Leisure hours among the gems

by Augustus C. Hamlin

The boiling waters of the Iceland geyser are projected into the air at a considerable height, and are heavily charged with silica. As the waters fall upon the earth, large piles of earthy and stony material are formed in process of time. When these silicious masses are broken open, translucent and transparent portions of silica are found, exhibiting the colored reflections of the noble opal as long as they remain hydrated, or, in other words, as long as they retain a certain quantity of water in their composition. This observation has led M. Descloizeaux to the belief that opals found in volcanic rocks or igneous rocks have had their origin in phenomena analogous to those of the Iceland geysers. The matrix of the opal is a varied one. The gem is not only found in porcelain earth, but it occurs in fissures and seams, in what appear to be old igneous rocks. It has also been deposited in recent periods, as in the limestones of the argillaceous beds, and even in the formations of the silicious waters of the hot springs of the present time. The decomposed cement of the old Roman ruins around the hot springs of Polombieres, uniting with certain chemical properties of the waters, has changed into opal and hyalite. Trees within historic times have been transformed into opal or semi-opal; and on the island of Unja one may see blocks and trunks of trees (some even showing the marks of the hatchet) converted into opal. Silicified trees forty or fifty feet in length, may be seen stretched from Cairo to Suez. In many other parts of the world trees and plants have been transformed by the mysterious processes of nature into a silicious substance possessing the characters of opal; but none of these vegetable metamorphoses exhibit the rainbow hues to any marked degree. Quartz, when flawed in the interior, sometimes exhibits a remarkable iridescence, and may imitate the opal, especially if viewed at a distance. Such specimens of iridized quartz are called “iris,” and they may be artificially produced by a sudden blow upon the stone, or by heating it and suddenly dropping it into cold water. The superb iris ornaments worn by the Empress Josephine were of remarkable brilliancy and play of colors. In ancient and mediæval times, iridescent quartz was held in great esteem; and fine specimens mounted in antique jewelry are preserved at the present day. It is described in the “Lapidarium” of Marbodeus as follows:—

“By the Red Sea the swarthy Arabs glean
The iris, splendent with the crystal’s sheen;
Its form six-sided, full of heaven’s own light,
Has justly gained the name of rainbow bright.”

The fire opal occurs in its greatest perfection in the porphyritic rocks at Zimapan in Mexico. It is generally of a translucent hyacinth-red color and flashes forth dazzling beams of fiery carmine-red with yellow and green reflections. This Mexican gem is the most beautiful and gorgeous of all the varieties of opal; but, alas! it is also the most sensitive, and is frequently irreparably injured by water or exposure, or even by sudden atmospheric changes. So easily affected are the opals by the vicissitudes of the weather that they are almost always brighter in summer than in winter. But there are some varieties that are not so easily influenced, and are not injured by contact with water. The fact that this variety of opal is injured in course of time by contact with moisture or careless exposure is not remarkable when some of the harder gems undergo a change from similar exposure. The hard amethystine quartz, when worn as a finger ornament, will completely bleach out and become colorless in a few years. The black opal is the product of art, and for this purpose harlequin opals are used. The harlequin opal is simply the matrix of other gems spotted here and there with flakes of color dispersed over an opaque ground, and its name was suggested by the resemblance to the motley tints of the harlequin’s dress. Masses of the matrix, with fragments or specks of opal interspersed in its substance, are soaked for a time in a saccharine solution, and afterwards in diluted sulphuric acid. The porous parts of the matrix absorb a minute quantity of the solution, which is afterwards charred by the sulphuric acid; while the solid and transparent parts remain unchanged and exhibit an increased play of colors upon the black ground.

The ancients undoubtedly obtained their opals from Syria and Arabia or other Eastern countries, for the Hungarian mines which now supply the world with most of the finest gems were not discovered until the fifteenth century. The famous mines are situated on a mountain which is one of the spurs of the Carpathians. They belong to the Seignory Peklin, and are near the village of Czernizka. In the early days of their discovery, and for a long period afterwards, they were explored casually and from time to time. At the present day, however, the explorations are conducted with regularity and the appliances of skilled labor. The surface of the mountain has been removed to a great extent during this long-continued search of many centuries, but as yet no explorations have been attempted into the interior of the ledges. The true matrix appears not to be more than four to eight yards in depth below the alluvial soil. It is arranged in continuous beds of little hardness, but resembling porphyry in color. The opal formation appears to extend to a considerable distance beyond the flanks of the mountain; for, in the cultivated fields below, the laborers often find beautiful gems washed out by violent rain-storms from the exposed and superficial soils.

