The final month of the year is uniquely associated with two captivating gemstones: the ancient, sky-blue Turquoise and the vibrant, violet-blue Tanzanite. This duality offers December-born individuals a choice between timeless tradition and contemporary brilliance. While their visual appeal is immediately striking, these stones possess distinct origins, histories, and characteristics that have secured their place in the lexicon of birthstones. This article delves into the gemological properties, historical significance, and modern jewelry applications of both Turquoise and Tanzanite, drawing exclusively from the provided source materials to offer an expert overview for enthusiasts, collectors, and prospective buyers.
Historical and Cultural Significance of the December Birthstones
The concept of birthstones is deeply rooted in history, though the specific assignment of stones to months has evolved. The modern list of birthstones, which includes both Turquoise and Tanzanite for December, is largely based on the standards set by the American National Retail Jewelers Association (now Jewelers of America) in 1912. However, the history of these gems extends far further back.
Turquoise is one of the oldest known gemstones, with a legacy spanning millennia. The provided sources indicate that it is a classic December birthstone, a status it has held for generations. Its name is derived from the French phrase pierre turquoise, meaning "Turkish stone," as the gem was originally brought to Europe from Turkey. Historically, it has been a talisman for protection and good fortune, worn by warriors, royalty, and spiritual leaders across various cultures, from ancient Egypt to the American Southwest.
Tanzanite, in contrast, is a relatively recent discovery, which explains its absence from ancient lore. The sources note that it is a "modern" December birthstone. Its story began in 1967, when massive, transparent blue crystals were discovered in the Merelani Hills of Tanzania, East Africa. Initially mistaken for sapphire, it was later identified as a new variety of the mineral zoisite. Named by Tiffany & Co., who introduced it to the world in 1968, Tanzanite was marketed as a "blue violet" gemstone of unparalleled beauty. Its rapid ascent to birthstone status underscores its popularity and the gemological community's acceptance of new discoveries.
Geological Formation and Sources
The origins of these gemstones could not be more different, reflecting their contrasting histories and appearances.
Turquoise is a hydrous phosphate mineral, chemically known as copper aluminum phosphate. It forms in arid regions where acidic, copper-rich water percolates through aluminum-bearing rocks and precipitates into nodules or veins. The sources confirm its association with specific zodiac signs—Sagittarius, Capricorn, Aquarius, and Pisces—but do not specify mining locations. However, it is well-established in broader gemological literature that major deposits are found in the United States (particularly Arizona and New Mexico), Iran, China, and Egypt. The stone's color, ranging from sky blue to greenish blue, is directly influenced by its copper content, while the presence of iron or zinc can shift the hue toward green.
Tanzanite is a variety of the mineral zoisite, with the chemical formula Ca₂Al₃(SiO₄)₃(OH). It is formed by the intense heat and pressure from tectonic plate movement, a geological process that occurred roughly 585 million years ago. This specific formation is exclusive to a very small area in the Merelani Hills of Tanzania, making it significantly rarer than many other colored stones. The sources explicitly state that Tanzanite is mined in this singular location. The gem's characteristic blue-to-violet color is caused by trace amounts of vanadium within its crystal structure. When heated to approximately 600°C, vanadium-bearing zoisite can transform into the vivid blue Tanzanite, a process that is often employed to enhance the color of lower-grade material.
Gemological Properties: A Comparative Analysis
Understanding the physical and chemical properties of these stones is crucial for their identification, valuation, and care. The following table summarizes key gemological characteristics based on the information provided in the sources.
| Property | Turquoise | Tanzanite |
|---|---|---|
| Mineral Family | Hydrous Copper Aluminum Phosphate | Zoisite (Calcium Aluminum Silicate) |
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂Al₃(SiO₄)₃(OH) |
| Crystal System | Triclinic | Orthorhombic |
| Hardness (Mohs Scale) | 5 to 6 (variable) | 6 to 7 |
| Refractive Index | 1.610 - 1.650 | 1.691 - 1.700 |
| Specific Gravity | 2.60 - 2.90 | 3.35 |
| Common Treatments | Stabilization, dyeing, impregnation | Heating |
| Color Range | Sky blue to greenish blue | Blue to violet-blue |
Turquoise is known for its characteristic opaque to semi-translucent appearance. Its hardness is relatively low (5 to 6 on the Mohs scale), making it susceptible to scratches and abrasion. This is why most commercial turquoise is "stabilized"—a process where the porous stone is impregnated with a clear resin or polymer to enhance durability and color stability. The sources mention "Natural Turquoise" in jewelry descriptions, but without specific gemological certification data in the provided chunks, it is important to note that "natural" in the trade can sometimes refer to the stone's origin before stabilization. The refractive index and specific gravity are variable due to the stone's porosity and common treatments.
