Pottery was another important industry. There were very many designs and all kinds of utensils and the workmanship was good. Gold was obtained from deposits in streams and silver was mined. These metals were cast, hammered, soldered, and inlaid, as the people were very skillful in working with these metals and did especially fine work. They made vases, bracelets, mirrors, necklaces, and all kinds of delicate ornaments. Copper was greatly used, tin having been mixed with it. They made from this various kinds of implements and tools and weapons. They were quite skillful in wood-carving and inlaying was widely practiced, not only on wood but also on bone and shell and stone. They displayed skill in stone-carving, being able to cut the hardest stones, as emeralds and other precious stones. Their implements were of copper or stone, as iron was not at all in use. Money was not in use among the Peruvians and so there was required an exchange of products. As the products of the country varied it became necessary that ways should be provided whereby people could have opportunity to exchange what they had for things greatly needed from other people of a different calling. This was done by means of fairs held throughout the empire. In the more populous places they took place three times a month. "These fairs afforded so many holidays for the relaxation of the industrious laborers."[21] =Training of the Inca and the Order of the Huaracu.= "In his early years, the royal offspring was intrusted to the care of the _amautas_, or 'wise men,' as the teachers of Peruvian science were called, who instructed him in such elements of knowledge as they possessed, and especially in the cumbrous ceremonial of their religion, in which he was to take a prominent part. Great care was also bestowed on his military education, of the last importance in a state which, with its professions of peace and good will, was ever at war for the acquisition of empire.