Rich mines of silver existed in the new world, particularly in Mexico and Peru. The conquest of Mexico by Cortes in 1519 was speedily followed by the development of the rich silver mines of that country. From a very early period the Aztecs had been familiar with silver, and wrought it into many ornamental and useful articles. The mines were opened and extensively worked by the Peruvians in Guanajuato, Zacatecas, and other districts, and their production was greatly increased by the abundance of quicksilver, and its employment in the reduction of ores. Quicksilver is used for this purpose to a greater extent in Mexico and Peru than in other countries.