Having thus succeeded, in all his enterprizes and established his authority in the south of Peru on such firm foundations that no opposition remained in the whole country, fortune seemed to determine to exalt him to the summit of his desires by the discovery of the richest mines which had ever been known. Some Indians who belonged to Juan de Villareal, an inhabitant of La Plata, happening to pass over a very high isolated mountain in the middle of a plain, about eighteen leagues from that city, named Potosi, noticed by some indications that it contained mines of silver. They accordingly took away some specimens of the ore for trial, from which they found that the mineral was exceedingly rich in pure silver; insomuch that the poorest of the ore produced eighty marks of pure silver from the quintal of native mineral[25], being a more abundant production than any that ever had been heard of before. When this discovery became known in the city of La Plata, the magistrates went to the mountain of Potosi, which they divided among the inhabitants of their city, setting up boundary marks to distinguish the allotments or each person in those places which appeared eligible for workings. So great was the resort to these new mines, that in a short time there were above seven thousand _Yanaconas_, or Indian labourers, established in the neighbourhood, who were employed by their Christian masters in the various operations of these mines. These men laboured with so much industry, that each Indian, by agreement, furnished two marks or sixteen ounces of silver weekly to their respective masters; and so rich was the mine, that they were able to do this and to retain an equal quantity to themselves[26]. Such is the nature of the ore extracted from the mineral veins of this mountain, that it cannot be reduced in the ordinary manner by means of bellows, as is customary in other places. It is here smelted in certain small furnaces, called _guairas_ by the Indians, which are supplied with a mixed fuel of charcoal and sheeps dung, and are blown up by the wind only, without the use of any mechanical contrivance. [Footnote 25: This produce is most extraordinarily large, being equal to _four_ parts of pure silver from _ten_ of ore, or 640 ounces of silver from the quintal or 1600 ounces of ore. At the present time, the silver mines in Mexico, which are the most productive of any that have ever been known, are remarkable for the poverty of the mineral they contain. A quintal or 1600 ounces of ore affording only at an average 3 or 4 ounces of pure silver. The profit therefore of these must depend upon the abundance of ore, and the facility with which it is procured and smelted.--E.]