Turquoise is a copper-rich, water-bearing phosphate mineral, part of a larger group of similar minerals (1) that vary in color from pale green to the rich, highly valued turquoise color. These minerals in the Turquoise Group are all hydrated phosphates, have similar structures, and contain varying amounts of Fe, Zn, Al and Cu.
One of the oldest known minerals found as human decoration in China to Egypt to the American West, Turquoise has generally been considered through the centuries as a talisman for good luck.
Unfortunately, real turquoise is relatively rare and most of what you find in stores and online is either another mineral (howlite and magnesite are common) which has been dyed or ground turquoise mixed with a resin.
To learn more than you probably want to know about the Turquoise Group minerals, here is an article reference.
Turquoise forms from waters percolating through rocks which have a certain amount of copper. Minerals from dark to light are usually associated with real turquoise as various amounts of other minerals from the same groups as well as amorphous silica, quartz and various clays are usually mixed with the turquoise mineral. For historical and gemological purposes, we call all the minerals of this group turquoise as they are all valued for their color.
(1) Foord, E.E. & Taggart, J.E. (1998): A reexamination of the turquoise group; the mineral aheylite, planerite (redefined), turquoise and coeruleolactite. Mineralogical Magazine, 62, 93-111.
Nevada, United States
Our turquoise has been sourced from an artisan mining operation in Nevada whose principals, Helen and Richard Stull, mine and cut their own turquoise. Each piece has a certificate identifying the mine, county, and gemstone cutter.
Damele Mine, Lander County
Ajax Mine, Canelaria District, Esmeralda County