Tanzanite, the captivating blue-violet gemstone designated as a modern birthstone for December, is a relatively recent addition to the world of fine gemology. Its discovery in the late 20th century and subsequent rise to prominence offer a fascinating narrative of geological rarity, commercial marketing, and evolving tradition. As a member of the zoisite mineral group, tanzanite is prized for its unique trichroic color display, shifting from vivid blue to violet and burgundy depending on the viewing angle. This article provides a comprehensive exploration of tanzanite, detailing its geological origins, gemological properties, historical journey, symbolic meanings, and practical care guidelines, all derived from authoritative gemological sources.
The establishment of modern birthstone lists, such as the one formalized in 1912 by the American National Retail Jewellers Association (now Jewelers of America), has seen periodic updates to reflect new discoveries and gemstone availability. Tanzanite represents one such update, a product of modern gemological exploration that has captured the imagination of collectors and jewelry enthusiasts worldwide. Its story is intrinsically linked to a single, remote location on the planet, making its scarcity a fundamental aspect of its identity and value. This article will delve into the science that defines tanzanite, the lore that surrounds it, and the practical considerations for those who wish to own or care for this December birthstone.
Historical Discovery and Journey to Birthstone Status
The history of tanzanite is exceptionally brief compared to ancient gems like garnet or sapphire, yet it is a story of remarkable serendipity. The gemstone was first identified in the late 1960s in the Merelani Hills of Northern Tanzania, a region that remains the only known commercial source of this gem. Its discovery is often attributed to a Maasai herdsman who found blue crystals in the region, though the systematic mining and gemological study began shortly thereafter. The gem's initial identity was as a variety of zoisite, a mineral known since the 19th century, but its intense blue-violet hue was unprecedented.
The gem's rapid ascent to global fame was largely orchestrated by the American jewelry company Tiffany & Co. In 1968, Tiffany introduced tanzanite to the market, naming it after its country of origin. The company's marketing campaign, which emphasized its rarity and stunning color, was highly successful. Tanzanite was initially marketed as a more affordable alternative to sapphire, but its unique color and compelling origin story quickly established it as a desirable gemstone in its own right. While not listed on the original 1912 birthstone chart, tanzanite's popularity led to its recognition as a modern birthstone for December. The sources indicate that the modern birthstone list has been updated over time to reflect new discoveries and availability, with some months now having multiple birthstones. For December, tanzanite is listed alongside turquoise and zircon in various modern charts, offering a contemporary choice for those born in the final month of the year.
The journey from a local curiosity to an internationally recognized birthstone highlights the dynamic nature of gemstone traditions. Unlike stones with centuries of documented use, tanzanite’s status is built on a foundation of modern marketing and its intrinsic gemological appeal. Its story is a testament to how new gems can enter the cultural lexicon and secure a place in long-standing traditions.
Geological Formation and Exclusive Sources
Tanzanite’s geological origin is as unique as its color. It forms under specific conditions involving heat and pressure, a process that is geologically rare. The gem is found in the Merelani Hills, a small mining area near the base of Mount Kilimanjaro in Tanzania. This area is the only known source of gem-quality tanzanite in the world, making it thousands of times rarer than diamond. The gemstone is a variety of the mineral zoisite, which is a calcium aluminum hydroxyl silicate. The blue color of tanzanite is caused by trace amounts of vanadium within its chemical structure. However, the raw zoisite crystals are typically brownish. The transformation to the coveted blue-violet color requires a natural heat treatment process, which occurs when the crystals are exposed to the intense heat of regional geological events, such as those associated with the formation of the East African Rift.
This natural heat treatment is a standard and accepted practice in the gem trade. While the brownish zoisite is naturally heated, some commercial tanzanite may undergo additional controlled heating in a lab to achieve a more consistent and desirable color. This process is permanent and does not affect the gem's durability or value, as the color change is considered a treatment to enhance the stone's natural beauty rather than an artificial coating or dye. The sources confirm that tanzanite is a transparent gem variety, and its color is its most defining characteristic.
