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Santa Anita, the produce has been at once richer, rarer, and more inconstant. Besides in this celebrated vein, there is a certain middle region which may be considered as a depositary of great riches; for above and below this region, the minerals have contained an inconsiderable share of silver. At Valenciana the rich minerals have been in the greatest abundance, between 100 and 340 metres* in depth below the mouth of the galery. This abundance appeared at Rayas at the surface of the earth; but the galery of Valenciana is pierced according to my measurements†, in a plain which is more than 156 metres above the level (galerie d'ecoulement) of Rayas; which might lead us to believe that the depository of the great wealth of Guanaxuato is found in this part of the vein, between 2130 and 1890 metres of absolute height above the level of the oceans. The deepest works of the mine of Rayas, (los planes) have never yet reached the inferior limit of this middle region; while the bottom (das tiefste) of the mine of Valenciana, the galery of San Bernardo has unfortunately passed this limit more than 70 metres. Hence

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* Between 328 and 1115 feet. Trans.

See my Recueil d'Observations Astronomiques, Vol. i. p. 324. No. 332-357.

511 feet. Trans.

Between 6987 and 6199 feet. Trans.

229 feet. Trans.

the mine of Rayas continues to furnish extremely rich minerals, while at Valenciana they have endeavoured for some years, to supply by the extraction of a greater quantity of minerals, the deficiency in their intrinsic value.

The mineral substances which constitute the mass of the vein of Guanaxuato, are common quartz, amethyst, carbonate of lime, pearl spar, splintery hornstone, sulfuretted silver, ramular native silver, prismatic black silver, deep red silver, native gold, argentiferous galena, brown blende, spar iron, and pyrites of copper and iron. We observe besides though much more rarely, crystalized felspar (the rhomboidal quartz of the Mexican mineralogists) calcedony, small masses of spar-fluor, capillary quartz (haarförmiger quartz), grey copper ore (fahlerz) and bacillary carbonated lead. The absence of the sulfate of barytes and muriated silver, distinguishes the formation of the vein of silver from that of Sombrerete, Catorce, Fresnillo, and Zacatecas. Those mineralogists who are interested in the study of regular forms, find a great variety of crystals in the mines of Guanaxuato, and especially in the mines of red and black sulfuretted silver, and in the calcareous spars, and the brown spar. *

* On the pearled spar of Guanaxuato, see Klaproth's Beiträge, B. iv. p. 128. This variety of brown-spar (braunspath) exhibits microscopic crystals embricked and collected

The abundance of waters which filtrate through the crevices of the rock and the gangue, vary very much in the different points of the vein. The mines of Animas and Valenciana are entirely dry, though the works of the latter occupy a horizontal extent of 1500, and a perpendicular depth of 500 metres*. Between these two mines, in which the miner is incommoded by the dust and extreme heat,† lie the mines of Cata and Tepeyac, which remain under inundation, because they do not possess sufficient mechanical force to draw off the water. At Rayas, it is drawn off in a very expensive manner by means of baritels a mulets, placed in the interior of the traverses, and raising the water, not by pumps, but by the action of chapelets de caissons of a very imperfect construction. One is astonished to see mines of such considerable wealth without any level‡, while the neighbouring ravins of Cata and Marfil, and

in very thin rods. The interlacing of these rods, (parillas) is so regular that they constantly form equilateral triangles. * 4920 and 1640 feet. Trans.

+ From 22° to 27° centigrade, (71° and 80°. Fahr. Trans.); the temperature of the exterior air being 17o (62o Fahr.)

In the district of the mines of Freiberg, which however do not yield annually the seventh part of the money extracted from the single mine of Valenciana, they have executed two levels, of which the one is 63,213 metres, and the other 57,310 metres in length (207,390 and 188,023, feet. Trans.)

the plains of Tenascatio, which are lower than the bottom of Valenciana, appear to invite the miners to undertake works which would both serve to draw off the water, and to transport the minerals to the place where they are smelted and amalgamated.

Valenciana is almost the sole example of a mine, which for forty years has never yielded less to its proprietors than from two to three million of francs* of annual profit. It appears that the part of the vein extending from Tepeyac to the North-West, had not been much wrought towards the end of the 16th century. From that period the whole country remained a desert, till 1760, when a Spaniard who went over very young to America, began to work this vein in one of the points which had till that time been believed destitute of metals (emborascado). M. Obregon † (the name of this Spaniard), was without fortune; but as he had the reputation of being a worthy man, he found friends who from time to time ad vanced him small sums to carry on his operations. In 1766, the works were already 89 metres in depth ‡, and yet the expences greatly surpassed the value of the metallick

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* From £82,506 to £123,759 per annum. Trans, + See Vol. i. p. 226.

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produce. With a passion for mining equal to what some display for gaming, M. Obregon preferred submitting to every sort of privation to the abandoning his undertaking. In the year 1767 he entered into partnership with a petty merchant of Rayas, of the name of Otero. Could he then hope that in the space of a few years, he and his friend, would become the richest individuals in Mexico, perhaps in the whole world? In 1768 they began to extract a very considerable quantity of silver minerals from the mine of Valenciana. In proportion as the pit grew deeper, they approached that region which we have already described as the depository of the great metallick wealth of Guanaxuato. In 1771 they drew from the pertinencia de Dolores enormous masses of sulfuretted silver, mixed with native and red silver. From that period till 1804, when I quitted New Spain, the mine of Valenciana, has continually yielded an annual produce of more than 14 millions of livres tournois *. There have been years so productive, that the net profit of the two proprietors of the mine, has amounted to the sum of six millions of francs t.

M. Obregon better known by the name of

* 583,380 sterling. Trans.

+ About £250,000 sterling. Trans.

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