The month of December is uniquely associated with not one, but two principal birthstones: tanzanite and turquoise. This duality offers a fascinating contrast in geology, history, and cultural significance. While turquoise is an ancient stone revered for millennia, tanzanite is a modern discovery, its vibrant blue-violet hue captivating the world only in the late 20th century. Together, they represent a spectrum of color from the deep, velvety blues of the African plains to the robin's egg sky of ancient deserts. This article delves into the distinct journeys of these two gemstones, exploring their geological origins, gemological properties, historical lore, and their celebrated status as December's birthstones. We will examine how these stones, born from vastly different environments, have secured their place in both the annals of gemology and the hearts of jewelry enthusiasts.
History and Lore: An Ancient Stone and a Modern Sensation
The historical narratives of turquoise and tanzanite could not be more divergent, spanning from the dawn of civilization to the present day.
Turquoise: The Stone of the Ages Turquoise is one of the world’s most ancient gemstones, with a history that stretches back over 6,000 years. It was treasured by ancient civilizations across the globe, including the Egyptians, Persians, Chinese, and Native American tribes. In ancient Egypt, turquoise was inlaid in the funerary mask of Tutankhamun and was associated with the goddess Hathor. The stone’s name itself derives from the French pierre turquoise, meaning "Turkish stone," as it was originally brought to Europe from the mines of Persia via Turkish trade routes. For the Native American peoples of the Southwestern United States, turquoise is a sacred stone, deeply embedded in their spiritual and cultural practices. It is seen as a piece of the sky that fell to earth, a bringer of good fortune, protection, and health. This enduring legacy makes turquoise a cornerstone of cultural heritage and one of the most historically significant gemstones in existence.
Tanzanite: A 20th-Century Discovery In stark contrast, tanzanite’s history is remarkably brief. It was discovered in 1967 in the Merelani Hills of northern Tanzania, hence its name. The gemstone was initially found by a Maasai tribesman named Ali Juuyawatu, who brought the blue crystals to the attention of the local gemological community. Its potential was quickly recognized by the international market. However, it was the strategic partnership between the mining company and the jewelry giant Tiffany & Co. that launched tanzanite into global fame. In 1968, Tiffany & Co. introduced the stone to the world, declaring it "the most beautiful blue gemstone to be discovered in 2,000 years." This marketing campaign was phenomenally successful, and tanzanite rapidly became a sought-after gem for fine jewelry. Its status as a December birthstone was officially recognized in 2002 by the American Gem Trade Association (AGTA), making it the first new birthstone to be added to the modern list in over a century.
Geological Formation and Sources
The origins of these stones are as distinct as their histories, formed under different geological conditions in specific regions of the world.
Turquoise: A Hydrated Mineral of the Arid Lands Turquoise is not a single mineral but a hydrous phosphate of copper and aluminum. It forms in arid regions where acidic, copper-rich groundwater percolates through rocks containing aluminum and phosphorus minerals. Over thousands of years, this process creates veins and nodules of turquoise. Its distinctive blue-to-green color is directly tied to its chemical composition: copper imparts the blue hues, while iron contributes to green tones. The most historically significant sources for turquoise include: * Iran (Persia): The Nishapur region of Iran has been the primary source for the finest "Persian turquoise" for centuries, prized for its intense, sky-blue color and minimal matrix. * United States: The Southwestern U.S., particularly Arizona, New Mexico, and Nevada, is home to numerous famous turquoise mines (e.g., Sleeping Beauty, Kingman, Morenci). American turquoise often features a distinctive brown or black matrix, which is the host rock, and is highly valued in Native American jewelry. * Other Sources: Significant deposits are also found in China, Egypt, and Afghanistan.
Tanzanite: A Single-Source Gemstone Tanzanite’s geological story is one of extreme rarity. It is a variety of the mineral zoisite, specifically the blue-to-violet gemstone-quality form. Its formation requires a unique combination of geological events: the presence of the mineral zoisite, the infiltration of silicon and calcium, and, crucially, the presence of vanadium and chromium to create its signature color. The heat from a natural forest fire, estimated to have occurred between 585 and 255 million years ago, is believed to have transformed the brownish zoisite into the vibrant blue tanzanite we know today. This specific set of conditions has only been found in one location on Earth: the Merelani Hills of Tanzania, a small mining area of just a few square kilometers. This makes tanzanite a "single-source" gemstone, exponentially rarer than diamond. The limited geographic area and finite supply underscore its value and desirability.
