What is Turquoise?

Turquoise is an opaque, blue-to-green mineral often used in jewelry from the American Southwest. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue.

The Southwest United States is a significant source of turquoise; Arizona, California, Colorado, New Mexico, and Nevada are (or were) especially rich. The deposits of California and New Mexico were mined by pre-Columbian Native Americans using stone tools. Some miners were local and but some came from as far away as central Mexico.

Cerrillos, New Mexico is thought to be the location of the oldest mines. Prior to the 1920s, New Mexico was the country's largest producer. Only one mine in California, located at Apache Canyon, operates at a commercial capacity today.

The substance has been known by many names, but the word turquoise was derived around the 16th century from the French language either from the word for Turkish (Turquois) or dark-blue stone (pierre turquin). This may have arisen from a misconception: turquoise does not occur in Turkey but was traded at Turkish bazaars to Venetian merchants who brought it to Europe. The color, however, has been employed extensively in the decorative tiles adorning Turkish places of worship and homes for hundreds of years and that may be the association that brought about the name.

Even the finest of turquoise is fracturable, only slightly harder than window glass. The color is as variable as the mineral's other properties, ranging from white to a powder blue to a sky blue, and from a blue-green to a yellowish green. The blue is attributed to copper while the green may be the result of either iron impurities (replacing aluminum) or dehydration.