Turquoise is probably one of the oldest gemstones known. Yet, only its prized blue color, a color so distinctive that its name is used to describe any color that resembles it, results in its being used as a gemstone.
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula Cu(Al,Fe3+)6(PO4)4(OH)8 · 4H2O.
The word turquoise dates to the 17th century and is derived from the French turquois for “Turkish” because the mineral was first brought to Europe through Turkey, from mines in the historical Khorasan Province of Persia.
As a secondary mineral, turquoise forms by the action of percolating acidic aqueous solutions during the weathering and oxidation of preexisting minerals. For example, the copper may come from primary copper sulfides such as chalcopyrite or from the secondary carbonates malachite or azurite; the aluminium may derive from feldspar; and the phosphorus from apatite. Climate factors appear to play an important role as turquoise is typically found in arid regions, filling or encrusting cavities and fractures in typically highly altered volcanic rocks, often with associated limonite and other iron oxides.
The increased acceptance of turquoise resulted in higher prices, some of the most desirable materials going for as much as $2,500 per kg. The increased demand could not be met through production of acceptable mine run materials. Therefore, an industry emerged–the business of turquoise stabilization, reconstitution, and the manufacture of synthetic and simulated turquoise.
Turquoise Group. Chalcosiderite-Turquoise Series. Planerite-Turquoise Series. The copper analogue of Faustite.
Spiderweb Turquoise is rare Turquoise that has matrix that is in the form of spiderweb’s.
Most American Turquoise that has spiderwebing comes from Nevada, however, it is found in Arizona and Colorado Turquoise as well. Spiderweb Turquoise Jewelry is considered to be some of the most valuable Jewelry made in the Southwest by collectors and Turquoise Connoisseurs.