The opaque, pale, bluish-green stone known as turquoise may not be quite as valuable as precious gems like diamonds, rubies, and sapphires, but it has long captured humanity's eye and imagination. What is turquoise? Where does it come from and how is it formed? Here's the scoop on this historically beloved stone.
What is Turquoise?
Turquoise is actually an opaque mineral that is a hydrous phosphate of copper and aluminum. In order for turquoise to form, very special conditions are required. First, both copper and acidic water must be present, along with a variety of other minerals, including aluminum and phosphorous.
These ingredients simmer in a hydrothermal replacement deposit (where one mineral takes the place of another) until crystals form. When acidic rainfall seeps into the soil, it can dissolve small amounts of copper. As this water evaporates, the copper remains, blending with aluminum, phosphorous, and often other minerals to form turquoise deposits.
Well-formed crystals are rare. Turquoise deposits are more often composed of aggregates of microcrystals. Once mined, turquoise is generally polished, and stones that are porous may be soaked in wax or plastic for aesthetic purposes.
What's in a Name?
It's a common misbelief that turquoise stones were so named because of their color. It was actually the stone that came first, and its popularity caused the color to become associated with the name of the stone.
Interestingly, the name of the stone is actually a historical blunder that, nonetheless, stuck. The stone was named turquois, meaning "Turkish stone," by the French, who assumed the stone came from Turkey because that's where it was commonly traded. It's much more likely, however, that the turquoise from Turkey was found in Persia.
Where is it Found?
Turquoise is most often found in arid climates, including areas of Iran (formerly Persia), Chile, China, Egypt, Mexico, and the United States. In the U.S., turquoise is found in the Southwest region.
Value Over Time
Turquoise has been considered a valuable stone for aesthetic purposes for thousands of years across a diverse array of cultures and civilizations. In ancient Egypt, it was used to make jewelry as early as about 6,000 years ago, and it's use in Native American culture dates back even further.
The Anasazi civilization, which dates from about 350 BCE to 1450 CE, was known to use turquoise as a trade good, and their stones have been traced to an area of New Mexico in the Burro Mountains, where the Cerillos Mine is now situated. Later, Native American tribes had many uses and beliefs pertaining to this blue stone.
Some believed it was formed from the tears of the People, shed in joy following a successful rain dance, mixing with rain. Others thought turquoise would protect the wearer from harm. The Apache were known to attach turquoise to weapons to improve accuracy. And of course, it has long been used for jewelry and other ornamentation. Today, this is the most common use of turquoise worldwide. It is also a modern birthstone for the month of December.