Chapter XIV: Value of the Diamond (2)

But one locality thus far has been discovered in the United States or even in North America, and this occurs in North Carolina. For several years previous to the year 1880, Mr. J. A. Stephenson, a collector of minerals, had obtained in Alexander County a number of beryls and crystals of transparent minerals which had the shape of beryl with a tint of the emerald hue, also other crystals of acicular form which exhibited the true color of the finest Granada specimens of emeralds.

Some of these minerals were shown in 1880 to William E. Hidden, a young naturalist then engaged in searching the mineral belts of North and South Carolina and Georgia for rare minerals. The beauty of these specimens led the young enthusiast to make a thorough search for the parent ledge; and, after a few weeks of earnest labor in cutting deep ditches in the soil near the spot where a number of crystals had been found, he was rewarded with the discovery of the original deposit in a rock of gneiss. In this rock, in which felspar preponderates, he found implanted in open pockets and lenticular fissures crystals of emeralds, quartz, rutile, monazite, beryl, and also many crystals of long and slender shapes which appeared to be diopside, but which exhibited colors of white, yellow, and green of the most beautiful emerald hues. The mineral which appeared to be diopside was submitted to the examination of the distinguished chemist, J. Lawrence Smith, who soon pronounced it to be a new form of spodumene, and named it Hiddenite after the young explorer. Since then the explorations have been continued, and have yielded many very beautiful specimens of both the emerald and the hiddenite. At the depth of thirty-three feet below the surface of the rock several pockets were discovered which yielded some beautiful emeralds and hiddenites. They occurred at the bottom of the pockets, just as the finest crystals of tourmaline are found in the cavities of the granite ledges at Mount Mica in Maine. Twelve of these pockets were found within an area of forty feet square, extending to thirty feet in depth. The largest crystal of emerald found was more than three inches in length and three quarters of an inch in breadth, but its color, although of the true emerald hue, is, however, rather faint. Some of the smaller crystals are of much deeper tint, and resemble the pure specimens from Granada. But the most interesting treasures of the mineral kingdom revealed by this exploration were the crystals which analysis proved to be composed of a silicate of alumina and lithia, otherwise known as spodumene. Some of these crystals were white or light yellow, others were of a rich yellow hue shading into brown, while others exhibited the purest prismatic green of various depths of hue. In some of the green crystals the color has been uniform, while in others it is more intense at one end of their extremities.

Quite a number of the crystals and their fragments have been cut and polished into gems which rival, by their lustre and beauty of color, the best of the South American emeralds. On account of their extreme rarity, as well as their beauty, they have been sought for by amateurs, and have commanded high prices. As the field of deposit thus far known is quite limited, we fear that the yield of this charming mineral will not meet even the demands of science.

Professor Cleaveland, who was one of the best authorities of his day, maintained more than half a century ago that emeralds which exhibited a lively and beautiful green hue were found in blasting a canal through a ledge of graphic granite in the town of Topsham in Maine. Several of the crystals presented so pure, uniform, and rich a green, that he ventured to pronounce them precious emeralds. But to-day we are unable to verify the assertion, or point to a single specimen similar in hue to the emerald from the above-mentioned locality.

The nearest approach to the emerald in color, with the exception of the incomparable green tourmalines from Maine, and the emeralds and hiddenites of North Carolina, are the beryls of North and South Royalston, in the State of Massachusetts. These beautiful stones exhibit the physical characteristics of emeralds, with the exception of the color, in which they differ very perceptibly. But to appreciate fully the difference in hue we must compare the two gems. Then the lively green of the beryl fades away before the overpowering hue of the emerald, whose rich prismatic green may be taken as the purest type of that color known to the chemist or the painter.

Several years ago we visited the localities in Massachusetts which were famous in the days of Hitchcock and Webster. We found that the beryls occurred in a very coarse granite, where the quartz appeared in masses and the felspar in huge crystals. These also occur in finer granite, and exhibit no indications of veins or connection with each other. They are few in number, and are soon exhausted by blasting, being generally very superficial. After removing several tons of the rock at the locality at North Royalston, where the beryls appear on the summit of the loftiest hill, our labors were at length rewarded with two beautiful crystals. One of them was a fine prism an inch in diameter, of perfect transparency and of a deep sea-green color, which, however, is far from being similar to the transcendent hue of the Granada emeralds, which exhibit an excess of neither blue nor yellow. The other was yellowish-green, resembling the chrysoberyls of Brazil.

Other but imperfect crystals were brought to light, some fragments of which exhibited the deepest golden tints of the topaz, and others the tints of the sherry-wine colored topazes of Siberia. Magnificent crystals have been found in these localities in times long past, and from the fragments and sections of crystals found in the _débris_ of early explorations, we observed the wide range of color, and the deep longitudinal striæ which characterize the renowned beryls from the Altai Mountains, in Siberia. Lively sea and grass green, light and deep yellow, also blue crystals of various shades, have been found here.

At the quarries on Rollestone Mountain in Fitchburg, beryls of a rich golden color have been blasted out. Some of these approach the chrysoberyl and topaz in hardness and hue. Others so closely resemble the yellow diamond that they may readily be taken for that superior gem. The refractive power of these yellow stones is remarkable; and the goniometer will probably reveal a higher index than is accorded to all the varieties of beryl by the learned Abbé Haüy.

