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BERYL

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Originally appearing in Volume V03, Page 817 of the 1911 Encyclopedia Britannica.
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BERYL , a See also:

mineral containing See also:beryllium and See also:aluminium in the See also:form of a silicate; its See also:formula is Bea All Si6 018. The See also:species includes the See also:emerald (q.v.), the See also:aquamarine (q.v.) and other trans-See also:parent varieties known as " See also:precious beryl," with certain coarse varieties unfit for use as See also:gem-stones. The name comes from the Gr. 3r1puXXos, a word of uncertain See also:etymology applied to the beryl and probably several other gems. It is notable that the relation of the emerald to the beryl, though proved only by chemical See also:analysis, was conjectured at least as far back as the See also:time of See also:Pliny. Beryl crystallizes in the hexagonal See also:system, usually taking the form of See also:long six-sided prisms, striated vertically and terminated817 with the basal See also:plane, sometimes associated with various pyramidal faces (see fig.). It cleaves rather imperfectly parallel to the See also:base. The See also:colour of beryl may he See also:blue, See also:green, yellow, See also:brown or rarely See also:pink; while in some cases the mineral is colourless. The specific gravity is about 2.7, and the hardness 7.5 to 8, so that for a gem-See also:stone beryl is comparatively soft. Whilst the gem-varieties are transparent, the coarse beryl may be opaque. The transparent crystals are pleochroic—a See also:character well marked in emerald. Beryl was much prized as a gem-stone by the ancients, and See also:Greek intaglios o very See also:fine workmanship are extant.

The See also:

Roman jewellers, taking See also:advantage of the columnar form of the natural crystal, worked it into long cylinders for See also:ear-pendants. It was a favourite stone with the artists of the See also:Renaissance, but in See also:modern times has lost popularity, except in the form of emerald, which remains one of the most valued gem-stones. It is notable that See also:English lapidaries of the 18th See also:century often included the See also:sard under the See also:term beryl—a practice which has led to some confusion in the nomenclature of engraved gems. Beryl occurs as an See also:accessory constituent of many granitic rocks, especially in See also:veins of See also:pegmatite, whilst it is found also in See also:gneiss and in See also:mica: schist. Rolled pebbles of beryl occur, with See also:topaz, in See also:Brazil, especially in the See also:province of See also:Minas Geraes. Crystals are found in drusy cavities in See also:granite in the Urals, not-ably near Mursinka; in the See also:Altai Mountains, which have yielded very long prismatic crystals; and in the See also:mining See also:district of See also:Nerchinsk in See also:Siberia, principally in the Adun-Chalon range, where beryl occurs in veins of topaz-See also:rock piercing granite. Among See also:European localities may be mentioned See also:Elba, See also:good crystals being occasionally found in the See also:tourmaline-granite of See also:San See also:Piero. In See also:Ireland excellent crystals of beryl occur in See also:druses of the granite of the Mourne Mountains in Co. Down, and others less fine are found in the See also:highlands of See also:Donegal, whilst the mineral is also known from the See also:Leinster granite. It occurs likewise in the granite of the See also:Grampians in See also:Scotland, and is not unknown in See also:Cornwall, specimens having been found, with topaz, See also:apatite, &c., in See also:joints of the granite of St See also:Michael's See also:Mount. Many localities in the See also:United States yield beryl, sometimes sufficiently fine to be cut as a gem. It is found, for example, at See also:Hiddenite and elsewhere in See also:Alexander See also:county, N.C.; at Haddam and See also:Monroe, See also:Conn.; at See also:Stoneham and at See also:Albany, in See also:Oxford county, See also:Maine; at Royalston, See also:Mass.; and at Mt.

Antero, See also:

Colorado, where it occurs with See also:phenacite. Beryl of beautiful pink colour occurs in San Diego county, See also:California. Coarse beryl, much rifted, is found in crystals of very large See also:size at See also:Grafton and Acworth, N.H.; a crystal from Grafton weighing more than 22 tons. A colourless beryl from See also:Goshen, Mass., has been called Goshenite; whilst crystals of coarse yellow beryl from Rubislaw See also:quarry in See also:Aberdeenshire, Scotland, have been termed Davidsonite. Beryl suffers alteration by weathering, and may thus pass into See also:kaolin and mica. (F. W.

End of Article: BERYL

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