Turquoise History
Turquoise has been prized around the world for thousands of years. The clear robin's egg blue colored gemstone worn by Pharaohs and Aztec Kings, is probably one of the oldest gemstones known to man. The pure sky blue variety of this stone is how turquoise came to be called as the "Sky Stone". The oldest known piece of turquoise jewelry was found on the mummified arm of Queen Zar, the second ruler of Egypt's first dynasty, dating from 5500 B.C.
Native peoples of North and South America, China, India, and Tibet treasured this stone, as did the early Persians. In fact, turquoise is thought to mean "Turkish stone", a reference to the long history of imports of Persian Turquoise, through Turkey, to the West. Historical references often suggest that the stone was believed to have healing properties. It was thought to have promoted good fortune, to have offered protection from falls in humans, and to have provided sure-footing for animals. It is shown that the Turks often attached turquoise to the bridles of their horses as amulets for protection.
The Native Americans of the Southwestern United States have known and used turquoise deposits for centuries. In Arizona a very active trade developed between the coastal tribes who gathered shells and the interior tribes who dug turquoise in the Camp Verde region of central Arizona. Native American Pueblo peoples dug the stony ground using antlers and stone mauls to unearth precious turquoise. To the Pueblos and the Navajos, turquoise is sacred, takes its color from the sky, and symbolizes the supreme, life-giving and healing power of the Creator.
When copper mining came to the New World turquoise became more readily available because turquoise forms in and around copper deposits. Today most turquoise being mined in North America is obtained under contract with one of the big copper mining companies.
Turquoise Mines
Turquoise depends on the whims of nature for its formation. It is not a material that originates as a primary mineral, but rather it relies on weathering and the ingredients of the earth’s crust for its formation. Each area of the planet and each mine produces unique material.
Be sure to visit this Turquoise Gallery for beautiful examples of turquoise from around the world!
American Turquoise
American Turquoise is mostly mined in the southwestern United States. Only about 20% of turquoise on the world market today is American, mainly coming from mines in Arizona and Nevada. Many American mines are producing very little or no turquoise becuase the stone has been depleted or the copper mining has ceased. Stones from these depleted mines are highly collectible and occasionally come to the market from private collections.
American Turquoise is marketed by the name of the mine that the material is excavated from, such as Cerrillos, Bisbee, Sleeping Beauty and Kingman. The oldest mine of any kind on the North American continent, the Cerrillos turquoise mine just south of Santa Fe, New Mexico, dates back at least 2000 years. Two types of American turquoise from mines in Arizona are:
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Sleeping Beauty Turquoise |
Kingman Turquoise |
Sleeping Beauty Turquoise is currently on eof the most prized types of turquoise in the world. It often exhibits a vivid blue color and is sometimes known as ''Persian'' turquoise. This material is mined in the Sleeping Beauty mines near Globe, Arizona. This mine is one of the largest in North America and is still operating today.
Many Sleeping Beauty stones are treated with the Zachery Process, a trademarked process in which the soft stone is made denser to harden the stone and to stabilize the color.
Kingman Turquoise comes from one of the largest turquoise mines in North America. The Kingman mine is located in northwestern Arizona. The mine became famous for its rounded, bright blue nuggets. Few turquoise mines produced nuggets especially of this quality. The terms "Kingman" and "high blue" refer to the blue color usually displayed in this stone. It has become a color standard in the industry. Old natural Kingman turquoise is rare and very collectible.
Chinese Turquoise
China and Tibet have large mines also. About 80% of all the turquoise on the world market today is Chinese or Tibetan. Turquoise has been mined in China for centuries, but Jade has always been the preferred stone. Tibetans on the other hand have always preferred turquoise to virtually any other stone.
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Natural Green Hubei |
Natural Blue Hubei |
Natural Ma'an Shan |
The currently popular chunky blue green turquoise nuggets with dark spider web matrix is mined north of Bhutan high in the mountains of the former Tibet. Northwest of Shanghai is the Ma'an Shan turquoise mine, and mines of the Hubei Province produce turquoise colors reminiscent of the much-prized blues and greens of the now closed mines in Nevada and Arizona.
Turquoise Composition
Chemically, a hydrated phosphate of copper and aluminum, turquoise is formed by the percolation of meteoric or groundwater through aluminous rock in the presence of copper. For this reason, it is often associated with copper deposits as a secondary mineral, most often in copper deposits in arid or desert environments.
Turquoise is a relatively soft stone, 5-6 on the Mohs Scale of Hardness and the colors span a wide range of greens and blues depending on the chemical composition of the stone. Shades of blue to blue-green depend on copper content, shades of green depend on chromium or vanadium content and shades of yellow-green depend on iron content. In general, US mines produce greenish blue, to green stone due to high iron and vanadium content in the region.
Turquoise Matrix
Most rough turquoise contains "matrix" in the form of patches, veins or webbing of the host rock in which it formed. In some parts of the world matrix is considered beautiful. This seems to be true in the U.S. and China. In other areas of the world, such as the Middle East, matrix is considered an imperfection and devalues the stone. Common matrix colors include:
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Black Matrix |
Brown Matrix |
Yellow Matrix |
Black Matrix is the most popular color as it contrasts nicely with the stone colors. Black matrix is most often iron pyrite.