Beautiful transparent beryls have been found among the granite hills of Oxford County in Maine; and the late Governor Lincoln, nearly half a century ago, possessed a splendid crystal, quite three inches in length and of great purity and brilliancy. Some very beautiful transparent blue crystals of beryl have recently been found in the western part of Oxford County, Maine, which have yielded gems of considerable value. Probably active search for this mineral in this region will bring to light some charming specimens.

New Hampshire is famous for its gigantic beryls; and the localities of Acworth and Grafton have yielded some enormous crystals. One was removed by Mr. Alger, of more than a ton in weight; and a still larger one was observed by Mr. Hubbard, who estimated its weight at two and one half tons. These gross specimens are generally opaque, with patches of translucent or even transparent mineral on their sides. The regularity of their crystalline forms is also much impaired or distorted.

At Haddam, in Connecticut, beautiful crystals of beryl have been discovered; and one of these of fine green color, an inch in diameter and several inches in length, was preserved in the cabinet of Colonel Gibbs. Professor Silliman possessed another fine one, seven inches in length.

The mountains in Colorado have yielded some fine specimens. But the finest of the beryl species come from Russia. In the Ural Mountains the crystals are small, but of fine color; in the Altai Mountains they are very large and of a greenish-blue; but in the granitic ledges of Odon Tchelon in Daouria, on the frontier of China, they are found in the greatest perfection. They occur on the summit of the mountain in irregular veins of micaceous and white indurated clay, and are greenish-yellow, pure pale-green, greenish-blue, and sky-blue. The chief matrix of the beryl all over the world is graphic granite, but it may occur in other rocks. The light green stones of Limoges, in France, appear in a vein of quartz traversing granite. At Royalston we observed them to spring seemingly from the felspar and project into smoky quartz, becoming more transparent as they advanced into the harder stone.

The beryl possesses the same crystalline form and specific gravity as the emerald, but its hardness, especially in the blue and white varieties, is sometimes greater. They are both silicates of alumina, and the only perceptible difference in the two stones is in the color. Cleaveland thought that as the emerald and beryl had the same essential characters, they might gradually pass into each other; and Klaproth, finding the oxides of both chrome and iron in one specimen, was led to take the same view. The crystals of true emerald are almost always small, with the exception of those found in the Wald district in Siberia, whilst those of the beryl vary from a few grains to more than a ton in weight. The crystals of both are almost invariably regular hexahedral prisms, sometimes slightly modified. Those of the beryl we sometimes find quite flat, as though they had been compressed by force; then again they are acicular and of extraordinary length, considering their slender diameter. Sometimes their lateral faces are longitudinally striated, and as deeply as the tourmaline, so that the edges of the prism are rendered indistinct. Other crystals are curved, and some perforated in the axis like the tourmaline, so as to contain other minerals. Sometimes they are articulated like the pillars of basalt, and separated at some distance by the intervening quartz. These modified forms give rise to curious speculations as to their formation and origin. If we admit the action of fire (which is improbable), then the separation may be easily explained; but if we insist that they were deposited in the wet way and by slow process, how can we account for the dislocation? “By electricity,” whispers a friend,--“by telluric magnetism, that wonderful unexplained and mysterious force which has caused the grand geological changes of the globe, and is still at work.”

Sometimes the crystals of beryl are of two distinct colors, but generally they are of one color, often shading into white at either extremity. They may exhibit the richest golden-yellow, or a light cerulean blue, or a clear sea-green like those described by Pliny, now called aqua-marines. “Qui viridatem puri maris imitantur.”

One distinction between beryl and quartz is afforded by the appearance of its fracture. A crystal of beryl breaks into smooth planes, the faces of which are at right angles to the axis of the prism; while the fracture of the surface of broken quartz is invariably conchoidal.

Blue beryls were highly prized by the ancients. Beautiful specimens are found in the glens of the Mourne Mountains in Ireland. But finer gems are brought from the granite district of Nertschinsk, in Siberia, and also from various localities in the Uralian and Altaian Mountains, where the Romans were supposed to have obtained them in early times.

Its name is derived from the Persian “belur,” which the Romans changed into “beryllus.” Sometimes it occurs of a rose color. A few have been found at Elba and one at Haddam by Colonel Gibbs. One of the most beautiful specimens of beryl known was discovered in Siberia. It consisted of a magnificent crystal of smoky quartz, in the base of which appeared several fine crystals of beryl, of an exquisite yellowish-green and greenish-blue.

In the princely collection of Mr. Vaux, of Philadelphia, may be seen a crystal of beryl from the Mourne Mountains of Ireland, two inches in length by five eighths of an inch in diameter. It is of a celestial blue color, much deeper in hue at one extremity than at the other. But the gem of this collection among the beryls is a specimen purchased in Russia, in 1875. It is a six-sided prism nine inches in length and six inches in circumference. The color is of a rich oily green, and several inches of its upper extremity is transparent, while the rest is translucent. It rests upon a mass of granite, and is a specimen of extraordinary size and beauty.

Mr. Clay of the same city has a remarkable prism of Siberian beryl two inches in diameter, which exhibits a tint of celestial blue externally but which appears of a decided green hue in its interior.

At the Centennial Exhibition Brazil exhibited a fine crystal of a warm celadine green color. Russia displayed some very beautiful specimens of the yellow, green, and blue beryls from Siberia. Some very beautiful crystals of emerald, both solitary and fixed in the matrix, were also exhibited from the same country.

