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QUANTITY OF SILVER EXPORTED, Catorce, in the Intendancy of San Luis Potosi. Zacatecas, in the Intendancy of the same name. Real del Monte, in the Intendancy of Mexico. Bolaños, in the Intendancy of Guadalaxara. Guarisamey, in the Intendancy of Durango. Sombrerete, in the Intendancy of Zacatecas. Tasco, in the Intendancy of Mexico. Batopilas, in the Intendancy of Durango. Zimapan, in the Intendancy of Mexico. Fresnillo, in the Intendancy of Zacatecas. Ramos, in the Intendancy of San Luis Potosi. Parral, in the Intendancy of Durango.

The veins of Tasco, Tlapujahua, Sultepeque, Moran, Pachuca, and Real del Monte, and those of Sombrerete, Bolaños, Batopilas, and Rosario, have afforded from time to time immense wealth; but their produce has been less uniform than that of the mines of Guanaxuato, Zacatecas, and

Catorce.

The silver extracted in the 37 mining districts into which the kingdom of Mexico or New Spain is divided, is deposited in the Provincial Treasuries, established in the chief places of the Intendancies; and it is from the receipts of these caxas reales that we are to judge of the quantity of silver furnished by the different parts of the country. The following is an account of the receipts of 11 Provincial Treasuries:

From 1785 to 1789, there were received in the Caxas Reales of

Silver-lbs. troy.

Guanaxuato

1,500,000

San Luis Potosi (Catorce, Charcas, San Luis

Potosi)

910,000

Zacatecas (Zacatecas, Fresnillo, Sierra de Pinos)

730,000

Mexico (Tasco, Zacualpa, Zultepeque)

640,000

Durango (Chihuahua, Parral, Guarisamey,

Cosiguiriachi)

545,000

Rosario (Rosario, Cosala, Copala, Alamos)

410,000

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That part of the Mexican mountains which at present contains the greatest quantity of silver, is situated between the parallels of 21 and 24 degrees. The celebrated mines of Guanaxuato are distant, in a straight line, from those of San Luis Potosi, 90 miles only: from San Luis Potosi to Zacatecas the distance is 102 miles; from Zacatecas to Catorce 93, and from Catorce to Durango 222 miles. It is remarkable enough that this metallic wealth of Mexico and Peru should be placed at an almost equal distance in the two hemispheres from the equator.

The silver supplied by the veins of Mexico is

CHARACTER OF ORES.

167

extracted from a great variety of ores, which from the nature of their mixture bear an analogy to those of Saxony, the Harz, and Hungary. The greatest quantity of silver annually brought into circulation, is derived from those ores which the Saxon miner calls by the name of durre erze, especially from sulphuret of silver (or vitreous silver), from arsenical (fahlerz) and antimonial gray copper, from muriate of silver, from prismatic black silver, and from red silver ore. We do not name native silver among these ores, because it is not found in sufficient abundance to admit of any very considerable part of the total produce of the mines of Mexico being attributed to it.

Sulphuret of silver and black prismatic silver are very common in the veins of Guanaxuato and Zacatecas, as well as in the veta Biscaina of Real del Monte. The silver extracted from the ore of Zacatecas exhibits the remarkable peculiarity of not containing gold. The richest gray copper (fahlerz) is that of Sierra de Pinos, and the mines of Ramos. In the latter, the fahlerz is accompanied with glaserz, with variegated copper ore, sulphuret of zinc, and vitreous copper, which is only wrought for the extraction of the silver, without applying the copper to any use. The antimoniated gray copper described by Mr. Karsten is found at Tasco, and in the mine of Rayas, south-east from Valenciana. The muriate of silver, which is so seldom found in the veins of Europe, is very

abundant in the mines of Catorce, Fresnillo, and the Cerro San Pedro, near the town of San Luis Potosi. That of Fresnillo is frequently of an olive green, which passes into leek-green. Superb specimens of this colour have been found in the mines of Vallorecas, which belong to the district de los Alamos in the intendancy of Sonora. In the veins of Catorce, the muriate of silver is accompanied with molybdate of lead and phosphate of lead. From the last analysis of Mr. Klaproth, it appears that the muriate of silver of America is a pure mixture of silver and muriatic acid, while that of Europe contains oxide of iron, alumine, and especially a little sulphuric acid. The red silver ore constitutes a principal part of the wealth of Sombrerete, Cosala, and Zolaga, near Villalta, in the province of Oaxaca. From this ore more than 425,000lbs. troy of silver have been extracted in the famous mine of la Veta Negra near Sombrerete, in the space of from five to six months. It is affirmed that the mine which produced this enormous quantity of metal, the greatest which was ever yielded by any vein on the same point of its mass, was not 16 fathoms in length. The true white silver ore is very rare in Mexico. grayish white variety, very rich in lead, is found, however, in the intendancy of Sonora, in the veins of Cosala, where it is accompanied with argentiferous galena, red silver, brown blende, quartz, and sulphate of barytes. This last substance,

Its

CHARACTER OF ORES.

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which is very uncommon among the lodes of Mexico, is to be also found at the Real del Doctor, near Baranca de las Tinajas, and at Sombrerete, particularly in the mine called Campechana. Fluor-spar has been only found hitherto in the veins of Lomo del Toro, near Zimapan, at Bolaños and Guadalcazar, near Catorce. It is constantly of a grass green or violet blue colour.

In some parts of New Spain, the operations of the miner are directed to a mixture of brown oxide of iron and native silver, disseminated in particles imperceptible to the naked eye. This ochreous mixture is the object of considerable operations at the mines of Angangueo, in the intendancy of Valladolid, as well as at Yxtepexi, in the province of Oaxaca. The ores of Angangueo, known by the name of colorados, have a clayey appearance. Near the surface, the brown oxide of iron is mixed with native silver, with sulphuret of silver, and black prismatic silver (sprodglaserz), all three in a state of decomposition. At great depths, the vein of Angangueo contains only galena and iron pyrites, yielding but a small quantity of silver. Hence the blackish pacos, of the mine of Aurora d'Yxtepexi, which must not be confounded with the negrillos of Peru, owe their richness rather to the glaserz, than to the imperceptible filaments of native dendritic silver. The vein is very unequal in its produce, sometimes sterile, and sometimes abundant. The colorados of Catorce, particularly

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