EMERALD  , a

bright green variety 9f beryl, much valued as a gem-stone . The word comes indirectly from the Gr. o-µapaybos (Arabic zumurrud), but this seems to have been a name vaguely given to a number of stones having little in common except a green colour . Pliny's " smaragdus " undoubtedly included several distinct species . Much confusion has arisen with respect to the " emerald " of the Scriptures . The Hebrew word nophek, rendered emerald in the Authorized Version, probably meant the carbuncle: it is indeed translated avOpaE in the Septuagint, and a marginal reading in the Revised Version gives carbuncle . On the other hand, the word baregath, rendered vtcapaylor in the LXX., appears in the A.V. as carbuncle, with the alternative reading of emerald in the R.V . It may have referred to the true emerald, but Flinders Petrie suggests that it meant rock-crystal . The properties of emerald are mostly the same as those described under BERYL . The crystals often show simply the hexagonal prism and basal plane . The prisms cleave, though imperfectly, at right angles to the geometrical axis; and hexagonal slices were formerly worn in the East . Compared with most gems, the emerald is rather soft, its hardness (7.5) being but slightly above that of quartz . The specific gravity is low, varying slightly in stones from different localities, but being for the Muzo emerald about 2.67 .

The refractive and dispersive

powers are not high, so that the cut stones display little brilliancy or " fire." The emerald is dichroic, giving in the dichroscope a bluish-green and a yellowish-green image . The magnificent colour which gives extraordinary value to this gem, is probably due to chromium, F . Wohler found o•186% of Cr2O3 in the emerald of Muzo,—a proportion which, though small, is sufficient to impart an emerald-green colour to glass . The stone loses colour when strongly heated, and M . Lewy suggested that the colour was due to an organic pigment . Greville Williams showed that emeralds lost about 9% of their weight on fusion, the specific ,gravity being reduced to about 2.4 . The ancients appear to have obtained the emerald from Upper Egypt, where it is said to have been worked as early as 165o B.C . It is known that Greek miners were at work in the time of Alexander the Great, and in later times the mines yielded their gems to Cleopatra . Remains of extensive workings were discovered in the northern Etbai by the French traveller, F . Cailliaud, in 1817, and the mines were re-opened for a short time under Mehemet Ali . " Cleopatra's Mines " are situated in Jebel Sikait and Jebel Zabara near the Red Sea coast east of Assuan . They were visited in 1891 by E .

A .

Floyer, and the Sikait workings were explored in rgoo by D . A . MacAlister and others . The Egyptian emeralds occur in mica-schist and talc-schist . On the Spanish conquest of South America vast quantities of emeralds were taken from the Peruvians, but the exact locality which yielded the stones was never discovered . The only South American emeralds now known occur near Bogota, the capital of Colombia . The most famous mine is at Muzo, but workings are known also at Coscuez and Somondoco . The emerald occurs in nests of calcite in a black bituminous limestone containing ammonites of Lower Cretaceous age . The mineral is associated with quartz, dolomite, pyrites, and the rare mineral called " parisite "—a fluo-carbonate of the cerium metals, occurring in brownish-yellow hexagonal crystals, and named after J . J . Paris, who worked the emeralds .

It has been suggested that the Colombian emerald is not in its

original matrix . The fine stones are called canutillos and the inferior ones morallicn . In 183o emeralds were accidentally discovered in the Ural Mountains . At the present time they are worked on the river Takovaya, about 6o m . N.E. of Ekaterinburg, where they occur in mica-schist, associated with aquamarine, alexandrite, phenacite, &c . Emerald is found also in mica-schist in the Habachthal, in the Salzburg Alps, and in granite at Eidsvold in Norway . Emerald has been worked in a vein of pegmatite, piercing slaty rocks, near Emmaville, in New South Wales . The crystals occurred in association with topaz, fluorspar and cassiterite; but they were mostly of rather pale colour . In the United States, emerald has occasionally been found, and fine crystals have been obtained from the workings for hiddenite at Stony-point, Alexander county, N.C . Many virtues were formerly ascribed to the emerald . When worn, it was held to be a preservative against epilepsy, it cured dysentery, it assisted women in childbirth, it drove away evil spirits, and preserved the chastity of the wearer . Administered internally it was reputed to have great medicinal value .

In consequence of its refreshing green colour it was naturally said to be

good for the eyesight . The stone known as " Oriental emerald " is a green corundum . Lithia emerald is the mineral called hiddenite; Uralian emerald is a name given to demantoid; Brazilian emerald is merely green tourmaline; evening emerald is the peridot; pyro-emerald is fluorspar which phosphoresces with a green glow when heated; and " mother of emerald " is generally a green quartz or perhaps in some cases a green felspar . See AQUAMARINE, BERYL . (F . W .