make artificial opals closely resembling the real; but the art has never been fully recovered, and we may hope it never will be. Hence, however much danger there may be in buying an opal that has not been properly " seasoned," or one that may lose its play of color, the purchaser may at least be sure he has an opal and not an imitation. The stones are usually cut in the cabochon form, this cutting being found to bring out their brilliancy better than any facetted form. The brilliancy of the stone may be increased in setting by giving it a backing of mother-of-pearl, or black silk. When a number of opals are placed together they seem to borrow brilliancy from one another, a fact which is taken ad­vantage of in settings by placing a number together, and also by opal dealers to dispose of inferior stones by grouping them with good ones. For this reason when opals are purchased they should be examined sep­arately. The value of opals depends almost wholly on the brilliancy of their coloring and their size. Stones without the play of colors are prac­tically worthless, while stones of ten to twenty carats' weight, with bril­liant coloring, may bring several hundred dollars. The most highly valued opals have long come from the mines qi Czernowitza, in northern Hungary. These opals are often known as Oriental opals, from the fact that in early days they were first purchased by Greek and Turkish mer­chants, and by them sent to Holland. There are, however, no known localities in the Orient where precious opals are found. The rock in which the Hungarian opals occur is eruptive, and of the kind known as andesite. It is considerably decomposed, and the opal occurs in clefts and veins. There is little doubt that it was from these mines that the Romans obtained the opals known to them, and the output has been quite constant since. It is said that the Hungarian opals are less likely to deteriorate than any others. Still the danger of deterioration is not great in any opal. The other important countries from which precious opals are obtained, are Mexico, Honduras, and Australia. The Mexican opals are mostly of the fire opal variety. They are mined in a number of the States of the Republic—Queretaro, Hidalgo, Guerrero, Michoacan, Jalisco, and San Luis Potosi. The oldest mines are in the State of Hidalgo, near Zimapan, where the opal occurs in a red trachyte. Most of the Mexican opals on the market at the present time, however, come from the State of Queretaro, where mining for them is conducted on an extensive scale. The opal here occurs in long veins, in a porphyritic trachyte, and is mined at various points. The stones are cut and polished by workmen in the city of Queretaro, who use ordinary grind­stones and chamois skins for the work, and are said to receive an aver­age wage of twenty-three cents a day. The Honduras opals reach 162