Tanzanite stands as one of the most remarkable gemological discoveries of the 20th century. A variety of the mineral zoisite, this gemstone is celebrated for its mesmerizing blue to violet hues, a color range that rivals the finest sapphires. Its journey from a local mineralogical curiosity to a globally recognized December birthstone is a story of geological rarity, commercial promotion, and cultural adoption. This article provides a comprehensive examination of tanzanite, drawing exclusively from authoritative sources to explore its history, formation, gemological properties, symbolism, and care. As a December birthstone, tanzanite offers a modern and vibrant alternative to traditional blue gems, symbolizing transformation and renewal for those born in the final month of the year.
The gemstone’s significance is rooted in its unique provenance. Found in only one location on Earth—the Merelani Hills of northern Tanzania—tanzanite is estimated to be approximately 1,000 times rarer than diamonds. This extreme scarcity, combined with its captivating color, has secured its place in the jewelry market and the hearts of collectors. The following sections will delve into the multifaceted identity of this enigmatic gem.
History and Lore
The history of tanzanite is exceptionally brief compared to ancient gemstones like emerald or ruby, yet it is no less compelling. For most of recorded history, the mineral zoisite was known in various colors such as green, pink, and brown, but the transparent, blue-violet variety now known as tanzanite remained undiscovered. The catalyst for its emergence was a chance discovery in 1967. According to historical accounts, a Maasai tribesman first found the initial specimens in the Merelani Hills of northern Tanzania. This event marked the beginning of a rapid ascent to global prominence.
The commercial promotion of tanzanite was instrumental in its swift popularity. In 1968, Tiffany & Co. launched a major advertising campaign for the gemstone, recognizing its potential. The company chose the name "tanzanite" over the mineralogical name "blue zoisite" specifically because it would stimulate customer interest and be easier to market. The name reflects the gem’s exclusive geographic origin, emphasizing its rarity. This strategic marketing, coupled with tanzanite’s beautiful color, accomplished a rapid rise to popularity that is unusual in the gemstone world, where most gems have been known for centuries.
The journey to birthstone status was equally swift. In 2002, tanzanite was officially recognized as a modern birthstone for the month of December. This addition was significant, as December previously had three other birthstones: turquoise, blue topaz, and zircon. Tanzanite’s inclusion introduced a new level of color and character to the month’s list of gemstones. Beyond its birthstone designation, tanzanite is also the gemstone associated with the 24th wedding anniversary, further cementing its role in modern celebratory traditions.
Geological Formation and Sources
Tanzanite’s geological story is one of extraordinary rarity. It is a variety of the mineral zoisite, which typically forms in metamorphic rocks—rocks transformed from existing rock types under intense heat and pressure. The specific conditions required for the formation of the blue-violet tanzanite variety are exceptionally rare. The presence of vanadium in the geological matrix, combined with extreme heat, is credited with developing the gemstone’s characteristic color.
The only known commercial source of tanzanite is a small area of approximately eight square miles in the Merelani Hills, near the base of Mount Kilimanjaro and the city of Arusha in northern Tanzania. This exclusive location contributes profoundly to the gem’s rarity and value. The geological conditions in this specific region are unique, and no other deposit of commercial importance has been found elsewhere in the world. This singular source means that the entire global supply of tanzanite originates from this limited area, making it one of the most geographically constrained gemstones in commerce.
Gemological Properties
Tanzanite possesses a distinct set of physical and optical characteristics that define its identity and value. Understanding these properties is essential for gemologists, jewelers, and consumers alike.
Color and Pleochroism: The most defining characteristic of tanzanite is its color. It ranges from blue to violet to violetish purple. This color is not static; tanzanite exhibits strong pleochroism, meaning it displays different colors when viewed from different angles. Typically, it shows blue, violet, and reddish hues depending on the crystal orientation. This property requires skilled cutting by lapidaries to ensure that the most desirable blue and violet hues are presented in the final gemstone. The color can also be enhanced through heat treatment. Most naturally occurring zoisite in the Merelani Hills is brown or red, and heating is a standard industry practice to convert these stones into the vibrant blue-violet tanzanite. Laboratory experiments in the 1960s confirmed that heating could both improve the color of naturally blue stones and transform brown or green zoisite into beautiful tanzanite.
Hardness and Durability: On the Mohs scale of mineral hardness, tanzanite has a rating of 6.5 to 7. This places it in the moderate range for gemstones. While it is suitable for jewelry, it requires more care than harder gems like sapphire (Mohs 9) or diamond (Mohs 10). Its relative softness means it is more susceptible to scratching and abrasion. Furthermore, tanzanite has one direction of distinct cleavage, which is a tendency to break along specific planes. This cleavage, combined with its moderate hardness, makes the gemstone vulnerable to impact and requires careful handling during cutting, setting, and daily wear.
Chemical Composition and Crystal System: Tanzanite is a variety of zoisite, which has the chemical formula Ca₂Al₃(SiO₄)₃(OH). The blue color is caused by trace amounts of vanadium. It crystallizes in the orthorhombic system. Other varieties of zoisite include thulite (pink) and anyolite (green with pink and blue).