Several of the mineralogical cabinets of Europe possess fine suites of the emerald and beryl in a great variety of forms and degrees of perfection. Those of the École des Mines at St. Petersburg, the Jardin des Plantes at Paris, and the British Museum, are of very great commercial value and mineralogical interest.

At the French Exposition in 1867, the celebrated jeweller, Froment Meurice, exhibited a beautiful specimen of modern glyptic art cut in beryl. It comprised the bust of the Emperor Napoleon III. carved in pure aqua-marine. The image was placed upon a miniature pedestal of blood-red jasper, before which the imperial eagle spread his wings and perched upon a base of red jasper, which was studded with stars of topazes, bosses of pearls, and bordered with roses formed of minute amethysts.

A beautiful blue stone adorns the summit of the crown of England, and has been described as a sapphire of unusual purity. But mineralogists affirm, that the gem is a blue beryl, and it is surmised by others that it is the identical and famous stone which Edward the Confessor wore in a ring. It is of a lovely color, oval in form, and measures 2¹⁄₁₀ inches in length by 1¹⁄₂ in width, and 1¹⁄₅ in depth.

A superb aqua-marine formerly adorned the tiara of Pope Julius II. and was considered as one of the most celebrated in the world, notwithstanding it exhibited a slight flaw. This gem, which was of an exquisite sea-green color, was 2¹⁄₁₀ inches in length and 2²⁄₅ in depth. After having been kept in the Museum of Natural History in Paris for more than three hundred years, Napoleon presented it to Pope Pius VII.

The Asiatics, and especially the Turkish officers, prize the prisms of beryl as handles to their scimetars and daggers. This fondness for decoration of sword-blades and arms is by no means confined to the soldiers of the East. The officers of Napoleon’s armies exhibited the same taste. Murat adorned the hilt of his sword with one of the finest beryls ever seen in Europe. Another famous aqua-marine formed the handle of the sword of the poet Moncrif, who, like another celebrated swordsman, the painter Caravaggio, compelled admiration of his works at the point of his sword. This blood-stained gem bore as inscription the epitomized history of the author, a quotation from the poet Theophile, “Tous mes jours sont des Mardis-gras.”

One of the most beautiful beryls known is that purchased by the English banker, Mr. Hope, and placed in his collection of gems. It weighs six and one half ounces, and cost its princely owner nearly twenty-five hundred dollars. It is reported to have come from the mine of Cangazum, in the district of Coimbatoor in India, a locality which has been long famous for its fine beryls.

The most magnificent aqua-marine described in history is that belonging to Dom Pedro. It was found in the diamond districts of Minas Geraes, in Brazil. In form and size it resembles the head of a calf. Only on one side does it preserve any trace of a crystalline form; the rest is water-worn. It is said to be of a fine color, without a flaw, and perfectly transparent.

For many ages the shrine of the Abbey of St. Denys, at Paris, received rare and valuable gems as offerings; and at the time of the French Revolution the collection had become very valuable. The iconoclasts ordered it to be separated and sold. It brought 80,000 francs, and was scattered along the commercial highways of the world, never again to be reunited. One of the finest aqua-marines, mounted in sapphires and pearls, and engraved with the portrait of Julia, the daughter of Titus, was fortunately rescued, and may now be seen in the collection of the National Library of France. This splendid gem is of the unusual magnitude of 2¹⁄₂ inches by 2¹⁄₈. For quite a thousand years it formed a part of a golden reliquary celebrated as “l’escrain de Charlemagne.” History relates that it was presented by the great Emperor before his death to the Abbey of St. Denys. This is one of the finest specimens of an ancient intaglio carved upon beryl that has survived the destructive pillage of armies and the wreck of time since the early days of the Roman Empire. It is said that specimens of antique engraving upon this gem are about as rare as those carved upon the emerald, and their rarity is believed to be due to their great value, as well as to their scarcity in the gem markets in ancient times.

Several royal relics of the lower Empire containing emeralds are still preserved, to attest the use of the gem in those days as well as the esteem in which it was held. The famous Iron Crown of Lombardy, made perhaps before the sixth century, contains several emeralds. This renowned relic is simply a circlet of gold, covering an iron nail of the cross, beaten out thin. The crown of the queen of one of the Gothic kings of Spain, of the seventh century, was recently exhumed at Toledo, and also exhibits emeralds among other gems. And there are other examples to prove the use of the emerald in mediæval times for ornamental purposes.

No other gem has been counterfeited with such perfection as the emerald; and in fact it is utterly impossible to distinguish the artificial from the real gems by the aid of the eye alone; even the little flaws, which lull the suspicions of the inexperienced, are easily produced by a dexterous blow from the mallet of the skilled artisan. Not only emeralds, but most of the gems and precious stones, are now imitated with such consummate skill as to deceive the eye; and none but experts are aware of the extent to which these fictitious gems are worn in fashionable society, for oftentimes the wearers themselves imagine that they possess the real stones. There is not one in a hundred jewellers who is acquainted with the physical properties of the gems; and very few can distinguish the diamond from the white zircon or the white topaz, the emerald from the tourmaline of similar hue, the sapphire from iolite, or the topaz from the Bohemian yellow quartz. Jewellers are governed generally by sight, which they believe to be infallible, whilst hardness and specific gravity are the only sure tests.

