The Spanish leader communicates these facts to his emperor in these few words:[2]—“Besides all kind of merchandise, I have seen for sale trinkets made of gold and silver, of lead, bronze, copper and tin.” Almost the same expressions are used in the memoirs of his companion, Bernal Diaz de Castillo:[3]—“And I saw _axes_ of _bronze_, and _copper_, and _tin_.” Under the influences of such a revelation the hearts of the distressed Spaniards must have been elated with joy and courage, when they saw not only a prospect of replacing the arms which their small band had lost, but also the source from which to equip the faithful Indian allies of Tlascala in an efficient manner. Immediately after having taken firm foothold on the conquered ground, Cortes ordered the goldsmiths of Tezcuco to cast eight thousand arrow-heads of copper, and these weapons were made ready for delivery within a single week.[4] At the same time, too, the hope to have a supply of cannon made was presented to the conqueror’s mind. The only question was from whence to procure a sufficient quantity of the material necessary to carry out this design. Copper is found to-day in nearly all the states of the Mexican Republic. We abstain, therefore, from quoting the localities. But as far as our information goes, no writer or historian has stated where Cortes and before him the natives themselves found it. To investigate this matter might be of direct utility, at least. We intend to use a source hitherto little explored, but which for the history of Mexico is of greatest importance, the picture tables, called the Codices Mexicana. These collections contain representations of their historical, religious, social and commercial life. The writer of this article has made himself familiar with these sources, expecting to find in them disclosures about the location of the ancient copper mines, as soon as he could discover what _copper_ was called in the language of the natives. The answer comes in this connection. The Mexicans had the habit of giving a name to their towns and districts from the objects which were found in abundance in their neighborhood. Therefore, copper regions ought to bear a name which related to this mineral.