The geographic exclusivity of tanzanite cannot be overstated. All commercially available tanzanite originates from a single, small area in Tanzania. This concentration of supply creates a high level of risk and contributes significantly to the gem's value and allure. The mining operations in the Merelani Hills are the sole source, and any disruption to production would have an immediate global impact on the availability of the stone. This geological singularity is a key factor in its classification as a rare and precious gemstone, despite its relatively recent discovery.
Gemological Properties and Characteristics
Understanding tanzanite requires a look at its specific gemological properties. As a member of the zoisite group, it possesses a set of characteristics that define its appearance, durability, and value in the jewelry market.
Color: The most celebrated property of tanzanite is its color. It exhibits strong trichroism, meaning it displays three different colors when viewed from three different crystallographic directions: blue, violet, and burgundy-red. The most desirable color is an intense, saturated violet-blue. The hue can vary based on the crystal's orientation and the viewer's angle. To minimize the perception of the brownish component and present the most vibrant blue, most tanzanite is cut with the table facet oriented perpendicular to the crystal's c-axis. The color can also be influenced by lighting conditions; for instance, fluorescent lighting may enhance the blue tones, while incandescent light may emphasize the violet.
Hardness and Durability: On the Mohs scale of hardness, tanzanite registers between 6 and 7. This places it in the category of moderately durable gemstones, suitable for jewelry but requiring some care. It is softer than sapphire (Mohs 9) and diamond (Mohs 10), but harder than opal (Mohs 5.5-6.5) and pearl (Mohs 2.5-4). Its toughness is considered fair to good, but it does have one direction of perfect cleavage, which means it can split if struck with force along that plane. This makes it important to protect tanzanite jewelry from hard impacts.
Clarity and Cut: Tanzanite is typically a transparent gemstone. Like many colored gemstones, it is often included, though high-quality specimens can be relatively clean. The clarity grade can affect its value, with cleaner stones commanding higher prices. The cut is critical in showcasing tanzanite's color. The most common cuts are oval, pear, and round, designed to maximize the return of light and the display of its characteristic color play. The precision of the cut directly influences the stone's brilliance and the evenness of its color distribution.
Chemical Composition and Refractive Index: Chemically, tanzanite is calcium aluminum hydroxyl silicate (Ca₂Al₃(SiO₄)₃(OH)). Its refractive index ranges from 1.691 to 1.700, with a birefringence of 0.009. These optical properties contribute to its brilliance and are measured by gemologists to confirm its identity and distinguish it from other blue gemstones.
The following table summarizes key gemological properties of tanzanite based on the available source information:
| Property | Details |
|---|---|
| Mineral Group | Zoisite (Calcium Aluminum Silicate) |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) |
| Mohs Hardness | 6 - 7 |
| Crystal System | Orthorhombic |
| Refractive Index | 1.691 - 1.700 |
| Birefringence | 0.009 |
| Specific Gravity | 3.35 (+0.01, -0.02) |
| Optical Character | Biaxial (-) |
| Color | Blue, violet, burgundy (trichroic) |
| Primary Source | Merelani Hills, Tanzania |
Symbolism, Lore, and Metaphysical Beliefs
Despite its modern origins, tanzanite has quickly accumulated a rich tapestry of symbolic meanings and metaphysical beliefs, often linked to its vibrant color and unique energy. While many of these associations are contemporary, they draw from broader traditions in crystal healing and gemstone lore.
One of the most prominent symbolic associations of tanzanite is with spiritual awakening and higher consciousness. Its striking blue and violet hues are often connected to the third eye and crown chakras, which are associated with intuition, insight, and spiritual connection. Practitioners of crystal healing believe that tanzanite can facilitate communication with higher realms, enhance meditation, and promote a sense of inner peace and clarity. It is sometimes called the "stone of transformation," believed to aid in navigating change and embracing one's destiny.
Communication and Truth are other key themes linked to tanzanite. Its color is reminiscent of the sky and the sea, elements associated with vastness and depth. Some believe that tanzanite can help one speak their truth with compassion and clarity, making it a beneficial stone for those in professions requiring eloquent communication or for anyone seeking to improve their personal relationships.
