Turquoise, a mineral that has fascinated cultures around the world for millennia, is renowned for its striking blue to green color and its use in jewelry and ornamental objects. The stone’s name comes from the French “pierre turquoise,” meaning “Turkish stone,” as it was first brought to Europe through Turkish trade routes. Despite its common association with Native American jewelry, turquoise is found in various parts of the globe, each region contributing to the diversity of this gemstone. This article delves into the different kinds of turquoise, exploring their origins, characteristics, and cultural significance.
Classification Based on Origin
1. American Turquoise
The American Southwest, particularly Arizona, Nevada, New Mexico, and Colorado, is one of the most famous sources of turquoise. Each state produces stones with distinct features:
- Arizona: Known for its high-quality turquoise, Arizona’s mines, such as the Sleeping Beauty Mine, produce stones with vibrant blues and minimal matrix (the host rock that surrounds the turquoise). The Bisbee mine, now closed, was once celebrated for its deep blue turquoise with distinctive black matrix.
- Nevada: Nevada is home to over 100 turquoise mines, making it the largest producer of turquoise in the U.S. Mines like Lone Mountain, Pilot Mountain, and Godber-Billie are known for their unique colors and patterns. Nevada turquoise often features a spider web matrix, which can be brown, black, or even gold.
- New Mexico: The Cerrillos Hills area in New Mexico has been mined for turquoise since prehistoric times. The stones from this region tend to have a more muted, greenish-blue color with a distinctive matrix pattern.
- Colorado: While not as prolific as other states, Colorado’s turquoise is prized for its rarity. The stones from this region often have a softer, more pastel hue.
2. Persian (Iranian) Turquoise
Iran: Historically, Iran (formerly Persia) has been one of the most important sources of turquoise. Persian turquoise is renowned for its pure, sky-blue color and lack of matrix, which makes it highly desirable among collectors. The Nishapur region in northeastern Iran has been producing turquoise for over 7,000 years. Persian turquoise is often considered the “gold standard” in terms of quality and color.
3. Chinese Turquoise
China: China has become a significant producer of turquoise in recent decades. Chinese turquoise is typically found in the Hubei province and is known for its bright blue color, often with a greenish tint. Chinese turquoise can have a wide range of matrix patterns, from subtle to bold. Some Chinese mines produce high-quality stones that rival those from the American Southwest, while others yield lower-grade material that may require stabilization.
4. Middle Eastern and Central Asian Turquoise
Turkey, Afghanistan, and Pakistan: These regions have also produced turquoise, though in smaller quantities compared to Iran and China. Turkish turquoise is often associated with the historical trade routes that brought the stone to Europe. Afghan and Pakistani turquoise tends to have a more greenish hue and can feature a distinctive matrix.
5. Other Sources
Mexico: Mexican turquoise has been used by indigenous peoples for centuries. The stones from this region often have a more greenish-blue color with a dark brown or black matrix. Mexican turquoise is sometimes referred to as “Aztec turquoise” due to its historical significance in Mesoamerican cultures.
Egypt: Ancient Egypt was another early source of turquoise. The Sinai Peninsula, in particular, was home to some of the earliest known turquoise mines. Egyptian turquoise is often characterized by its soft, pale blue color and can feature a distinctive matrix.
Types of Turquoise Based on Appearance
Solid Color Turquoise
Sky Blue Turquoise: This type of turquoise is highly prized for its pure, intense blue color, often described as “robin’s egg blue.” It is the most sought-after variety and is commonly associated with Persian turquoise. Sky blue turquoise is rare and valuable, especially when it lacks any matrix.
Green Turquoise: Green turquoise can range from a light, minty green to a deep, forest green. This color is more common in American and Chinese turquoise. Green turquoise is often associated with copper content, as higher levels of copper can result in a bluer hue, while iron can cause a greener tone.
Matrix Turquoise
Spider Web Matrix: One of the most distinctive features of turquoise is its matrix, which refers to the host rock that surrounds the turquoise. Spider web matrix refers to a fine, intricate network of lines that resemble a spider’s web. This pattern is highly valued, especially when the matrix forms a symmetrical design. Nevada turquoise is particularly known for its spider web matrix.
Black Matrix: Black matrix turquoise features dark, almost black lines or patches within the stone. This type of matrix is often associated with Arizona and New Mexico turquoise. Black matrix can add depth and contrast to the stone, making it visually striking.
Brown Matrix: Brown matrix is more common than black matrix and can range from light tan to deep chocolate brown. This type of matrix is often found in turquoise from the American Southwest, particularly in Nevada and Colorado. Brown matrix can create a warm, earthy appearance.
Gold Matrix: Gold matrix is relatively rare and is found in some Nevada turquoise mines. The golden-brown lines or patches within the stone can give it a unique, luxurious look.
Variegated Turquoise
Bisected Turquoise: This type of turquoise features two distinct colors or patterns within the same stone. For example, one half of the stone might be sky blue, while the other half is green. Bisected turquoise is highly collectible and can be found in various regions, including the American Southwest and China.
Tricolor Turquoise: Tricolor turquoise contains three distinct colors or patterns within the stone. This can include combinations of blue, green, and matrix. Tricolor turquoise is rare and highly prized for its complexity and visual interest.
Chemical Composition and Formation
Chemical Formula
Turquoise has the chemical formula CuAl6(PO4)4(OH)8·4H2O. This complex formula indicates that turquoise is a hydrated phosphate of copper and aluminum. The presence of copper is responsible for the blue color, while iron can cause a greenish tint. The amount of water in the stone’s structure can also affect its color and hardness.
