Turquoise, with its distinctive sky-blue to greenish-blue hue, stands as one of the most recognizable and culturally significant gemstones in human history. Revered for millennia as a protective talisman and a symbol of wealth and status, it was officially designated as a modern birthstone for the month of December in 1912 by the American National Association of Jewelers (now Jewelers of America). This article delves into the rich tapestry of turquoise, exploring its geological origins, historical journey, gemological characteristics, and enduring symbolism, drawing exclusively from authoritative sources to provide a comprehensive overview for gemstone enthusiasts and collectors.
History and Lore
The history of turquoise is as ancient as civilization itself, with evidence of its use dating back over 6,000 years. One of the earliest known uses of turquoise was by the ancient Egyptians, who mined it from the Sinai Peninsula. The stone was often used in elaborate jewelry, such as the famous burial mask of Tutankhamun, which is adorned with turquoise inlay. Egyptian artisans prized the stone for its color and durability, believing it possessed protective qualities, particularly for the dead on their journey to the afterlife.
Across the Atlantic, pre-Columbian cultures of the Americas held turquoise in equally high esteem. The Aztec and Maya civilizations of Mesoamerica, as well as the Pueblo peoples of the American Southwest, incorporated turquoise into ceremonial objects, jewelry, and even architecture. For these cultures, the stone was deeply connected to the earth and sky, representing water, vegetation, and spiritual protection. The ancient Puebloans of Chaco Canyon, for instance, established a vast trade network to acquire turquoise from mines in present-day New Mexico and Arizona, using it in ritualistic practices and as a currency.
In Asia, turquoise has a long and storied history, particularly in Tibet and Persia (modern-day Iran). Persian turquoise, often characterized by a clear, robin's-egg blue color, was highly sought after and traded along the Silk Road. It was used to adorn everything from mosques to royal jewelry, and it was believed to ward off the "evil eye" and bring good fortune. Tibetan culture has a profound connection to turquoise, where it is considered a symbol of wisdom, purity, and spiritual well-being, often set into elaborate silver jewelry and ceremonial objects.
The journey of turquoise to become a modern birthstone began in the early 20th century. In 1912, the American National Association of Jewelers standardized a list of birthstones, officially recognizing turquoise as the birthstone for December. This list was later updated and expanded, but turquoise has remained a steadfast member, its popularity enduring through changing fashion trends. Its inclusion was a nod to its historical significance and its desirable color, which evokes the clear skies and deep waters of the winter month.
Geological Formation and Sources
Turquoise is a hydrous phosphate of copper and aluminum, forming in arid regions where acidic, copper-rich water percolates through host rocks containing aluminum and phosphorus. This process occurs in the upper oxidized zones of copper deposits, where the interaction between copper minerals and aluminum-rich rocks (such as volcanic ash or granite) leads to the precipitation of turquoise. The gemstone is typically found in veins or nodules within a host rock, often accompanied by a matrix of brown or black veining, which can be composed of iron oxides or other minerals.
The color of turquoise is primarily determined by its chemical composition. The presence of copper imparts the characteristic blue to greenish-blue hues, while iron content tends to shift the color toward green. The most prized turquoise, often described as "sky blue" or "robin's egg blue," typically has a low iron content and a fine, even color. The gemstone's structure is relatively porous and can be susceptible to discoloration from oils, chemicals, and even the natural oils from human skin, which is why it is often stabilized in modern jewelry.
Turquoise deposits are found in several locations worldwide, each producing stones with distinct characteristics. The most significant sources include:
- United States: The American Southwest, particularly Arizona, New Mexico, and Nevada, is renowned for its turquoise mines. Historic mines such as Sleeping Beauty, Kingman, and Morenci have produced stones of various colors and matrix patterns. The "Lander Blue" turquoise from Nevada is particularly famous for its intense blue color and spiderweb matrix, making it one of the most valuable varieties.
- Iran (Persia): Iranian turquoise, historically mined in the Nishapur region, is celebrated for its pure, uniform blue color and is often free of matrix. It has been a benchmark for quality for centuries.
- China: China has become a major producer of turquoise in recent decades, with mines in Hubei and other provinces. Chinese turquoise is often available in large quantities and a range of colors, from light blue to green.
- Egypt: The ancient mines in the Sinai Peninsula, such as Serabit el-Khadim, are historically significant, though modern production is limited.
- Other Sources: Turquoise is also found in Afghanistan, Chile, and Mexico, each contributing to the global supply.
It is important to note that the availability of natural, untreated turquoise from many historic mines is limited, leading to a market where stabilized and reconstituted turquoise is common. Stabilization involves impregnating the porous stone with a clear resin to enhance its durability and color, a practice widely accepted in the gem and jewelry trade.
