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(bĕr`ĭl), mineral, a silicate of beryllium and aluminum, Be3Al2Si6O18, extremely hard, occurring in hexagonal crystals that may be of enormous size and are usually white, yellow, green, blue, or colorless. Beryl is commonly used as a gemstone. The refractive index is low, and the stones have little or no fire. The most valued variety of beryl is emeraldemerald,
the green variety of beryl, of which aquamarine is the blue variety. Chemically, it is a beryllium-aluminum silicate whose color is due to small quantities of chromium compounds.
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. An aquamarineaquamarine
[Lat.,=seawater], transparent beryl with a blue or bluish-green color. Sources of the gems include Brazil, Siberia, the Union of Myanmar, Madagascar, and parts of the United States. Oriental aquamarine is a transparent crystalline corundum with a bluish tinge.
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 is a blue to sea-green beryl; morganites are rose-red beryls. It is the principal raw material for the element beryllium and its compounds.



a mineral of the silicate class. Its chemical formula is Al2Be3(Si6O18), but because of the constant presence of alkalies (Na, Cs, Rb), Li, Mn, Fe2+, Fe3+, and Cr3+, and also water and gases (helium and argon), the composition of beryl is much more complicated. Various types of beryl—alkali-free, sodium, sodium-lithium, and lithium-cesium—are distinguished according to the alkali and lithium content. Beryl crystallizes in a hexagonal system, forming prismatic, acicular, or tabular crystals or complete granular masses. Beryl’s hardness on the mineralogical scale is 7.5, and its density is 2,650–2,800 kg/m3. The color of beryl is extremely varied. Depending upon the color, transparency, and impurities, the following types of beryl are distinguished: beryl proper—a green or yellowish-white cloudy crystal; aquamarine—transparent greenish-blue (the color of seawater) or dark blue crystals, colored with Fe2+ impurities; heliodor—yellow because of Fe2+ impurities; emerald—a transparent crystal of a deep grass-green color, colored by Cr3+; rosterite—colorless or pink owing to 5 percent or more Li1+ and Cs1+ impurities; and morganite—pink owing to Mn3+ impurities. Beryl forms in granitic pegmatites, greisens, skarns, and pneumatolytic-hydrothermal deposits of the metasomatic type. Beryl is one of the major minerals in beryl ore, from which beryllium is smelted. Transparent beautifully colored or clear crystals are cut to make high-quality precious stones.


Beus, A. A. Geokhimiia berilliia i geneticheskie tipy berillievykh mestorozhdenii. Moscow, 1960. G. P. Barsanov


a white, blue, yellow, green, or pink mineral, found in coarse granites and igneous rocks. It is a source of beryllium and used as a gemstone; the green variety is emerald, the blue is aquamarine. Composition: beryllium aluminium silicate. Formula: Be3Al2Si6O18. Crystal structure: hexagonal