Tanzanite is a gemstone of remarkable recent history and profound rarity, distinguished by its captivating violet-blue hue and exclusive geographic origin. As one of the modern birthstones for December, it stands alongside zircon and turquoise, offering a contemporary alternative to the traditional blue palette of the month. Its journey from a local curiosity to a globally celebrated gem is a story of geological serendipity and cultural adoption. This article provides a comprehensive exploration of Tanzanite, detailing its unique geological formation, the specific mining locations that underscore its scarcity, its defining gemological properties, and the rich symbolism that has come to be associated with this extraordinary stone.
History and Lore: A Modern Legend
Unlike gemstones with millennia of recorded human history, Tanzanite’s story is exceptionally brief, adding to its mystique and modern allure. The gemstone was only discovered in the mid-1960s, making it one of the youngest major gemstones in the mineral kingdom. Its origin is rooted in the Merelani Hills of Tanzania, near the city of Arusha and the iconic Mount Kilimanjaro.
Local lore surrounding the discovery adds a layer of mythical narrative to its history. According to Masai tradition, the stones were unearthed when lightning struck their fields, setting them ablaze and revealing the brilliant blue crystals within the earth. This dramatic origin story, involving a celestial event, resonates with the gem’s otherworldly appearance.
The commercial journey of Tanzanite began after its discovery by a Tanzanian prospector. Recognizing its potential, he brought the stone to the attention of the New York jeweler Tiffany & Co., which quickly identified its beauty and rarity. The company named the gem "Tanzanite" after its country of origin and began promoting it heavily in the 1960s and 1970s. This marketing effort was instrumental in establishing Tanzanite as a desirable and fashionable gemstone, particularly in the United States. Its rapid ascent in the jewelry world culminated in its official designation as a modern birthstone for December, solidifying its place in the gemological calendar.
The journey to becoming a birthstone was not instantaneous. For many years, the primary birthstones for December were Turquoise and Lapis Lazuli, with Zircon also being a traditional choice. The addition of Tanzanite reflects the dynamic nature of birthstone lists, which can evolve to incorporate newly discovered and popular gemstones. The American Gem Trade Association (AGTA) officially added Tanzanite to its list of modern birthstones for December, acknowledging its growing importance in the market and its desirability among consumers.
Geological Formation and Sources
The geological story of Tanzanite is as unique as its history. The gemstone is a variety of the mineral zoisite and owes its signature blue-to-violet color to the presence of vanadium and other trace elements. What makes its formation truly exceptional is the specific and limited geological conditions required for its creation.
Tanzanite is believed to have been formed approximately 600 million years ago during a massive geological event in the Precambrian era. This event involved the tectonic shifting and heating of the Earth's crust, which transformed pre-existing zoisite crystals. The intense heat and pressure, combined with the presence of specific chemical elements, imbued the crystals with their distinctive color. However, the process is not fully understood, and the precise conditions that created Tanzanite remain a subject of scientific study.
The most critical aspect of Tanzanite’s geology is its extreme rarity, stemming from the fact that it has been found in only one location on the entire planet. The sole source of gem-quality Tanzanite is a tiny, eight-square-kilometer area in the Merelani Hills of northern Tanzania. This exclusivity is a primary driver of its value and rarity. Unlike diamonds, which are mined in numerous countries across the globe, or sapphires and rubies, which have various deposits worldwide, Tanzanite’s entire global supply comes from this single, confined area near Mount Kilimanjaro.
The mining operations in the Merelani Hills range from small-scale, artisanal efforts to larger, more organized commercial ventures. The gem is typically found in a brownish form in its natural state and requires a controlled heating process to achieve the vibrant blue and violet hues for which it is famous. This heating process is a standard industry practice and is considered permanent, enhancing the stone’s color without compromising its structure.
Gemological Properties
Tanzanite possesses a unique set of physical and chemical characteristics that define its identity and value in the gemological world. Understanding these properties is essential for gemologists, jewelers, and buyers alike.
Color and Pleochroism The most celebrated feature of Tanzanite is its color, which ranges from a pure, ultramarine blue to a deep, royal violet. The most prized specimens exhibit a rich, saturated violet-blue hue. A defining gemological characteristic of Tanzanite is its strong pleochroism. Pleochroism is the phenomenon where a gemstone displays different colors when viewed from different crystallographic directions. In the case of Tanzanite, it typically shows three distinct colors: blue, violet, and a reddish-brown or burgundy hue. Gem cutters must orient the rough stone carefully to present the most desirable face-up color (usually blue-violet) in the finished gem.
Hardness and Durability On the Mohs scale of mineral hardness, Tanzanite registers between 6 and 6.5. This places it in the moderate range for gemstones, meaning it is softer than sapphire (Mohs 9) or diamond (Mohs 10), but harder than stones like opal or turquoise (both around 5.5-6). This relative softness requires that Tanzanite jewelry be worn and handled with a degree of care to avoid scratches and abrasions. It is not recommended for daily-wear rings, especially for those with an active lifestyle, and is better suited for pendants, earrings, and occasion rings.
