The world of birthstones offers a unique lens through which to view history, geology, and human culture. For individuals born on December 29th, the designated gemstone is Tanzanite, a relative newcomer to the gemological stage that has nonetheless captured the global imagination with its singular beauty and compelling origin story. Unlike ancient stones steeped in millennia of lore, Tanzanite’s narrative is one of modern discovery, rapid market ascent, and a profound connection to a single, remote location on Earth. This article provides a comprehensive exploration of Tanzanite, detailing its geological formation, its unique gemological properties, its journey from the mines of Tanzania to jewelry showcases worldwide, and the symbolism it has accrued. We will also address the broader context of December birthstones and provide practical guidance for the care and preservation of this remarkable gem.
The December 29th Birthstone: An Introduction to Tanzanite
For those born on the cusp of a new year, Tanzanite serves as a potent symbol of individuality and transformation. Officially recognized as a modern birthstone for December, it stands alongside traditional options like Turquoise and Zircon. However, its distinct coloration and limited geographic availability set it apart.
Tanzanite is the blue-to-violet variety of the mineral zoisite. Its discovery in the late 1960s in Tanzania marked one of the most significant gemological finds of the 20th century. The gem is prized for its mesmerizing pleochroism, a phenomenon where the stone displays different colors—typically sapphire blue, violet, and sometimes reddish-brown—when viewed from different crystallographic directions. This dynamic interplay of light and color gives the gem a depth and complexity that few other stones can match.
The allure of Tanzanite extends beyond its physical appearance. It is a gem of profound symbolism, representing wisdom, intuition, and the promise of new beginnings. Its rapid rise from an unknown mineral to a globally coveted jewel is a testament to its inherent beauty and the power of modern gem marketing. For the December 29th birthstone holder, Tanzanite is not merely an accessory; it is a personal talisman of metamorphosis and a connection to the ancient geological processes of East Africa.
History and Lore: A Modern Legend
The history of Tanzanite is exceptionally brief when compared to gemstones like Ruby or Emerald, which have been revered since antiquity. Its story is entirely 20th-century, making it a truly modern birthstone.
Discovery and Identification
Tanzanite was first identified in 1967 in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. The discovery is credited to a tailor and part-time prospector named Manuel d’Souza, who initially believed he had found a deposit of sapphire due to the stone’s compelling blue color. This initial misidentification highlights the gem’s exceptional visual appeal, which can rival that of more established blue gemstones.
While d’Souza is credited with the commercial discovery, it is noted that local Maasai tribesmen had known of the violet-blue crystals for some time. They held a folk belief that the stones were connected to the heavens and that their presence signified impending rain—a belief that speaks to the gem’s deep connection with its place of origin.
The Tiffany Touch
The gem’s ascent to international prominence is inextricably linked to the renowned jewelry house Tiffany & Co. After recognizing the stone’s potential, Tiffany secured a major source of the material and launched an extensive marketing campaign in 1968. The company named the gem “Tanzanite,” after its country of origin, and proclaimed it “the most beautiful blue stone in a generation.” This strategic branding and promotion were instrumental in establishing Tanzanite as a desirable and sophisticated gemstone, quickly making it a favorite of jewelers and collectors.
The Gem of Transformation
In the short time it has been on the market, Tanzanite has developed a rich tapestry of symbolism. It is widely regarded as a stone of transformation. This belief is rooted in the gem’s own journey from a rough, unassuming mineral to a brilliantly polished jewel. It is said to facilitate a higher consciousness, intuition, and spiritual awakening. For those born on December 29th, it is believed to encourage personal growth, continual development, and a deeper understanding of oneself and others. Furthermore, it is associated with promoting calmness, composure, and clear communication, making it a popular choice for individuals seeking balance and clarity in their lives.
Geological Formation and Sources
The geological story of Tanzanite is as unique as its color. It is a product of a rare and specific set of geological conditions that have occurred only in one place on Earth, contributing to its rarity and value.
