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countries annually throw into circulation nearly
In Silver, 22 millions of Piastres."
The Mexican gold is for the most part extracted from alluvious grounds, 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, grains of native gold (pepitas) have been found of the weight of from five to six pounds. In these desert regions, the incursions 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 intersect the
* Vol. ii. p. 299.
mountains of primitive rock. The veins of native gold are most frequent in the province of Oaxaca, either in gneiss or micaceous slate (glimmerschiefer). This last rock is particularly rich in gold, in the celebrated mines of Rio San Antonio. These veins of which the gangue is lacteous quartz, are more than half a metre in thicknesst, but their richness is very unequal. They are frequently strangled, and the extraction of gold in the mines of Oaxaca, is in general by no means considerable. The same metal is to be found either pure or mixed with silver ore, in the greatest number of veins which have been wrought in Mexico; and there is scarcely a single silver mine which does not also contain gold. Native gold is frequently found crystallized in écta hedra, lamina, or in a reticulated form, in the silver minerals of the mines of Villalpando and Rayas near Guanaxuato, in those of Sombrero (intendancy of Valladolid), Guarisamey to the west of Durango, and Mezquital in the province of Guadalaxara. The gold of Mezquital is looked upon as the purest, that is to say, as being least alloyed with silver, iron, and copper. The principal vein in the mine of Santa Cruz, at Villalpando, which I visited in the month of September, 1803, is intersected by a great number of small rotten
veins, (hilos del desposorio) of exceeding richness. The 'argillaceous slime with which these small veins are filled, contains so great a quantity of gold disseminated in impalpable parcels, that the miners are compelled when they leave the mine nearly in a state of naked ness, to bathe themselves in large vessels, to prevent any of the auriferous clay from being carried off" by them on their bodies. The silver mineral of Villalpando generally contains only two ounces of gold per load, (carga of 12 arrobas); but it frequently contains even eight or ten ounces per load, or 17. ounces per quintal. It may be of use to mention here that at the Harz, the pyrites of Rammelsberg contain only a 29 millionth part of gold, which is however extracted with profit*.
The District of the mines of Guanaxuato, has furnished according to the registers of the Provincial Treasuryt,
In 38 years . . | 43,080 18,723,537), 0.0023 * Brongniart, Mineralogie, T. ii. p. 345.
+ Estado de la Tresoreria principal de Real Hacienda de Guanacuato, del 21 de Novembre de 1799, (M. S.)
The result of this table is, that the silver extracted from the vein of Guanaxuato, contains from one to three thousand parts of its weight in gold.
Platina is erroneously stated to be found in the auriferous sands of Sonora. This metal has never yet been discovered to the north of the Isthmus of Panama, on the Continent of North America. Platina in grains is only found in two places of the known world; in Choco one of the provinces of the kingdom of New Granada, and near the shores of the South Sea, in the province of Barbacoas, between the 2o and 6° of north latitude. It is peculiar to alluvious grounds of a surface of 600 square leagues, the extent of which is scarcely equal to two of the departments of France. The Lavaderos, which at present yield the greatest quantity of platina, are those of Condoto, Santa Rita, or Viroviro, and Santa Lucia, and the Ravin (quebrada) of Iro, between the villages of Novita and Taddo. There are several lavaderos in Choco, (for instance, those of the districts of San Augustin, and Guaicama,) where no trace of platina is to be found. The price of this metal in grain on the spot is eight piastres, or 40 francs the pound, while at Paris it is generally from 130 to 150 francs. I shall examine in another place the quantity of platina, which in the present state of the mines of Choco, Ame
rica can furnish to Europe. It is also an absolutely false assertion, that platina has ever been found near Carthagena or Santa Fe, at the Islands of Porto Rico and Barbadoes, and in Perut, although their different situations are pointed out in the most esteemed and popular works. Perhaps it will one day be proved by chemical analysis, that platina exists in several silver ores of Mexico, as it exists in the fuhlerz (grey-cop-. per) of Guadalcanal in Spain.'
T'he silver supplied by the veins of Mexico, is extracted from a great variety of minerals, which from the nature of their mixture, bear an analogy to those of Saxony, the Harz, and Hungary. The traveller must not expect to find a complete collection of these ores, in the school of mines of Mexico. The mines being all in the hands of individuals, and the Mexican government possessing but a very feeble influence on the administration of the mines, it was not in
* Hauy Mineralogie, T. iii. p. 370. In a memoir inserted in the Annales de Ciencias Naturales, published by the Abbe Cavanilles, we read that platina is found in Chopo, (Choco) at Barbados, (Barbacoas) and at Carthagena a sea port, a hundred and thirty leagues distant from the gold lavaderos of Taddo. Yet more than 18 years ago, M. Berthollet com. municated a very accurate account of the places where platina is procured ( Annales de Chimie, Juillet 1792) I brought to Europe a pepita of platina of an extraordinary size. It weighs 1088 8. grains ; and its specific weight is according to M. Tralles, 18,947.(Karsten, Min. Tabellen, 1808, p. 96.)