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Sombrerete, Zacatecas, and Tasco; antimony, which is common to Catorce and los Pozuelos, near Cuencame; arsenic, which is found among the minerals of Zimapan, combined with sulphur, as orpiment. Cobalt, as far as I know, has never yet been discovered among the minerals of New Spain ; and manganese *, which M. Ramirez recently discovered in the Island of Cuba, appears to me in general much less abundant in Equinoctial America, than in the temperate climates of the Old Continent.
Mercury, which is very remote from tin, with respect to its relative antiquity, or the period of its formation, is almost as uncommon as it, in every part of the globe. The inhabitants of New Spain have procured for centuries the mercury necessary in the process of amalgamation, partly from Peru, and partly from Europe ; and hence they are accustomed to consider their country as destitute of this metal. However, when we consider the examinations carried on under the reign of Charles the 4th, we are forced to admit that few countries have so many indications of cinnabar, as the table land of the Cordilleras from the 19° to the 22 of north latitude. In the intendancies
To the west of the town of Cuenca, in the kingdom of Quito, there exists earthy grey manganese, which forms a bed in sandstone.
of Guanaxuato and Mexico, we find it almost wherever pits are dug between San Juan de la Chica and the town of San Felipe; near Rincon del Centeno, in the environs of Celaya; and from Durasno, and Tierra Nueva to San Luis de la Paz, especially near Chapin, Real de Pozos, San Rafael de los Lobos, and la So. ledad. Sulphuret of mercury has been also discovered at Axuchitlan and Zapote *, near Chirangangueo, in the intendancy of Valladolid; at los Pregones near Tasco, in the district of mines of the Doctor; and in the valley of Te. nochtitlan to the south of Gassavé in the road from Mexico to Pachuca. The works carried on for the discovery of these different mineral repositories have been so frequently interrupted, and they have been conducted with so little zeal, and generally with so little intelligence, that it would be very imprudent to advance, as has been often done, that the mercury mines of New Spain are not worth the working. It appears, on the contrary, from the interesting information which we owe to the labours of M. Chovel, that the veins of San Juan de la Chica, as well as
* In the mines of San Ignacio del Zapote, where the cinnabar is constantly mixed with blue carbonate of copper, while at Schemnitz and Poratich in Hungary the untimoniated grey copper (graugültigerz) contains 0.60 mercury. Klaproth, iv. p, 65.
those of the Rincon del Centeno, and the Gigante, are very deserving of the attention of the Mexican miners. Was it to be expected that superficial works which were merely begun, should in the very first years yield a net profit to the shareholders?
The mercury mines of New Spain are of very different formations. Some are found in beds in secondary rocks, and others in veins which traverse trap porphyries. At Durasno, between Terra Nueva and San Luis de la Paz, cinnabar, mixed with a number of globules of native mercury, forms a horizontal bed (manto) which rests on porphyry. This manto, which has been pierced by pits of five or six metres* in depth, is covered with beds of slate-clay, which contains fossil wood, and coals. On examining the roof of the manto, we find from the surface, first a bed of slateclay (schieferthon) impregnated with nitrate of potash, and containing fragments of petrified vegetables ; then a stratum of slate-coal (schieferkohle) of a metre † in thickness; and lastly
slate e-clay which immediately covers the ore of cinnabar. From this mine there was drawn, eight years ago, in a very few months, nearly 700 quintals of mercury, which were
* 16 or 19 feet.
not sufficient to pay the expences of working, although the ore contained a pound of mercury for every load of three quintals and a half. The carelessness with which the mine of Durasno was wrought, has been so much the more pre.. judicial, as on account of the small degrees of solidity of the rock of the roof, and its horizontal position, it very frequently fell in.' The mine is at present drowned, and to resume the operations would not be attended with profit. It has constantly enjoyed very high celebrity in the country, not on account of its wealth, which is inferior to that of the veins of San Juan de la Chica, but because it admitted of being wrought sub dio, and because its produce was very abundant. They attempted in vain to discover a second bed of mercurial ore below that of Durasno.
The cinnabar vein of San Juan de la Chica is two or three and sometimes even six metres in width. It traverses the mountain of los Calzones, and extends to Chichindara. Its ores are extremely rich, but by no means abundant; I have seen there masses of compact and fibrous cinnabar of a bright red, twenty centimetres in length, and three in thickness* ; and these specimens resembled from their purity the richest produce of Almaden and
*7.87 inches by 1.18. Trans.
Wolfstein in Europe. The mine of Chica has been only yet wrought to the depth of fifty metres *; and it is found, and this geological fact is very remarkable, not in sandstone or slate, but in a true pitchstone porphyry, divided into balls with concentric layers, of which the interior is lined with mammillated hyalite (müllerisch-glass). The cinnabar and a little native mercury, are sometimes observed in the middle of the porphyritic rock at a very considerable distance from the vein. During my stay at Guanaxuato, only two mines were wrought in all Mexico; those of Lomo del Toro, near San Juan de Chica, and Nuestra Señora de los Dolores, a quarter of a league to the south-east of the Gigante. In the first of these mines a load of ore yields from two to three pounds of mercury; and the expences of working are very moderate. The mine of the Gigante, from which there is even drawn six pounds of
mercury per load (carga) of ore, furnished from 70 to 80 pounds weekly; and it is wrought on the account of a rich individual, Don Jose del Maso, who has the merit of having first excited his countrymen during the last war to the working of the quicksilver mines, and the manufacture of steel. The cinnabar
* 164 feet. Trans.