Major Macdonald gives the following account of a new field for the turquoise which he discovered in Arabia Petræa. ‘In the year 1849, during my travels in Arabia in search of antiquities, I was led to examine a very lofty range of mountains, composed of iron sandstone, many days’ journey in the desert; and whilst descending a mountain of about six thousand feet high, by a deep and precipitous gorge, which in the winter time served to carry off the water, I found a bed of gravel, where I perceived a great many small blue objects mixed with the other stones; on collecting them I found they were turquoises of the finest colour and quality. On continuing my researches through the entire range of mountains, I discovered many valuable deposits of the same stones, some quite pure in pebbles, and others in the matrix. The action of the weather gradually loosens them from the rock, and they are rolled into the ravines, and, in the winter season, mixed up by the torrents with beds of gravel, where they are found.’
The Occidental or Bone Turquoise, which has generally but one-fourth of the value of the oriental, is said to be fossil bones or teeth, coloured with oxide of copper.
The Garnet, a silicate of some base which may be lime, magnesia, oxide of iron, or chromium, is in its finer specimens one of the most beautiful coloured products of nature’s laboratory. By jewellers the garnets are classed as Syrian, Bohemian, or Cingalese, rather from their relative value and fineness than with any reference to the country from which they are supposed to have been brought. Those most esteemed are called Syrian garnets, not because they come from Syria, but after Syrian, the capital of Pegu, which city was formerly the chief mart for the finest garnets. Their colour is violet purple, which in some rare instances vies with that of the finest oriental amethyst; but it may be distinguished from the latter by acquiring an orange tint by candlelight. The Bohemian garnet is generally of a dull poppy-red colour, with a very perceptible hyacinth orange tint, when held between the eye and the light. When the colour is a full crimson, it is called pyrope or fire-garnet, a stone of considerable value when perfect and of large size. Garnet is easily worked, and when facet-cut is nearly always (on account of the depth of its colour) formed into thin tables, which are sometimes concave or hollowed out on the under side. Cut stones of this latter kind, when skilfully set, with a bright silver foil, have often been sold as rubies.
Though Lapis Lazuli, a silicate of soda, lime, and alumina, with the sulphide of iron and sodium in minute quantities, is without transparency, and without much lustre, yet its beautiful azure-blue tints, often interspersed with yellow specks, and veins of iron pyrites, which, from their brilliant appearance in the comparatively dull blue stone, might easily be mistaken for gold, entitle it to be ranked among the semi-precious stones. The finest quality, which sells in the mass for 30l. per pound, is used for jewellery, and for making costly vases and ornamental furniture. Lapis lazuli was also the source from which the beautiful pigment ultramarine was obtained; but this colour is now prepared artificially at a very cheap rate. This beautiful mineral is found in crystalline limestone of a greyish colour on the banks of the Indus, and in granite in Persia, China, and Siberia.
In the long list of the crystalline or hyaline quartzes, consisting of silex or silica in various degrees of purity, there is but one variety, the Noble Opal, that ranks among precious stones of the first quality. In this beautiful gem, minute fissures are apparently striated with microscopic lines, which, diffracting the light, flash out rainbow tints of the purest and most brilliant hues. The Noble Opal, which is one of the favourite jewels of modern times, was no less highly esteemed by the ancients, ‘for in this stone,’ says Pliny, ‘we admire the fire of the ruby, the brilliant purple of the amethyst, the lustrous green of the emerald, all shining together in a wonderful mixture.’ For the sake of a magnificent opal, set in a ring, and valued at 20,000l. of our money, the senator Nonius was exiled by Mark Antony. He might have escaped banishment by presenting his opal to the covetous triumvir; but he preferred exile with his gem to staying in Rome without it.