Clarity and Cut: Tanzanite is typically found with high clarity, often being "eye-clean," meaning inclusions are not visible to the naked eye. This clarity, combined with its rich color, makes it an excellent gem for faceted cuts. Common cuts include traditional shapes like round and princess cuts, as well as emerald and cushion cuts. Its versatility also allows for carving and sculpting into intricate designs.
Carat Weight: Tanzanite is available in a wide range of sizes. Because it is not as dense as some other gemstones, a tanzanite of a given carat weight may appear larger than a sapphire of the same weight.
The following table summarizes key gemological properties of tanzanite based on the provided sources:
| Property | Description |
|---|---|
| Mineral Species | Zoisite |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) |
| Color | Blue, violet, violetish purple |
| Pleochroism | Strong; displays blue, violet, and reddish hues |
| Hardness (Mohs) | 6.5 to 7 |
| Crystal System | Orthorhombic |
| Primary Source | Merelani Hills, Tanzania (exclusive) |
| Treatment | Commonly heat-treated to enhance color |
| Birthstone Month | December |
| Anniversary | 24th wedding anniversary |
Symbolism and Metaphysical Beliefs
Despite its modern discovery, tanzanite has quickly been imbued with a rich tapestry of symbolic meanings and metaphysical beliefs. These associations have contributed significantly to its popularity, particularly in the realm of alternative and spiritual practices.
Tanzanite is most commonly associated with transformation, intuition, and emotional healing. Its deep blue and violet hues are believed to resonate with the throat and third eye chakras, which are central concepts in many spiritual traditions. The throat chakra is linked to communication and self-expression, while the third eye chakra is associated with spiritual insight, intuition, and higher consciousness. As such, tanzanite is often used by practitioners to enhance communication, deepen meditation, and foster a connection to one’s inner wisdom.
The gemstone’s symbolism of transformation is directly tied to its geological and commercial history. From a brown or green zoisite rough to a brilliant blue-violet gem through the process of heating, tanzanite undergoes a literal transformation. This physical change is seen as a metaphor for personal growth, spiritual awakening, and the ability to navigate life’s changes with clarity and grace.
While tanzanite itself is a modern gem, its symbolic meanings draw from a long tradition of blue stones in various cultures. In ancient times, blue stones were often revered for their perceived ability to enhance spiritual awareness and promote emotional balance. Although tanzanite did not exist in these ancient eras, it has quickly adopted and been associated with these enduring symbolic meanings, bridging its contemporary status with a sense of ancient wisdom.
Care and Cleaning
Given its gemological properties, tanzanite requires specific care to maintain its beauty and integrity over time. Its moderate hardness (6.5 to 7 on the Mohs scale) and distinct cleavage make it more delicate than many other popular gemstones.
Cleaning: The safest method for cleaning tanzanite is with warm water, a mild soap, and a soft brush. Ultrasonic cleaners and steam cleaners should be avoided, as the vibrations and heat can potentially damage the stone, especially if it has any internal fractures or if the setting is not secure. After cleaning, rinse the jewelry thoroughly in clean water to remove any soap residue and pat it dry with a soft, lint-free cloth.
Storage: To prevent scratches, tanzanite jewelry should be stored separately from other pieces. It is advisable to keep it in a soft-lined jewelry box or a dedicated compartment where it will not come into contact with harder gemstones like diamonds, sapphires, or rubies.
Handling and Wear: Due to its cleavage, tanzanite should be protected from hard blows and impacts. It is not recommended for daily-wear rings, especially for those with an active lifestyle, as it is vulnerable to chipping or breaking if struck. Earrings, pendants, and brooches are safer jewelry choices for tanzanite, as they are less likely to experience accidental impact. When putting on or removing tanzanite jewelry, it should be handled gently.
Professional Inspection: It is prudent to have tanzanite jewelry inspected by a professional jeweler periodically. They can check the security of the setting, look for any potential damage, and provide professional cleaning.
Conclusion
Tanzanite is a gemstone of extraordinary rarity and beauty, distinguished by its exclusive origin in the Merelani Hills of Tanzania and its captivating blue-violet coloration. Its history is a modern marvel, transitioning from a recent discovery in 1967 to a globally celebrated December birthstone in just a few decades, largely due to strategic promotion and its inherent allure. Geologically unique, it forms under specific conditions that yield a gem with strong pleochroism and a color that can be enhanced through heat treatment.
As a birthstone, tanzanite symbolizes transformation and renewal, offering a vibrant and meaningful option for December-born individuals. Its symbolism extends into metaphysical beliefs, where it is associated with intuition, communication, and spiritual insight. However, its moderate hardness and cleavage necessitate careful handling and specific cleaning methods to preserve its integrity. For gemstone enthusiasts, jewelry buyers, and students of gemology, tanzanite represents a fascinating case study in the convergence of geology, commerce, and culture, solidifying its status as a premier gemstone of the modern era.