Return to turquoise (thing)

[Periodic Table of Elements|Chemical Composition]: CuAl6((OH)2/PO4)4.4H2O
[Mohs Hardness Scale|Mohs' Hardness]: 5-6
[Specific Gravity]: 2.90-2.80
[Cleavage]: None
Transparency: Opaque
[Refractive Index]: 1.61-1.65
Double Refraction: +.0.04
[Dispersion]: None

The mineralogical name for turquoise is [calaite], which is derived from a name used by [Pliny] to describe the stone. However, this name is rarely used, it is more commonly called Oriental Turquoise, [true] or mineral Turquoise or Turquoise de la vieille roche, or just plain turquoise. The name, turquoise, means Turkish stone, as this stone came to [Europe] through various trade routes, origionating in [Persia], the [Sinai Peninsula] or further east, all of which went through [Turkey].

Turquoise is always [opaque] and varies in color from a light sea green to a deep blue. The color comes from [Copper Sulfate|Copper] and [Iron sulfate] found throughout the stone. The coloration comes from various colored bands spread evenly across defined spaces in the stone. When a [heat] of 482°[Farenheit|F] (250°[Celsius|c]) is applied to the stone discoloration occurs, as blues change to a [dull] green color. Very thin sections of the gem are [clear|colorless] to a light yellow in [hue]. Turquoises are also known to lose their color in [sunlight]. A dying technique has been formed to counteract this bleaching effect. But the technique does not work perfectly, and the dye on the stone can be chipped off with a [knife].

Turquoise is found in cracks and cevices of other rocks. It is found in irregularly shaped masses. While turquoise was thought to be [amorphous] for a long time, it actually consists of an array of very small microcrystals. Geographically, turquoise is found all over the globe, from [Mexico] and [New Mexico] to [Iran] and [Afghanistan], [Tibet], [Israel], eastern [Austrailia] and [Virginia]. One of the first clutches of turquoise was found on the Sinai Peninsula, but this was mined out over 4,000 years ago.

Today, the more blue a turquoise is, the more expensive it is considered. However, Mexicans and southwestern Native Americans did not share this belief. They considered both the blue and the green variations equally valuable. In fact, they called all blue/green stones that were similar to turquoise, [chalchihuitl]. This included [jadeite], turquoise and [amazonite].

In ancient Tibet, turquoise, along with [gold], was the most common offering to gods and demons. Thrones for kings and [lama|Lamas] were often adorned with turquoise, as was a special [cape] the Lamas wore. In early 17th century Europe, turquoise was thought to change its opacity as the [health] of the wearer changed. One author at the time claimed "A true [wife] should be like a turquoise stone, clear in [heart] in her husband's health, and cloudy in his sickness."


Sources:
Precious Stones, by Dr. Max Bauer. Charles E. Tuttle Company: Rutland Vermont and Tokyo, Japan, 1969
Gemstones of the World, by Walter Schumann. Sterling Publishing Co., New York, 1979
Simon and Schuster's guide to Rocks and Minerals, Simon and Schuster Inc. New York, 1978
The Magic of Jewels and Charms, Dr. George Frederick Kunz. J.B. Lippincott company, Philadelphia and London, 1915
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