The Amerinds were practically all in the so-called Stone Age of culture; that is, they were unacquainted with the _common use_ of metals. Some tribes worked silver, gold, and copper, to a limited extent and in an ornamental way, and a high authority asserts that the Eskimo have known iron for nine hundred years. Those Eskimo who came in contact with the Northmen on the North-east coasts very likely saw specimens of manufactured iron, and possessed some, nearly a thousand years ago, but it was a bare acquaintance, and this and the limited working of the other metals do not affect the general statement that the Amerinds were practically a Stone-Age people. Even the Maya, with all their varied skill and knowledge superior to any other Amerinds, still used stone tools for carving in stone. They had no way of sufficiently hardening the metals they could secure and their stone tools were far more serviceable. So the tools, weapons, and implements throughout the continent were chiefly wood, bone, and stone, with a few exceptions in Mexico, Central America, and the Mississippi valley. In the last region there was some working of copper obtained from the rich deposits of native metal in northern Michigan,[218] but the main thing they could do with it was to beat and grind it into shape with stones. Arrow-heads, spear-heads, chisels, and knife-blades of copper have been found in the Mississippi and Atlantic regions, but there is no certainty that all of them were made by the Amerinds.[219] The Spaniards and other Europeans were speedily engaged in a considerable traffic with the Amerinds in which copper was an important medium of exchange. Large quantities were therefore early brought into the country from Europe, and we do not always know in what form. It is certain that the traders would try to give it the most attractive shape, and if arrow-heads were found to be good, it would not take long to manufacture them. This is not to say that the Amerind could not have made the implements or copper articles thus far found, but only to question whether he did make all of them. [Illustration: FORMS OF THE BOW]