Since the 1970s, researchers have attempted to pin down the source of turquoise--that lovely blue-green mineral aka hydrated copper aluminum phosphate, cherished and used as jewelry and inlay by so many ancient societies.

Raw Turquoise at the 2004 Lincoln (Nebraska) Gem and Mineral Show
Photo Credit: Karin Dalziel

The usual method for such studies is called trace element analysis, essentially breaking down the mineral to its component parts and comparing the various ratios to quarry sites. Unfortunately, in this case, the component parts vary too much within mines and artifacts to allow the precise source identification.

However, according to a new paper in the May 2008 issue of the Journal of Archaeological Science, researcher Sharon Hull and associates have identified the source of turquoise artifacts from the American southwest as having come from specific mines in the Cerillos Hills of central New Mexico. Using stable isotopes of hydrogen and copper, Hull et al. have been able to characterize mines in the Cerillos Hills and then compare those ratios to raw materials from those mines, and finally to artifacts of previously unknown provenance.

Whether the technique will be able to be extended to other mines and artifacts around the world remains to be seen, but the method does seem to show promise.

Sources

Read the glossary entry on Turquoise for more information on turquoise in the Americas and the rest of the world.

Hull, Sharon, Mostafa Fayek, Frances Joan Mathien, Phillip Shelley, and Kathy Roler Durand. (2008). A new approach to determining the geological provenance of turquoise artifacts using hydrogen and copper stable isotopes. Journal of Archaeological Science, 35(5), 1355-1369. DOI: 10.1016/j.jas.2007.10.001