The Merelani Hills
All commercially viable Tanzanite is found in a very small mining area in the Merelani Hills of the Manyara Region in northern Tanzania. The precise location is near the town of Arusha and the iconic Mount Kilimanjaro. This single, confined source is a primary factor in the gem's rarity. The mining area itself is divided into four blocks, with Block D being the most famous for producing the highest quality material.
A Unique Geological Process
Tanzanite’s formation is a testament to the extraordinary forces of nature. It is believed to have formed approximately 585 million years ago during a massive geological event in the East African Orogeny, a mountain-building period that created the supercontinent Gondwana.
The process began when immense heat and pressure from tectonic plate movements altered the parent rock, which contained the mineral zoisite. During this metamorphic event, the presence of elements like vanadium and chromium, along with specific temperature and pressure conditions, caused the originally brownish zoisite crystals to transform into the vibrant blue and violet hues we recognize as Tanzanite. This process is considered a geological rarity, a perfect storm of conditions that is unlikely to have been replicated elsewhere.
Gemological Properties
Understanding Tanzanite’s gemological properties is essential for appreciating its value, identifying it, and ensuring its proper care. The following table summarizes its key characteristics.
| Property | Description |
|---|---|
| Mineral | Zoisite (Calcium Aluminum Silicate Hydroxide) |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) |
| Crystal System | Orthorhombic |
| Hardness (Mohs Scale) | 6.5 - 7 |
| Hardness (Absolute) | 720 Knoop |
| Cleavage | Perfect in one direction |
| Refractive Index | 1.691 - 1.700 |
| Specific Gravity | 3.35 (+0.10 / -0.05) |
| Luster | Vitreous (Glass-like) |
| Transparency | Transparent to translucent |
| Color | Blue, violet, purple (pleochroic) |
Color
Color is the most critical factor in determining Tanzanite’s value. The most prized specimens exhibit a deep, saturated violet-blue color, often described as "vivid." The gem’s pleochroism is a defining feature. When viewed along different crystal axes, it can display three distinct colors: sapphire blue, violet, and a reddish-brownish-purple. Gem cutters must skillfully orient the rough stone to display the most desirable blue-violet hue from the top of the gem, minimizing the visibility of the other colors.
Hardness and Durability
With a hardness of 6.5 to 7 on the Mohs scale, Tanzanite is moderately hard, making it suitable for most types of jewelry, including rings. However, it is softer than stones like Sapphire (Mohs 9) or Diamond (Mohs 10). More importantly, Tanzanite has perfect cleavage in one direction. Cleavage is the tendency of a mineral to break along flat, parallel planes of weakness in its crystal structure. This means that a sharp, hard blow or significant pressure can cause the stone to chip or split along these planes. This property makes careful handling and protective settings essential.
Clarity and Treatments
Tanzanite is typically a Type I gemstone, meaning it is usually found "eye-clean," with no visible inclusions to the naked eye. Any inclusions present are often fine needles or inclusions of other minerals.
Virtually all Tanzanite on the market has been heated to achieve its stable blue and violet colors. The raw zoisite as found in the ground is often a brownish-orange color. This brownish hue is removed by a controlled heating process, typically at temperatures between 370°C and 400°C, which is a permanent and stable treatment that enhances the gem’s color without affecting its durability. This heating process is widely accepted in the gem trade and is not considered a treatment that diminishes the gem’s value, as it is necessary to produce the desirable colors.
Symbolism and Metaphysical Beliefs
As a relatively new stone, Tanzanite has quickly accumulated a wealth of metaphysical associations. These beliefs, while not scientifically proven, contribute significantly to its appeal and cultural significance.
- Transformation and Metamorphosis: This is the primary symbolic meaning of Tanzanite. It is believed to be a powerful aid for those undergoing significant life changes, encouraging them to embrace new paths and perspectives. It represents the journey from the rough to the refined, mirroring personal growth.
- Intuition and Spiritual Awareness: Tanzanite is associated with the Crown Chakra and the Throat Chakra. By activating these energy centers, it is said to enhance intuition, promote clear communication, and open the wearer to higher spiritual guidance.
