Earth Notes: Turquoise Sourcing

Nov 9, 2016

Long before Europeans arrived in the Western Hemisphere, turquoise was an exceptionally prized stone—used in jewelry and masks, for example. But the blue-green mineral doesn’t occur naturally in many of the same places where such artifacts have been found in the Southwest. 

Turquoise from Cerillos, New Mexico, Smithsonian Institution
Credit Tim Evanson

So where was it from and how did it get here?

Scientists are using a technique called “geochemical fingerprinting” to get at the answer. They discovered unique designs in trace elements of turquoise that can indicate where individual stones were mined. Particularly strong are patterns in lead and strontium called isotope signatures. Like human fingerprints, each holds a one-of-a-kind imprint of the source rock.

Using this method, researchers have matched ancient jewelry from Zuni archaeological sites in New Mexico with turquoise samples collected near Santa Fe, a source mentioned in Zuni history.

By comparing the chemicals in other artifacts with turquoise mined in the American Southwest and Mexico, researchers hope to learn more about long-distance trade and social interaction between these areas and the Aztec and Maya civilizations. It’s thought the Mayans may have exchanged tropical birds and chocolate for supplies of the precious mineral.

If the sources of turquoise items found in museums can be firmly established, we may learn where and how Mesoamerican cultures without local turquoise got their stones.