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 striae 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 which would have rivaled the superb prism found at Mouzzinskaia, and which the Russians value so highly. The extended and unexplored ledges of granite which rise from the shores of the ocean at Harpswell in Maine, and stretch north-westward for nearly a hundred miles, quite to the base of the White Mountain group, are not only rich in beryls, but they contain many of the rarest minerals known to the mineralogist. And perhaps there is no other field of equal extent in the country which offers to the mineralogist such a harvest of the rare and curious productions of the mineral kingdom.
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 yellow varieties) is sometimes greater. 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."
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 jewelers 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. Jewelers are governed generally by sight, which they believe to be infallible, whilst hardness and specific gravity are the only sure tests.
Artificial gems rivaling 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 employ a thousand persons, and fabulous quantities of the glittering pastes are 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 lustrous are they than modern glass. The ancient Phoenician 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.