The productions of the country are Indian corn, alfalfa (a species of lucern), and potatoes. The potato, in this its native country, is small, but very fine. They saw here a vegetable of the potato kind called _oca_. Boiled or roasted, it is very agreeable to the taste, in flavor resembling green corn. Here they entered upon the mining region. "The Earth here shows her giant skeleton bare: mountains, rather than rocks, rear their gray heads to the skies; and proximity made the scene more striking and sublime." Lieut. Herndon had brought letters to the superintendent of the mines, who received the travellers kindly and hospitably. This establishment is managed by a superintendent and three assistants, and about forty working hands. The laborers are Indians,--strong, hardy-looking fellows, though low in stature, and stupid in expression. The manner of getting the silver from the ore is this: The ore is broken into pieces of the size of an English walnut, and then ground to a fine powder. The ground ore is then mixed with salt, at the rate of fifty pounds of salt to every six hundred of ore, and taken to the ovens to be toasted. After being toasted, the ore is laid in piles of about six hundred pounds upon the stone floor. The piles are then moistened with water, and quicksilver is sprinkled on them through a woollen cloth. The mass is well mixed by treading with the feet, and working with hoes. A little calcined iron pyrites, called _magistral_, is also added. The pile is often examined to see if the amalgamation is going on well. It is left to stand for eight or nine days until the amalgamation is complete; then carried to an elevated platform, and thrown into a well, or cavity: a stream of water is turned on, and four or five men trample and wash it with their feet. The amalgam sinks to the bottom, and the mud and water are let off by an aperture in the lower part of the well. The amalgam is then put into conical bags of coarse linen, which are hung up; and the weight of the mass presses out a quantity of quicksilver, which oozes through the linen, and is caught in vessels below. The mass, now dry, and somewhat harder than putty, is carried to the ovens, where the remainder of the quicksilver is driven off by heat, and the residue is _plata pina_, or pure silver. The proportion of pure silver in the amalgam is about twenty-two per cent. This is an unusually rich mine.