The gemstone associated with the month of December is Turquoise, a captivating opaque mineral prized for its distinctive blue-to-green hues. Its name, derived from the French pierre turquoise meaning "Turkish stone," reflects its historical trade routes, though its origins are deeply rooted in ancient Persia and the American Southwest. As a birthstone, Turquoise holds a unique position, celebrated not only for its vibrant color but also for its rich tapestry of cultural significance and metaphysical beliefs. This article will explore the history, geological formation, gemological properties, and enduring symbolism of Turquoise, drawing exclusively from the available factual data to provide a comprehensive guide for enthusiasts and collectors.
History and Lore
Turquoise is one of the oldest known gemstones, with a history spanning thousands of years. Its use dates back to ancient civilizations, where it was revered for its protective and ornamental qualities. The stone was particularly significant in ancient Egypt, where it was used in elaborate jewelry and funerary artifacts. The famous burial mask of Tutankhamun, for instance, is adorned with turquoise, highlighting its status as a stone of royalty and divinity.
The journey of Turquoise from its mining sources to global markets is a story of cultural exchange. While the name suggests a Turkish origin, the primary sources of Turquoise in antiquity were from Persia (modern-day Iran). The stone was traded extensively along the Silk Road, reaching Europe and the Americas. In the Americas, indigenous cultures of the Southwestern United States and Mexico developed their own profound relationship with Turquoise, considering it a sacred stone connected to the sky and water. The Navajo, Zuni, and Pueblo peoples have a long tradition of crafting turquoise jewelry, often incorporating intricate silverwork.
The modern designation of Turquoise as a December birthstone is a relatively recent development. The concept of birthstones can be traced back to the Breastplate of Aaron described in the Old Testament, which featured twelve stones representing the twelve tribes of Israel. This tradition evolved over centuries, and in 1912, the American National Association of Jewelers (now Jewelers of America) established a standardized list of birthstones. Turquoise was assigned to December, solidifying its place in contemporary culture. Its association with the winter month may be linked to its cool, refreshing color, reminiscent of icy landscapes or clear winter skies.
Geological Formation and Sources
Turquoise is a hydrous phosphate of copper and aluminum, formed in arid regions through a complex geological process. It is a secondary mineral, meaning it is not formed directly from magma but through the alteration of primary rocks. The process typically begins with the weathering and erosion of copper-rich rocks, such as porphyry or granitic igneous rocks. Water, carrying dissolved minerals, percolates through these rocks and reacts with aluminum-rich rocks like alunite. In the presence of phosphorus, often derived from the breakdown of apatite or other minerals, the elements combine to form turquoise.
The color of Turquoise is primarily determined by its copper content, which imparts the characteristic blue hue. Higher copper concentrations result in a more vivid blue, while iron impurities can lead to greenish tones. The presence of water in the mineral's structure is crucial for its formation and stability.
Turquoise deposits are found in only a few regions globally, making it a relatively rare gemstone. The most significant historical and modern sources include:
- Iran (Persia): The Nishapur region in Iran has been the source of some of the finest "Persian turquoise" for over 2,000 years. Known for its pure sky-blue color with minimal matrix (the host rock), Iranian turquoise is highly prized.
- United States: The Southwestern states of Arizona, New Mexico, and Nevada are major producers. Famous mines include the Sleeping Beauty mine in Arizona (known for its pure blue color, often with little matrix) and the Morenci mine (known for its spiderweb matrix). The Cerrillos Hills in New Mexico are also a significant source, with a history of use by indigenous peoples.
- China: China has emerged as a major producer in recent decades, with deposits in Hubei and Xinjiang provinces. Chinese turquoise often exhibits a wide range of colors and matrix patterns.
- Other Sources: Additional deposits are found in Afghanistan, Egypt, Mexico, and Australia, though these are generally less significant in terms of global production.
The quality of turquoise is heavily influenced by its matrix. The host rock can form intricate patterns within the gem, ranging from fine, even spiderweb patterns to bold, irregular veins. The most valued turquoise is typically that which is solid blue (matrix-free or with a minimal, fine matrix) and has been stabilized for durability.
Gemological Properties
Turquoise is an opaque mineral with a distinctive color range, making it easily identifiable. Its physical and chemical properties are consistent, though they can vary slightly based on its composition and matrix.
Chemical Composition: The ideal chemical formula for turquoise is CuAl₆(PO₄)₄(OH)₈·4H₂O. It is a hydrous copper-aluminum phosphate. Trace elements, particularly iron (Fe) and zinc (Zn), can substitute for copper or aluminum, leading to variations in color and properties.
Crystal System: Turquoise is triclinic, but it is almost always found in massive or nodular form rather than as well-defined crystals.
Hardness: On the Mohs scale of hardness, turquoise ranges from 5 to 6. This makes it relatively soft compared to many other gemstones like quartz (7) or diamond (10). Its softness means it can be scratched by harder materials and requires careful handling.
Specific Gravity: The specific gravity of turquoise typically falls between 2.60 and 2.90, which is relatively low, indicating a less dense mineral.
Refractive Index: Turquoise has a refractive index between 1.61 and 1.65, measured on the surface due to its opacity.
