BERYLL, in mineralogy, a species of the flint genus, divided by Werner into two sub-species. 1st. Precious beryll, which is green, passing on the one side in to blue, and on the other into yellow ; it is commonly mountain green and sela, don ; from the former it passes through various shades to the wine yellow ; from the latter it passes into smalt, sky, and, in rare instances, into azure blue. Its colours are generally pale, sometimes two at once. It is crystallized in long equiangular six sided prisms, which are perfect or truncated on the edges and angles. The crystals approach to tribe dral, and sometimes to the oblique tetra. hedral prisms: they are sometimes heaped. on each other, the smaller ones being al most uppermost, thus forming a shape like a tower : and in other cases they are perforated in the direction of their axes. It is commonly transparent, but passing to the translucent, and is slightly duplicat ing. It is hard ; scratches quartz; nearly equal in hardness to topaz, with which the mountain green variety has often been confounded. Easily frangible : and the) specific eravity is 2.6 or 2.7. Before the blowpipe it is difficultly fusible without addition, but with borax it melts easily : it is composed of Silica 68 0 Alumina . . . . 15.0
Glucine . . . . 14.0 Lime 2 0 Oxide of iron . . 1.0 100.0 It becomes very electrical by rubbing : is found in primitive rocks, accompanied with quartz, felspar, garnet, mica, fluor spar, and topaz. The most beautiful specimens are brought from China and the Brazils. They are also found in the Uralian mountains, in France, and in Sax ony. When pure, it is cut into stones for rings and necklaces. Its plenty renders it of no great value. It was well known to the ancients, who procured it from se veral places where it is now found. It is mentioned by Pliny and others : the blue varieties were denominated sapphire, the green aqua marine, and the yellow topaz.
The 2d variety is denominated schor Ions beryll, which is of a straw colour, passing to white, green, and yellow. The crystals are large, middle sized, and hard, but yielding to the file ; it is brittle, and very easily frangible : specific gravity about .3.5. It melts with borax into a pure transparent glass, and consists of Silica . . . . 50 Alumina . . . 50 100 • It is found embedded in quartz and mica, in many parts of Germany : it is the link that unites the precious beryll with schorl.