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Date: 14-12-2018
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Date: 15-10-2018
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Date: 14-12-2018
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Beryllium is in approximately 100 of the 4000 known minerals, such as bertrandite, beryl, chrysoberyl, and phenakite. Beryllium is also present in precious gems such as aquamarine, bixbite, and emerald. Of the many beryllium minerals, only two are of commercial importance in the preparation of beryllium metal and its compounds. Bertrandite (Be4Si2O7(OH)2) contains less than 1% Be and is the main beryllium mineral mined in the U.S., while beryl (Be3Al2(SiO3)6 is mined in other countries and contains approximately 4% Be. In the U.S., beryllium is mainly mined at Gold Hill and Spor Mountain in Utah, and in Alaska on the Seward Peninsula.
Beryllium metal began commercial production in 1957, but did not live up to its expectation of expanding the industry. Beryllium is made by reducing beryllium fluoride with magnesium metal in the following equation:
Emerald is less common than diamond and more expensive than gold. Columbia produces the most emerald in the world, where the Muzo mine and eastern emerald belt are located.
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تفوقت في الاختبار على الجميع.. فاكهة "خارقة" في عالم التغذية
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أمين عام أوبك: النفط الخام والغاز الطبيعي "هبة من الله"
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قسم شؤون المعارف ينظم دورة عن آليات عمل الفهارس الفنية للموسوعات والكتب لملاكاته
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