oxide of brown iron and native silver, disseminated in molecules 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 minerals of Angangueo, known by the name of colorados, have a clayey appearance. Near the surface, the oxidated brown iron is mixed with native silver, with sulfuretted silver, and black prismatic silver (sprödglaserz), all three in a state of decomposition. At great depths, the vein of Angangueo contains only galena and pyrites of iron, possessing but a small quantity of silver. Hence the blackish pacos of the mine of Aurora d'Yxtepexi, which must not be confounded with the negrillos of Peru, owe their richness rather to the glaserz, than to the imperceptible filaments of native ramular 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 brick red, 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 of the veins, (eiserne huth).

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 seams 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 dendritic and silver, which intersects that of carbonated lime. Native silver is constantly accompanied by glaserz in the seams 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

* 444lb. avoird.

sometimes contained in folia of selenite. At Sierra de Pinos near Zacatecas, this last metal is constantly accompanied with blue radiated copper (strahlige kupferlazur) crystallized in small quadrilateral prisms.

A great part of the silver annually produced in Europe, is derived from the argentiferous sulfuretted lead (silberhaltiger bleiglanz) which is sometimes found in the veins which intersect primitive and transition mountains, and sometimes on particular beds (erzflöze) in rocks of secondary formation. In the kingdom of New Spain, the greatest part of the veins contain very little argentiferous galena; but there are very few mines in which lead ore is a particular object of their operations. Among the latter, we can only include the mines of the districts of Zimapan, Parral, and San Nicholas de Croix. I observed that at Guanaxuato, as well as several other mines in Mexico*, and every where in Saxony, the galenas contain the more silver, the smaller they are in the grain.

• We may adduce as galenas extremely rich in silver in very small grains, those of the new mine of Talpan, in the Cerro de las Vegas, belonging to the district of Hostotipaquillo. This galena, which sometimes passes into a compact and antimonial sulfuretted lead (bleischweif) is accompanied with mnch coppery pyrites, and carbonated lime.

A very considerable quantity of silver is produced from the smelting of the martial pyrites (gemeine schwefelkiese) of which New Spain sometimes exhibits varieties richer than the glaserz itself. It has been found in the Real del Monte, on the vein of Biscaina, near the pit of San Pedro, the quintal of which contained even so much as three marcs of silver. At Sombrerete, the great abundance of pyrites disseminated in the mine of red silver, is a great obstacle to the process of amalgamation.

It

We have described the minerals which produce the Mexican silver, and it remains for us to examine into the mean riches of these minerals, considering them as all mixed together. is a very common prejudice in Europe, that great masses of native silver are extremely common in Mexico and Peru, and that in general, the mines of mineralised silver, destined to amalgamation, or smelting, contain more ounces, or more marcs of silver, to the quintal, than the meagre minerals of Saxony and Hungary. Full of this prejudice, I was doubly surprised on my arrival in the Cordilleras to find that the number of poor mines greatly surpasses those of the mines to which in Europe we give the name of rich. An European traveller who visits the famous mine of Valenciana in Mexico after examining

the metalliferous veins of Clausthal, Freiberg, and Schemnitz, can scarcely conceive how a vein which, for a great part of its extent contains sulfuretted silver, disseminated in the gangue in almost imperceptible particles, can regularly supply thirty thousand marcs, per month, a quantity of silver equal to the half of what is annually furnished by all the mines of Saxony. It is no doubt true that blocks of native silver (papas de plata) of an enormous weight, have been extracted from the mines of Batopilas in Mexico and Guantahajo in Peru; but when we study attentively the history of the principal mines of Europe, we find that the veins of Kongsberg in Norway, Schneeberg in Saxony, and the famous mass of minerals of Schlangenberg in Siberia, have produced much more considerable quantities. We are not in general to judge from the size of the blocks, of the wealth of the mines of different countries. France does not altogether produce more than 8000 marcs of silver annually; and yet there are veins in that country (those of Sainte Marie aux Mines) from which unshapen masses of native silver have been extracted, of the weight of 30 kilogrammes*.

It appears that at the formation of veins

* 66lb. avoird. Trans.