- Calming and Composure: The serene violet and blue hues of the stone are believed to have a calming effect on the mind and emotions. It is thought to alleviate stress, anxiety, and panic, promoting a state of peace and tranquility.
- Wisdom and New Beginnings: As a modern December birthstone, it is thought to bestow wisdom and protection upon its wearer. It is a symbol of new beginnings, making it a popular gift for those starting a new chapter in their lives, such as a new job, marriage, or personal journey.
Broader Context: The Birthstones of December
While Tanzanite is the specific birthstone for December 29th, it is part of a larger family of gems associated with the month of December. Understanding this context is important for appreciating the choices available.
According to established modern birthstone lists, December is represented by three primary stones: Turquoise, Zircon, and Tanzanite.
- Turquoise: One of the oldest known gemstones, Turquoise has a rich history spanning millennia and many cultures. It is an opaque, light-to-sky-blue copper aluminum phosphate. Its hardness ranges from 5 to 6 on the Mohs scale, making it relatively soft and porous.
- Zircon: Not to be confused with the synthetic cubic zirconia, natural Zircon is one of the oldest minerals on Earth. It occurs in a variety of colors, but the blue variety is the traditional December birthstone. Zircon is known for its high refractive index and brilliance, and it has a hardness of 7.5 on the Mohs scale, making it quite durable.
The availability of multiple birthstones for a single month allows for greater variety in terms of price, color preference, and durability. Tanzanite, with its unique violet-blue color, offers a modern and exclusive alternative to the traditional stones.
Care and Cleaning
Proper care is paramount to preserving the beauty and integrity of Tanzanite jewelry, given its perfect cleavage and moderate hardness.
Cleaning Instructions
- Use Warm, Soapy Water: The safest and most effective method for cleaning Tanzanite is with warm water and a few drops of mild dish soap.
- Use a Soft Brush: Gently scrub the gemstone with a very soft brush, such as a baby toothbrush or a soft-bristled jewelry brush, to remove any accumulated dirt or oils, especially from behind the stone and in the setting.
- Rinse Thoroughly: Rinse the jewelry completely under clean, running warm water to remove all soap residue. Be sure to plug the sink drain to prevent accidental loss.
- Dry with a Soft Cloth: Pat the jewelry dry with a clean, soft, lint-free cloth.
What to Avoid
- Ultrasonic Cleaners: Never place Tanzanite in an ultrasonic cleaner. The intense vibrations can cause the stone to fracture along its cleavage planes.
- Steam Cleaners: High heat and steam are also dangerous for Tanzanite and can cause damage.
- Harsh Chemicals: Avoid exposing Tanzanite to household chemicals, including bleach, ammonia, and chlorine, as they can damage the stone and its setting. Always remove Tanzanite jewelry before cleaning, swimming, or applying cosmetics and perfumes.
Storage and Handling
- Separate Storage: Store Tanzanite jewelry separately from other gemstones and metals to prevent scratches. A soft pouch or a lined jewelry box with individual compartments is ideal.
- Protect from Impact: Due to its perfect cleavage, protect Tanzanite from sharp blows and hard surfaces. Remove rings and bracelets before engaging in strenuous activities or manual work.
- Professional Inspections: Periodically have your Tanzanite jewelry inspected by a professional jeweler to ensure the setting is secure and the stone is in good condition.
Conclusion
Tanzanite is a gemstone that embodies the magic of modern discovery. Its story, rooted in the ancient geology of Tanzania, is a narrative of breathtaking beauty, rapid market acceptance, and profound symbolism. For those born on December 29th, it offers a personal connection to a stone that represents transformation, intuition, and the dawn of new beginnings. Its unique pleochroism and captivating violet-blue hues make it a standout in the world of colored gemstones. While it requires mindful care due to its perfect cleavage, its rarity and singular beauty make it a treasured addition to any jewelry collection. As the 20th century’s most significant gemological find, Tanzanite has secured its place as a timeless jewel for generations to come.