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Jeremejevite is a rare borate mineral, best known for its aesthetic blue and gemmy crystals. It is one of the more difficult minerals to pronounce; the correct pronunciation is "Yeremiyaivite." Jeremejevite was first described in Siberia in 1883, and is named after Russian mineralogist Pavel Vladimirovich Jeremejev (1830–1899). The last name is Germanized from the Russian "Eremeev".
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Chemical Formula |
Al6B5O15F3 |
Composition |
Aluminum fluoro-borate |
Variable Formula |
Al6B5O15(F,OH)3 |
Color |
Blue, light blue, purplish-blue, yellow, golden-brown. Sometimes color zoned, with a deeper blue zone and lighter blue color to nearly colorless zone. |
Streak |
White |
Hardness |
7 |
Crystal System |
Hexagonal |
Crystal Forms and Aggregates |
Crystals are in prismatic hexagonal shape, sometimes with terminations closely resembling Quartz. Crystals may be very tall and slender, though rarely larger than 5 cm. Deeply etched floater crystals are also known. Also in micro-crystal aggregates of prismatic crystals, radiating, and in micro ball-shaped aggregates. |
Transparency |
Transparent |
Specific Gravity |
3.2 - 3.3 |
Luster |
Vitreous |
Cleavage |
None |
Fracture |
Conchoidal |
Tenacity |
Brittle |
In Group |
Borates; Anhydrous Borates |
Striking Features |
Crystal habits, hardness, and mode of occurrence |
Environment |
Granite pegmatites and xenoliths in volcanic scoria. |
Rock Type |
Igneous |
Popularity (1-4)
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1 |
Prevalence (1-3)
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3 |
Demand (1-3) |
1 |
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Jeremejevite is a rare mineral, and good examples of this mineral are highly valued by collectors. It is occasionally cut as a rare and valuable collector's gemstone.
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The best known examples of Jeremejevite are from the Erongo Region, Namibia, where beautiful, gemmy blue prismatic crystals up to 5 cm have been found. The two most important localities in Erongo are the Ameib Farm 60, Usakos, Karibib District; and the beach at Mile 72, Swakopmund District.
A relatively new find of Jeremejevite, in large prismatic yellow and golden brown crystals, is the Pantahole Mine, Loi-sau mountain, Mogok, Myanmar (Burma). The type locality of Jeremjevite, which produced crystals resembling Aquamarine, is Mount Soktuj, Adun-Chilon Mountains, Nerchinsk, Russia. Micro crystal with interesting habits come from the volcanic areas of the Eifel Mountains, Rhineland-Palatinate, Germany, with clustered crystal groups from the Emmelberg Quarry, Üdersdorf; and radiating micro blue crystals and balls from the Wannenköpfe Quarry, Ochtendung.
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