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Sec. III, Ch. 10: The Opal

Sec. III, Ch. 10: The Opal Page of 366 Sec. III, Ch. 10: The Opal Text size:minus plus Restore normal size   Mail page  Print this page
218                                   The Opal.
has the curious property of improving by the warmth of the hand, which brings out the brilliant tints for which this stone is so famed.
HUNGARIAN OPALS.
The Precious Opal, used in jewellery, was formerly obtained almost exclusively from Hungary. It was called Oriental Opal by the Greek and Turkish merchants, who obtained it from the celebrated mines near Czerwenitza, and then carried it to the East for the purpose of giving the title Oriental to it, which always conveyed a sense of goodness and value to stones.
The Hungarian Opal was found in the Tokai-Esperieser mountains, not far from Czerwenitza, the principal mines being in the Libanka mountain, west of Dubnik. It is believed that it was from this district that the ancient Romans obtained their Opal. The matrix of the gem is an old lava of brown or grey colour, known as andésite. In the clefts and cavities of this rock, especially in the decomposed part, the Opal is irregularly distributed as veins and nests. It is probable that alkaline thermal waters, from volcanic sources acted upon the rock, decom­posing some of its silicates and setting free the silica, which was deposited from the solution in a gelatinous condition and solidified in the form of Opal.
The opal mountains have been extensively worked by subterranean galleries of great extent ; the rock being brought down by blasting, and the shattered fragments then carefully picked over by hand. Most of the Hungarian Opal is of the common variety, and specimens displaying vivid colours fit for jewellery are comparatively rare.
There is, in the Imperial Cabinet of Vienna, an Opal
Sec. III, Ch. 10: The Opal Page of 366 Sec. III, Ch. 10: The Opal
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