Artificial gems, rivalling in beauty of color the most brilliant and delicately tinted of the productions of Nature, are now made at Paris and in other European cities. The establishments at Septmoncel in the Jura alone employed a thousand persons, and fabulous quantities of the glittering pastes were made there and sent to all parts of the world.

A fine specimen of prase, when cut, affords a fair imitation of the emerald. The green fluor-spar which Haüy called “emeraude de Carthagène” may also be substituted, but the application of the file detects the trick with ease. Some of the green tourmalines approach the emeralds in hue very closely, and by artificial light it is impossible to distinguish them from each other. Fragments of quartz may be stained by being steeped in green-colored tinctures. The Greeks stained quartz so like the real gem, that Pliny exclaimed against the fraud, while declining to tell how it was done. The Ancona rubies at the present day are made by plunging quartz into a hot tincture of cochineal, which penetrates the minute fissures of the rock.

But notwithstanding the high art reached by modern glass-makers, they are yet far behind the ancients in imitating the emerald in point of hardness and lustre. Many emerald pastes of Roman times still extant are with difficulty distinguished from the real gem, so much harder and more lustrous are they than modern glass. The ancient Phœnician remains found in the island of Sardinia by Cavalier Cara, in 1856, show fine color in their enamels and glass-works. The green pigment brought home from the ruins of Thebes by Mr. Wilkinson, was shown by Dr. Ure to consist of blue glass in powder, with yellow ochre and colorless glass. From Greek inscriptions dating from the period of the Peloponnesian war, we learn that there were signets of colored glass among the gems in the treasury of the Parthenon.

Of all the emerald imitations that have descended to us from antiquity, none are more remarkable, none more interesting to the antiquary and historian, than the famous Sacro Catino of the cathedral of Genoa. This celebrated relic is a glass dish, or patera, fourteen inches in width, five inches in depth, and of the richest transparent green color, though disfigured by several flaws. It was bestowed upon the Republic of Genoa by the Crusaders, after the capture of Cæsarea in 1101, and was regarded as an equivalent for a large sum of money due from the Christian army. It was traditionally believed to have been presented to King Solomon by the Queen of Sheba, and afterward preserved in the Temple; and some accounts relate that it was used by Christ at the institution of the Lord’s supper. The Genoese received it with so much veneration and faith, that twelve nobles were appointed to guard it, and it was exhibited but once a year, when a priest held it up in his hand to the view of the passing throng. The State, in 1319, in a time of pressing need, pawned the holy relic for 1,200 marks of gold ($200,000), and redeemed it with a promptness which proved its belief in the reality of the material, as well as in its sanctity. And it is also related that the Jews, during a period of fifty years, lent the Republic 4,000,000 francs, holding the sacred relic as a pledge of security. Seven hundred years passed away, when Napoleon came; and as he swept down over Italy, gathering her art treasures, he ordered the “Holy Grail” to be conveyed to Paris. It was deposited in the Cabinet of Antiquities in the Imperial Library, and the mineralogists quickly discovered it to be glass. It is due to the memory of Condamine to state that he was the first to doubt the material of the Sacro Catino; for, when examining it by lamplight in 1757, in the presence of the Princes Corsini, he observed none of the cracks, clouds, and specks common to emeralds, but detected little bubbles of air. In 1815, the Allies ordered its return to the cathedral of Genoa. During this journey the beautiful relic was broken; but its fragments were restored by a skilful artisan, and it is now supported upon a tripod, the fragments being held together by a band of gold filigree. This remarkable object of antiquity, which is of extraordinary beauty of material and workmanship, furnishes a theme over which the antiquaries love to muse and wrangle.

Another of the antique monster emeralds, weighing twenty-nine pounds, was presented to the abbey of Reichenau, near Constance, by Charlemagne. Beckman has also detected this precious relic to be glass. And probably the great emerald of two pounds weight brought home from the Holy Land by one of the dukes of Austria, and now deposited in the collection at Vienna, is of the same material. Another, more than eight inches long, was preserved in the chapel of St. Wenceslaus at Prague. The hardness of our glass is yet far inferior to that of the ancients; and even the ruby lustre of the potters of Umbria, which was so precious to the _dilettanti_ of the Cinque Cento period, has not been recovered.

The enormous emerald dishes and statues and obelisks described by Herodotus, Theophrastus, Appian, and others were undoubtedly constructed of glass, and exhibited to the ignorant multitudes as formed of monster emeralds.

One of the most curious of these impositions was the sculptured lion on the tomb of Hermias on the island of Cyprus, which had emerald eyes which shone so brightly as to frighten away the fish in the sea near by.

The wonderful “Table of Solomon” which formed a part of Alaric’s Roman spoils, and was taken by his Goths to Spain, where it was captured by the Arab invaders and afterwards sent to Damascus, was probably another specimen of the ingenuity of the glass-workers of Alexandria or Tyre. It is described by one of the Arabian historians as of a marvellous beauty, being formed of a single slab of solid emerald, encircled with rows of pearls, and supported on many feet composed of gems and gold.

