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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

ULEXITE


ULEXITE (Ulexit—Ulexite—”лексит) (Ulex, G.L., 1849 in Dana, J.D. 1850), after George Ludwig Ulex (1811-1883), a Germ. chemist who maked the first correct analysis of the mineral.

Composition & Properties. Borate – CaNa-[B5O6(OH)6]•5H2O, triclinic system. Hardness 1-2.5. Density 1.6-2.0. Silk luster to pearl one. Perfect cleavage in one direction. Fragile. Ulexite is found in fine-needle crystals, but usually in fibrous aggregates, which form nodules of twisted-fibrous texture or solid parallel-fibrous veins. Color: white or colorless. Along the fibers ulexite is transparent to translucent. Because of its fibrous texture, it displays the effect of cat’s-eye in cabochon. As a typical optical wave guide, it is able to transfer images through its fibers, that are why it is called television stone.

Deposits. Deposits of ulexite are of chemical mineral formations of the low-water basins of arid regions. In Russia, there are no ulexite deposits. In the Ukraine, its Bulganak deposit is situated in Crimea, near Kerch. In Kazakhstan, ulexite in Inder Ozero borate deposit is extracted. In Turkey, ulexite occur in fibrous aggregates up to 10 cm. thick at Emet, Kütahya vilayet. In China, its deposit is known on the Tibet Plateau. In the U.S.A., the most important deposits of ulexite are in the desert of Mohawe, in the south of California. In the same state, at the Boron deposit, Kern Co., occur aggregates of ulexite up to 30 cm. It is found with admixture of colemanite and inclusions of fine-dispersed realgar. Owing to it ulexite displays the texture of timber and looks like golden-yellow ulexite tiger’s-eye. In the western part of Nevada, there is a series of ulexite deposits, and also in Texas. In Canada, in the Nova Scotia Prov., ulexite was discovered at Wentworth gypsum deposit; and at Hillsborough, Albert Co., New Brunswick. In Chile, the Iquique deposit of ulexite is situated in the Tarapacá Prov. In the Argentina it was extracted at salt mines at the Tincalayu deposit and others in the Salta Prov.; and in Peru – at the Salinas deposit, in the region of Arequipa, where it is known under the local name of tiza.

Synonyms. Borocalcite | Boronatrocalcite | Ulexite cat’s-eye | Hydroborocalcit | Natroborocalcite | Raphite, obs. | Stiberite, from Gk. “stibe” – frost, after its color | Tincalcit.

As an ornamental stone, it is cut out in balls and cabochons, it is valued especially for the effect of cat’s-eye.

Synthesis. Nowadays, natural ulexite is completely replaced in jewelry with its more solid and durable imitation from borosilicate glass, which is produced in a variety of colors in many countries for bijouterie manufacturing.

Among synthetic borate used in jewelry, we should mention also synthetic yttrium-aluminum borate and rare-earth gallium borate. They display high level of refraction and hardness up to 8. Because of different admixtures they can be colored in various tones.

Similarity. Ulexite looks like hydroboracite and colemanite.

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