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CHAPTER XII.

Intendancy of Zacatecas-extent-towns-mines-geolo

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THIS singularly ill-peopled province is a mountainous and arid tract, exposed to a continual inclemency of climate. It is bounded on the north by the intendancy of Durango, on the east by the intendancy of San Luis Potosi, on the south by the province of Guanaxuato, and on the west by that of Guadalaxara. Its greatest length is 255 miles, and its greatest breadth, from Sombrerete to the Real de Ramos, 153 miles.

The intendancy of Zacatecas is nearly of the same extent with Switzerland, which it resembles in many geological points of view. The relative population is hardly equal to that of Sweden.

GEOLOGICAL STRUCTURE.-TOWNS.

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The table-land which forms the centre of the intendancy of Zacatecas, and which rises to more than 6561 feet in height, is formed of syenites, a rock on which repose, according to the excellent observations of M. Valencia, strata of primitive schistus and schistous chlorites (chlorith-schiefer). The schistus forms the base of the mountains of grauwacke and trappish porphyry. North of the town of Zacatecas are nine small lakes, abounding in muriate, and especially carbonate, of soda. This carbonate, which, from the old Mexican word tequixquilit, goes by the name of tequesquite, is of great use in the dissolving of the muriates and of the sulphurets of silver. M. Garces, an advocate

of Zacatecas, has recently fixed the attention of his countrymen on the tequesquite, which is also to be found at Zacualco, between Valladolid and Guadalaxara, in the valley of San Francisco, near San Luis Potosi, at Acusquilco, near the mines of Bolaños, at Chorro near Durango, and in five lakes round the town of Chihuahua. The central tableland of Asia is not more rich in soda than Mexico.

The most remarkable places of this province are: Zacatecas, at present, after Guanaxuato, the most celebrated mining place of New Spain. Its polation is at least 33,000.

Fresnillo, on the road from Zacatecas to Durango.

Sombrerete, the head town, and residence of a Diputacion de Mineria.

Besides the three places above named, the intendancy of Zacatecas contains also interesting metalliferous veins near the Sierra de Pinos, Chalchiguitec, San Miguel del Mezquitas, and Mazapil. It was this province, also, which in the mine of the Veta Negra de Sombrerete exhibited an example of the greatest wealth of any vein yet discovered in the two hemispheres.

Diputaciones de Mineria, or Districts.

2. Zacatecas.

3. Sombrerete.
4. Fresnilio.

5. Sierra de Pinos.

Reales, or places surrounded by mines: Zacatecas; Guadalupe de Veta Grande; San Juan Baptista de Panuco; La Blanca; La Blanca; Sombrerete; Madroño; San Pantaleon de la Noria; Fresnillo ; San Demetrio de los Plateros; Cerro de Santiago; Sierra de Pinos; la Sauceda Cerro de Santiago; Mazapil.

The celebrated mines of Zacatecas, called by Robertson Sacotecas, are, as we have already observed, older than the mines of Guanaxuato. They began to be worked immediately after the veins of Tasco, Zultepeque, Tlapujahua, and Pachuca. They are situated on the central table-land of the Cordilleras, which descends rapidly towards New Biscay, and towards the basin of the Rio del Norte.

GEOLOGICAL STRUCTURE.

253

The climate of Zacatecas, as well as that of Catorce, is much colder than the climate of Guanaxuato and Mexico. Barometrical measurements will one day determine whether this difference is owing to a more northern position, or to the elevation of the mountains.

The nature of the latter has been examined by two very intelligent mineralogists, MM. Sonnesschmidt and Valencia, the one a Saxon and the other a Mexican. From the whole of their observations it appears, that the district of mines of Zacatecas bears great resemblance in its geological constitution to that of Guanaxuato. The oldest rocks which appear at the surface are syenitic; they are overlaid by clay-slate, which from the beds of Lydian stone, grauwacke and greenstone which it contains, has a resemblance to transition clay-slate. The most part of the veins of Zacatecas are found in this clay-slate. The veta grande, or principal vein, has the same direction as the veta madre of Guanaxuato; the others are generally in a direction from east to west. A porphyry destitute of metals, and forming those naked and perpendicular rocks which the natives call buffas, covers in many places the clay-slate especially on the side of the Villa de Xeres, where a mountain rises in the midst of these porphyritic formations, in the form of a bell, the basaltic cone of the Campana de Xeres.

The savage aspect of the metalliferous mountains

of Zacatecas, forms a singular contrast to the great wealth of the veins which they contain. This wealth is displayed-and the fact is very remarkable-not in the ravines, and where the veins run along the gentle slope of the mountains, but most frequently on the most elevated summits, on points where the surface appears to have been violently torn in the ancient revolutions of the globe. The mines of Zacatecas produce yearly, on an average, from 2500 to 3000 bars of silver, at 82 ounces each*.

The mass of the veins of this district contains a great variety of minerals, viz: quartz, splintery hornstone, calcareous spar, a little sulphate of barytes and brown spar; prismatic black silver, called in the country azul acerado; sulphuret of silver, (azul plomilloso) mixed with native silver; black silver, (the silber-schwärtze of the Germans, polvorilla of the Mexicans); pearl gray, blue, violet, and leek green muriate of silver (plata parda azul y verde) at very inconsiderable depths; a little red silver (petlangue or rosicler); and native gold, particularly to the south-west of the town of Zacatecas; argentiferous sulphuret of lead (soroche plomoso reluciente y tescatete); carbonate of lead; black, brown, and yellow sulphuret of zinc, (estoraque and ojo de vivora); copper and iron pyrites (bronze nochistle or dorado, and bronze chino); magnetic oxydulated iron; blue and green carbonate of copper, and sulphuret of antimony. The

*From 219,866 to 263,839lbs. troy.

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