The famous Barberini vase, found in one of the tombs of the Roman emperors, and exhibiting white figures upon a dark-blue ground, was long thought to be carved from some variety of sardonyx, but proved in modern times to be of hard antique glass. Of similar material the unique ewer in the Brescian Museum and the vases in the Palace Borbonico are composed, and all of these are of great antiquity. The sapphire cup of Theolinda, the once celebrated Queen of Lombardy, now preserved in the Cathedral at Monza, is glass.

There are but very few stones whose colors resemble that of the emerald, and therefore frauds are easily detected. A well-selected specimen of prase may be passed as an inferior emerald, as well as the translucent stones cut from the Chinese jade; but their want of transparency offers a serious objection to them as a gem. The green tourmaline, when it approaches the emerald in hue, is of equal value. The green zircon and the green spinel would be far superior to the emerald in brilliancy, and therefore of greater value to the amateur. The chrome-green garnet of Hungary and the emerald-green garnet of Siberia would command a high price, if of pure color, as they surpass the glucina emerald in eclat and are moreover exceedingly rare. The peridot may assume the exact hue of the Granada emerald. The glass imitations are almost _fac-similes_ in hue, and are far superior in brilliancy to the mineral itself; but their softness, which readily yields to the file, betrays their nature without difficulty.

Since the time of the Spanish Conquest, New Granada has furnished the world with the most of its emeralds. The most famous mines are at Muzo, in the valley of Tunca, between the mountains of New Granada and Popayan, about seventy-five miles from Santa Fé de Bogota, where every rock, it is said, contains an emerald. At present the supply of emeralds is very limited, owing to restrictions on trade, and want of capital and energy in mining operations.

Blue as well as green emeralds are found in the Cordillera of the Cubillan. The Esmeraldas mines in Equador are said to have been worked successfully at one period by the Jesuits. The Peruvians obtained many emeralds from the barren district of Atacama, and in the times of the Conquest there were quarries on the River of Emeralds near Barbacoas. Emeralds of a poor quality are found at Limoges in France, and also in Norway. In some of the felspar quarries in Finland they occur in large thick crystals, several feet in thickness, of a fine color, but not transparent.

Emeralds are found in Siberia, and some of the localities may have furnished to the ancients the Scythian gems which Pliny and others mention. In the Wald district magnificent crystals have been found embedded in mica-slate. One of these--a twin-crystal, now in the imperial cabinet at St. Petersburg--is seven inches long, four inches broad, and weighs four and a half pounds. There is another mass in the same collection which measures fourteen inches long by twelve broad and five thick, weighing sixteen and three-quarter pounds troy. This group shows twenty crystals from a half inch to five inches long, and from one to two inches broad. They were discovered by a peasant cutting wood near the summit of the mountain. His eye was attracted by the lustrous sparkling amongst the decomposed mica where the ground had been exposed by the uprooting of a tree by the violence of the wind. He collected a number of the crystals, and brought them to Katharineburg and showed them to M. Kokawin, who recognized them and sent them to St. Petersburg, where they were critically examined by Van Worth and pronounced to be emeralds. One of these crystals was presented by the Emperor to Humboldt when he visited St. Petersburg, and it is now deposited in the Berlin collection. Quite a number of emeralds are now brought from the Siberian localities, and it is believed that enterprise and capital would produce a large supply of the gem.

Near Salsberg, in the Tyrol, the emerald occurs in a mica-slate which appears on the face of a very steep precipice difficult of access, and about 8,700 feet above the sea-level. They are of good color, but much impaired in their transparency by foreign matter and imperfect crystallization. Some of the finest stones yielded by this locality were exhibited as cabinet specimens by the Emperor of Russia at the Paris Exposition.

The supply of emeralds from South America is very limited, and may be ascribed to want of skilful mining, as well as to climate, the political condition of the country, and the indolence of its inhabitants. The localities cannot be exhausted, for they are too numerous and extensive. The elevated regions in Granada admit of scientific exploration by Europeans, and at the present day the only emerald-mining operations conducted in South America have been prosecuted near Santa Fé de Bogota by a French company, which has paid the Government $14,000 yearly for the right of mining, all the emeralds obtained being sent to Paris to be cut by the lapidaries of that city. In the Atacama districts, and along the banks of the River of Emeralds, the physical obstructions are difficult to overcome; and pestilential diseases of malignant character forbid the long sojourn of the European. Yet the introduction of Chinese labor may prove successful and highly remunerative, since the coolie reared among the jungles and rice-swamps of Southern China is quite as exempt from malarial fevers as the negro.

Hassaurek was surprised not to find emeralds for sale at Guayaquil, as they had been found in abundance in Equador at the time of the Conquest. The Alcalde of the region around the River Bechile gave Stephenson, the traveller, three emeralds which were found in the sands at the mouth of the river.

Concerning the emerald mines whence the ancients drew their supplies of gems, there remains but little positive information. They were undoubtedly established in Arabia, Africa, and Scythia, but all record of them is lost. As regards the Egyptian mines, modern travellers have proved their existence. At the ancient mines at Gebel Zabara, which were worked in the time of the Ptolemies, M. Callaud found the tools of the miners as they had left them, and also many inferior emeralds among the _débris_ of the pits. Mehemet Ali attempted to reopen them, but was unsuccessful, as the matrix of the gem proved to be exhausted. This discovery establishes the truth of Pliny’s remark concerning some of the localities of the emerald. They are the same gems whose beauty was praised by the Persian poets. We have no evidence of ancient mines of emeralds in Asia; and Tavernier, who sought in vain to discover them, ventured to state that he believed that some of the emeralds he saw in India must have come from Peru, by way of the Philippine Islands, long before the Conquest by the Spaniards.