Brown Matrix usually consists of an iron oxide, of which there are sixteen different types. The best known of the iron oxides is hematite.
Yellow Matrix is often rhyolite, an igneous, volcanic rock. Since turquoise usually forms in rock with a volcanic origin, the presence of rhyolite is not surprising.
Turquoise Enhancements
100% natural turquoise is rare in today’s market, is always very expensive and is often set as a gemstone in very high end jewelry. Most costume jewelry grade turquoise on the market today has been enhanced in some way to prolong the life of the stone. Enhancements improve the color, hardness, and durability of turquoise to the point that inexpensive, porous, poorly colored, or nearly colorless materials become acceptable for use in jewelry. As long as these materials are represented as treated, stabilized, or reconstituted, you can choose to accept or reject them based on personal taste. The positive side of enhanced or “naturally processed” turquoise is that the color will remain stable. Untreated turquoise can oxidize and turn green over a long period of time.
Some common methods of enhancement include:
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Dyed Turquoise |
Stabilized Turquoise |
Reconstituted Mosaic |
Dyed – a method of coloring Chalk Turquoise with chemical dye to improve or even out color.
Stabilized– a method of injecting epoxy resin into natural material that was either too soft or too porous to hold a luster. This process increases hardness and enhances color. Stabilized turquoise is an excellent value.
Reconstituted– a method of mixing pulverized stone material with binders and pressing into a solid material that can be cut for jewelry uses.
Waxed– a method of pressure infusing natural stone with paraffin wax to improve the surface luster.
“Zachary Process” is a trademarked process that hardens the stone and stabilizes the color. This process first chemically strengthens the turquoise and then heat is used to dissipate any traces of residual chemical used in the treatment. Turquoise that has been treated with the 'Zachary Process' is difficult to differentiate from untreated material.
Turquoise Imitations
Since the increased demand for natural turquoise can no longer be met through mining production, the manufacture of synthetic and simulated turquoise has arisen. Materials sold in the market today that can be mistaken for natural turquoise include:
Chalk “Turquoise” is a porous white stone from China. This form of natural turquoise has a white chalk-like consistency and has the same chemical composition as turquoise with one exception, it does not contain any copper, the element that causes the blue color of naturally occurring blue turquoise. After this material is stabilized and dyed, is often referred to as chalk turquoise. It is generally dyed lively shades of blue, apple green, lime green and fuchsia pink.
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Blue Chalk "Turquoise" |
Green Chalk "Turquoise" |
African "Turquoise" is dyed jasper that resembles turquoise in color and texture but is not a true turquoise. This stone when dyed has an exotic blend of green base colors and dark matrix, making it a great turquoise substitute.
Yellow "Turquoise" is a quartz and jasper material that often comes from the same mines as turquoise. This earthy material is a subtle blend of golds, greens, browns and black colors.
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African "Turquoise" |
Yellow "Turquoise" |
White "Turquoise" is actually white magnesite, a creamy white stone that has either a brown or black matrix. Magnesite is easily dyed and is commonly seen in dark shades of turquoise blue and green that accentuate the deep black or brown matrix patterns. This material can also be seen dyed orange, red and other bright colors.
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Natural Magnesite |
Dyed Magnesite |
Howlite is a matrix-free off-white material found in evaporite or other borate mineral deposits and appears as nodules that resemble cauliflower. Howlite is a popular and very affordable alternative to natural turquoise. The color of turquoise-blue dyed howlite is rarely permanent, so application of an artists' fixative is recommended to stabilize the color.
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Natural Howlite |
Dyed Howlite |
Turquoise Care
No artificial changes are made to 100% natural turquoise, but because it is a soft and porous stone the color may change over time and the surface can be easily scratched or damaged. Even enhanced turquoise must be carefully cared for to avoid color change and surface damage.
Handle With Care - Turquoise jewelry should be handled carefully to avoid scratching it. Don't store turquoise with harder gemstones or other materials that might rub against the stone and cause damage.
Avoid Sun and Heat - Keep turquoise away from prolonged sun exposure and heat as this can permanently fade or otherwise alter the color of the stone.
Avoid Chemicals - Exposure to chemicals such as oils, perfumes, alcohol based cosmetics and household cleaners may cause dulling or damage to the surface of the stone.
Avoid commercial jewelry cleansers.
Remove Jewelry - Be sure to remove turquoise jewelry before washing dishes or bathing to avoid prolonged exposure to moisture and detergent. Excessive exposure to moisture can permenantly alter the stones color.
Clean turquoise jewelry occasionally in warm, sudsy water, rinse thoroughly and dry it immediately with a soft cloth. Air dry recently cleaned turquoise to ensure complete drying before storing.
SOURCES:
The Curious Lore of Precious
Stones by George F. Kunz
www.americana.net/tourq.html
www.gemsociety.org/info/gems/turquoise.htm
http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/turquoise.html
http://www.indianvillage.com/turquoisemines.htm
http://www.turquoiseguide.com/articles/turquoise/turquoise-basics/name.htm |