Gemological Properties
Turquoise is an opaque to semi-translucent gemstone with a distinctive waxy to vitreous luster. Its gemological properties are key to its identification and valuation. The following table summarizes its primary characteristics based on standard gemological references.
| Property | Description |
|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O (Hydrated Copper Aluminum Phosphate) |
| Crystal System | Triclinic (rarely seen in crystals; usually massive) |
| Color | Sky blue, greenish-blue, apple green; color is due to copper (blue) and iron (green). |
| Hardness (Mohs Scale) | 5 to 6 |
| Refractive Index | 1.610 to 1.650 (typically not measurable due to opacity) |
| Specific Gravity | 2.60 to 2.90 |
| Luster | Waxy to vitreous |
| Transparency | Opaque to semi-translucent |
| Cleavage | None, but may show uneven fracture |
| Durability | Fair to good. Softer and more porous than many gemstones, making it susceptible to scratching, chipping, and discoloration. |
The hardness of turquoise (5-6 on the Mohs scale) means it can be scratched by harder materials. This is a crucial consideration for jewelry, as it should be stored separately from other gemstones to prevent abrasion. Its porous nature also makes it vulnerable to chemicals, including perfumes, lotions, and acids, which can cause permanent discoloration or etching.
The value of turquoise is influenced by several factors, including color, matrix pattern, and size. Stones with a uniform, intense blue color and minimal matrix (or an attractive, consistent matrix) command the highest prices. The "Lander Blue" variety, for example, is highly prized for its deep blue color and distinctive black or brown spiderweb matrix. The origin of the stone can also affect its value, with Persian and certain American varieties (like Lander Blue) historically being among the most valued.
Symbolism and Metaphysical Beliefs
Beyond its physical properties, turquoise has been imbued with profound symbolic meaning across cultures and centuries. As a talisman, it has been believed to offer protection, healing, and good fortune.
- Protection and Safety: One of the most consistent beliefs associated with turquoise is its protective power. Ancient warriors, such as the Persians and Native American tribes, wore turquoise amulets into battle, believing it would shield them from harm and injury. It was also thought to protect the wearer from falls, particularly from horses, which is why it is sometimes called the "horseman's stone."
- Healing and Well-being: Turquoise has long been associated with physical and spiritual healing. In Tibetan medicine, it is used in various remedies and is believed to support the immune system and detoxify the body. It is also linked to the throat chakra, thought to aid in communication and self-expression.
- Spiritual Connection: For many indigenous cultures of the Americas, turquoise is a sacred stone that connects the wearer to the earth and sky. It is often used in prayer and meditation to foster a sense of balance, peace, and spiritual awareness. Its color is seen as a representation of water, a vital element in arid landscapes, symbolizing life and renewal.
- Friendship and Love: In some cultures, turquoise is given as a token of friendship and affection. It is believed to foster loyalty and trust, and its color is associated with tranquility and harmony in relationships.
These metaphysical beliefs, while not scientifically verified, contribute to the gemstone's enduring cultural appeal. For many, wearing turquoise is a way to connect with these ancient traditions and the symbolic meanings that have been passed down through generations.
Care and Cleaning
Due to its relative softness and porosity, turquoise requires careful handling and maintenance to preserve its beauty and integrity. Proper care is essential for anyone who owns turquoise jewelry.
- Cleaning: Turquoise should be cleaned gently with a soft, damp cloth. Avoid using ultrasonic cleaners, steam cleaners, or harsh chemicals, as these can damage the stone. For a deeper clean, use a mild soap and lukewarm water solution, but ensure the stone is dried thoroughly afterward. Never soak turquoise for extended periods, as water can penetrate the porous structure and cause discoloration or damage to any stabilizing resins.
- Storage: Store turquoise jewelry separately from other gemstones and metals to prevent scratching. A soft pouch or a lined jewelry box is ideal. Keep it away from direct sunlight and extreme temperatures, which can cause fading or cracking over time.
- Handling: Apply perfumes, lotions, and hairsprays before putting on turquoise jewelry to minimize exposure to chemicals. Remove jewelry before swimming (chlorine is damaging) or engaging in activities that could cause impact or abrasion.
For stabilized turquoise, the care is similar, though the resin impregnation provides slightly more resistance to discoloration. However, the stone's hardness remains the same, so protection from scratches is still paramount.
Conclusion
Turquoise is a gemstone of remarkable depth, bridging the ancient and the modern, the scientific and the spiritual. From the tombs of Egyptian pharaohs to the silver jewelry of the American Southwest, its history is a testament to its universal appeal. As the birthstone for December, it continues to captivate with its serene color and rich cultural legacy. Understanding its geological formation, gemological properties, and proper care allows enthusiasts and collectors to appreciate not just its beauty, but the complex story embedded within each stone. Whether valued for its historical significance, metaphysical properties, or simply its vibrant color, turquoise remains a timeless and cherished gemstone.