Other mines undoubtedly were worked in Africa; and we know that in the time of Justinian, the Abyssinians searched the coast, even as far as the equator. The African emeralds were not of the first quality; and at a later period of Roman history the Scythian emeralds were reckoned as the first in value and beauty, the Bactrian second, while the African were classed as third. About the fourth century the throne of the White Huns was famous for the splendid Scythian emeralds which adorned it.

The price of the emerald has no fixed and extended scale, like that of the diamond, and the fluctuations of its value during the past three centuries form an interesting chapter in the history of gems. In the time of Dutens (1777) the price of small stones of the first quality was one louis the karat; one and a half karats, five louis; two karats, ten louis; and beyond this weight no rule of value could be established. In De Boot’s day (1600) emeralds were so plenty as to be worth only a quarter as much as the diamond. The markets were glutted with the frequent importations from Peru, and thirteen years before the above-mentioned period one vessel brought from South America two hundred and three pounds of fine emeralds, worth at the present valuation more than seven millions of dollars. At the beginning of this century, according to Caire, they were worth no more than twenty-four francs (or about five dollars) the karat, and for a long time antecedent to 1850, they were valued at only $15 the karat. Since this period they have become very rare, and their valuation has advanced enormously. In fact, the value of the emerald now exceeds that of the diamond, and is rapidly approaching the ratio fixed by Benvenuto Cellini in the middle of the sixteenth century, which rated the emerald at four times, and the ruby at eight times, the value of the diamond. Fine stones (the emerald is exceedingly liable to flaw, the beryl is more free, and the green sapphire is rarely impaired by fissures or cracks) of one karat in weight are worth at the present day $200 or more. Fine gems of two karats weight will command $500; while larger stones are sold at extravagant prices.

Most of our aqua-marines come from Brazil and Siberia, and small stones are sold at trifling prices. Some of them, however, when perfect and of fine color, command fabulous sums. The superb little beryl found at Mouzzinskaia is valued by the Russians at the enormous sum of $120,000, although the crystal weighs but little more than one ounce. Another rough prism preserved in the Museum at Paris, and weighing less than one hundred grains, has received the tempting offer of 15,000 francs.

THE OPAL.

“What radiant changes strike the astonished sight!
What glowing hues of mingled shade and light!”

FALCONER.

THE OPAL.

What is the composition of this wonderful stone, which displays such wondrous hues? What is the nature of this remarkable mineral, which seems to concentrate within its substance all the glories of the rainbow, and which rivals in its hue the finest gem of the mineral world? The Turk believes that it falls from heaven in the lightning’s flash, and it is often regretted by the mineralogist that the theory cannot be sustained. Surely a gem so beautiful, so delicate and so pure ought to be of celestial origin, and free from the impurities and imperfections of the earth. Alas, we have but one precious stone that comes to us from the far-off region of celestial space,--olivine,--and that as yet has been found only in minute grains.

But if we cannot ascribe the origin of our beautiful gems directly to the stars and other bodies in space, we may affirm that their birth or development in the bosom of our earth may be due in a great measure to extra-terrestrial influences. And as regards the precious opal, if we cannot prove it of divine origin, we can with truth affirm that there is a deep mystery connected with the mineral both in its composition and its physical properties. The liberal-minded physicist to-day finds himself somewhat baffled when attempting to explain the phenomena of the gem in accordance with our imperfect knowledge of natural laws. Apparently it is nothing more than hydrated silica or quartz; but it is of a lower specific gravity, and some of its varieties are so tender and delicate in structure as to be at the caprice of the atmosphere.

It has been maintained that the peculiarities of the opal depend in a great measure upon the quantity of water it contained, and which, mixed mechanically with the silica, varies from three to twenty per cent. But some chemists who have interested themselves in the study of the composition of the mineral do not regard the presence of water as absolutely essential for the development of the varied flashes of color. We will only state in this brief sketch that there is certainly a mystery connected with the part water plays in producing and perfecting the beauty of the opal. This quantity or factor of water varies greatly in the different varieties of opal. Apparently when heat is applied to the mineral the brilliancy of its hues is increased, either from evaporation of its water or some structural change. But if the degree of heat is too great, or its application too prolonged, the hues of the opal vanish and cannot be recalled by human skill. The same results from the effects of heat may be noticed in other gems of greater density and hardness, as the emerald, the topaz, and the tourmaline. It has been maintained that a faded opal may be restored to beauty by immersion for a time in water, with the view of restoring the fancied loss by evaporation; but we fear that the experimentalist will be often disappointed with his results. However, there is one singular variety of the mineral known as the hydrophane, which does not exhibit colors until after it has been immersed for a time in water, and when removed from its bath and becomes dry again its hues vanish. Therefore, we may justly affirm that there is a mystery in connection with the influence of water in producing the color of the opal. The optical properties of this mineral do not afford decisive distinction, and it never crystallizes in regular and definite form like quartz, neither does it exhibit a trace of double refraction.