The Precious Opal is so rare a stone that, with all our mining enterprise and geological research, we know of only two certain localities for it, namely, in Hungary and in Mexico, though some specimens are said to have been found in the province of Honduras and in the stormy Feroe Islands. The opal mines of Hungary, situated at Czernewitza, in the county of Saros, belong to the Crown, and are at present farmed by Herr Goldschmidt of Vienna, for 10,000 florins annually. About 150 workmen are employed, and as good stones occur but rarely, and are of a corresponding value, it may easily be imagined that, what with the constant fear of being robbed, and that of not being able to cover his expenses, poor Herr Goldschmidt is no less to be pitied than Governor Pitt while in possession of his diamond.
The finest and largest opal in the world is in the Imperial Mineralogical Cabinet in Vienna. It has the most magnificent play of colours, chiefly green and red, weighs seventeen ounces, and is irregularly cut, so as not to diminish the mass. An Amsterdam jeweller is said to have offered half a million of florins for this unique gem. Unfortunately, its large size prevents its being used as an ornament, as for this purpose it would have to be cut to pieces, which would be an unpardonable piece of Vandalism.
Their relative beauty increases the value of opals so considerably that fine stones of a moderate bulk have, in modern times, been frequently sold at the price of diamonds of equal size. The so-called ‘Mountain of Light,’ an Hungarian opal in the Great Exhibition of 1851, weighed 526½ carats, and was estimated at 4,000l. The black opals, which allow the red fire of the ruby to flash out from the dark ground-colour of the stone, are also highly esteemed. Besides the commoner varieties of opal, such as semi-opal, opal jasper, wood opal, different kinds of quartz crystal, including amethyst, Cairngorm stone, and a long and beautiful array of jaspers and chalcedonies, such as agate, onyx, sard, plasma, and chrysoprase, may be placed in a list of stones of the second degree in point of value, if that value be estimated by rarity and price.
The cutting, or grinding and polishing of most of these stones, which are commonly comprised under the name of agates, is chiefly carried on in the small towns of Oberstein and Idar, situated in the picturesque valley through which the rapid Idar flows into the Nahe, a tributary of the Rhine. The sterile soil yields but a scanty produce, but the neighbouring hills abound in chalcedonies, which afford the people an ample indemnity[indemnity] for the barrenness of their land. As early as the fourteenth century, the art of agate-cutting was introduced into this remote valley, from Italy, where it had long been practised; but for a long time the trade was conducted in a very rude manner. The workmen themselves undertook the sale of their ware, and wandered as pedlars to the neighbouring castles or towns, where they could hope to dispose of their agates to the best advantage. It was not before the middle of the last century that the industry of Oberstein made a considerable progress. Gold and silversmiths settled in the small town to set the stones as they came out of the hands of the grinders, and gradually a more wealthy class of traders was formed, who undertook long voyages, and extended their operations to distant countries. The fairs of Frankfort and Leipzig were regularly attended by the merchants of Oberstein and Idar, and some of them even ventured as far as Smyrna or Archangel. The taste and the ability of the workmen improved as their market extended, but now the want of the raw material began to be felt. The neighbouring hills were no longer able to meet the demand, the stones continually rose in price, the better qualities could hardly be procured, and thus the agate manufactory was menaced with decline, when a fortunate circumstance gave it a new impulse.
Some of the inhabitants of Idar who in 1827 had emigrated to Brazil discovered in their new home an inexhaustible supply of stones. Enormous masses of chalcedony were found scattered as boulders near the banks of some rivers or disseminated in the plains, and could be sent as ballast at a trifling expense across the ocean. Thus almost all the rough material that Oberstein needs comes at present from Brazil or even India, and only the rarer varieties of agate-jaspis are at present collected in the neighbourhood of Idar. In possession of the best materials, supplied by a number of localities, and comprising all imaginable varieties of chalcedony—carnelion, plasma, heliotrope, jaspis, rock-crystal, amethyst, topaz, lapis lazuli, malachite—and commanding a market which extends further and further over the globe, the prosperity of Oberstein and Idar steadily increases. One hundred and eighty-three water-mills (with 724 large grinding-stones), situated along the romantic Idar, give employment to about 3,000 workmen, and the value of the manufactured stones amounts to at least 220,000l. annually.