In the context of physical and emotional healing, tanzanite is sometimes attributed with properties that can soothe the mind and alleviate stress. Its calming energy is said to help overcome panic attacks, phobias, and compulsive behaviors. Some traditions suggest it can support the body's detoxification processes and aid in healing issues related to the throat, eyes, and immune system. It is important to note that these metaphysical claims are part of a belief system and are not supported by modern scientific evidence, as acknowledged in the sources.
As a December birthstone, tanzanite carries the symbolism of the winter month. It is said to bring good fortune, luck, and protection to those born in December. Its cool, serene color evokes the tranquility of a winter landscape, while its vibrant energy is believed to kindle warmth and passion during the colder months. For individuals seeking a birthstone that is both visually stunning and rich in contemporary meaning, tanzanite offers a compelling choice.
Care and Cleaning Guidelines
Given its moderate hardness and perfect cleavage, tanzanite requires careful handling and specific cleaning methods to maintain its beauty and structural integrity. Proper care will ensure that a tanzanite piece remains a treasured heirloom for generations.
Cleaning: The safest method for cleaning tanzanite jewelry is with warm, soapy water and a soft brush. Use a mild dish soap and gently scrub the stone and its setting with a soft toothbrush to remove any accumulated dirt or oils. Rinse thoroughly with clean, lukewarm water and pat dry with a soft, lint-free cloth. Avoid using harsh chemicals, as they can damage the stone or its setting.
It is generally recommended to avoid ultrasonic cleaners and steam cleaners for tanzanite. The vibrations from an ultrasonic cleaner can potentially cause fractures in stones with inclusions or exacerbate existing cleavage planes, leading to damage. Steam cleaners use high heat and pressure, which could also pose a risk. Always check with a professional jeweler before using any automated cleaning method on tanzanite.
Storage: When not being worn, tanzanite jewelry should be stored separately from other pieces to prevent scratches. While tanzanite has a hardness of 6-7, it can be scratched by harder gems like diamond, sapphire, and ruby. It is best to keep it in a soft pouch or a separate compartment in a jewelry box lined with fabric.
Handling and Wear: Due to its perfect cleavage, tanzanite should be protected from hard blows and rough treatment. It is not an ideal choice for everyday rings that are subject to frequent knocks, such as engagement rings or work rings. Instead, it is better suited for pendants, earrings, and occasion rings. When putting on or taking off tanzanite jewelry, do so over a soft surface to avoid accidental drops.
Environmental Considerations: While tanzanite is generally stable, prolonged exposure to extreme heat or sudden temperature changes should be avoided. As with many gemstones, it is wise to remove tanzanite jewelry before engaging in activities like gardening, sports, or heavy household chores to protect it from potential impact and chemical exposure.
By following these care guidelines, owners can preserve the vivid color and structural integrity of their tanzanite, ensuring it remains a brilliant and meaningful part of their jewelry collection.
Conclusion
Tanzanite stands as a remarkable gemstone in the modern birthstone landscape. Its story—from a single, remote location in Tanzania to a globally celebrated December birthstone—is a testament to the power of geological rarity and human ingenuity. As a variety of zoisite, its unique trichroic color, ranging from deep blue to violet and burgundy, sets it apart from all other blue gemstones. With a moderate hardness of 6 to 7 on the Mohs scale and a single direction of perfect cleavage, it requires thoughtful care to maintain its beauty.
The gem's symbolism is deeply connected to spiritual awakening, clear communication, and transformation, aligning with its vibrant and shifting hues. While its metaphysical properties are a matter of belief, its gemological credentials are firmly established. As a birthstone, tanzanite offers December-born individuals a choice that is both contemporary and deeply connected to the natural world, representing a unique piece of Earth's history. Its exclusivity to one small mining area in the Merelani Hills underscores its precious status, making it a gemstone that is as rare in origin as it is captivating in appearance.