We will say no more at present concerning the composition of this interesting substance except to allude briefly to the experiment of Damour, who found the opal to turn black when sulphuric acid was applied to it; hence he inferred that the substance contained some organic matter, but precisely what he could not determine, although he suspected the presence of bituminous matter. Similar foreign bodies have been detected in many other precious stones. In fact, many of our gems are impaired by impurities; and so generally, that a stone of absolute purity is of rare occurrence. Even the diamond, which is regarded as the emblem of light and purity, is reckoned by microscopists as one of the foulest of gems.

Werner divided the opal into four sub-species, and Jameson has separated it into seven varieties. The principal divisions, however, may be classed as follows: precious or noble opal, presenting refulgent tints; fire opal, with fire-like reflections; girasole, with reddish reflections when exposed to the sunlight; common opal, translucent and without reflections; wood opal or petrified opal, possessing the characters of common opal; hyalite, clear and colorless as glass. There is another kind of opal which we have never seen, but which is described as the asteriated opal. We are not able to give a minute description of its appearance or draw a comparison between it and that of asteriated quartz, sapphire, or garnet. It is said to display great beams of light which undulate over its surface like the flashings of lightning piercing the storm cloud. The variety known as the moss opal sometimes displays in its interior dendritic crystallization of a dark substance resembling delicate mosses, ferns, or trees. And the gleam of the colored rays flashing amidst these miniature forests and groups of foliage often present charming effects.

The grand characteristic which gives to the gem its value and renown is the wonderful play of the colored reflections which it displays, and which embrace all of the prismatic tints of the solar spectrum. As we view its vivid rainbow flashes when the gem is held in the sunlight, we must admit it to be the most magnificent of gems, and join with the Latin philosopher, who remarked that it was made up of the glories of the most precious stones. For as the light falls upon it in varied directions, its reflections recall the lively green of the emerald, or the tender blue of the sapphire, the rich yellow of the topaz, or the gorgeous red of the ruby.

This mineral has not only been an object of delight to the fashionable world, but it has also been a wonder and a perplexity to the philosophers. In admiring its beauties and attempting to account for its phenomena, Newton was led to the series of experiments and to that train of sublime reasoning that gave to science the most brilliant and extraordinary of his discoveries. The colored refractions of the gem reminded the philosopher of the iridescence of the soap-bubble, and the soap-bubble suggested the undulatory theory of light. Newton, after long study of the opal, is said to have declared that its hues were produced by the refractions and reflections of light at the numerous minute fissures which traverse the stone in all directions. But this theory is denied by many at the present day, and especially by Mohrs, who maintains that the thin films of air filling the cavities of the stone would produce iridescence only. Other opticians believe the colored reflections to be due to laminæ formed by incipient crystallization, as seen in the equally remarkable mineral known as labradorite. Babinet believes the brilliant colors of the opal to be due to the narrow fissures in the stone, like those produced in the partial fracture of glass or quartz. He also refers for example to the colors of thin transparent plates, and believes that the colors of flowers are produced in like manner from the overlaying of the transparent tissues of which the petals are composed. This, then, according to the French philosopher, is the secret of the gorgeous hues of vegetation from their first development to the period of their final decay. The diamond, when cut in a regular form, displays the most magnificent flashes of the prismatic hues by artificial light; and although the mineral is composed of an infinite number of laminæ, no one maintains the theory that the color is produced by thin films of air like those in the soap-bubble. We also may observe the same hues sparkling among the dew-drops in the morning sunlight, and likewise in the artificial diamonds, which are composed of solid glass and apparently homogeneous.

In examining the interior of an opal, we often fail to perceive any cause for the reflections of color, especially in the limpid varieties. The flashes appear when the light enters the stone at a certain angle, but when viewed in any other direction the gem presents the usual appearance of common transparent quartz. In other varieties of the mineral, however, especially the milky or translucent, a cause for the colored reflections is easily observed. We have under observation the beautiful opal known as the “Oberon,” and beneath its translucent surface appear thin films of a faint reddish hue suspended at different depths within its interior. They are so well defined that their edges may be recognized, and they lie like thin clouds suspended in a hazy sky. But as the gem is turned so that the light strikes the film at a different angle, the scene is instantly changed, and a mass of flame replaces the sombre tint. It is a little curious that some of the films exhibit the different colors of the spectrum as the angle of light is changed, while others display only the green and blue color, no matter how the light strikes them. In fact, the films or patches, which are apparently alike, produce different results from the same rays of light; and some display the continuous spectrum, while others exhibit but one color. It is a little singular that all transparent minerals when fractured do not exhibit alike in their fractures the prismatic gleams displayed by quartz and glass. We have before us a beautiful transparent white crystal of adularia or moon-stone from St. Gothard, and although it is fissured and fractured in a thousand places, yet we observe little iridescence in it even when exposed to the sunlight.

The localities where the precious opal is now found are but few, and none of them were probably known to the ancients. All record of the old opal mines is now lost; but there were undoubtedly deposits of the mineral in Arabia, Syria, and in Asia, whence the ancients derived their gems. The famous Hungarian mines were not discovered until late in the fifteenth century, and the country was quite unknown to the Romans.

