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The Mineral & Gemstone Turquoise

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PHYSICAL PROPERTIETurquoise Rough
Chemistry: CuAl6(PO4)4(OH)8*5(H2O
Composition:
Hydrated copper
aluminum phosphate
Class: Phosphates
Crystal System: triclinic; bar 1
Fracture:
conchoidal and smooth
Hardness:
5-6
Specific Gravity: 2.6-2.9
Refractive Index: 1.62
Luster: dull to waxy
Streak: white with a greenish tint
Color: Blue, green, blue-green
Cleavage: perfect in two direction
Transparency:
opaque
Associated Minerals: pyrite. limonite. quartz and clays. In the American southwest turquoise is almost invariably associated with the weathering products of copper sulfide deposits in or around potassium feldspar bearing porphyritic intrusives. In some occurrences alunite, potassium aluminium sulfate, is a prominent secondary mineral

Turquoise is one of the oldest known gem materials:

When turquoise first came to the attention of man is unknown. There are archeological as well as literary references that pre date the Christian era by five millennia. The four bracelets of Queen Zar, found on her mummified arm, date to the second ruler of the Egypt's First Dynasty, approximately 5500 BC. Turquoise was used for beads by the Egyptians. Combined with other ornamental stones, the turquoise was inlaid in gold by Sumerians and Egyptians to produce very sophisticated articles of Jewelry.

Large mines were reported around 3,200 BC in the Sinai. The oldest known source of turquoise is the Maghara Wadi mines in the Sinai Peninsula. Mining expeditions of up to several thousand laborers were sent there annually. These mines were worked for the pharaohs for 2000 years. They, were rediscovered in the mid-nineteenth century and worked on and off until the beginning of this century.

Turquoise was worn by Pharaohs and Aztec Kings. Its prized blue color, is so distinctive that its name is used to describe any color that resembles it. Pre-Columbian Indians used turquoise for beads and pendants. From,500 BC Burial grounds, in Central America and Mexico. Teeth were found decorated with turquoise. A tribute to early dentistry as well as a different idea for adornment. It was also extensively used around 200 BC, by both southwestern US Native Americans and by many of the Indian tribes in Mexico.

The Anasazi and Hohokam mined turquoise throughout our Southwest. Absolute evidence exists that these prehistoric people mined turquoise at Cerillos and the Burro Mountains of New Mexico, Kingman and Morenci in Arizona and the Conejos areas of Colorado. Turquoise was a popular trade item. We know this because so much has been found in archeological sites. Many hundreds of miles away from its source. A prime example is the Cerillos, New Mexico, turquoise found with the Aztecs.

The Native American Jewelry or "Indian style" jewelry with turquoise mounted in or with silver is relatively new. Some believe this style of Jewelry was unknown prior to about 1880, when a white trader persuaded a Navajo craftsman to make turquoise and silver jewelry using coin silver. Prior to this time, the Native Americans had made solid turquoise beads, carvings, and inlaid mosaics.

According to American Indians, the stone brought together the spirits of sea and sky to bless warriors and hunters; a turquoise arrowhead assured accurate aim. It was said that a fine turquoise was hidden in the damp ground at the end of the rainbow. A Navajo belief is that a piece of turquoise cast into a river, accompanied by a prayer to the god of rain, will cause rainfall.


The Name Turquoise:
May have come from the word Turquie, French for Turkey, because of the early belief that the mineral came from that country (the turquoise most likely came from Alimersai Mountain in Persia (now Iran) or the Sinai Peninsula in Egypt, two of the world's oldest known turquoise mining areas.) Another possibility could be the name came from the French description of the gemstone, "pierre turquin" meaning dark blue stone.

For thousands of years the finest intense blue turquoise in the world was found in Persia, and the term "Persian Turquoise" became synonymous with the finest quality.

