Indeed the flint knives which he probably meant may be seen in museums.

But this peculiar usage was most likely kept up for some mystical reason, and does not affect the general question.

Almost as soon as the Spaniards brought iron to Mexico, it superseded the old material.

The "bronze age" ceased within a year or two, and that of iron began.
The Mexicans called copper or bronze "tepuztli," a word of rather uncertain etymology.

Judging from the analogous words in languages allied to the Aztec, it seems not unlikely that it meant originally _hatchet_ or _breaker_, just as "itztli," or obsidian, appears to have meant originally _knife_.[12] When the Mexicans saw iron in the hands of the Spaniards, they called it also "tepuztli," which thus became a general word for metal; and then they had to distinguish iron from copper, as they do at the present day, by calling them "_tliltic_ tepuztli," and "_chichiltic_ tepuztli;" that is, "black metal," and "red metal." When the subject of the use of bronze in stone-cutting is discussed, as it so often is with special reference to Egypt, one may doubt whether people have not underrated its capabilities, when the proportion of tin is accurately adjusted to give the maximum hardness; and especially when a minute portion of iron enters into its composition.