a mixture of almost imperceptible particles of native silver, with brown oxyde of iron. In Mexico, on the other hand, the greatest quan-. tity of silver annually brought into circulation, is derived from those ores which the Saxon miner calls by the name of dürre erze * especially from sulphuret of silver, (or vitreous silver) from arsenical (fahlerz), and antimonial grey copper, (grau or schwarzgiltigerz) from muriate of silver, (hornerz), from prismatic black silver, (sprödglaserz), and from red silver (rothgiltigerz). We do not name native silver among these ores, because it is not found in sufficient abundance to admit of any very considerable part of the total produce of the mines of New Spain being attributed to it. Sulphuret of silver, and black prismatic silver, are very common in the veins of Guanaxuato and Zacatecas, as well as in the veta Biscaina of Real del Monte. The silver extracted from the ore of Zacatecas, exhibits the remarkable particularity of not containing gold. The richest grey copper, (fahlerz) is that of Sierra de Pinos, and the mines of Ramos. In the latter, the fahlerz is accompanied with glaserz, with * See the very instructive work of M. Daubuisson, under the title of Description des Mines de Freiberg. I have followed in the course of this chapter, in whatever relates to the art of mining, and the mode of occurring of minerals, the terminology of M. M. Brochant, Daubuisson, and Brongniart. variegated copper ore (bunt kupfererz), sulphuret of zinc and vitreous copper (kupferglas,) which is only wrought for the extraction of the silver, without applying the copper to any use. The graugiltigerz or antimoniated grey copper described by Mr. Karsten, is found at Tasco, and in the mine of Rayas, south east from Valenciana. The muriate of silver which is so seldom found in the veins of Europe, is very abundant in the mines of Catorce, Fresnillo, and the Cerro San Pedro, near the town of San Luis Potosi. That of Fresnillo is frequently of an olive green, which passes into leek-green. Superb specimens of this colour have been found in the mines of Vallorecas, which belong to the district de los Alamos in the intendancy of Sonora. In the veins of Catorce, the muriate of silver is accompanied with molybdate of lead, (gelb blei-erz) and phosphate of lead (grün bleierz.) From the last analysis of Mr. Klaproth, it appears that the muriate of silver of America*, is a pure mixture of silver and muriatic acid, while that of Europe contains oxid of iron, alumine, and especially a little sulphuric *The Mineralogists at present distinguish four kinds of muriate of silver, the common, the earthy, the conchoidal, and the radiated. The two last species, which are exceedingly beautiful, have been described by Mr. Karsten: they are among the minerals brought by me from Peru. Karsten, in the Magazine der Berliner Gesellschaft Naturforschender Freunde, b. i. § 156. Klaproth's Beiträge, b. iv. § 10. * acid. The red silver ore constitutes a principal part of the wealth of Sombrerete, Cosala, and Zolaga, near Villalta, in the province of Oaxaca. From this ore more than 700,000 marcs of silver have been extracted, in the famous mine of la Veta Negra near Sombrerete, in the space of from five to six months. It is affirmed that the mine which produced this enormous quantity of metal, the greatest which was ever yielded by any vein on the same point of its mass, was not thirty metres in length. † The true white silver ore, (weissgiltig-erz) is very rare in Mexico. Its greyish white variety, very rich in lead, is found, however, in the intendancy of Sonora, in the veins of Cosala, where it is accompanied with argentiferous galena, red silver, brown blende, quartz and sulphate of barytes. This last substance, which is very uncommon among the gangues of Mexico, is to be also found at the Real del Doctor, near Baranca de las Tinajas, and at Sombrerete, particularly in the mine called Campechana. Fluor-spar has been only found hitherto in the veins of Lomo del Toro, near Zimapan, at Bolaños and Guadalcazar, near Catorce. It is constantly of a grass green or violet blue colour. In some parts of New Spain, the operations of the miner are directed to a mixture of * See vol. i. c. vii. " brown oxide of iron, and native silver, disseminated in particles imperceptible to the naked eye. This ochreous mixture, which they call paco in Peru, and of which we have already had occasion to speak, is the object of considerable operations at the mines of Angangueo, in the intendancy of Valladolid, as well as at Yxtepexi, in the province of Oaxaca. The ores of Angangueo, known by the name of colorados, have a clayey appearance. Near the surface, the brown oxide of iron is mixed with native silver, with sulphuret of silver, and black prismatic silver (sprödglaserz), all three in a state of decomposition. At great depths, the vein of Angangueo contains only galena and iron pyrites, yielding but a small quantity of sil ver. Hence the blackish pacos, of the mine of Aurora d'Yxtepexi, whieh must not be confounded with the negrillos of Peru, owe their richness rather to the glaserz, than to the imperceptible filaments of native dendritic silver. The vein is very unequal in its produce, sometimes sterile, and sometimes abundant. The colorados of Catorce, particularly those of the mine of Conception, are of a tile-red color, and mixed with muriate of silver. In general it is observed both in Mexico and Peru, that those oxidated masses of iron which contain silver, are peculiar to that part of the veins, nearest to the surface of the earth. The pacos of Peru present to the eyes of the geologist, a very striking analogy with the earthy masses called by the miners in Europe the iron hat (eiserne huth) of the veins. Native Silver, which is much less abundant in America than is generally supposed, has been found in considerable masses, sometimes weighing more than 200 kilogrammes *, in the mines of Batopilas in New Biscay. These mines, which are not very briskly wrought at present, are among the most northern of New Spain. Nature exhibits the same minerals there that are found in the vein of Kongsberg in Norway. Those of Batopilas contain filiform, dentritic and knitted silver, traversing strata of limestone. Native silver is constantly accompanied by glaserz in the veins of Mexico, as well as in those of the mountains of Europe, These very minerals are frequently found united in the rich mines of Sombrerete, Madroño, Ramos, Zacatecas, Hapujaha and Sierra de Penos. From time to time small branches, or cylindrical filaments of native silver, are also discovered in the celebrated vein of Guanaxuato ; but these masses have never been so considerable as those which were formerly drawn from the mine del Encino near Pachuca and Tasco, where native silver is sometimes contained in |