The final month of the year is uniquely distinguished in the world of gemology by not one, but three official birthstones: Turquoise, Tanzanite, and Zircon. While Zircon is a recognized member of this group, the provided materials focus exclusively on the two most commercially prominent and visually distinct options: the ancient, sky-blue Turquoise and the modern, violet-blue Tanzanite. This article provides an in-depth exploration of these two remarkable gemstones, delving into their geological origins, gemological properties, historical significance, and their celebrated role as birthstones for December.
For centuries, Turquoise has been revered across numerous cultures, its distinctive color making it a staple in ceremonial jewelry and ornamental arts. In contrast, Tanzanite is a recent discovery, a 20th-century marvel that rapidly ascended to prominence due to its singular beauty and rarity. Understanding these two stones offers a fascinating glimpse into both the ancient traditions of gemology and the dynamic nature of the modern market. This guide will examine the science behind their formation, the sources from which they are mined, the cultural beliefs they have inspired, and the practical considerations for their care and use in fine jewelry.
History and Lore
The historical narratives of Turquoise and Tanzanite could not be more different. Turquoise is steeped in millennia of human history, while Tanzanite’s story is one of modern serendipity.
Turquoise: An Ancient Talisman
Turquoise is among the oldest gemstones known to humanity, with a history of use and reverence that spans continents and civilizations. Its name is derived from the French phrase pierre tourques, or "Turkish stone," a reference to the gem's introduction to Europe through Turkish trade routes originating from Persia (modern-day Iran). However, its use predates these trade routes by thousands of years. Ancient civilizations, including the Egyptians, Persians, and the indigenous peoples of the Americas, prized Turquoise for its potent symbolic power and its captivating color, which was often associated with the heavens and the life-giving sky.
In ancient Egypt, Turquoise was a symbol of rebirth and was intricately worked into burial masks, such as the famous funerary mask of Tutankhamun, and jewelry for the elite. It was believed to offer protection and ensure a safe passage to the afterlife. Similarly, in Persian culture, Turquoise was worn as a protective amulet, thought to ward off unnatural death and ensure good fortune. The stone was so integral to their culture that it was often set into swords, bridles, and turbans. Across the Atlantic, Native American tribes, particularly in the Southwestern United States, have a profound connection to Turquoise. For them, it is not merely a decorative stone but a piece of the sky that has fallen to earth, a sacred element used in ceremonies and as a conduit for communicating with the spirit world. This rich tapestry of historical use solidifies Turquoise’s status as a gemstone of immense cultural and spiritual weight.
Tanzanite: A Modern Marvel
In stark contrast to Turquoise's ancient lineage, Tanzanite is a distinctly modern gemstone. Its history begins in the mid-20th century. The story is one of remarkable chance: in 1967, a Masai tribesman named Ali Juuyawatu discovered translucent blue crystals of a previously unknown mineral in the Merelani Hills of northern Tanzania. Initially, prospectors dismissed the find, believing it to be the common blue mineral zoisite. However, the material’s exceptional color and clarity soon attracted the attention of gemologists.
The gem's potential was quickly recognized by the New York-based jewelry company Tiffany & Co., which saw it as a potential blockbuster. After securing the rights to the material, Tiffany & Co. launched a major marketing campaign in 1968, branding the gem "Tanzanite" after its country of origin. This strategic move was immensely successful, positioning Tanzanite as a rare and desirable alternative to more traditional blue gemstones like sapphire. Its introduction was a landmark event in the gem trade, creating an entirely new market for a gemstone that, geologically speaking, had existed for millions of years but was only just discovered. Its rapid rise to become a modern birthstone for December is a testament to its captivating beauty and the power of modern gemological marketing.
Geological Formation and Sources
The origins of these two gemstones are as distinct as their histories. One is a product of geological processes that occur near the Earth's surface, while the other is born from immense heat and pressure deep within the planet's crust.
