Aztecs, others did not import Southwest turquoise, research shows from the University of Arizona grad | Science

New research by Alyson Thibodeau, graduate of the University of Arizona with a PhD. in geoscience in 2012 and studied the southwestern turquoise deposits as part of his doctoral work, suggests that Mesoamericans have used turquoises extracted locally, reversing the hypothesis of more than 150 years that he was imported.

Thibodeau is now Assistant Professor of Earth Sciences at Dickinson College in Pennsylvania.

Her new research is based on the work she has done with David Killick, AU anthropologist, Joaquin Ruiz, Dean of the UA and Professor of Geoscience, and collaborators at California State University. San Bernardino and the Museo del Templo Mayor de Mexico.

Turquoise, or Xihuitl, "Figure prominently in Aztec poetry, ritual and cosmology," according to the study. It has been used in mosaics, jewelry, ceremonial shields and more.

Copper deposits form deep in the earth. The natural movement of the earth's crust can lift copper to the surface, where it can interact with groundwater.

The water is copper, changing chemically. Under certain conditions, new minerals, such as turquoise, are left in its wake.

During the process, the turquoise acquires a geochemical signature corresponding to the environment in which it was formed, such as a chemical postal code that corresponds to other rocks and minerals in the area, determined Thibodeau during his doctorate. job.

She collected and analyzed samples of turquoise from deposits throughout southern Arizona.

"At the end of my thesis, I had a ton of empirical data across the Southwest," she said.

For this study, Thibodeau analyzed turquoise samples from Aztec and Mixtec cultures from the period just prior to contact with Spain and compared them to deposits in the southwest.

The Mesoamerican samples had chemical signatures that were "not only different from what we detected in the southwestern turquoise examples," she said, but they "also corresponded very well to the copper deposits of the Mesoamerica. "

"It's not sure to hypothesize that (Mesoamerican turquoise) comes over from the Southwest, at least in this time and this place, it does not seem to be true," she said. said. "You should be skeptical of this longstanding claim."

However, it is established that there were other forms of trade between regions.

In this region, there is evidence of ritual consumption of cocoa (chocolate) and the presence of scarlet macaws, which are not indigenous, she said.

"It was widely assumed that turquoise was going in the opposite direction, but no one has ever substantiated this claim with any evidence," she said, which is why her study is so important.

But if the turquoise used by the Mesoamericans was of local origin, then where are the mines?

She added that turquoise mines and copper mines may be small entities in the landscape, and there are examples of those smaller mines that are being destroyed by open-pit copper mines or others. changes.

"It is possible that people find these mines, but it is also possible that they are not," she said. "I think the important part of geochemistry is that you do not necessarily need a mine to compare artifacts – it's not necessary to come to that conclusion."

Then, Thibodeau wants to continue with a similar study to get a more complete picture of trade between cultures of the Americas by probing the turquoise from a longer period of time or cultures in Mesoamerica.