beryl

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beryl

(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.

Beryl

 

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.

REFERENCE

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

beryl

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
References in periodicals archive ?
Beryl, a former fund raiser for Birmingham Dogs Home, runs the Harborne-based charity A1 Petline.
Beryl the giant Kune Kune has been adopted by Beryl Romano, pictured below.
Beryl mining ceased in Egypt with Spain's discovery of superior-quality Colombian emeralds in the 16th century AD.
Beryl is a beryllium alumino-silicate mineral with the chemical formula [Be.
His smaragdus included the Egyptian beryl among other green stones, but he also recognized its relationship with beryllus: "many people consider the nature of berulli to be similar to, if not identical with, that of smaragdi" (Pliny's Natural History 37.
The poor quality of Egyptian green beryl has been attested to repeatedly in both the ancient and modern literature (for a partial summary see Sinkankas, 1981, p.
The geologic occurrence of beryl in Wadi Sikait has been well described by Basta and Zaki (1961) and Abdalla and Mohamed (1999), and their findings are consistent with what is known generally about the origins of beryl deposits elsewhere (Sinkankas, 1981, p.
Only minute amounts of Cr substituting for A1 in the beryl crystal structure are needed to give the mineral a green colour, with darker shades produced by higher Cr concentrations.
Beryl occurs mainly in the phlogopite schist and quartz/pegmatite veins, and is restricted to within tens of centimetres of their contact.
Figure 2 shows the extent of beryl mining in Wadi Sikait.
Past attempts at reopening the Wadi Sikait mine were all unsuccessful because of the generally poor quality and, hence, low market value of the beryl.
The ancient miners knew that beryl was to be found along the contact between the quartz/pegmatite veins and phlogopite schist, and so probably rested every such association where visible on the surface (Fig.