The products of none of the mines that have just been mentioned can on the whole compare with the beautiful stones which have come from South America. At the time when the Spaniards grimly conquered Peru and ruthlessly despoiled the country of the treasures which could be carried away, immense numbers of emeralds—some of almost incredible size—were literally poured into Spain, and eventually found their way to other parts of Europe. These stones were known as Spanish or Peruvian emeralds, but in all probability none of them were actually mined in Peru. Perhaps the most extraordinary were the five choice stones which Cortez presented to his bride, the niece of the Duke de Bejar, thereby mortally offending the Queen, who had desired them for herself, and which were lost in 1529 when Cortez was shipwrecked on his disastrous voyage to assist Charles V at the siege of Algiers. All five stones had been worked to divers fantastic shapes. One was cut like a bell with a fine pearl for a tongue, and bore on the rim, in Spanish, “Blessed is he who created thee.” A second was shaped like a rose, and a third like a horn. A fourth was fashioned like a fish, with eyes of gold. The fifth, which was the most valuable and the most remarkable of all, was hollowed out into the form of a cup, and had a foot of gold; its rim, which was formed of the same precious metal, was engraved with the words, “Inter natos mulierum non surrexit major.” As soon as the Spaniards had seized nearly all the emeralds that the natives had amassed in their temples or for personal adornment, they devoted their attention to searching for the source of these marvels of nature, and eventually in 1558 they lighted by accident upon the mines in what is now the United States of Colombia, which have been worked almost continuously since that time. Since the natives, who naturally resented the gross injustice with which they had been treated, and penetrated the greed that prompted the actions of the Spaniards, hid all traces of the mines, and refused to give any information as to their position, it is possible that other emerald mines may yet be found. The present mines are situated near the village of Muzo, about 75 miles (120 km.) north-north-west of Bogota, the capital of Colombia. The emeralds occur in calcite veins in a bituminous limestone of Cretaceous age. The Spaniards formerly worked the mines by driving adits through the barren rock on the hillsides to the gem-bearing veins, but at the present day the open cut method of working is employed. A plentiful supply of water is available, which is accumulated in reservoirs and allowed at the proper time to sweep the debris of barren rock away into the Rio Minero, leaving the rock containing the emeralds exposed. Stones, of good quality, which are suited for cutting, are locally known as canutillos, inferior stones, coarse or ill-shaped, being called morallons.
Emerald, unlike some green stones, retains its purity of colour in artificial light; in fact, to quote the words of Pliny, “For neither sun nor shade, nor yet the light of candle, causeth to change and lose their lustre.” Many are the superstitions that have been attached to it. Thus it was supposed to be good for the eyes, and as Pliny says, “Besides, there is not a gem or precious stone that so fully possesseth the eye, and yet never contenteth it with satiety. Nay, if the sight hath been wearied and dimmed by intentive poring upon anything else, the beholding of this stone doth refresh and restore it again.” The idea that it was fatal to the eyesight of serpents appears in Moore’s lines—
“Blinded like serpents when they gaze
Upon the emerald’s virgin blaze.”
The crystals occur attached to the limestone, and are therefore never found doubly terminated. The crystal form is very simple, merely a hexagonal prism with a flat face at the one end at right angles to it. They are invariably flawed, so much so that a flawless emerald has passed into proverb as unattainable perfection. The largest single crystal which is known to exist at the present day is in the possession of the Duke of Devonshire (Fig. 71). In section it is nearly a regular hexagon, about 2 inches (51 mm.) in diameter from side to side, and the length is about the same; its weight is 276·79 grams (9¾ oz. Av., or 1347 carats). It is of good colour, but badly flawed. It was given to the Duke of Devonshire by Dom Pedro of Brazil, and was exhibited at the Great Exhibition of 1851. A fine, though much smaller crystal, but of even better colour, which weighs 32·2 grams (156½ carats), and measures 1⅛ inch (28 mm.) in its widest cross-diameter, and about the same in length, was acquired with the Allan-Greg collection by the British Museum, and is exhibited in the Mineral Gallery of the British Museum (Natural History). The finest cut emerald is said to be one weighing 30 carats, which belongs to the Czar of Russia. A small, but perfect and flawless, faceted emerald, which is set in a gold hoop, is also in the British Museum (Natural History). It is shown, without the setting, about actual size, on [Plate I], Fig. 5.
