Tanzanite is a gemstone of extraordinary rarity and captivating beauty, celebrated for its unique blue-violet hue and singular geographic origin. Designated as an official modern birthstone for December in 2002, it joined a select group of gems representing the final month of the year. Its discovery in the mid-20th century is one of the most significant events in modern gemology, introducing a new variety of the mineral zoisite to the world. The stone's journey from a remote Tanzanian hillside to global jewelry showcases is a story of geological uniqueness, commercial promotion, and cultural adoption. This article explores the history, formation, gemological properties, and symbolic significance of tanzanite, drawing exclusively from the provided source materials to present a comprehensive overview for gemstone enthusiasts, collectors, and students of gemology.
History and Lore
The history of tanzanite is remarkably brief, setting it apart from gemstones with centuries or millennia of human use. Its story began in 1967, when the gemstone was first discovered in Tanzania. Initial reports suggest it was first found by a Maasai tribesman, Ali Juuyawatu, who stumbled upon the vibrant crystals. Another account credits prospector Manuel de Souza with the initial discovery, who initially mistook the stones for olivine. Regardless of the specific individual, the gemological community quickly recognized it as a unique variety of zoisite, a mineral previously known in various colors but never in this distinct blue-violet spectrum.
The rapid rise of tanzanite to international prominence is inextricably linked to the marketing power of Tiffany & Co. In 1968, the renowned New York jewelers brought the stone to the world market. Henry Platt of Tiffany & Co. christened the gem "tanzanite" in honor of its country of origin. The company's promotional campaign was masterful, declaring it "the loveliest blue gemstone discovered in over 2000 years" and famously stating that tanzanite could only be found in two places on Earth: "in Tanzania and at Tiffany's." This strategy capitalized on the stone's extreme rarity and single-source origin, creating an aura of exclusivity that captivated collectors and consumers alike.
A pivotal moment in tanzanite's official recognition came in 2002. The Jewelers of America, a leading trade association, added tanzanite to its official birthstone chart as a modern birthstone for the month of December. This designation, which it shares with zircon, turquoise, and blue topaz, significantly amplified its demand and cemented its status within the jewelry industry. The addition of tanzanite was part of a periodic update to the birthstone list, reflecting the gem's growing popularity and cultural acceptance.
The lore surrounding tanzanite is largely modern, reflecting its recent discovery. Some contemporary sources attribute metaphysical properties to the stone, suggesting it can boost intuition and deepen meditation. It is also associated with emotional healing, purported to clear away negative feelings and support mental rebirth by encouraging self-reflection and inner strength. Furthermore, some beliefs connect tanzanite to the throat and third-eye chakras, associating it with communication and spiritual insight. While these metaphysical claims are part of the gem's modern cultural narrative, they should be understood as popular beliefs rather than established gemological facts.
Geological Formation and Sources
Tanzanite's geological story is one of extreme rarity, as it is found in only one location on the planet. The gem is mined exclusively in a small area of northern Tanzania, near the foothills of Mount Kilimanjaro. The primary mining district is the Merelani Hills (also spelled Mererani Hills), located approximately 40 kilometers southeast of the city of Arusha. This localized occurrence makes tanzanite, by some estimates, up to 1,000 times rarer than diamond, which is found in numerous locations worldwide.
The formation of tanzanite is linked to a specific set of geological conditions. It is a variety of the mineral zoisite, which forms during metamorphic processes. The unique blue-violet color of tanzanite is a result of the presence of vanadium within its chemical structure, combined with a specific geological history. The rough crystals often exhibit a range of colors, including brown, green, and yellow, alongside the prized blue-violet hues. This natural color variation is key to understanding why most tanzanite on the market has been treated.
Heat treatment is a standard and accepted practice in the enhancement of tanzanite. Laboratory experiments conducted soon after its discovery determined that heating could improve the color of some naturally blue stones. More significantly, heat can convert naturally brown or green zoisite into the vibrant blue-violet tanzanite. This process typically involves heating the rough material to temperatures of around 300-500°C (572-932°F), which removes the brownish or greenish tints and stabilizes the blue-violet color. It is crucial to note that while most tanzanite is heat-treated, the gemstone itself is completely natural. The treatment is permanent under normal conditions, though extreme heat or prolonged exposure to intense sunlight could potentially alter the color slightly.
Mining in the Merelani Hills is conducted on various scales, from large commercial operations to small-scale artisanal mining. A notable recent event occurred in June 2020, when a small-scale miner named Saniniu Laizer discovered two record-breaking tanzanite stones. These massive gemstones weighed 9.27 kg (20.4 pounds) and 5.103 kg (11.25 pounds) respectively. Laizer sold the two stones to the Tanzanian government for $3.4 million, highlighting both the potential scale of finds and the significant economic impact of the gemstone on the local region. The finite nature of the deposit is a constant topic of discussion within the industry, with some estimates suggesting the supply could be exhausted within the current generation, further enhancing the gem's rarity and value.
Gemological Properties
Tanzanite is the blue to violetish blue variety of the mineral zoisite. Its gemological characteristics are what define its appearance, durability, and value in the market.
Color and Trichroism: The most defining feature of tanzanite is its mesmerizing color, which ranges from a pure, vibrant blue to a violetish blue and bluish violet. This color is not static; tanzanite exhibits a strong trichroism, a property where a crystal shows three different colors when viewed from three different directions under white light. For tanzanite, these colors are typically a deep blue, a violet, and a burgundy or reddish-brown. The orientation of the crystal during cutting is critical; cutters must decide which color direction to emphasize to maximize the gem's weight and beauty, often resulting in a final gem that shows a dominant blue or violet hue. The mineral zoisite naturally occurs in a wide range of colors, including colorless, gray, yellow, brown, pink, green, and blue. The name "tanzanite" is specifically reserved for the blue to violetish purple variety, following a naming convention similar to "ruby" for red corundum or "emerald" for green beryl.
