MINES 285 



extent, but it comprehends the rich workings of Pachuca, Real del Monte, and Moram. 

 The district of Real del Moute contains only a single principal vein, named Veto, Bezi- 

 oana of Real del Monte, in which there are several workings ; it is, however, reckoned 

 among the richest of Mexico. 



4. The group of Zimapan. It is very near the preceding, about 40 leagues north 

 of Mexico, towards the eastern slope of the plateau. Besides numerous silver 

 mines, it includes abundant deposits of lead, and some mines of yellow sulphuret 

 of arsenic. 



5. The Central group, of which the principal point is Guanaxuato, a city of 70,000 

 inhabitants, placed at its southern extremity, and 60 leagues NN.W. of Mexico. It 

 comprises among others the famous mine districts of Guanaxuato, C'atorce, Zacatccas, 

 and Sombrerete ; the richest in Mexico, which alone furnish more than half of all the 

 silver which this kingdom brings into circulation. 



The district of Guanaxuato presents only one main vein, called the Veto, Madre. This 

 vein is enclosed principally in clay-slate, to whoso beds it runs parallel, but occa- 

 sionally it issues out of them to intersect more modern rocks. The vein is composed 

 of quartz, carbonate of lime, fragments of clay-slate, &c. ; and includes thesulphurets of 

 iron, of lead, and of zinc in great quantities, some native silver, sulphide of silver, and 

 red silver ; its power (thickness of the vein) is from 43 to 48 yards. It is recognised 

 and worked throughout a length of upwards of three leagues, though the principal 

 workings are within 2,000 yards ; and contains 19 exploitations, which produced an- 

 nually nearly 1,200,000^. in silver. One of the explorations, that of Valenciana, 

 produces 320,000/. ; being equal to about one-fifteenth of the total product of the 3,000 

 mines of Mexico. Since 1764, the period of its discovery, its nett annual product has 

 never been less than from two to three millions of francs (80,000^. to 120,OOOZ.) ; and 

 its proprietors, at first men of little fortune, became, in ten years, the richest indivi- 

 duals in Mexico, and perhaps in the whole globe. 



The workings of this mine are very extensive, and penetrate to a depth of 2,000 feet. 



The district of Zacatecas presents in like manner only a single vein in greywacke ; 

 which, however, is the seat of several workings. 



The deposits mined at Catorce are in limestone ; the mine called Purissima de 

 Catorce has been explored to about 650| yards in depth ; and yielded in 1796 nearly 

 220,000^. There are also mines of antimony in the district of Catorce. 



Since the year 1824, several English companies, on a large scale, have undertaken 

 the working of some of the Mexican silver mines. Of late years many of them have 

 been fairly successful. 



Towards the western part of the group of which we are now speaking, copper mines 

 are worked in the provinces of Yalladolid and Guadalaxara ; the ores being chiefly 

 composed of suboxide of copper (ruby copper), sulphide of copper, and native 

 copper. These mines produce about 2,000 metric quintals of copper annually 

 (440,000 Ibs. English). In the same district, ores of tin are collected in the alluvial 

 soils, particularly near Mount Gigante. The concretionary oxide of tin, so rare in 

 Europe, is here the most common variety. This metal occurs also in veins. 



The central part of Mexico contains many indications of sulphide of mercury 

 (cinnabar); but in 1804 it was worked only in two places, and to an inconsiderable 

 extent. 



6. The group of Neu Gallicia is situated in the province of this name, about 1 00 

 leagues N.W. from Mexico. It comprises the mines of Bolanos, one of the richest 

 districts. 



7. The group of Durango and Soaora, in the iutendancies of the same name. It is 

 very extensive. The mines are situated in part on the table-land, and in part on the 

 western slope. Durango is 140 leagues NN.W. of Mexico. Tin ore is found here. 



8. The group of Chihuahua. It takes its name from the town of Chihuahua, situated 

 100 leagues N. of Duraugo. It is exceedingly extensive, but of little value; and ter- 

 minates at 29 10' of north latitude. 



Mexico possesses, besides, several mines which are not included in the eight 

 preceding groups. Thus the provinces of New Leon and of New Santander present 

 abundant ores of lead. New Mexico contains copper mines and many others. 



Lastly, rock-salt is mined in several points of New Spain ; and coal seems to occur 

 in Now Mexico. 



The richness of the different districts of the silver mines or reales is extremely un- 

 equal. Nineteen-twentieths of these reales do not furnish altogether more than one- 

 twelfth of the total product. This inequality is owing to the excessive richness of 

 some deposits. The ores of Mexico are principally in veins ; beds and masses are 

 rare. The veins traverse chiefly, and perhaps only, igneous anil transition rocks, 

 among which certain porphyries are remarked as very rich in deposits of gold and 

 silver. The silver ores are mostly sulphide of silver, black antimoniatcd sulphide 



