Ulexite
Ulexite is named after G.L. Ulex, German chemist who performed the first correct analysis of the mineral.
Ulexite is called the "TV rock" or "television stone" for its its unusual optical characteristics. Each thin fibrous crystal acts as an optical fibre, transmitting light along its length by internal reflection. A piece of writing placed underneath the stone appears on the surface.
Ulexite decomposes in hot water.
| General Information |
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| Chemical Formula | Michael O’Donoghue, Gems, Sixth Edition (2006) |
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| Physical Properties of Ulexite |
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| Mohs Hardness | 2 to 2.5Walter Schumann, Gemstones of the world (2001) More from other references |
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| Specific Gravity | 1.65 to 1.99Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Tenacity | BrittleAnthony et al, Handbook of mineralogy (2001) |
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| Cleavage Quality | PerfectWalter Schumann, Gemstones of the world (2001) More from other references |
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| Fracture | UnevenAnthony et al, Handbook of mineralogy (2001) |
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| Optical Properties of Ulexite |
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| Refractive Index | 1.491 to 1.520Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Optical Character | Biaxial/+Michael O’Donoghue, Gems, Sixth Edition (2006) |
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| Birefringence | 0.029Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Pleochroism | AbsentWalter Schumann, Gemstones of the world (2001) |
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| Dispersion | NoneWalter Schumann, Gemstones of the world (2001) |
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| Chatoyancy | YesUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) |
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| Colour |
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| Colour (General) | WhiteUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Transparency | Transparent,TranslucentWalter Schumann, Gemstones of the world (2001) More from other references |
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| Lustre | SilkyHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Fluorescence & other light emissions |
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| Fluorescence (General) | May fluoresce yellow, greenish yellow, cream, white under SW and LWAnthony et al, Handbook of mineralogy (2001) |
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| Fluorescence (Short Wave UV) | Blue, greenHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) |
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| Crystallography of Ulexite |
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| Crystal System | MonoclinicWalter Schumann, Gemstones of the world (2001) More from other references |
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| Habit | Fibrous crystalsHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references |
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| Geological Environment |
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| Where found: | Ulexite occurs in dry lakes and playa deposits, with other borates.Michael O’Donoghue, Gems, Sixth Edition (2006) More from other references |
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| Further Information |
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| Mineral information: | Ulexite information at mindat.org |
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| Significant Gem Localities |
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| USA | | |
| Gemstones of the world, W.Schumann, 2001, p 202 |
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