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.