This changed during the late 1800's and early 1900's when modern miners discovered or rediscovered significant deposits of high-quality turquoise in the western and southwestern United States. Material from many of these deposits was just as fine as the finest "Persian."

Today, the term "Persian Turquoise" is more often a definition of quality. Rather than a statement of origin. The majority of the world's finest-quality turquoise comes from the United States.

Old and New Locations of Turquoise:
The mines of Nishapur, in northeastern Iran, described in 1300 AD as having belonged to Isaac, the son of Abraham, supplied turquoise to Europe and Western Asia for centuries, and to the United States for years before production ceased.

While turquoise has been produced in Tibet, China, Australia, Mexico, Peru, Chile, Turkestan and Afghanistan, the principal source today is the Southwest region of the United States-New Mexico, Nevada and Arizona. It has also been found in Texas, Colorado and California.

Some of the old Southwest mines were Lander, Lone Mountain, Red Mountain, Morenci, Bisbee, Sleeping Beauty, Old #8, Tyrone and Fox.

The Formula For Turquoise:
Chemically, a hydrated phosphate of copper and aluminum. Turquoise is usually found in the"alteration zones," of arid or desert regions. These zones are areas where the native, original rocks have been altered through the intrusion of other rocks from some volcanic or other thermal influence. The hydrothermal alteration is created by magma solutions from deep in the earth being forced to the surface through fractures or pores which eventually change the original rocks.

Several steps and processes are necessary to create turquoise. First there must be a source of copper. This occurs in a rather limited number of areas in the world. There must be a source of phosphorus CO-located with the copper. Usually from the mineral, Apatite. Which is not always in rocks associated with copper.

There must also be feldspar for the aluminum. Along with deep hydrothermal alteration. Which breaks down the feldspars and frees the aluminum needed for the turquoise. The phosphorus usually comes from phosphoric acid leached from the Apatite, during the hydrothermal alteration.

The copper is usually introduced into the "host" rocks by the rising hot magma. The copper readily oxidizes near the surface when it is in the hot magma solution. It reacts freely with the aluminum and phosphoric acid to form turquoise.

At this time other minerals enter into the turquoise structure and create color variations. The chemical formula of turquoise is: (CuAl6 (PO4)8 4H2O) this structure will very greatly with the introduction of Iron, Calcium, Magnesium, Manganese, Silicon, and Zinc. These additional elements when incorporated in the molecular structure of turquoise influence its color and hardness. The color of turquoise can vary from a deep blue to a deep green, with every variation of color in-between.

Generally, the more copper in the molecular structure the bluer the turquoise. The introduction of iron causes the greener cast to the stone. Turquoise creation is affected by many other factors too. For example; the best, hardest turquoise is found within 100 feet of the earth's surface

This is not to say that turquoise has not been found in areas without igneous or volcanic activity. Turquoise has been found in the Sinai and in Australia. In these two areas it is found in sandstone and shale.

Its One other key geological activity is called silicification. It too is an act of hydrothermal and intrusive alteration. Here silica, which is a common associate of turquoise, is introduced into the turquoise deposit. This addition and periods of intense heat are responsible for the hardness of the turquoise and frequently the matrix as well.

Physical Properties of Turquoise:
Turquoise is opaque and has a Mohs scale hardness that varies greatly. The deeply mined chalk like turquoise may only have a mohs hardness slightly over 2. Where as a gem specimen mined closer to the surface may be up to 6. The hardness varies due to several factors. Environment and matrix are key. In silica verities quartz particles are present and the stone will be hard enough for use as a gem stone. Silicification will strengthen some of the matrix as well.

If silicification has not occurred the turquoise will likely be chalky, porous, and soft. It will not be usable in jewelry without undergoing treatment. Usually stabilization. Stabilization may also be used because moisture will cause turquoise to turn toward green This can occur in the ground or in jewelry by absorbing moisture and oils. This is not unlike blue azurite changing to green malachite as its creation environment increases its water content.

