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Turquoise, an opaque mineral that is well known for it’s alluring design pattern that is made up of naturally crafted mixes of blue, green and yellow colors, has been a treasured gemstone for thousands of years. Chemically, turquoise is a hydrated phosphate of copper and aluminum that forms through the weathering and oxidation of naturally occurring metals.
Turquoise deposits typically follow the pattern of areas that contain high copper concentrations such as in certain areas of the United States, Egypt, Chile, Brazil, Australia, Turkey, Israel and several other countries around the world1. In fact, southwestern states in the U.S. including Arizona, Colorado, New Mexico, California, Nevada and Utah contain some of the most abundant turquoise deposits in the world.
Uses
The popular addition of turquoise stones into statement jewelry pieces can be dated back to as early as 6,000 years ago when ancient Egyptians would incorporate this precious mineral into burial masks for royalty. Specifically within the aforementioned regions of the U.S., indigenous groups treasure the mineral as a sacred stone. The Navajos and other indigenous groups of the U.S. often associate turquoise with various religious values and beliefs in the strength of rainfall, the sky and personal and familial vitality, all of which play an important role in their given cultures2.
The Worth of Turquoise: Now and Then
The global demand and subsequent value of turquoise has continually undergone rises and falls throughout history. Large-scale mining of turquoise did not begin until the late 1880s, where the value of this gemstone at the time was worth more than gold. Despite several turquoise mining deposits being found within the U.S. and other areas of the world since interest in extraction of the metal began, only about 5% of turquoise that is mined around the world can actually be cut and set into jewelry.
Since the presence of turquoise must always be accompanied by a greater amount of copper in a given area, the mining of turquoise often occurs in conjunction with copper extraction operations. Regardless of whether the mining project is on a large- or small-scale level, the extraction of this gemstone remains a careful process so as not to tarnish the details of the metal during the process. The extraction of turquoise, as well as any other type of gemstone, is often obtained by the crushing of large rocks within the ore in an effort to reduce the size of the desirable rocks.
Revisiting the Canyon Creek
The Canyon Creek mine is located on the Fort Apache Indian Reservation in Arizona. Here, the previously ancient mining of turquoise has been revisited as a new potential source of large turquoise quantities. In a recent research initiative conducted by Anthropology Graduate Students at the University of Arizona, various isotopic analyzes within the Canyon Creek mine has determined its value as a primary source of turquoise for future expeditions.
In their findings, the Researchers led by David J. Killick found that in the primary mining regions which were referred to as Loci 0, 1, 2 and 3 contained important lead (Pb) isotopes that indicate prolific turquoise deposits. Samples that were analyzed from Loci 0, 1 and 2 were found to contain 2 Pb isotopes ratios of 207Pb/204Pb and 206Pb/204Pb. No notable difference in the various analyzed strontium (Sr) isotope ratios of 87Sr/86Sr were found at any of the Loci in Canyon Creek3. Additionally, while no uranium (U) deposits were located within the Canyon Creek mine, the Researchers found that small quantities of metatorbernite, which is a rare copper-uranium phosphate mineral that is specific to turquoise, was found at this location.
Image Credit:
Bobbi Joy/ Shutterstock.com
References:
- “Turquoise Mines List” – Durango Silver
- “Why is Turquoise Becoming Rarer and More Valuable Than Diamonds?” – Smithsonian Magazine
- “Canyon Creek revisited: New investigations of a late prehispanic turquoise mine, Arizona, USA” S. Hedquist, A. Thibodeau, et al. Journal of Archaelogical Science. (2017). DOI: 10.1016/j.jas.2017.09.004.
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