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by the super position of strata of basalt, amygdaloid, porphyry with greenstone base, and other rocks, comprehended by geologists under the general name of trapp-formation.

With respect to the Mexican mines in particular, they may be considered as forming eight groups (Erz-refiere), which are almost all placed either on the ridge or on the Western slope of the Cordillera of Anahuac. The first of these groups is the most considerable in produce; it includes the contiguous districts of Guanaxuato, San Luis Potosi, Charcas, Catorce, Zacatecas, Asientos de Ybarra, Fresnillo, and Sombrerete. The mines situated to the West of the town of Durango, as well as those of the province of Cinaloa, belong to the second; for the mines of Guarisamey, Copala, Cosala, and Rosario are near enough to one another to be classed under the same geological division. The third group, the most northern of New Spain, is that of Parral, which comprehends the mines of Chihuahua and Cosiguiriachi. It extends from the 27° to the 29° of latitude. To the northnorth-east of Mexico, the Real del Monte or Pachuca, and those of Zimapan, or the Doctor, may be stiled the fourth and fifth groups. Bolaños (in the Intendancy of Guadalaxara), Tasco, and Oaxaca are the central points of the sixth, seventh, and eighth groupes of mines of New Spain. This general view is sufficient

to prove that this kingdom, like the antient Continent, contains vast extents of country, apparently almost totally destitute of metalliferous veins. No considerable operation has been hitherto carried on in the Intendancies of Puebla and Vera Cruz, or in the plains of secondary formation, situated on the left bank of the Rio del Norte, or in New Mexico.

The following table indicates not the relative wealth, or unequal distribution of the metals, considered in a geographical point of view, but the quantity of money, which in the present state of the mines is extracted from the different parts of the kingdom of New Spain. We have classed the mines according to the order already laid down, indicating the name of the chief place which is the central point of the group, and the surface of the country in which the different works are to be found. Several groupes are naturally divided into districts, which form so many subdivisions or particular systems.

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Mean Produce of the Mines of New Spain, including the Mines of the northern part of New Biscay, and those of Oaxaca, above

Marcs of silver.

2,500,000

We shall afterwards compare the produce of the silver mines of Mexico, with that of the different mines of Europe. It will suffice in this place to observe, that the two millions and a half of marcs of silver annually exported from Vera Cruz, are equal to two thirds of the silver annually extracted from the whole globe. The eight groups into which we have divided the mines of New Spain, occupy a surface of 12,000 square leagues, or a tenth of the whole extent of the kingdom. When we look at the immense wealth of a very small number of mines, for example, the mine of Valenciana, and that of Reyas at Guanaxuato, or the principal veins, (vetas madres) of Catorce, Zacatecas, and Real del Monte, we easily perceive that more than 1,400,000 marcs of silver are produced in an extent of surface, not equal in size to that of the district of the mines of Freiberg.

If the quantity of silver annually extracted from the mines of Mexico is ten times greater than what is furnished by all the mines of Europe, on the other hand, gold is not much more abundant in New Spain than in Hungary and Transylvania. These two last countries annually throw into circulation nearly

5,200 marcs; and the gold delivered into the mint of Mexico, only amounts in ordinary years to 7000 marcs. We may reckon that in times of peace, when the want of mercury does not impede the process of amalgamation, the annual produce of New Spain is,

In Silver, 22 millions of Piastres

In Gold, 1

23

The Mexican gold is for the most part extracted from alluvial ground, by means of washing. These grounds are common in the province of Sonora, which as we have already observed *, may be considered as the Choco of North America. A great deal of gold has been collected among the sands, with which the bottom of the valley of the Rio Hiaqui, to the east of the missions of Tarahumara, are covered. Farther to the north in Pimeria Alta, under the 31° of latitude, lumps of native gold (pepitas) have been found of the weight of from five to six pounds. In these desert regions, the incur-sions of the savage Indians, the excessive price of provisions, and the want of the necessary water for working, are all great obstacles to the extraction of gold.

Another part of the Mexican gold is extracted from the veins, which traverse the pri-· mitive mountains. The veins of native gold

*Vol. ii. p. 299.

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