Turquoise must consist of copper, aluminum and phosphorus. Other elements can replace various percentages of these and change the molecular structure. For example, two very rare minerals, chalcosiderite (where iron replaces the aluminum) and faustite (where zinc replaces the aluminum) do exist in turquoise environments. Usually there will only be a partial replacement of the aluminum with iron and zinc, thus leaving the turquoise altered only in color.

Turquoise Natural, Treated & Pricing:
At best This is a difficult task for even those of us who have been around the business for many years. There are many verities of natural and treated turquoise on the market today. Not to mention a myriad of fake and created turquoise. To make matters even worse. There are many different varieties from different mines, which appeal differently to many peoples. Then there are the closed mines, which give way to the collector type stones.

Our best advice for those interested in natural and collector stones. Is to know your jeweler, know your source. Use jewelers and sources like our selves who have been around a long time and intend to stay awhile longer. It will be a better bargain in the long run.

One thing that an individual can be aware of is stabilization. A hot pin will give off the smell of the resin and leave a deep mark in stones that are just plastic. Many other false stones such as dyed Howelite or the new stove top synthetics can be very deceiving.

Please take note that just plain stabilized turquoise is a natural turquoise, usually in nugget form, that is too porous or soft to hold a luster. It is submerged into a stabilizing compound, most likely an epoxy resin. The natural capillary action of the porous stone draws this stabilizing compound throughout the stone. It is then dried, cut, drilled, cabbed, etc. and prepared for jewelry. The turquoise has not been altered. The pores of the stone have been filled with a clear resin that makes the stone usable.

If this type of turquoise was not on the market, many jewelry artisans would not be employed. It allows wide diversity. For example, necklaces of tiny turquoise beads now can be made and tiny inlay is possible. Colors will not change because the pores are sealed. It is not practical to use a high-grade natural stone for heishe. For example, too much turquoise is wasted in the grinding and the resultant bead will be fragile and will eventually change color as well.

Once again there are draw backs on pricing these. Some stabilized turquoise is "color shot" or "color stabilized", Color stabilized, is misleading because it infers that it is the natural color which is "stabilized." This of course is not true, color has been added. This is not necessarily bad, as jewelry making is art, this color enhancement can improve the appearance of the piece. It goes without saying. The value is less than if the turquoise was naturally the color desired.

Also synthetic turquoise, frequently chemically perfect, has appeared on the market in some quantity. This is literally stovetop turquoise. It has a very natural matrix created by placing stones in the "batter" or sprinkling in pyrite, etc. When the mix is cut then cabbed these foreign additives, which are real, add to the illusion that the entire stone is natural.

As mentioned above this may not be all bad. Allot of jewelry is just fun stuff. We use it to adorn and accessorize ourselves. These days there is allot of turquoise jewelry on the market in the $25-$100 range. Most of which is imported and priced well below what it should be, for just the metal work.

Turquoise is considered a precious stone. At one time in history superior specimens were valued by weight, more than gold. Today it ranges from a few cents per carat to over $50.00 per carat for a superb gem stone. It is widely regarded as our nation's "national stone."

In conclusion, there is allot of natural turquoise still on the market today Just be aware that most of it is from currently operating mines. Such as some of the Chinese and our own Morenci mine. These are still relatively inexpensive. Somewhere between $2 and $5 per CT. Perhaps a good investment for the future

Turquoise Mirth & Myth:
Color enhancement has existed for thousands of years. In ancient times a common way to enhance turquoise. Was to submerge the stone in animal or vegetable oil and let it dry. It. Would then have a luster that did not previously exist. This would not last for a very long and the certain advent of oil stains appearing, when worn. Prompted the seller to leave the area shortly after the sale.

Turquoise became a major trade and barter item for the early Persians. Persian turquoise was found in ancient graves in Turkistan, and in the first to third century AD, in graves throughout the Caucausus. Persian stones were much coveted in Afghanistan, and as far north as Siberia.

