Ulexite
California, USA
8.89 carats
© Rarestone.com
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.
Ulexite Gemstones by Colour
This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
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Ulexite Gemstones by Size
This table shows distribution of Ulexite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:4.71 cts
Heaviest:8.89 cts
Average:6.73 cts
Total photos:3
Do you have a larger Ulexite? Why not upload a photo?
| General Information | |||||||||||||||||||||
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| Chemical Formula |
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| Photos of natural/un-cut material from mindat.org | |||||||||||||||||||||
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| Physical Properties of Ulexite | |||||||||||||||||||||
| Mohs Hardness | 2 to 2.5, Gemstones of the world (2001) More from other references | ||||||||||||||||||||
| Specific Gravity | 1.65 to 1.99, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Tenacity | Brittle, Handbook of mineralogy (2001) | ||||||||||||||||||||
| Cleavage Quality | Perfect, Gemstones of the world (2001) More from other references | ||||||||||||||||||||
| Fracture | Uneven, Handbook of mineralogy (2001) Uneven across fiber groups | ||||||||||||||||||||
| Optical Properties of Ulexite | |||||||||||||||||||||
| Refractive Index | 1.491 to 1.520, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Optical Character | Biaxial/+, Gems, Sixth Edition (2006) | ||||||||||||||||||||
| Birefringence | 0.029, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Pleochroism | Absent, Gemstones of the world (2001) | ||||||||||||||||||||
| Dispersion | None, Gemstones of the world (2001) | ||||||||||||||||||||
| Chatoyancy | Yes, Gemmological Tables (2004) | ||||||||||||||||||||
| Colour | |||||||||||||||||||||
| Colour (General) | White, Gemmological Tables (2004) More from other references | ||||||||||||||||||||
| Transparency | Transparent,Translucent, Gemstones of the world (2001) More from other references | ||||||||||||||||||||
| Lustre | Silky, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Fluorescence & other light emissions | |||||||||||||||||||||
| Fluorescence (General) | May fluoresce yellow, greenish yellow, cream, white under SW and LW, Handbook of mineralogy (2001) | ||||||||||||||||||||
| Fluorescence (Short Wave UV) | Blue, green, Blue Chart Gem Identification (2010) | ||||||||||||||||||||
| Crystallography of Ulexite | |||||||||||||||||||||
| Crystal System | Monoclinic, Gemstones of the world (2001) More from other references | ||||||||||||||||||||
| Habit | Fibrous crystals, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Geological Environment | |||||||||||||||||||||
| Where found: | Ulexite occurs in dry lakes and playa deposits, with other borates., Gems, Sixth Edition (2006) More from other references | ||||||||||||||||||||
| Further Information | |||||||||||||||||||||
| Mineral information: | Ulexite information at mindat.org | ||||||||||||||||||||
| Significant Gem Localities | |||||||||||||||||||||
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