Tanzanite, a gemstone of captivating violet-blue hues, stands as a testament to both geological rarity and modern gemological innovation. Designated as one of December's four official birthstones, it has swiftly ascended from a recently discovered curiosity to a cornerstone of contemporary fine jewelry. Its story is intrinsically linked to a single, remote location, making its scarcity a defining characteristic. As a birthstone, tanzanite offers December celebrants a choice that is both visually dramatic and symbolically rich, embodying themes of transformation and clarity. This article will explore tanzanite's unique geological origins, its gemological properties, its journey to birthstone status, its metaphysical associations, and practical considerations for its care and selection.
Historical Discovery and Geological Formation
Tanzanite's history is remarkably brief in the annals of gemstones, a fact that contributes to its mystique. Unlike ancient stones with millennia of lore, tanzanite's origin story is a modern geological event. The gemstone is found in a single, small mining area in the Merelani Hills of northern Tanzania, located near the majestic Mount Kilimanjaro. This specific location is the only known commercial source of tanzanite in the world, a condition that naturally limits its supply and enhances its value. The formation of tanzanite is tied to a unique geological event: a massive tectonic shift that occurred approximately 585 million years ago. This event subjected the mineral zoisite to intense heat and pressure, transforming it into the vibrant blue-violet variety known as tanzanite.
The gemstone's journey from the earth to the market began in the mid-20th century. While local miners had collected blue crystals for years, the gemological community officially recognized and named the stone in 1967. It was named "tanzanite" in honor of its country of origin, Tanzania. The discovery is often credited to a Maasai herdsman who found blue crystals on the slopes of the Merelani Hills in 1967, which were subsequently brought to the attention of a geologist. This relatively recent discovery means that tanzanite lacks the deep historical and cultural layers of older birthstones like turquoise or zircon, but it has rapidly accumulated its own narrative of rarity and modern luxury.
Gemological Properties
Tanzanite is a variety of the mineral zoisite, with the chemical formula Ca2Al3(SiO4)3(OH). It is prized for its pleochroism, a property that causes the gem to display different colors when viewed from different crystal directions. Typically, tanzanite appears blue when viewed along one axis and violet-purple along another. This characteristic makes the cut of the gemstone critically important, as the cutter must orient the stone to present the most desirable blue-violet hue from the table (the top of the gem). The color range of tanzanite is generally from light lavender to a deep, vivid blue-violet, with the most valued stones exhibiting a rich, saturated blue with violet undertones.
On the Mohs scale of hardness, tanzanite registers between 6 and 7. This places it in a category of relative durability but one that requires careful handling. It is softer than quartz (7) and significantly softer than diamond (10) or sapphire (9). This moderate hardness, combined with its good cleavage (a tendency to split along certain planes), means tanzanite is susceptible to scratching, chipping, and breakage if subjected to rough wear or impact. Its refractive index ranges from 1.691 to 1.700, and it has a specific gravity of approximately 3.35. The vast majority of tanzanite on the market has been heat-treated to enhance its blue color. This treatment is stable and widely accepted, as it mimics the natural geological processes that create the gem's most desirable hues.
| Property | Description |
|---|---|
| Mineral Species | Zoisite |
| Chemical Formula | Ca2Al3(SiO4)3(OH) |
| Hardness (Mohs) | 6 - 7 |
| Crystal System | Orthorhombic |
| Refractive Index | 1.691 - 1.700 |
| Specific Gravity | ~3.35 |
| Typical Treatments | Heat to enhance blue color |
Path to Birthstone Status
Tanzanite's inclusion as a December birthstone is a relatively recent development. Historically, December was associated primarily with turquoise and zircon. The list expanded in 2002 when the American Gem Trade Association (AGTA) added tanzanite as a modern birthstone for the month. This addition reflected the gemstone's growing popularity and commercial significance. While some sources note that the Gemological Institute of America (GIA) still lists turquoise, tanzanite, and zircon as December's primary birthstones, others acknowledge that blue topaz has also become a mainstream option, particularly in the United States. This expansion provides consumers with greater flexibility in choice, allowing for a range of prices, styles, and symbolic meanings.
