Turquoise trade of the Ancestral Puebloan: Chaco and beyond

Thousands of turquoise artifacts have been recovered from archaeological sites in Chaco Canyon and other Ancestral Puebloan (formerly known as the Anasazi) sites across the San Juan Basin in northwestern New Mexico suggesting that turquoise was an important commodity in these ancient trade networks. Although the well documented group of turquoise deposits in the Cerrillos Hill have been the main contender for the geological source of Chacoan turquoise because they are the closest in proximity to the canyon, recent studies show that turquoise was obtained through long-distance trade networks that extended hundreds of kilometers to the west. To investigate Ancestral Puebloan turquoise procurement strategies and trade networks, we analyzed 74 turquoise artifacts from Puebloan sites in the San Juan Basin and the Virgin Puebloan area in southern Utah and the Moapa Valley in Nevada by a technique we developed that identifies the geological source of turquoise artifacts using the isotope ratios of hydrogen and copper and a comparative database that contains the isotope fingerprints of 22 turquoise resource areas. Here we present geochemical evidence of multiple turquoise trade routes into Chaco Canyon linking turquoise from the San Juan Basin with deposits along the Rio Grande Rift and resource areas in Nevada and the Mojave region of southeastern California. By linking Chacoan turquoise with the western turquoise resource areas, our data supports the proposal that the Virgin Puebloan may have played an important role in the movement of turquoise, shell, and salt to the San Juan Basin. Our turquoise sourcing technique establishes the foundation for future turquoise provenance studies in additional regions beyond the American Southwest including Mexico, South America, China, and Persia. The use of isotope ratios should be tested as unique discriminators for other complex minerals.