The finest color, sometimes referred to as Persian, is an even robin's egg blue. The ancients preferred blue because a gem-grade blue stone would not change color (King Tut's treasures include a substantial amount of this type of blue turquoise and it appears unchanged today.

The less hard blues would eventually shade towards green. At this point in history green was not as good. Time has proven this wrong. Some green hued turquoise such as Skyhorse, China Mountain (both are names given to turquoise from China), Cerillos, Blue Gem, Fox, to name a few are ranked in the top three grades.

Turquoise may be fashioned to include portions of the rock in which it was found. This rock is referred to as matrix. The matrix often forms a pattern called "spiderweb," which many people prefer. Rather than clear blue stones without matrix.

Although not specifically mentioned in the Bible, scholars believe that the robe worn by the high priest Aaron was adorned with turquoise. Aristotle, Pliny and others refer to stones that must have been turquoise. After the fourth or fifth century AD, many writings appeared discussing the stone. Explorers such as Marco Polo took time to write about it.

Turquoise jewelry, has always been popular in the Orient. Tibet also had it's own source of turquoise usually a green cast, very hard stone. It has a significant amount of spider webbing. Turquoise was a highly revered item to the Tibetans who ranked them in six grades, the most expensive valued well above gold. Every Tibetan wore or carried a piece of turquoise throughout life. Turquoise was used for currency in many areas of Tibet.

The history of turquoise in China dates to the thirteenth century AD Although mining did exist, most stone came from trade with the Persians, Turks, Tibetans, and the Mongols. Much Chinese turquoise was used for carving and in other art and decorative ways. It never became a precious stone for the Chinese as was Jade for example. Turquoise was unknown until the 18th Century in Japan.

Turquoise was not of great import in early and medieval Europe. However, as Asian conquests and incursions into Europe, occurred. Seventeenth century Englishmen traveling there. Brought the style back with them, but not until Victorian time was it fashionable for European women to wear the stone. Victorian and Art Nouveau jewelry featured a good deal of turquoise.

Ancient doctors exploited the stone's medicinal potentials. These varied from land to land and age to age. It was thought to prevent injury through accident, prevent blindness by placing perfect stones over the eyes. It was ground into a salve or powder. It was rubbed on or ingested to cure stomach disorders, internal bleeding, ailments of the hip. Even for bites and stings. From snakes and scorpions.

It found its way into the mystic arts. Its color could forecast good or bad, predict the weather and influence dreams. It was good for nearly every ailment including insanity. As a good luck talisman it found usage in nearly every culture. The Egyptians also mounted turquoise in silver to treat eyes suffering from cataract. Since the fourteenth century, harnesses of dogs, horses and other animals have been decorated with turquoise to protect the animal and master from falling injuries.

Turquoise has been believed to confer foresight as well as protect the wearer from danger. In various countries, it is believed to fade when illness or danger is near. Another belief is that a fading stone indicates a lover's faithlessness or a friend's disaffection. In many cultures, the stone is regarded as a harbinger of good fortune, success and health.

Aztecs and Egyptians considered it a symbol of prosperity. In India, one was to wear a turquoise on the little finger and look at the stone after seeing the new moon to gain great wealth. The turquoise from Iran is characteristically an intense medium blue color and takes a fine polish. American and Mexican turquoises range from light blue to greenish-blue to bluish-green. Egyptian turquoise contains more green, showing greenish-blue to yellowish green. Turquoise was likely found and used by early man. Certainly the prehistoric peoples of the Western hemisphere knew of turquoise. Turquoise has been found in burial and archeological sites throughout the two continents. It seems clear that turquoise was always considered a stone of life and good fortune and it even had healing properties. The stone was used in religion, art, trade, treaty negotiations as well as for jewelry. It was considered by some tribes to be associated with life itself. Tuequoise is the Birthstone for December & the 11th anniversary.