Formation
Turquoise forms in arid environments where water percolates through rocks rich in copper and aluminum. Over time, the water dissolves these metals and deposits them in cracks and crevices, where they crystallize into turquoise. The process can take millions of years, and the resulting stone is often found in association with other minerals, such as quartz and feldspar.
Hardness and Durability
Turquoise is relatively soft, with a Mohs hardness of 5 to 6. This means it can be easily scratched or damaged if not handled carefully. However, the hardness can vary depending on the stone’s composition and whether it has been treated or stabilized. Untreated turquoise is generally softer and more porous, while stabilized turquoise is harder and more durable.
Treatment and Enhancement
Stabilization
Stabilization is a common treatment for turquoise, especially for stones that are too soft or porous to be used in jewelry. During the stabilization process, the turquoise is infused with a clear resin or epoxy, which fills in the pores and strengthens the stone. Stabilized turquoise is more durable and less likely to crack or fade over time. However, it is important to note that stabilization does not enhance the color of the stone; it only improves its structural integrity.
Dyeing
Some lower-grade turquoise is dyed to improve its color. Dyeing can make a greenish or grayish stone appear more blue, but it is not a permanent treatment. Dyed turquoise can fade over time, especially when exposed to sunlight or heat. Ethical jewelers will always disclose whether a piece of turquoise has been dyed.
Reconstituted Turquoise
Reconstituted turquoise is made by crushing low-quality turquoise and binding it together with a resin. The resulting material can be cut and polished into cabochons or beads. While reconstituted turquoise can mimic the appearance of natural turquoise, it is not as valuable or durable. It is important to be aware of this distinction when purchasing turquoise jewelry.
Impregnation
Impregnation is similar to stabilization, but it involves using a wax or oil instead of a resin. Impregnated turquoise is less durable than stabilized turquoise and may need to be reapplied over time. This treatment is often used on high-quality turquoise to enhance its luster.
Cultural Significance and Symbolism
Native American Traditions
In many Native American cultures, turquoise is considered a sacred stone with spiritual and protective properties. It is often associated with the sky and water, symbolizing life, fertility, and abundance. Turquoise is used in ceremonies, rituals, and as a talisman to ward off evil spirits. Navajo, Hopi, Zuni, and Pueblo tribes, among others, have incorporated turquoise into their jewelry, pottery, and artwork for centuries.
Persian and Middle Eastern Beliefs
In ancient Persia, turquoise was believed to protect against the evil eye and bring good fortune. Persian kings would wear turquoise on their crowns and swords, believing that the stone could absorb harm and negative energy. In Islamic tradition, turquoise is associated with paradise and is often used in religious art and architecture.
Ancient Egyptian Uses
In ancient Egypt, turquoise was one of the most important gemstones, symbolizing immortality and rebirth. It was used in the creation of elaborate jewelry, amulets, and funerary masks, including the iconic death mask of Tutankhamun. Egyptian turquoise was also used in cosmetics, particularly in eye shadow, which was believed to protect the wearer from evil forces.
Modern Symbolism
Today, turquoise continues to be a symbol of protection, healing, and wisdom. It is often given as a gift to wish someone good luck or to celebrate a new beginning. In contemporary jewelry, turquoise is prized for its beauty and versatility, and it remains a popular choice for both traditional and modern designs.
Collecting and Investing in Turquoise
Factors That Affect Value
When evaluating turquoise for collecting or investment purposes, several factors come into play:
- Color: As mentioned earlier, sky blue turquoise is the most valuable, followed by green turquoise. The intensity and purity of the color are key considerations.
- Matrix: The presence and quality of matrix can significantly impact the value of a turquoise stone. Fine, intricate matrix patterns are highly prized, while excessive or unsightly matrix can reduce the stone’s worth.
- Origin: Turquoise from certain regions, such as Iran or the American Southwest, is more valuable than turquoise from other areas. The reputation of the mine or location can also affect the stone’s desirability.
- Treatment: Untreated, natural turquoise is generally more valuable than treated or enhanced stones. However, stabilized turquoise can still be valuable if it is of high quality and from a reputable source.
- Size and Shape: Larger, well-shaped turquoise stones are rarer and more valuable. Cabochons, beads, and carvings are all popular forms of turquoise, but the size and symmetry of the stone can influence its value.
Investment Potential
Turquoise has historically been a stable investment, with prices fluctuating based on supply and demand. High-quality, untreated turquoise from reputable sources tends to hold its value over time, making it an attractive option for collectors and investors. However, it is important to do thorough research and work with reputable dealers when investing in turquoise, as the market can be complex and varied.
Care and Maintenance
Cleaning
Turquoise should be cleaned gently with a soft cloth and mild soap. Avoid using harsh chemicals, ultrasonic cleaners, or steam cleaners, as these can damage the stone. If the turquoise has a matrix, be careful not to scratch or chip the surrounding rock.
Storage
Turquoise should be stored in a cool, dry place away from direct sunlight, which can cause the stone to fade. It is best to store turquoise in a soft cloth or velvet pouch to prevent scratches. If the turquoise has been stabilized, it is generally more durable, but it is still important to handle it with care.
Handling
Turquoise is relatively soft and can be easily scratched or chipped. Avoid wearing turquoise jewelry during activities that involve heavy contact, such as sports or household chores. Regularly inspect your turquoise pieces for signs of wear or damage, and have them professionally cleaned and repaired if necessary.
Conclusion
Turquoise is a gemstone of immense diversity, with variations in color, matrix, and origin that make each stone unique. From the vibrant blues of Persian turquoise to the intricate matrix patterns of American varieties, this mineral has captivated people for thousands of years. Whether you are a collector, investor, or simply an admirer of beautiful jewelry, turquoise offers something for everyone. By understanding the different types of turquoise and how to care for them, you can appreciate this timeless gemstone in all its glory.
