Some historians have proved to their own satisfaction that copper was unknown to the Indians; but had they taken the trouble to read, however slightly, any authority on the subject, they would have paused before they advanced a theory which is entirely at variance with all writers, both ancient and modern. It is an ascertained fact that very rich copper-mines have been worked since the Conquest;[20] and in 1873, whilst sinking a shaft in a copper-mine at Aguila, in the State of Guerrero, the miner lost suddenly the vein; and on examining the cause of the accident an excavation was found 4 ft. 4 in. long, 4 ft. 9 in. deep, and over 3 ft. wide, in which was a rich copper vein from 2 to 4 in. in thickness. The engineer, Felipe Lorainzar, could see no sign of iron or powder having been used, but the walls showed marks of fire; and both the copper ore and the rock in which it was embedded, were shattered and split in various places. In the rubbish were found 142 stones of different dimensions, shaped like hammers and wedges, the edges of which were blunt or broken; these stones were of a different substance from the surrounding rock, clearly indicating that the mine had originally been worked by the natives.[21]
Copper was likewise found in Chili, Columbia, Chihuahua, and in New Mexico. Before the Conquest, the Indians procured lead and tin from the mines of Tasco, but copper was the metal used in mechanic arts. Hatchets, arms, and scissors were made of copper found in the mountains of Zocatollan. The letters of Cortez tell us that among the taxes paid by the conquered people, figured copper hatchets and lingots of the same metal, which were paid every eighty days. Bernal Diaz[22] says that in his second expedition with Grijalva, the inhabitants of Goatzacoalco brought them upwards of six hundred copper hatchets in three days, having wood handles exquisitely painted, and so polished that “we thought at first they were gold.” Copper was also found in Venezuela, where, at the present day, jewels of copper, or mixed with gold, crocodiles, lizards, and frogs are found. We procured some and placed them in the Trocadéro, having the same dimensions as those in Central America. Those we found on our first visit to Mitla, are thin, shaped like a _tau_, and hardly 4 in. long. Dupaix found similar hatchets at Mitla, and he thinks they were used as currency, a supposition all the more probable, that an Indian from Zochoxocotlan, near Oaxaca, found an earthen pot containing twenty-three dozen of these taus, but differing slightly from each other both in size and thickness. We read in Torquemada,[23] that copper tablets, varying in thickness and shaped like a tau, were used as currency in various regions, and that they contained a large proportion of gold.