380 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



Precious opal just as fine as that of Czerwenitza is found under the same conditions at 

 other places in the north of Hungary. It occurs, for example, in a quartz-trachyte at 

 Nagy-Mihdly, east of Kaschau on the Laborcza in the Ujheiy Coraitat. The mineral, 

 however, is not abundant and the occurrence has no commercial importance. The same is 

 also true of other localities in Europe, such as, for example, in the neighbourhood of 

 Frankfurt-on-the-Main in Germany, and at Neudeck in Bohemia ; also in the basalts of the 

 north of Ireland and the Faroe Islands, where precious opal has, on rare occasions, been 

 found with the abundantly occurring common variety. 



There are a few localities outside Europe at which precious opal has been found in 

 considerable amount, but inferior in quality to that found in Hungary, which, in fact, at 

 present is the finest known. These localities, all of which are situated in America and 

 Australia, must now be enumerated. 



The Central American State of Honduras may be first mentioned. The occurrence 

 of opal here is already of some commercial importance, and the resources of the district are 

 apparently not fully exploited. The stones resemble Hungarian opals in some respects, but 

 are usually more transparent and less fiery. Their one undesirable feature is the tendency 

 of the colours gradually to fade when exposed to the air. This, however, is not the case 

 with all stones, and some have been found comparable, both in beauty and in the permanence 

 of their play of colours, to the finest Hungarian opals. The precious opal found in 

 Honduras occurs for the most part in the department of Gracias, in the west of the State, 

 under the same conditions as in Hungary, namely, in a weathered volcanic rock. Here also 

 all the varieties of opal occur in association together, in some districts in masses of gigantic 

 size. The dark-coloured trachyte of the central districts, especially of the depai-tment 

 named above, is penetrated by veins and bands of different varieties of opal, some being of 

 large size and extent. Precious opal is found embedded in these veins and bands at 

 numerous places, and here mines are worked. These mines are usually very inaccessible 

 and far distant from lines of communication, and on this account the deposit is less- 

 extensively worked than is the Hungarian. 



The best known mines are in the neighbourhood of the town of Gracias (Gracias a 

 Dios), others are situated near Intibukat and a few others of importance at Erandique. 

 Here also the mineral resources are undeveloped, and a largely increased yield would probably 

 follow the employment of systematic methods of working. The different varieties of opal 

 occur here in small irregular veins in the trachyte ; these, which are almost vertical, stretch 

 from north-east to south-west, and often divide, or string out, only to reunite further on- 

 The precious opal occurs in isolated plates in the common opal, sometimes interlaminated 

 with this so as to produce an onyx-like stone of peculiar but pretty appearance ; at other- 

 times it is met with in larger masses. Mining operations are carried on principally in a 

 hill of red trachyte three miles long and 250 feet high. For a distance of half-a-mile along 

 this hill precious opal has been found at every point where search has been made. Mines 

 have also been sunk in the neighbourhood of Erandique, but the deposits have nowhere been 

 systematically worked. 



At the places hitherto mentioned, opal is actually known to occur and has indeed been 

 mined there. There are other places, however, in this country where opal has not been 

 actually found, but where all the conditions point to its probable existence. There are some 

 such promising localities between Intibukat and Las Pcdras, also in the neighbourhood of" 

 Le Pasale and Yukusapa, and on the slopes of the large mountain of Santa Rosa. The 

 opal mines in the valley between Tamba and the Pass of Guayoca also give promise of an. 

 abundant yield, large masses of opal of all kinds having been found. Among these different 