Chemical Composition and Clarity Tanzanite is a member of the zoisite mineral group. Its chemical formula is Ca2Al3(SiO4)3(OH), with the blue color resulting from trace amounts of vanadium. High-quality Tanzanite is known for its exceptional clarity, with inclusions being relatively uncommon in fine grades. The stone is typically "eye-clean," meaning no visible inclusions are present to the naked eye, which contributes to its brilliance and transparency.
The Importance of Heating As mentioned, nearly all Tanzanite on the market has been heat treated to remove the brownish tones and enhance the blue-violet color. This process is done at relatively low temperatures (around 370-400°C) and is considered stable. The treatment is permanent and is not detectable in the finished gem, making it an accepted and essential part of preparing Tanzanite for the market.
The following table summarizes key gemological data for Tanzanite:
| Property | Description |
|---|---|
| Mineral Species | Zoisite |
| Chemical Formula | Ca2Al3(SiO4)3(OH) |
| Color | Blue, Violet (Pleochroic: also shows reddish-brown) |
| Hardness (Mohs) | 6 - 6.5 |
| Crystal System | Orthorhombic |
| Refractive Index | 1.691 - 1.700 |
| Origin | Merelani Hills, Tanzania (exclusive) |
Symbolism and Metaphysical Beliefs
Given its recent introduction to the global market, Tanzanite does not have the ancient metaphysical lore associated with gemstones like ruby or emerald. However, a distinct set of modern beliefs and symbolic meanings has quickly formed around this captivating stone, often linked to its unique origin and transformative color.
Transformation and New Beginnings A central theme in Tanzanite’s symbolism is transformation. This is derived from two sources: its geological creation story, involving a dramatic event of heat and pressure, and its physical property of color change under different lighting conditions. As a modern birthstone for December, it is seen as a gem that encourages spiritual awakening and the shedding of old patterns to embrace new ways of thinking. It is believed to help its wearer in asserting their identity and to not be unduly influenced by others.
Intuition and Creativity Tanzanite is often associated with enhancing intuition, stimulating creativity, and promoting a higher consciousness. Its connection to the "third eye" is a common belief in crystal healing circles, suggesting it can open up psychic channels and improve spiritual awareness. For those in creative fields, it is thought to be a powerful tool for brainstorming, problem-solving, and breaking through creative blocks.
Calming Energy and Communication The serene, cool tones of Tanzanite are also linked to calming energies. It is said to promote a sense of tranquility and peace, helping to soothe anxiety and stress. Some traditions suggest that the stone can aid in effective communication, allowing its wearer to express themselves more clearly and compassionately.
A Stone for Newborns A local tradition in Tanzania, its country of origin, holds that Tanzanite can bestow health upon a newborn child if the mother wears the stone after giving birth. This belief underscores the gem’s connection to life and well-being within its native culture.
Care and Cleaning
Proper care is paramount to maintaining the beauty and longevity of Tanzanite jewelry, primarily due to its moderate hardness and lack of cleavage. While it is relatively tough, it is more susceptible to damage than many other popular gemstones.
Cleaning The best method for cleaning Tanzanite is with warm, soapy water and a soft brush. A mild dish soap diluted in lukewarm water is ideal. Use a soft-bristled brush, such as a baby’s toothbrush, to gently scrub the stone and its setting, paying attention to the areas underneath the gem where dirt can accumulate. After cleaning, rinse the jewelry thoroughly with clean water to remove any soap residue and pat it dry with a soft, lint-free cloth.
It is crucial to avoid harsh chemicals and ultrasonic cleaners. Chemicals found in household cleaners, cosmetics, and hairspray can damage the stone’s surface or erode any polish. Ultrasonic cleaners use high-frequency vibrations that can cause existing, tiny fractures within the stone to worsen, potentially leading to breakage. Steam cleaning is also not recommended due to the risk of thermal shock.
Storage and Handling To prevent scratching, store Tanzanite jewelry separately from other gemstones, preferably in a soft-lined jewelry box or a fabric pouch. When not being worn, keep it in a safe place where it will not be knocked against harder surfaces.
Wearing with Care Due to its hardness of 6 to 6.5, Tanzanite is not ideal for jewelry that will be subjected to daily wear and tear, such as engagement rings, bracelets, or rings worn on the hand. It is an excellent choice for pendants, earrings, and rings worn for special occasions, where it is less likely to be bumped or scratched. When putting on Tanzanite jewelry, it should be the last item you put on after applying makeup, lotions, and perfume, and the first item you take off at the end of the day.
Conclusion
Tanzanite represents a remarkable convergence of geological rarity, modern gemology, and cultural storytelling. Its exclusive origin in a single, small area of Tanzania makes it one of the world’s most scarce gemstones, a fact that underpins its significant value and desirability. While it lacks the ancient history of many other birthstones, it has rapidly cultivated a rich narrative of its own, centered on themes of transformation, intuition, and spiritual awakening. For those born in December, Tanzanite offers a sophisticated and meaningful alternative to traditional birthstones, its captivating violet-blue hue a constant reminder of the beauty born from the Earth’s powerful and rare processes. Its combination of stunning color, unique properties, and profound rarity ensures that Tanzanite will remain a celebrated and treasured gemstone for generations to come.