Ulexite
Ulexite
(From USA. 1.91 carat; 8.9 x 8.0 x 4.9mm)
Image © supplied by Freakingcat Gems
The gemstones of Ulexite are extremely rare characterized by their fascinating ability to transmit an image from the bottom of the gemstone to the top of the gemstone.
Ulexite History & Etymology:
Ulexite was discovered in 1850 and since then are considered to be grandfathered crystals by the IMA. Ulexite were discovered by the German chemist, George Ludwig Ulex. Ulexite are hence named in honor of their discoverer.
Ulexite Occurrence:
Ulexite are extremely rare and hence are found in very few localities. Ulexite are found in the Bigadic mine and the Marmara region in Turkey. Ulexite are also found in Boron Pit in the Kramer district in the Kern County in California, USA. Ulexite are also found in the White Basin located in Clark County in the state of Nevada in USA.
Ulexite yielded from the Marmara region in Turkey are the best gemstone quality crystals of Ulexite. Ulexite found in the Marmara region in Turkey are also the largest.
Ulexite Properties:
Ulexite is composed of varying percentages of sodium, calcium and boron. The dominant presence of boron in the composition of the Ulexite crystals classifies the Ulexite mineral as a borate mineral. Ulexite display triclinic and pinachoidal properties and Ulexite occur as elongated as well as articulated crystals in their natural form.
Ulexite also occur as fibrous balls which are at least 5 cm in size as well occur in nodular groups. Twinning is commonly observed on Ulexite and is usually polysynthetic in nature. The cleavages on Ulexite are perfect and distinct. Ulexite also display irregular fracturing. Some of the Ulexite crystals also display uneven fracturing across the fibrous groups. The perfect cleavages along with the fracturing make the Ulexite crystals quite brittle.
Ulexite is also not very hard, with a Moh’s hardness of 2.5. It also not very dense with an approximate density of 1.9 g/cm3. Ulexite does not display properties of luminescence nor is itradioactive. Ulexite is available in only two forms either in white color or as colorless crystals. Ulexite crystals are usually transparent in nature but due to inclusions the gemstones of Ulexite can also appear to be translucent and sometimes they even appear opaque.
Ulexite have a vitreous shine which turns into a silky and sometimes satiny shine on the edges as well as on the fibrous aggregates. The refractive index of the Ulexite varies between 1.4 and 1.5. Similarly the birefringence of Ulexite is at 0.028. Ulexite also do not show dispersion or pleochroism.
Ulexite is typically found in the salty marsh deposits in the extremely dry regions of sedimentary rocks. Such localities almost contain one billion tons of the Ulexite mineral. The gemstones of Ulexite are most sought after by the gemstone collectors and experts.
Ulexite is very rarely made into a gemstone.
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