Hardness and Durability: On the Mohs scale of hardness, zoisite (tanzanite's parent mineral) has a hardness of approximately 6 to 7. This places tanzanite in the "fair to good" range for durability in jewelry. It is softer than quartz (Mohs 7) and significantly softer than corundum-based gems like sapphire and ruby (Mohs 9). As a result, tanzanite is more susceptible to scratches and abrasions from everyday wear. This relative softness makes it less ideal for rings intended for constant, rough wear, such as engagement rings, unless set in a protective setting (e.g., a bezel) and worn occasionally. For other jewelry types like earrings, pendants, and brooches, tanzanite's durability is generally sufficient.
Chemical Composition and Crystal System: Tanzanite is a variety of zoisite, a calcium aluminum hydroxyl silicate mineral. Its chemical formula is Ca₂Al₃(SiO₄)₃(OH), with the blue-violet color typically caused by trace amounts of vanadium. It crystallizes in the orthorhombic crystal system.
Clarity and Inclusions: Like many colored gemstones, tanzanite is typically found with some inclusions. Clean, eye-clean specimens are highly valued. The presence of inclusions can affect the stone's transparency and brilliance.
Cut: The trichroic nature of tanzanite dictates its cutting. Cutters must orient the rough crystal to showcase the most desirable color while minimizing the visibility of less appealing hues (like the burgundy). The most common cut shapes are oval, cushion, and pear, which allow for a good display of color and brilliance.
Carat Weight: Tanzanite is available in a wide range of sizes. While smaller stones are more common, large, high-quality tanzanite gems are rare and command premium prices. The discovery of stones weighing over 9 kg, as mentioned, underscores the potential for large crystals, though such sizes are exceptional.
Symbolism and Metaphysical Beliefs
As a relatively new gemstone, tanzanite lacks the ancient mythological and religious symbolism associated with gems like sapphire or emerald. Its symbolism is largely a product of modern marketing and New Age spiritualism. Tiffany & Co.'s initial promotion framed tanzanite as a stone of discovery and luxury, emphasizing its rarity and unique beauty. The company's description of it as "the loveliest blue gemstone discovered in over 2000 years" imbued it with a sense of historic significance, even though its history was just beginning.
In contemporary crystal healing and metaphysical circles, tanzanite is attributed with various properties. It is often called a "stone of transformation," believed to facilitate profound personal growth and spiritual awakening. Its association with the throat and third-eye chakras links it to communication, intuition, and psychic abilities. Some practitioners believe it can enhance meditation, promote deeper self-reflection, and help clear emotional blockages. It is also sometimes connected to the zodiac signs Sagittarius, Capricorn, Pisces, and Gemini, with specific traits attributed to each. For example, it is said to help Sagittarians balance their adventurous spirit and aid Geminis in focusing their dual nature.
It is important to emphasize that these symbolic and metaphysical beliefs are not part of established gemological science. They represent a cultural layer that has been applied to tanzanite since its introduction. For many collectors and wearers, the primary "symbolism" of tanzanite is its tangible rarity and the unique geological conditions that produced it.
Care and Cleaning
Due to its moderate hardness and potential for cleavage (a tendency to break along flat planes), tanzanite requires careful handling and cleaning. Proper care will preserve the gemstone's beauty and integrity for generations.
Daily Wear and Storage: Because tanzanite is softer than many other gemstones, it is advisable to remove tanzanite jewelry before engaging in activities that could subject it to hard blows or abrasive surfaces, such as gardening, sports, or heavy manual work. When not in use, store tanzanite pieces separately in a soft-lined jewelry box or a fabric pouch. This prevents scratches from harder stones (like diamonds, sapphires, or rubies) or from metal parts of other jewelry pieces.
Cleaning Methods: The safest way to clean tanzanite is with warm water, a mild soap (like dish detergent), and a soft brush (such as a baby toothbrush). Gently scrub the stone, rinse thoroughly with clean water, and pat dry with a soft, lint-free cloth. Avoid using harsh chemicals, including household cleaners, as they can damage the stone or its setting.
What to Avoid: Ultrasonic cleaners and steam cleaners are generally not recommended for tanzanite. The vibrations from an ultrasonic cleaner can cause existing fractures or inclusions to worsen, potentially damaging the stone. Steam cleaning can introduce intense heat and moisture, which might affect the stone's stability or cause thermal shock. As noted in the sources, while tanzanite does not fade under normal conditions, extreme heat or prolonged exposure to intense sunlight could potentially alter its color slightly. Therefore, it is wise to avoid leaving tanzanite jewelry in direct, hot sunlight for extended periods.
Conclusion
Tanzanite stands as a remarkable testament to the geological wonders still being discovered on Earth. Its journey from a single, remote deposit in Tanzania to the global jewelry market is a modern narrative of rarity, beauty, and strategic promotion. As a December birthstone, it offers a unique and vibrant alternative to its traditional counterparts, symbolizing clarity, transformation, and spiritual insight for those who choose to wear it. Its distinctive trichroism and captivating blue-violet color palette, achieved through both natural processes and standard heat treatment, make it a subject of fascination for gemologists and a prized possession for collectors. While its metaphysical properties belong to the realm of personal belief, its geological story is unequivocal: tanzanite is a product of a unique and finite set of conditions, a gemstone that truly can only be found in one place on Earth. Its legacy is still being written, but its place as one of the most significant gemological discoveries of the 20th century is already secure.