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Date: 23-2-2019
795
Date: 12-1-2018
973
Date: 30-3-2019
924
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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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علامات بسيطة في جسدك قد تنذر بمرض "قاتل"
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أول صور ثلاثية الأبعاد للغدة الزعترية البشرية
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مدرسة دار العلم.. صرح علميّ متميز في كربلاء لنشر علوم أهل البيت (عليهم السلام)
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