For those born in the month of December, the birthstone selection is uniquely abundant, offering a trio of blue-hued gems: tanzanite, turquoise, and zircon. Among these, tanzanite stands apart as a modern marvel, a gemstone whose geological story is confined to a single location on Earth and whose vibrant color palette captivated the global gemological community within the last half-century. This article provides an in-depth exploration of tanzanite, detailing its singular origin, remarkable gemological properties, its rapid journey to birthstone status, and the symbolic meanings attributed to it. We will examine the science behind its captivating trichroism, its geological formation in the foothills of Mount Kilimanjaro, and the practical considerations for its care and preservation.
Tanzanite’s significance is not merely aesthetic; it is a testament to the dynamic nature of the gemstone world, where new treasures can still be unearthed and integrated into long-standing traditions. As a variety of the mineral zoisite, tanzanite’s story begins in 1967, and its official designation as a December birthstone occurred in 2002. This relatively recent history provides a fascinating contrast to ancient stones like turquoise, yet its rarity and beauty have secured its place as a cherished symbol of transformation, creativity, and emotional clarity for December-born individuals and gemstone enthusiasts alike.
History and Lore: A Modern Gem with Ancient Roots
While tanzanite itself is a product of the 20th century, its mineral family, zoisite, has a longer history. The gemstone’s modern narrative, however, is defined by its discovery and rapid ascent in the gem trade. Tanzanite was first identified in 1967 in the Merelani Hills of Tanzania, a region in the northern part of the country. The discovery was made by a local Masai tribesman, and the gem’s name is directly derived from its country of origin. The stone’s potential was quickly recognized by gemologists and jewelers due to its vivid coloration and unique optical properties.
The pivotal moment in tanzanite’s history came in 1968, when the renowned jewelry company Tiffany & Co. recognized its international appeal and launched a major advertising campaign to promote it. This strategic move catapulted tanzanite from a local curiosity to a global sensation. With its vivid colors, high clarity, and potential for large cut stones, tanzanite became a staple in high-end jewelry. Its journey to becoming an official birthstone was a logical progression. In 2002, the American Gem Trade Association (AGTA) added tanzanite to the list of birthstones for December, joining the traditional stones of turquoise and blue zircon. This designation cemented its status in contemporary gemstone culture. Today, tanzanite is not only a December birthstone but also the gemstone for the 24th wedding anniversary, a testament to its enduring appeal and symbolic value.
The lore surrounding tanzanite is inherently modern, focusing on themes of transformation and new beginnings. Its discovery in the 1960s, a decade of significant social and cultural change, aligns with its symbolic association with transformation and emotional balance. Unlike stones with centuries of mythological baggage, tanzanite’s meaning is more personal and introspective, often linked to spiritual growth and enhanced intuition. While it lacks the ancient legends of turquoise or the medieval superstitions of zircon, its story is one of modern discovery and the symbolic power of a new gemstone entering the human cultural lexicon.
Geological Formation and Sources
Tanzanite’s most defining characteristic is its extreme geographic rarity. It is found in only one location on the planet: the Merelani Hills of northern Tanzania, situated at the foothills of the majestic Mount Kilimanjaro. This small mining area, covering just a few square kilometers, is the exclusive commercial source of all tanzanite in the world. The landscape of the Merelani Hills is described as grass-covered hillsides with scrub brush, rocky soil, and occasional trees, providing a stark backdrop to the deep, mechanized mines that extract the gem.
The geological formation of tanzanite is a fascinating story of heat and pressure. It begins as brownish zoisite, which is subjected to intense natural heat. This process, which can occur through natural geological events or be replicated in a laboratory, transforms the brownish mineral into the characteristic blue to violet hues that define tanzanite. This heat treatment is a permanent alteration, and there are no additional durability concerns stemming from it. In fact, the vast majority of tanzanite available on the market has undergone this treatment to achieve its desirable color. The resulting color is stable and does not fade over time.
The mining operations in the Merelani Hills are significant, with thousands of workers recovering tanzanite from mines dug over 100 meters (more than 300 feet) deep into the earth. The depth and complexity of these mines underscore the challenges and costs associated with extracting this rare gem. The exclusivity of its source is a primary factor in its rarity and value. While other blue gemstones are found in multiple locations worldwide, tanzanite’s confinement to this single, small area in Tanzania makes it one of the rarest gemstones in the world. This geographic singularity adds a layer of mystique and desirability, making it a "modern marvel" highly sought after by collectors and connoisseurs.
Gemological Properties
Tanzanite’s appeal is rooted in its exceptional gemological properties, which distinguish it from all other blue gemstones. As a variety of the mineral zoisite, its chemical composition is Ca₂Al₃(SiO₄)₃(OH), with traces of vanadium and chromium responsible for its blue color. However, its most famous property is its trichroism—a form of pleochroism where the stone exhibits three different colors depending on the viewing angle. When viewed from one direction, tanzanite may appear a deep, vivid blue; from another, a rich violet; and from a third, a reddish-burgundy. This dynamic color play is a hallmark of the gem and is a key factor in its captivating beauty. The cutting of tanzanite is therefore a skilled art, as the cutter must orient the stone to display the most desirable color face-up.