Luster: It exhibits a waxy to subvitreous (glass-like) luster when polished.
Durability and Treatments: Due to its porosity and softness, most commercial turquoise is treated to enhance its durability and color. The most common treatments include: * Stabilization: Impregnating the stone with a clear resin or wax to reduce porosity, prevent cracking, and improve polish. This is a standard and accepted industry practice. * Dyeing: Some lower-quality or pale stones are dyed to achieve a more uniform or intense blue color. This treatment should be disclosed. * Reconstitution: In some cases, crushed turquoise is mixed with a binder and dye to create a composite material, often used in inexpensive jewelry.
Natural, untreated turquoise is rare and commands a premium. When evaluating turquoise, gemologists consider color, uniformity, hardness, and the nature of the matrix.
| Property | Specification | Notes |
|---|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Hydrous copper-aluminum phosphate |
| Hardness (Mohs) | 5 - 6 | Relatively soft; prone to scratching |
| Specific Gravity | 2.60 - 2.90 | Low density |
| Refractive Index | 1.61 - 1.65 | Measured on the surface |
| Luster | Waxy to subvitreous | Polished appearance |
| Color | Blue to green | Determined by copper (blue) and iron (green) content |
| Transparency | Opaque | Never transparent or translucent |
Symbolism and Metaphysical Beliefs
Beyond its physical beauty, Turquoise is one of the most symbolically rich gemstones. Across cultures and millennia, it has been attributed with powerful protective, healing, and spiritual properties.
Protection and Luck: In many traditions, Turquoise is considered a protective amulet. Ancient Persian warriors believed it could deflect evil and protect from injury. In the American Southwest, it is often called the "sky stone" and is thought to connect the wearer to the heavens, offering protection from danger and bad luck. It is also widely regarded as a stone of good fortune and success.
Healing and Wellness: Turquoise is strongly associated with physical and emotional healing. It is believed to aid in the absorption of nutrients, enhance the immune system, and support the respiratory and circulatory systems. Emotionally, it is said to promote inner calm, balance, and creativity, helping to release old patterns and encourage self-expression.
Spiritual Connection: The stone is linked to the throat chakra, which governs communication and self-expression. Wearing turquoise is thought to facilitate honest and clear communication. It is also associated with the heart chakra, fostering compassion and love. For many indigenous peoples of the Americas, Turquoise is a sacred stone used in ceremonies and rituals, representing the earth and sky.
Modern Beliefs: In contemporary crystal healing, Turquoise is often recommended for those born in December, as it is believed to align with the energetic and personality traits associated with this month. It is also a popular stone for artists and communicators, used to overcome creative blocks and enhance intuition.
It is important to note that while these metaphysical beliefs are deeply held by many, they are not supported by scientific evidence and fall outside the realm of gemological study. They represent a significant aspect of the stone's cultural legacy.
Care and Cleaning
Due to its relatively low hardness and porosity, Turquoise requires specific care to maintain its beauty and integrity. Proper maintenance is essential, especially for jewelry that is worn regularly.
Cleaning: * Avoid Harsh Chemicals: Never expose turquoise to harsh chemicals, including household cleaners, perfumes, lotions, hairsprays, and cosmetics. These can damage the stone's surface and cause discoloration. * Warm Water and Mild Soap: The safest method for cleaning is to use lukewarm water, a drop of mild dish soap, and a soft brush (like a baby toothbrush). Gently scrub the stone and the setting, then rinse thoroughly with clean water. * Drying: Pat the jewelry dry with a soft, lint-free cloth. Avoid using ultrasonic or steam cleaners, as the vibrations and heat can cause cracking or damage to the stone and its setting. * Stabilized vs. Natural: Stabilized turquoise is more resistant to damage from cleaning solutions but should still be treated with care. Natural, untreated turquoise is more susceptible to damage and should be cleaned with extra caution.
Storage: * Store turquoise jewelry separately from other jewelry to prevent scratches. A soft pouch or a lined jewelry box is ideal. * Keep it away from direct sunlight and extreme heat, as prolonged exposure can cause fading and dehydration, leading to cracking.
Handling: * Remove turquoise jewelry before engaging in physical activities, sports, or household chores to avoid impact and abrasion. * Apply cosmetics, perfumes, and lotions before putting on turquoise jewelry to minimize exposure.
By following these care guidelines, the vibrant color and luster of Turquoise can be preserved for generations, allowing this ancient gemstone to continue its legacy as a cherished December birthstone.
Conclusion
Turquoise stands as a gemstone of profound historical depth, unique geological origin, and enduring cultural significance. Its journey from the arid mines of Persia and the American Southwest to the jewelry boxes of December-born individuals worldwide is a testament to its timeless appeal. As a December birthstone, it offers a cool, vibrant splash of color against the winter landscape, carrying with it the legacy of ancient protective amulets and sacred sky stones. While its gemological properties—characterized by a soft hardness and a distinctive blue-to-green palette—require mindful care, its value is amplified by the rich symbolism and metaphysical beliefs that have been woven around it for millennia. For gemstone enthusiasts, jewelry buyers, and students of gemology, Turquoise remains a captivating subject, embodying the perfect fusion of natural artistry and human heritage.