The Hydrous Copper Aluminum Phosphate of Turquoise
Turquoise is not a single mineral but a hydrous copper aluminum phosphate. Its formation is a relatively low-temperature, near-surface process. It occurs in arid regions where acidic, copper-rich groundwater percolates through rocks that contain aluminum-bearing minerals, such as feldspar. Over long geological periods, this process results in the precipitation of the turquoise mineral in nodules and vein fillings.
The presence of copper is what gives Turquoise its characteristic blue to blue-green color, while traces of iron can shift the hue toward green. The quality and color of the deposit are highly dependent on the specific geological conditions of its formation. Historically, the most prized Turquoise has come from Persia (modern-day Iran), known for its consistent, "robin's egg" blue color. Other significant sources include the Southwestern United States (Arizona, New Mexico, Nevada), Egypt, and China. The material from these locations varies widely in color, matrix (the host rock embedded within the stone), and durability.
The Vanadium-Bearing Zoisite of Tanzanite
Tanzanite's formation requires a far more specific and violent set of geological circumstances. It is a variety of the mineral zoisite, and its unique violet-blue color is the result of trace amounts of vanadium within its chemical structure. The gemstone is found in only one place on Earth: a small, four-square-kilometer mining area in the Merelani Hills of Northern Tanzania, near the base of Mount Kilimanjaro.
The geological event that created Tanzanite was a unique combination of tectonic plate movement and metamorphism. Approximately 585 million years ago, the region experienced a massive tectonic collision that subjected the local rocks to intense heat and pressure. This event caused the existing zoisite crystals to be "recrystallized" and infused with vanadium, creating the conditions necessary for the formation of the blue-violet crystals. Due to the highly localized and specific nature of this event, Tanzanite is considered one of the most rare gemstones in the world. Its exclusivity to this single location in Tanzania is a key factor in its market value and allure.
Gemological Properties
A scientific examination of Turquoise and Tanzanite reveals their significant differences in hardness, composition, and clarity. These properties are critical for gemologists, jewelers, and consumers alike, as they directly impact a stone's durability, appearance, and value.
| Property | Turquoise | Tanzanite |
|---|---|---|
| Chemical Composition | Hydrous copper aluminum phosphate | Calcium aluminum hydroxyl sorosilicate |
| Crystal System | Triclinic | Orthorhombic |
| Hardness (Mohs Scale) | 5 - 6 | 6.5 - 7 |
| Refractive Index | 1.610 - 1.650 | 1.691 - 1.700 |
| Specific Gravity | 2.60 - 2.90 | 3.35 |
| Luster | Waxy to subvitreous | Vitreous |
| Transparency | Opaque to translucent | Transparent to translucent |
Turquoise: A Study in Opaque Beauty
Turquoise is prized for its opaque nature. Its value is determined by its color, which ranges from sky blue to bluish-green, and its texture. The most desirable color is an even, intense, medium to light "sky blue." Greenish shades generally command lower prices, although some high-quality "spiderweb" matrix patterns can be highly valued.
With a hardness of only 5 to 6 on the Mohs scale, Turquoise is a relatively soft gemstone. This makes it susceptible to scratching and abrasion, and it can be damaged by acids and even prolonged exposure to skin oils and cosmetics. Most of the Turquoise on the market has been stabilized or treated in some way to enhance its color and durability. Stabilization involves impregnating the porous stone with a clear resin or wax, which helps it resist damage and hold a polish. Natural, untreated Turquoise of high quality is rare and commands a significant premium.
Tanzanite: A Trichroic Treasure
Tanzanite is a member of the zoisite group and is known for its exceptional clarity and transparency. Its most remarkable gemological characteristic is its strong trichroism—the ability to display three different colors when viewed from three different crystallographic directions. A trichroic Tanzanite will typically show a blue, a violet, and a reddish-brown hue. This property presents a significant challenge for gem cutters, who must orient the rough stone precisely to showcase the most desirable blue-violet color from the top of the finished gem.
