No stones are so porous or so easily coloured by artificial means as the varieties of chalcedony. In ancient times the onyxes from the Nerbudda were ‘baked in ovens,’ and to this day, in the neighbourhood of Brooch, the nodules of onyx dug in the dry season from the beds of torrents are packed in earthen pots with dry goat’s-dung, which is set on fire. By this baking process the grey or dark green iron hydrate which permeates their pores and gives them a dull colour is changed into the red oxyde, which imparts to the improved stones rich hues of orange and hyacinthine red, and the more ornamental of the mottled onyxes that come from Cambay are those thus artificially beautified.

The art of baking and colouring is now fully understood in Oberstein. Some agates consist of impermeable white bands or layers alternating with others of a grey or dull colour, and of a porous nature. When placed in honey and exposed to a moderate heat for eight or ten days, the saccharine matter penetrates into the microscopical pores. Then the stones are boiled in sulphuric acid, which, carbonising the honey, imparts a deep black colour to the porous layers which it had permeated, and by thus setting-off the white layers to the best advantage, changes a previously almost worthless stone into a beautiful onyx or sardonyx. An Italian who came to Oberstein to buy rough agates for the cameo-cutters of Rome made the Germans acquainted with this method, which had long been practised by his countrymen. By other chemical processes, some of which are generally known, while others are kept a secret, rich yellow, or apple-green, or blue tints are imparted by the agate-dealers of Oberstein to the rough produce of nature. A description of all the varieties of quartz used for ornamental purposes would lead me too far; but a few words on rock-crystal may not be uninteresting.

This beautiful mineral occurs in many varieties, such as the violet, rock-crystal, or amethyst, the most beautiful specimens of which are procured from India, Ceylon, and Persia; the false topaz when yellow, the morion when black, the smoky quartz when smoke-brown. The limpid and colourless kinds are often called Bristol or Irish diamonds, after the various localities in which they are found. Rock-crystal frequently occurs in the Alps, as is well known to every traveller in Switzerland. Small rock-crystals have hardly any value, but considerable prices are paid for very large specimens, which are accordingly much sought for by chamois-hunters and goatherds. About a century since a quartz cave was opened at Zinken, which afforded 1,000 cwt. of rock-crystal, and at that early period brought 300,000 dollars. One crystal weighed 800 pounds.

In 1867 a party of tourists, descending from the solitudes of the Galenstock, discovered, in a band of white quartz traversing a precipitous rock-wall about a hundred feet above the Tiefen Glacier, some dark spots which the guide, Peter Sulzer, of Guttannen, declared to be cavities in which undoubtedly rock-crystals would be found. The weather being unpropitious, no search was made at the time; but a few weeks after Sulzer and his son revisited the spot, and after having clambered up to the holes with great difficulty, found that they communicated with a dark cavity, from which the intrepid explorers extracted some pieces of black rock-crystal with the curved handles of their alpenstocks.

In the August of the following year the Sulzers, accompanied by a few friends from Guttannen, to whom they had imparted the secret, made a more decisive attempt to force their way into the cave, by widening the entrance with gunpowder. To clamber and maintain one’s position on a nearly vertical rock on ledges only a few inches broad is at all times a matter of no small difficulty; but this difficulty is very much increased when at the same time the hammer and other implements for blasting are to be handled. The weather was also very bad, and every now and then a dreadful gust of wind threatened to hurl the hardy adventurers from the rock upon the glacier. Hail and rain stiffened their limbs; and thus they passed a miserable night closely huddled together on a narrow projection before the cavity. Wet to the skin, and their teeth chattering with cold, they resumed their labours on the following morning, and at length sufficiently widened the entrance to open a passage into a cave which was found to penetrate to a considerable depth into the mountain. The cave was filled nearly up to its roof with a mound consisting of pieces of granite and quartz mixed with chlorite sand; but here and there, imbedded in the rubbish, glistened the large planes of jet black morions which showed that their toil had not been fruitless. Originally the crystals had grown from the sides or the roof of the cave; and who can tell the ages that were required for their formation, or the mysterious circumstances that favoured their growth?—then at an equally unknown time the concussion of an earthquake, or maybe their own weight, had detached them from the rock to which they clung, and precipitated them upon the floor. Upon the whole more than a thousand large crystals were found in the cave, many of them weighing from fifty pounds to more than three cwt.

After the first explorers had collected about a ton, the whole able-bodied population of Guttannen, provided with hammers, spades, ropes, baskets, and trucks, came forth to carry away the remainder. As the report had spread that the Canton of Uri, on whose territory the cave was situated, intended to stop their proceedings, they worked night and day with feverish haste, and in the space of a week had entirely stripped it of its treasures, which were partly conveyed to the new Furca Road, and partly transported over the glaciers to the Grimsel. One of the party fell into a crevice with a crystal of a hundred pounds upon his back, but extricated himself, though he was obliged to abandon his prize. Thus when the authorities from Uri made their appearance on the spot nearly all the crystals had been removed out of their reach. Seven of the finest specimens, each rejoicing in an individual name, like the mammoth-trees of America, now form a magnificent group in the museum of Berne, to which they were sold for 8,000 francs. The ‘king,’ 32 inches high and 3 feet in circumference, weighs 255 pounds; the 'grandfather,’ though of inferior height, makes up for this deficiency by a superior girth, and weighs 276 pounds. Many other fine crystals were sold to various museums and private collections for six or seven francs per pound, so that Sulzer’s discovery will long be gratefully remembered in the annals of the poor village of Guttannen.

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