The principal mines explored at the present day, and whence most of our opals are now derived, are those of Hungary and Honduras. The Hungarian mines are of great extent and are now scientifically explored, but those of Central America are undetermined and but rudely mined. It is believed that there are other mines in Central America besides those of Honduras, for the natives at times bring fine specimens to the coast from localities widely separated. It is quite true that most of the opals of America are less hard than the Hungarian, but they are no less brilliant, and some of them withstand atmospheric effects and the wear of time quite as well. The Honduras opals are found near Gracias a Dios in porcelain earth, and are extracted in irregular masses, sometimes uniform or globular concretions, with rough and deeply indented surfaces. These masses do not exhibit the least tendency to crystallization like quartz, and they are generally quite small. Their natural colors are pale, and vary from brown to a pearly gray. They often exhibit a rich and varied play of the rainbow hues, even in their natural and rough condition. But sometimes, when this rough exterior is removed by the lapidary’s wheel, and the gem is highly polished, the colors vanish as if by magic. The polished stone no longer displays a single ray of the brilliant fires which illuminated every angle of the stone when in its rough state. This singular disappearance may be explained by the theory that the surface has been too highly polished, and the substance of the stone is rendered too transparent to permit the requisite degree of reflection, for when the surface is slightly roughened the play of colors again returns. The finest specimens are therefore those which are translucent, or those which, being transparent, are backed by an opaque ground which refracts the light.

The opal-bearing districts in Central America are far more extensive than is generally supposed. The Province of Honduras abounds in them, and we have evidence of others occurring in the State of Guatemala on the Pacific coast. The following descriptions of some of the opal mines of Honduras were published by Dr. J. Le Conte, in 1868, in his report of the Inter-oceanic Railroad survey:--

“Extensive beds of common opal and semi-opal are seen along a belt extending through the central part of the department of Gracias; but these varieties, though very beautiful and possessing high interest to the mineralogist, are without commercial value from the ease with which artificial products may be made which precisely resemble them. The localities worthy of exploration are those in which the opal forms veins (not beds) in compact but brittle trachyte of a dark color. The veins, as will be seen, are not confined to such rock, but seem to have their origin in it, and are probably not found except in connection with it. The best-known mines of precious opal are in the department of Gracias; several localities have yielded valuable gems, but they are all remote from the line of road. Some are in the vicinity of the town of Gracias, others near Intibucat; but the most important are at Erandique. The working is now carried on in a very small way; but the locality is extensive, and in my opinion mining on a large scale would be attended with profit. The country near by abounds with beds of common opal, as in many other places, but the gems occur in somewhat irregular veins running in a northeast and southwest direction, and with a nearly perpendicular dip. The veins are not continuous, but branch off and disappear at short intervals; neither are the contents of uniform quality, but the valuable parts are usually in belts in the vein, and limited on each side by portions of ordinary opal without play of colors. These lines of light are sometimes numerous and narrow, alternating with the common opal forming a very beautiful gem. Many again, even of large size, are uniform in structure, and exhibit a play of colors as brilliant as the finest opals from Hungary. The hill in which they are found is about two hundred and fifty feet high, and two or three miles in length, and for a width of half a mile for its whole length opals have been found wherever excavations have been made. The rock in which they occur is a hard, brittle trachyte of a vitreous lustre, and splintering into acute fragments when struck; a bed several feet in thickness overlying this rock is of a gray color and soft consistence, and also contains opal veins; it is probably a trachyte changed by atmospheric action.

“Other localities within two leagues of Erandique have furnished very fine opals, but as they are not now worked I did not visit them. Many places on the road between Intibucat and Las Piedras appear favorable to the existence of opal mines; but only careful scrutiny by a number of explorers can discover them. I would mention as most worthy of future attention the vicinity of Lepasale and of Yucusapa and the ascent of the great mountain of Santa Rosa. Greater expectations and indeed almost certain success will attend the search for opal mines in the valley leading from Tambla towards the pass of Guayoca, nearly on the line of the proposed road. Within half a mile of Tambla are immense beds of common opal of various shades of color. Near Guayoca are banded opals of alternate layers of opaque and semi-transparent white, having the appearance of onyx; these occur in a red vitreous trachyte and sometimes in contact with the masses of petrified wood which strew the ground for a considerable distance. Veins of a pearl-colored opal, with red reflections, are also found here; they have no commercial value, but serve as indications of better things in the neighborhood.

“Between the two localities mentioned (that near Tambla and that of Guayoca), Mr. W. W. Wright, chief assistant of the survey, has, by following some obscure indications, arrived at a vein of very pretty glassy opals and yellow fire opals, not of great value, but serving to strengthen the opinion expressed of the ultimate discovery of precious opals in the vicinity. Near Choluteca are found fire opals, some of which I was told possess merit. One (not of the best) given me is precisely similar to those obtained by Mr. Wright near Tambla. Within one league of Goascoran, as I am informed by Fernando Gaillardo, a resident of that town, is a mine producing opals with a good play of colors.”

Another remarkable deposit of opal was found by Mr. Wright about five miles east of Villa San Antonio in the plains of Camayagua. Though not of high value, it may be of use for ornamental purposes, being of a fine red color with transparent amethystine bands. It occurs in veins in gray porphyry, sometimes several inches thick, and may be procured in large quantities. Precious opal has been discovered in the iron mines at Barcoo in Queensland, and a number of specimens were exhibited at Philadelphia, at the Centennial. Some of these specimens were very fair, and gave promise of choice gems. The blue tints displayed by some of them were of great purity. They appeared to be of the hard variety, and therefore less liable to be affected by the ravages of time, or influence of exposure.