Fig. 71.—Duke of Devonshire’s Emerald.
(Natural size.)
The ever great demand and the essentially restricted supply have forced the cost of emeralds of good quality to a height that puts large stones beyond the reach of all but a privileged few who have purses deep enough. The rate per carat may be anything from £15 upwards, depending upon the purity of the colour and the freedom from flaws, but it increases very rapidly with the size, since flawless stones of more than 4 carats or so in weight are among the rarest of jewels; a perfect emerald of 4 carats may easily fetch £1600 to £2000. It seems anomalous to say that it has never been easier to procure fine stones than during recent years, but the reason is that the high prices prevailing have tempted owners of old jewellery to realize their emeralds. On the other hand, pale emeralds are worth only a nominal sum.
The other varieties of beryl are much less rare, and, since they usually attain to more considerable, and sometimes even colossal, size, far larger stones are obtainable. An aquamarine, particularly of good deep blue-green colour, is a stone of great beauty, and it possesses the merit of preserving its purity of tint in artificial light. It is a favourite stone for pendants, brooches, and bracelets, and all purposes for which a large blue or green stone is desired. The varying tints are said to be due to the presence of iron in different percentages, and possibly in different states of oxidation. Unlike emerald, the other varieties are by no means so easily recognized by their colour. Blue aquamarines may easily be mistaken for topaz, or vice versa, and the yellow beryl closely resembles other yellow stones, such as quartz, topaz, or tourmaline. Stones which are colourless or only slightly tinted command little more than the price of cutting, but the price of blue-green stones rapidly advances with increasing depth of tint up to £2 a carat. The enormous cut aquamarine which is exhibited in the Mineral Gallery of the British Museum (Natural History), affords some idea of the great size such stones reach; a beautiful sea-green in colour, it weighs 179·5 grams (875 carats), and is table-cut with an oval contour.
The splendid six-sided columns which have been discovered in various parts of Siberia are among the most striking specimens in any large mineral collection. The neighbourhood of Ekaterinburg in the Urals is prolific in varieties of aquamarine; especially at Mursinka have fine stones been found, in association with topaz, amethyst, and schorl, the black tourmaline. Good stones also occur in conjunction with topaz at Miask in the Government of Orenburg. It is found in the gold-washings of the Sanarka River, in the Southern Urals, but the stones are not fitted for service as gems. Magnificent blue-green and yellow aquamarines are associated with topaz and smoky quartz in the granite of the Adun-Tschilon Mountains, near Nertschinsk, Transbaikal. Stones have also been found at the Urulga River in Siberia. Most of the bluish-green aquamarines which come into the market at the present time have originated in Brazil, particularly in Minas Novas, Minas Geraes, where clear, transparent stones, of pleasing colour, in various shades, are found in the utmost profusion; beautiful yellow stones also occur at the Bahia mines. Aquamarine was obtained in very early times in Coimbatore District, Madras, India, and yellow beryl comes from Ceylon. Fine blue crystals occur in the granite of the Mourne Mountains, Ireland, but they are not clear enough for cutting purposes; similar stones are found also at Limoges, Haute Vienne, France. Aquamarines of various hues abound in several places in the United States, among the principal localities being Stoneham in Maine, Haddam in Connecticut, and Pala and Mesa Grande in San Diego County, California. The last-named state is remarkable for the numerous stones of varying depth of salmon-pink that have been found there. It is, however, surpassed by Madagascar, which has recently produced splendid stones of perfect rose-red tint and of the finest gem quality, some of them being nearly 100 carats in weight. These stones, which have been assigned a special name, morganite (cf. supra), are associated with tourmaline and kunzite. Pink and yellow beryls and deep blue-green aquamarines occur in the island in quantity. The pink beryls from California are generally pale or have a pronounced salmon tint, and seldom approach the real rose-red colour of morganite; one magnificent rose-red crystal, weighing nearly 9 lb. (4·05 kg.), has, however, been recently discovered in San Diego County, California, and is now in the British Museum (Natural History). Blue-green beryl, varying in tint from almost colourless to an emerald-green, occurs with tin-stone and topaz about 9 miles (14½ km.) north-east of Emmaville in New South Wales, Australia.