The mining stations of gold and silver in New Spain amount to more than 450. They are divided into thirty-seven districts, each governed by a council of the mines. Humboldt supposes that near three thousand actual mines exist in these 450 stations. The principal and most valuable are those of the provinces of Guanaxuato, Zacatecas, San Luis Potosi, Mexico, Guadalaxara, Durango, Sonora, Valladolid, Oaxaca, Puebla, Vera Cruz, and Old California. The veins exist mostly in primitive and transition rocks, and the richest silver veins, which are single, run to an amazing breadth and length; the poorest are those in which the silver is dispersed in small and numerous ramifications. The best and most productive of the silver mines of New Spain, are situated at a height of from 5900 to 9840 feet above the level of the sea, and there are three which supply more than half as much again as all the rest put together; these are the mines of Guanaxuato, Catorce, and Zacatecas. The quantity of silver exported from New Spain to Europe and India, per annum, is about one million six hundred and fifty thousand pounds in weight. After the three above mentioned, the mines of Real del Monte, Tasco, and Zimapan in Mexico; Guarisamez, Batopilas, and Parral in Durango; Bolaños in Guadalaxara; Sombrerete and Fresnillo in Zacatecas and Ramos in San Luis Potosi, are those which afford the greatest quantity of ore. Gold is generally procured in the sands of torrents by washings. It is produced abundantly in Sonora, where it is found in the alluvious grounds; in the sands of Hiaqui and in Pimeria, where grains of very large size have been discovered. It is also procured from the mines of Oaxaca in veins, as well as in most of the silver mines, mixed with the silver, crystallized, in plates, &c. The produce of gold in New Spain is stated to amount, in the most favourable seasons, to a million of piastres, or 218,333_l._ sterling; the produce of silver at twenty-two millions of piastres, is 4,812,500_l._ sterling. Native silver is sometimes found in great masses in the mines of Batopilas, as well as in some others.