Beryl

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Beryl, mineral and, in certain varieties, a valuable gem material. Chemically it consists of aluminum beryllium silicate and it is the chief commercial ore of beryllium. Pure beryl is colorless and transparent. Emerald, one of the most valuable gems, is a variety that is colored green by minute amounts of chromium. Aquamarine, also a gemstone, is a blue beryl, more common than emerald. Golden beryl and morganite or rose beryl are less valuable. Colorless beryl is occasionally used as a gem under the name goshenite. Beryl has a vitreous luster with little fire or brilliancy, and so its value depends principally on hardness, transparency, and color. It has a hardness of 7.5 to 8 and a specific gravity of 2.75 to 2.8.

Beryl crystallizes in the hexagonal system. Large lettuce-green opaque crystals, some weighing over a ton, are found embedded in a variety of granite called pegmatite. Large, transparent crystals of the colored varieties are occasionally found.

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