Gemological Properties: A Scientific Profile
Understanding the physical and chemical properties of these stones is essential for gemologists, jewelers, and collectors alike. The following table provides a comparative overview of their key characteristics, based on established gemological data.
| Property | Turquoise | Tanzanite (Zoisite) |
|---|---|---|
| Chemical Formula | CuAl₆(PO₄)₄(OH)₈·4H₂O | Ca₂Al₃(SiO₄)₃(OH) |
| Crystal System | Triclinic | Orthorhombic |
| Hardness (Mohs) | 5 - 6 | 6.5 - 7 |
| Refractive Index | 1.610 - 1.650 | 1.691 - 1.700 |
| Specific Gravity | 2.60 - 2.90 | 3.35 |
| Durability | Fair to good; soft, porous, prone to scratching and breaking. | Good; can be brittle due to cleavage. |
| Color | Sky blue to blue-green, sometimes with a brown or black matrix. | Blue to violet; often exhibits pleochroism (shows different colors from different angles). |
Turquoise's Properties: Turquoise is a relatively soft and porous stone. Its hardness of 5 to 6 on the Mohs scale makes it susceptible to scratches from everyday items like keys or coins. Its porosity means it can absorb oils, lotions, and chemicals, which can alter its color over time. The presence of a matrix (the host rock) is common and can affect both the stone's appearance and its structural integrity. High-quality, "matrix-free" turquoise is rare and valuable.
Tanzanite's Properties: Tanzanite is harder than turquoise, with a Mohs hardness of 6.5 to 7, making it more suitable for daily wear in jewelry like rings. However, it has perfect cleavage in one direction, meaning it can split if struck with sufficient force along that plane. This requires careful cutting and setting by experienced jewelers. A defining characteristic of tanzanite is its strong pleochroism. When viewed from different angles, a single stone can appear sapphire blue, violet, and reddish-brown. This property is carefully considered during the cutting process to maximize the stone's most desirable color in the final gem.
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, both stones are imbued with deep symbolic meaning and are believed by many to possess metaphysical properties.
Turquoise: The Master Healer and Protector Across cultures, turquoise has been revered as a stone of protection, healing, and good fortune. Ancient Persians believed it warded off the "evil eye" and would change color to warn its wearer of impending danger. For Native Americans, it is a conduit to the spiritual world, a stone of the sky that brings rain and peace. In modern crystal healing, turquoise is known as the "master healer," believed to align all chakras, enhance communication, and provide emotional balance. It is often associated with courage, wisdom, and tranquility.
Tanzanite: The Stone of Transformation As a modern gemstone, tanzanite’s metaphysical lore is more recently developed but no less potent. It is often called the "stone of transformation," believed to facilitate a higher consciousness and a clearer understanding of one's purpose. Its connection to the throat and third-eye chakras makes it a powerful stone for communication and spiritual insight. Advocates believe tanzanite can alleviate stress, calm an overactive mind, and encourage a deeper, more meaningful connection to the universe. Its vivid color is said to stimulate the imagination and inspire a sense of wonder.
Care and Cleaning: Preserving the Beauty
The differing physical properties of tanzanite and turquoise dictate distinct care and cleaning protocols to ensure their longevity.
Caring for Turquoise: Due to its softness and porosity, turquoise requires gentle handling. * Cleaning: Use only a soft, dry cloth. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, including soaps and detergents, which can damage the stone's surface and color. * Storage: Store turquoise jewelry separately to prevent scratches from harder gems or metals. * Wearing: It is best to put on turquoise jewelry after applying lotions, perfumes, and hairsprays. Prolonged exposure to sunlight, heat, or extreme dryness can cause the stone to crack or lose its color.
Caring for Tanzanite: While harder than turquoise, tanzanite’s cleavage makes it vulnerable to impact. * Cleaning: The safest method is warm water, a mild dish soap, and a soft brush. Rinse thoroughly and dry with a soft cloth. Avoid ultrasonic cleaners, as the vibrations can cause the stone to cleave. * Storage: Store tanzanite pieces separately in a soft cloth or padded jewelry box to protect them from scratches and impacts. * Wearing: While suitable for rings, it is often recommended for earrings, pendants, or bracelets where the risk of impact is lower. Avoid wearing it during strenuous activities.
Conclusion
Tanzanite and turquoise, while both designated as December’s birthstones, offer a compelling study in contrasts. Turquoise is an ancient, earthy stone, its history woven into the fabric of human civilization, valued for its protective qualities and soothing blue-green hues. It is a gem of heritage, culture, and enduring tradition. Tanzanite, on the other hand, is a child of modernity—a geological rarity born from a unique event, its discovery and rise to prominence a testament to the power of marketing and the allure of a truly unique color. Its deep, velvety blue-violet represents innovation and transformation. Together, they provide December-born individuals with a choice between timeless legacy and contemporary brilliance. Whether drawn to the serene sky-blue of an ancient mineral or the vibrant violet-blue of a modern marvel, the wearer of a December birthstone carries a gem that is as unique and remarkable as the month itself.