New research published today in the journal Science Advances overturns more than a century of thought about the source of turquoise used by ancient civilizations in Mesoamerica, the vast region that extends from Central Mexico to Central America. For more than 150 years, scholars have argued that the Aztec and Mixtec civilizations, which revered the precious, blue-green mineral, acquired it through import from the American Southwest. However, extensive geochemical analyses reveal that the true geologic source of Aztec and Mixtec turquoise lies within Mesoamerica.