In terms of physical properties, tanzanite has a Mohs hardness of 6 to 7. This places it in the moderate range of gemstone durability—softer than quartz (7) but harder than apatite (5). This relative softness means it is susceptible to scratching and abrasion. It is also important to note that tanzanite has perfect cleavage in one direction, meaning it can split if struck with sufficient force along that plane. This makes it more vulnerable to damage from hard knocks, which is why it is often recommended for jewelry settings that offer protection, such as earrings and pendants, rather than rings worn for daily activities.
The gem’s refractive index ranges from approximately 1.691 to 1.700, contributing to its brilliance when properly cut. Its specific gravity is around 3.35, and it is typically found with high clarity, often with few inclusions. The color is primarily a result of the vanadium content, and the heat treatment process is essential for developing the blue-violet hues from the initial brownish state. The clarity of tanzanite is generally high, allowing for exceptional transparency and light performance.
Summary of Key Gemological Properties
| Property | Description |
|---|---|
| Mineral Family | Zoisite |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) |
| Color | Blue, violet, burgundy (trichroic) |
| Mohs Hardness | 6 - 7 |
| Cleavage | Perfect in one direction |
| Refractive Index | 1.691 - 1.700 |
| Specific Gravity | ~3.35 |
| Origin | Merelani Hills, Tanzania (exclusive) |
| Treatment | Commonly heat-treated to enhance color |
Symbolism and Metaphysical Beliefs
As a relatively new gemstone, tanzanite’s metaphysical beliefs are contemporary and often tied to its color and discovery story. It is widely regarded as a stone of transformation, aligning with its geological origin as a mineral that undergoes a dramatic color change through heat. This symbolism resonates with individuals seeking personal growth, new beginnings, or emotional healing. The deep blue and violet hues are associated with the higher chakras—specifically the throat and third eye chakras—making tanzanite a popular choice for those focused on communication, intuition, and spiritual awareness.
Tanzanite is also believed to promote emotional balance and calm. Its serene colors are thought to soothe anxiety and foster a sense of peace, making it a favored stone for meditation and mindfulness practices. Some modern sources suggest that wearing tanzanite can enhance creativity and imagination, linking its vibrant colors to the flow of artistic energy. While these metaphysical properties are not supported by scientific evidence, they form a significant part of the gem’s cultural identity and appeal to a community interested in the symbolic and healing aspects of crystals.
It is important to distinguish these modern, popular beliefs from the historical lore of older stones. For instance, zircon was once believed to lull one into a deep sleep and ward off evil spirits, and turquoise has been associated with protection for millennia. Tanzanite’s symbolism is more introspective and personal, reflecting its status as a gemstone of the modern era. Its meaning is often tied to the individual’s journey of self-discovery and the pursuit of clarity and emotional depth.
Care and Cleaning
Given its moderate hardness and perfect cleavage, tanzanite requires careful handling to maintain its beauty and integrity. The gem’s vulnerability to scratches, abrasions, and impact means that the choice of jewelry setting is crucial. Tanzanite is best set in earrings or pendants, where it is less likely to encounter hard surfaces. While it can be set in rings, it is not recommended for daily wear unless placed in a protective mounting, such as a bezel or a halo setting, which can shield the stone from accidental knocks. For special-occasion rings, tanzanite can be an attractive choice with proper care.
Cleaning tanzanite should be done with gentle methods. The best and safest way to clean this December birthstone is with warm, soapy water and a soft brush. It is imperative to avoid ultrasonic cleaners and steam cleaners, as the vibrations and sudden temperature changes can cause the stone to crack or fracture, exploiting its cleavage. After cleaning, it should be thoroughly rinsed and dried with a soft, lint-free cloth.
When storing tanzanite jewelry, it should be kept separately from other gemstones and jewelry to prevent scratches. A soft pouch or a compartmentalized jewelry box is ideal. It is also important to protect tanzanite from extreme temperatures and sudden temperature changes, as it can become damaged. While tanzanite is resistant to the effects of normal heat, light, and common chemicals, it can be attacked by hydrochloric and hydrofluoric acids, so it should be removed before using harsh chemicals or engaging in activities like swimming in chlorinated pools.
Regular inspections by a professional jeweler are advisable, especially for rings, to ensure the setting is secure and the stone is not damaged. If any damage, such as a chip or crack, is noticed, it should be addressed promptly to prevent further issues. By following these care guidelines, the vibrant beauty and symbolic significance of tanzanite can be preserved for generations.
Conclusion
Tanzanite represents a unique chapter in the story of gemstones—a modern discovery that has rapidly ascended to the status of a cherished birthstone. Its singular origin in the Merelani Hills of Tanzania, coupled with its extraordinary trichroic properties, makes it one of the most distinctive and rare gemstones in the world. From its introduction to the global market in the late 1960s to its official designation as a December birthstone in 2002, tanzanite’s journey has been marked by rapid recognition and enduring appeal.
For those born in December, tanzanite offers a profound connection to their birth month, symbolizing transformation, emotional balance, and spiritual clarity. Its vibrant hues, ranging from deep blue to rich violet, provide a captivating alternative to the traditional turquoise and zircon, while its geological rarity adds a layer of exclusivity. Understanding its gemological properties—its moderate hardness, perfect cleavage, and the necessity of heat treatment—is essential for proper care and appreciation. While it may not have the ancient lore of other birthstones, tanzanite’s significance is rooted in its modern history and the personal meanings it holds for its wearers. As a testament to the ongoing wonders of the natural world, tanzanite continues to enchant gemstone enthusiasts, jewelry buyers, and students of gemology, securing its place as a treasured gem for the winter month of December.