The opals from these mines are the hardest and most enduring of all the known localities of the earth, yet they have to be carefully tempered to heat and moisture before they can be utilized. M. Frangoll Delius, the Commissioner of the Austrian mines, states that these opals, when first extracted from their rocky beds, are soft, friable, and tender, and not in a condition to be worked. But after they have been exposed to the air and sunlight for some days or a definite time, they become harder, and the stones also become decidedly smaller from contraction. This exposure is required to be carefully regulated lest the stone become fissured by sudden contraction. When exposed to the effects of artificial heat, colors appear sooner than when it is submitted to the action of the sun’s rays. It is curious to watch the gradual unfolding and the display of these beautiful hues. At first the stone is limpid and rayless as pellucid quartz. But as the quarry water is evaporated by the effect of heat or time, and the stone contracts in volume, the iridized reflections then begin to appear, increasing in perfection and variety, until the requisite degree of moisture is expelled. If this evaporation is carried too far by heat the splendors of the gem vanish completely, never to be recalled. It is a singular fact that exposure to the sun’s rays gives the opal much finer hues than the action of artificial heat. And it is also a remarkable circumstance that of all the variety of prismatic hues displayed by this gem, the violet invariably appears the first, according to M. Delius.

The ancients rarely engraved upon the opal, influenced perhaps partly from its enormous value in those times, and partly from its soft and fragile nature. They imitated the gem, however, with such perfection that Pliny declared that it was almost impossible to distinguish the false from the real. Modern gem imitators have utterly failed in producing anything approaching the precious opal in beauty. The assertion of Pliny in regard to the imitation of the glories of this gem has always been received with incredulity by the moderns on account of the failures of our most skilled artisans; but the discoveries among the ancient Phœnician tombs in the island of Cyprus by Di Cesnola rather strengthen Pliny’s remark.

In this collection we may view a great and elegant variety of glass-ware exhumed from the tombs of the Phœnician nobility who lived three thousand years ago or more. Many of these vessels gleam with what appear to be iridescent tints of gold, blue, red, and other colors of the loveliest tints, recalling to mind the most beautiful and gorgeous reflections of the opal. Some of the articles are entirely of one color, while others are composed of patches of various hues resembling enormous opals with broad gleams of pure color. Peligot maintains that these superb colors are clue to the effect of great age; and the substance of the glass being separated into laminæ, the colors may be explained by the law of iridescence. But we are half inclined to believe that they may be due to the skill of the artisan in a great measure,—hence the variety of color in different vessels of the same age. In the famous collection of Signor Castellani there is a solid glass ring quite two inches in diameter taken from the ancient Etruscan tombs. This interesting relic exhibits patches of color as bright as the prismatic gleams, and they do not appear to arise from any disintegration of the material, but rather to be produced by the design of the workman. We surely will not ascribe to effect of age the decided iridescent glaze which we see in the Maiolica pottery of Hispano-Moresque objects of the thirteenth or fifteenth centuries, or in the Gubbio products of the sixteenth century.

The famous opal of history was that which was worn in a ring by the Roman Senator Nonius in the days of the Triumvirate. Its size scarcely exceeded that of a hazel-nut, yet its beauty and perfection were such that it was considered a marvel among the dilettanti of Rome, and valued at the enormous sum of nearly a million dollars. Marc Antony, remembering the sacrifice of the matchless pearl by Cleopatra, and still enslaved by her irresistible charms, sought to obtain the opal, intending it as a present to the siren queen of Egypt. But Nonius refused to part with the treasure which was the idol of his heart, and sought safety in flight. The beauty and charm of the gem may be estimated by the fact that banishment then to a Roman was worse than death. History makes no further mention of this wonderful opal, and even if preserved among the spoils of ancient Byzantium its glories have probably vanished ere this, yielding to the destructive effects of time.

The finest opal of modern times was that which was worn by the Empress Josephine in the days of Imperial splendor. It was indeed a magnificent gem. Its flashing beams of light were so strong and vivid as to give the appearance of living flames of fire, and hence the name of l’incendie de Troie,—“the burning of Troy,”—was bestowed upon it. The base of this opal was completely opaque, but the superior portion was perfectly transparent, and through it were reflected a multitude of fiery gleams of red light. The fate of this beautiful gem is unknown. There are two splendid opals still to be seen among the Crown jewels of France, notwithstanding the frequent change of dynasties. One is placed in the centre of the Order of the Toison d’Or, and the other forms the clasp of the royal mantle.

In the imperial cabinet at Vienna is exhibited the grandest specimen of this gem yet discovered. It was found in the mines of Hungary in 1770, and purchased by the Austrian Government. It measures 3³⁄₄ inches in length, and is 2¹⁄₂ inches in thickness. Its weight is about seventeen ounces, and its value is estimated at about $300,000. Although it is injured by several cracks and fissures, it possesses a brilliant play of color, and is justly regarded as the finest specimen known, even surpassing the beautiful fire opal brought home from Mexico by Humboldt, and which is still preserved in the museum at Berlin.