The addition of tanzanite is often linked to its distinctive color, which aligns with the cool, wintry palette associated with December. Its deep blue-violet hues evoke the deep twilight and icy skies of the season. As a modern birthstone, it offers a narrative of discovery and rarity that contrasts with the ancient history of its counterparts. For December-born individuals, tanzanite represents a choice that is both contemporary and deeply connected to a specific, tangible place on Earth.
Symbolism and Metaphysical Beliefs
Tanzanite is rich in symbolic meaning and metaphysical beliefs, which, while not part of formal gemology, are widely reported in consumer and new-age literature. The stone is frequently associated with themes of transformation, new beginnings, and spiritual awakening. Its connection to the third eye chakra (governed by intuition and insight) and the throat chakra (governed by communication and truth) is a common theme. Believers suggest that tanzanite can facilitate deep meditation, enhance psychic abilities, and help individuals recover their personal power. It is thought to encourage a sense of calm and clarity, helping to clear out old, stagnant patterns and open the mind and heart to new possibilities.
These metaphysical associations add a layer of personal significance to tanzanite jewelry. For many, wearing tanzanite is not merely an aesthetic choice but a way to connect with these symbolic attributes. The stone's story—born from a single, dramatic geological event and known for its transformative color shift—is itself a powerful metaphor for personal growth and change, making it a meaningful birthstone for those navigating new chapters in their lives.
Care and Cleaning
Given its moderate hardness and good cleavage, tanzanite requires specific care to maintain its beauty and structural integrity. It is not suitable for daily wear in rings or bracelets if the setting exposes the stone to potential knocks and abrasions. Pendants and earrings are generally safer settings, as they are less likely to encounter hard impacts. When cleaning tanzanite, it is crucial to avoid harsh chemicals, ultrasonic cleaners, and steam cleaners, which can damage the stone or its setting.
The safest method for cleaning tanzanite jewelry is with warm water, a mild soap (like dish soap), and a soft brush. After gently brushing, it should be rinsed thoroughly and dried with a soft, lint-free cloth. It is important to store tanzanite separately from other jewelry to prevent scratching. For pieces like the flexible bangles described in the provided materials, which feature tanzanite crystals, care instructions typically recommend keeping the jewelry away from prolonged soaking, abrasives, and chemicals. The flexible wire itself may be water-friendly, but the gemstones and any plating require gentle handling. A soft, dry cloth is recommended for cleaning, as even mild soap can leave residue on plated metals.
Market Value and Selection
Tanzanite's value is determined by the classic gemological factors of color, clarity, cut, and carat weight, with color being the most significant driver. The most valuable tanzanites exhibit a deep, saturated blue with violet undertones, free of brownish or grayish modifiers. Clarity is also important; while inclusions are common, eye-clean stones (without visible inclusions) are preferred. The cut is critical for maximizing the stone's pleochroic color and brilliance. Carat weight affects price, with larger stones being rarer and more valuable per carat.
As a birthstone, tanzanite offers a range of price points. While high-grade tanzanite can be quite valuable, there are also more affordable options, making it accessible for various budgets. When purchasing tanzanite jewelry, it is advisable to buy from reputable sellers who provide clear information about the stone's origin and any treatments. Certificates or gem reports can offer additional assurance of quality. Given its relative fragility, the setting should also be evaluated for security and appropriateness for the intended wear.
Conclusion
Tanzanite is a gemstone that captivates with its unique violet-blue color, fascinating modern history, and profound symbolic meaning. As a December birthstone, it provides a compelling option that is both visually striking and rich in narrative. Its formation in the foothills of Mount Kilimanjaro and its journey to international gem markets tell a story of rarity and natural wonder. While it requires more care than some other birthstones due to its moderate hardness and cleavage, its beauty makes it a cherished addition to jewelry collections. Whether chosen for its aesthetic appeal, its symbolic ties to transformation, or its status as a modern birthstone, tanzanite remains a truly remarkable jewel of the modern era.