Tanzanite has a hardness of 6.5 to 7 on the Mohs scale, making it more durable than Turquoise but still softer than sapphire or diamond. It is also pleochroic, meaning its color can appear to change depending on the lighting conditions. In daylight or fluorescent light, the blue component is often more dominant, while in incandescent light, the violet tones are more pronounced. This color shift adds to the stone's mystique and appeal. Due to its relative softness and cleavage (a tendency to split along certain planes), Tanzanite requires careful handling and is often set in protective settings like bezels for jewelry intended for daily wear.
Symbolism and Metaphysical Beliefs
Throughout history, gemstones have been imbued with symbolic meaning and metaphysical powers. Turquoise and Tanzanite are no exception, though their attributed properties reflect their respective ancient and modern origins.
Turquoise: The Master Healer and Protector
As one of the world's oldest talismanic stones, Turquoise is associated with a vast array of beliefs. It is widely regarded as a stone of protection, said to guard the wearer against harm and attract good fortune. Its connection to the sky has made it a symbol of wisdom, tranquility, and spiritual grounding. In many traditions, Turquoise is considered a master healing stone, believed to align all the chakras, purify energy fields, and support the body's natural healing processes. It is also associated with honest communication and emotional balance, making it a popular stone for those seeking to overcome anxiety or depression. The ancient belief that the stone would change color to warn its owner of danger or illness persists in some modern metaphysical circles.
Tanzanite: The Stone of Transformation
As a newly discovered gem, Tanzanite lacks the ancient lore of Turquoise. However, it has quickly acquired its own set of modern metaphysical associations. It is often called the "Stone of Transformation," believed to facilitate a higher consciousness, intuition, and spiritual perception. Metaphysical practitioners suggest that Tanzanite can help one move from a state of confusion to a state of clarity and purpose, making it a powerful tool for spiritual awakening and personal growth. Its connection to the throat and third-eye chakras is emphasized, linking it to enhanced communication and psychic abilities. Some also associate Tanzanite with calmness and stress relief, making it a popular choice for meditation.
Care and Cleaning
The differing physical properties of Turquoise and Tanzanite necessitate distinct approaches to their care and maintenance.
Caring for Turquoise
Due to its porosity and relatively low hardness, Turquoise requires gentle care. It is highly sensitive to chemicals, including those found in cosmetics, perfumes, hairspray, and even some soaps. These substances can cause the stone to discolor or its polish to dull over time. To clean Turquoise, simply use a soft, dry cloth. If necessary, a mild soap and lukewarm water solution can be used, but the stone must be dried immediately and thoroughly. Avoid ultrasonic cleaners and steam cleaners, as the heat and vibrations can damage the stone, especially if it has been stabilized with resin. It is best to store Turquoise jewelry separately to prevent it from being scratched by harder gems.
Caring for Tanzanite
While harder than Turquoise, Tanzanite still demands careful handling. It has perfect cleavage in one direction, meaning a sharp blow along this plane can cause the stone to split. For this reason, it is not recommended for rings that will be worn during heavy manual work. The safest method for cleaning Tanzanite is warm water, a small amount of mild dish soap, and a soft brush. As with Turquoise, avoid harsh chemicals and extreme temperature changes. Ultrasonic and steam cleaners should never be used, as the vibrations and heat can cause existing internal fractures to expand or can damage the stone if it has been fracture-filled (a common treatment for lower-clarity material). Storing it in a soft cloth or a separate compartment in a jewelry box will protect it from being scratched by other jewelry.
Conclusion
The December birthstones, Turquoise and Tanzanite, offer a compelling study in contrasts. Turquoise represents an enduring link to human history, a gemstone revered for its protective qualities and sky-blue color for millennia. Its formation near the Earth's surface and its use by ancient civilizations from Persia to the Americas underscore its timeless appeal. Tanzanite, on the other hand, is a product of a singular, violent geological event and a testament to modern discovery. Its unique trichroism, exclusive origin, and rapid ascent in the gem market highlight the dynamic and ever-evolving world of gemology.
Together, they provide those born in December with a choice between ancient tradition and contemporary rarity. Whether one is drawn to the deep, historical significance of Turquoise or the singular, transformative beauty of Tanzanite, both stones possess a unique character and a rich story, making them exceptional and meaningful additions to any collection.