The rise in the prices of grain and other products of agriculture or human industry, about the middle of the sixteenth century, and especially from 1570 to 1595, indicates the true beginning of the plentiful flow of the precious metals to the Old World, in consequence of which their value diminished and the results of European industry increased in price. This is accounted for by the commencement of the beneficial working of the American mines about that period. The real opening of the mines of Potosi, by the Spanish conquerors, dates from the year 1545; and it was between this epoch and 1595, that the splendid masses of silver from Tasco, Zacatecas, and Pachuca, in New Spain; and from Potosi, Porco and Oruro, in the chain of Peruvian Andes, began to be distributed more uniformly over Europe, and to affect the price of its productions. From the period of the administration of Cortéz to the year 1552, when the celebrated mines of Zacatecas were just opened, the export from Mexico, rarely reached in value, annually, 100,000 pesos de oro, or nearly $1,165,000. But from that date it rose rapidly, and in the years 1569, 1578 and 1587, it was already, respectively-- 931,564 Pesos de oro. } The Peso de oro, is rated by Prescott, 1,111,202 " " } at $11.65 cents, and by Ramirez, 1,812,051 " " } at $2.93 cents.[17] During the last peaceful epoch of the Spanish domination, Baron Humboldt calculates the annual yield of the mines of Mexico at not more than $23,000,000, or nearly 1,184,000 pounds, avoirdupois, of silver, and 3,500 pounds, avoirdupois, of gold. From 1690 to 1803--$1,330,772,093 were coined in the _only_ mint of Mexico; while, from the discovery of New Spain until its independence, about $2,028,000,000, or two-fifths of all the precious metals which the whole of the New World has supplied during the same period, were furnished by Mexico alone.[18] It appears from these data that the exhaustion of the mines of Mexico is contradicted by the geognostic facts of the country, and as we shall hereafter show, by the recent issues of Mexican mints. The mint of Zacatecas, alone, during the revolutionary epoch, from 1811 to 1833, struck more than $66,332,766, and, in the eleven last years of this period, from four to five millions of dollars were coined by it every year uninterruptedly. The general metallic production of the country,--which was of course impeded by the revolutionary state of New Spain between 1809 and 1826,--has arisen refreshed from its slumber, so that, according to the best accounts it has ascended to perhaps twenty millions annually in total production, in consequence of the prolific yield of the workings at Fresnillo, Chihuahua, and Sonora, independent of the abundant production at Zacatecas.