Villa Rica, in Brazil; in Peru, and is said to have been found in Siberia. It is very rare, and for this reason not much used as a gem; it resembles much the aquamarine when cut.
The emerald proper and the beryl belong to this mineral species, and are distinguished by their color and crystalline form. The emerald occurs in six-sided prisms with their modifications; it scratches quartz, and is scratched by topaz. The streak-powder is white; its hardness is 7.5 to 8.0; specific gravity, 2.73 to 2.76 ; it becomes electric by rubbing; it is rounding before the blowpipe, and forms an opaque black, but becomes a green or limpid glass, having the hardness of borax. Its constituents are glucia, alumina, and silica.
THE EMERALD PROPER.
The emerald appears to have been known in the most remote ages, and was the third stone, according to Cal-met's arrangement, on the high priest's breastplate of judgment, with the name of Zebulon inscribed on it. In the time of Pliny, this stone was held in such high estimation that it was seldom if ever engraved upon. The moderns, however, did engrave on the same, as we find in the royal collection at Paris a head of Henry IV., and one of Louis XIV. It has been excavated from the ruins of Rome, and from Herculaneum and Pompeii. But the ancients often included under this name other gems of the same color; such as the green fhtor, aquamarine, jasper, malachite, &c. They appear to have- obtained the emerald from Egypt. Cailloud has in modern times succeeded in finding the old emerald mines in the Theban deserts," on the Arabian Gulf —which have been noticed by the ancient authors, and by