit is as lustrous, tiny, emerald-green crystals densely coating a matrix. Uvarovite is the only true chromium Garnet; other forms of Garnet such as Andradite and Grossular may have a deep green color due to chromium impurities and can sometimes be mistakenly labeled as Uvarovite. Uvarovite was first discovered in 1832 by Germain Henri Hess, who named the new mineral after Count Sergei Semenovitch Uvarov (1765-1855), a Russian statesman and mineral collector. Hide
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Uvite is an uncommon form of Tourmaline , and it forms different crystal formations t... More
Uvite is an uncommon form of Tourmaline, and it forms different
crystal formations than the most of the other Tourmalines. Though it
lacks the color diversity as some of the other Tourmaline forms, it does
occur in beautiful green and reddish-brown crystals, as well as
lustrous submetallic crystals. The name Uvite is derived from the
type locality of the Uva Province, in Sri Lanka, where it was first
identified.
Uvite is very similar to Dravite Tourmaline, and they sometimes for together in a single crystal. It can sometimes be very
difficult to make an exact distinction between Dravite, Uvite, and the newly designated Fluor-uvite. Hide
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