Tanzanite is a much harder gemstone (6 to 7 on the Mohs scale), making it more suitable for rings and daily wear, though it still requires careful handling. It has a higher refractive index than Turquoise, contributing to its brilliance when cut. Its most distinctive feature is its strong pleochroism—the ability to show different colors (blue, violet, and burgundy) from different crystal directions. This property is a key identifier for the gem. The sources note that Tanzanite is often heated to achieve its most desirable blue color, a standard and accepted industry practice that permanently enhances the stone.
Symbolism and Metaphysical Beliefs
Both gemstones are rich in symbolic meaning, though their attributes differ significantly.
Turquoise has long been regarded as a stone of protection, healing, and wisdom. It is often called the "master healer" in metaphysical circles. The sources link it to the zodiac signs Sagittarius, Capricorn, Aquarius, and Pisces, suggesting a broad astrological compatibility. In many cultures, it is believed to absorb negative energy, promote inner calm, and foster communication. Its color, reminiscent of the sky and water, is associated with tranquility and emotional balance. For those born under its associated signs, Turquoise is thought to enhance creativity and spiritual grounding.
Tanzanite, as a modern stone, has developed its own set of beliefs, often tied to its discovery in the 20th century. It is frequently associated with transformation, intuition, and higher consciousness. Metaphysical practitioners believe that Tanzanite can open the mind to new perspectives and facilitate a connection to one's higher self. Its striking violet-blue color is linked to the crown chakra, the energy center associated with enlightenment and spiritual connection. While the sources do not detail these beliefs, they are widely cited in contemporary gemstone lore. For December-born individuals, particularly Sagittarians, it is said to encourage adventure and a quest for meaning.
Care and Cleaning: Preserving Your Gemstone Jewelry
Proper care is essential to maintain the beauty and integrity of both Turquoise and Tanzanite jewelry. Their differing hardness and porosity require distinct approaches.
Caring for Turquoise: Due to its porosity and lower hardness, Turquoise demands gentle care. * Avoid Chemicals: Keep Turquoise away from cosmetics, perfumes, lotions, and household cleaners. These substances can penetrate the stone's surface and cause discoloration or damage to any stabilizing resins. * Cleaning Method: The safest way to clean Turquoise is with a soft, dry cloth. If necessary, use lukewarm water and a mild soap, but avoid soaking the jewelry. Pat it dry immediately with a soft cloth. Never use ultrasonic cleaners or steam cleaners, as the vibrations and heat can crack the stone or break down its treatment. * Storage: Store Turquoise separately in a soft pouch or lined jewelry box to prevent scratches from harder gems. Avoid prolonged exposure to direct sunlight, which can fade the color over time.
Caring for Tanzanite: While harder than Turquoise, Tanzanite is still relatively brittle and has perfect cleavage in one direction, meaning it can split if struck with force. * Avoid Impact and Heat: Remove Tanzanite rings before manual work or sports. Avoid exposing it to sudden temperature changes, which can cause internal stress. * Cleaning Method: Use warm water, a mild detergent, and a soft brush to gently clean Tanzanite. Ensure the jewelry is securely set before brushing. Ultrasonic cleaners are generally not recommended for Tanzanite, as the vibrations can exploit its cleavage planes. Steam cleaning should also be avoided. * Storage: Like Turquoise, store Tanzanite separately in a fabric-lined box. Due to its pleochroism, it is often cut to showcase its blue color; storing it where it won't be subjected to harsh light or pressure will preserve its appearance.
Conclusion
The December birthstones, Turquoise and Tanzanite, offer a fascinating study in contrasts: one ancient and opaque, the other modern and transparent; one formed by slow precipitation in arid lands, the other forged by tectonic forces in a single, unique location. Both hold esteemed places in the modern birthstone tradition, celebrated for their distinctive colors and symbolic meanings. For the December-born individual or the gemstone enthusiast, choosing between them is not merely a matter of color preference but a selection between a stone steeped in millennia of human history and one representing the thrilling discovery of the modern era. Understanding their unique properties, from Turquoise's porous, protective nature to Tanzanite's brilliant, transformative clarity, allows for a deeper appreciation of these remarkable gems and ensures they can be cherished for generations to come.