Mesoamerica’s central location allowed it to benefit from technologies developed within both South and North America. Metalworking in South America dates back to at least 1936 BC and appears to have been created for ornamental purposes. While indigenous tribes in South America were making Golden bracelets, tribes in North America were making copper tools. By around 1000 BC North and South America were connected by trading routes bringing jewelry to the North, and tools to the South. Mesoamerica enjoyed the best of both worlds.
Unfortunately, Mesoamerica is a humid wet area. Due to the corrosive nature of the rainforest, it is extremely difficult to pinpoint specific dates for the first use of metals because archaeological artefacts, such as metal tools, would quickly oxidize, rust, and decompose. This area is prone to flooding, and has several large rivers which occasionally change their coarse washing away everything in their path. Mesoamerica has also been plagued with many wars and conquests in which invading armies have desecrated and carried off everything of value. All that now remains of some of the past great Mesoamerican civilizations are the rock foundations of ancient plazas and temples.
We do know that early Mesoamerican civilizations were quite advanced. They had a written language, used complex calendars requiring an advanced knowledge of mathematics, and built incredible temples and statues. It is hard to imagine that such an advanced culture would not have a working knowledge of metallurgy.
Archeological excavations in Mesoamerica have found evidence for the use of smelting, casting, and alloying of metals starting in the Late Postclassic period around 800AD, although indirect evidence exists which indicates metal was used much earlier. Hard precisely cut granite stones are one indication of metal tools. The metal tools have corroded away, but the rocks they cut are still around. Mesoamerica is rich in natural outcroppings of gold, copper, and silver, especially along the western coast of Mexico. Iron ore is generally not refined until later periods due to the high temperatures required in its processing, but meteoric rocks can be used as an early source of iron. Metalworking, or cold hammering naturally occurring nuggets of metals into the desired shapes, was easy to do, and did not require smelting. Cold working has been practiced in the Americas for thousands of years.
In more recent times (for which the corrosive environment and wars have not taken their toll) many small metal tools, bells, and other various ornaments have been recovered. From 800-1300 AD Mesoamerican metallurgy shared many common traits with Peru. Along with cold-worked objects, wax casting was used, and a variety of copper alloys were found. There was a metallurgical boom during the years of 1300-1500 in which copper alloys were significantly improved to have superior strength and elastic properties. Metals were also designed for color with alloys containing as much as 23% tin and arsenic which created a brilliant golden finish. In 1492, Columbus sailed the ocean blue. The rest is a history of a united world, rather than a divided one.
Additional resources with Mesoamerican metals are as follows. A collection of pre-Columbian metal artifacts can be found at http://www.precolumbiangold.com/. The Dallas museum of art also has a collection of ancient American metalwork. The book “Iron Age America before Columbus” by William D. Conner contains many interesting pictures and artifacts detailing early Metallurgy in the Americas. The wesite http://precolumbianartifact.com/ also has an impressive collection of artifacts from Ancient America. Dorothy Hosler has done extensive work on the metallurgy of Mesoamerica and has many publications. The archaeologyfieldwork.com forum is another great resource to learn about the latest finds in America.