The mines of Guanaxuato, of which the most celebrated is the one named _Valenciana_, are said to produce double the quantity of gold and silver to that of the celebrated Potosi in South America. In this mine the great vein is twenty-two feet in breadth; and, as the chasm is entirely dry, it is easier worked than almost any other American mine. The pits extend to the breadth of 4900 feet, and the lowest is 1640 feet in depth. The undertaking employs upwards of 900 men in carrying the ores to the surface up the stairs on their backs, 1800 workmen in procuring and sorting the ore, with 400 women and children, carrying the minerals to the sorters; the total expences of the materials, workmen, overseers, &c., is above 187,500_l._ sterling per annum, and the net profit, during the same period, to the proprietors, after deductions of the kingʼs fifth, and all expences, is from 82,500_l._ to 123,759_l._ per annum. The mine of Sombrerete in Zacatecas yielded in one year a profit of above 833,400_l._ sterling to its proprietor. In San Luis Potosi, the mine of La Purissima Catorce yields annually to its owners a profit of upwards of 43,700_l._ sterling. The others we have mentioned, as being the richest, yield immense revenues to their holders and to the government. In these rich mines the miners and labourers contrive occasionally to steal the valuable metals. They, however, undergo a very rigorous search on leaving the pit; nevertheless, like the Indians in the diamond mines of Golconda, they frequently are adroit enough to secrete the ores, notwithstanding many of them go nearly naked. The greater part of the silver is procured by the means of mercury from the ores, smelting being not much used for want of fuel: the quantity of mercury used in the process of amalgamation is estimated at upwards of two millions one hundred pounds troy weight. Copper, of which the ancient Mexicans made their tools, is found both native and in the mines of Valladolid; as well as in those of New Mexico. Tin is found in grains and in wood tin in the clayey soil of Guanaxuato and Zacatecas.