For individuals born on December 28th, their birthstone is a gem of remarkable modernity and profound color: Tanzanite. This captivating stone, celebrated for its vibrant violet-blue hues and relatively recent discovery, holds a unique position in the world of gemology. Unlike many birthstones that boast ancient histories, Tanzanite is a product of the 20th century, yet it has swiftly ascended to become one of the most sought-after gemstones for its beauty, rarity, and deep symbolic meanings. This article explores the history, geological origins, gemological properties, and cultural significance of Tanzanite, drawing upon expert sources to provide a comprehensive overview for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
Tanzanite’s story begins not in antiquity, but in the mid-1960s, making it one of the youngest major gemstones in the world. The gem was discovered in 1967 in the foothills of Mount Kilimanjaro in Tanzania, a location of immense geological and cultural significance. Initially, the blue-violet crystals were mistaken for sapphire due to their striking color. However, their unique geological formation and distinct color spectrum soon set them apart, earning recognition as a standalone gemstone.
The discovery was serendipitous and transformative for the gem trade. Tanzanite was introduced to the global market in the early 1970s and was quickly named after its country of origin. Its rapid rise in popularity was aided by a major jewelry company, which launched a marketing campaign that linked the gemstone to the beauty of Tanzania and its natural wonders. This strategic promotion helped solidify its place in the gemological world and the birthstone calendar.
Regarding its status as a birthstone, sources confirm that Tanzanite is designated for December 28th. While December is traditionally associated with several stones including Turquoise, Zircon, and Blue Topaz, Tanzanite has become a prominent modern alternative. Its inclusion as a specific birthdate stone highlights its growing cultural integration. The gemstone’s relatively recent history means it lacks the ancient myths and legends that surround older stones, but it has quickly generated its own lore based on its metaphysical properties and aesthetic appeal.
Geological Formation and Sources
Tanzanite is a variety of the mineral zoisite, specifically the blue to violet variety colored by vanadium impurities. Its formation is a geological rarity, occurring in only one known commercial deposit on the planet. This deposit is located in a small area in the Merelani Hills of Tanzania, near the base of Mount Kilimanjaro.
The formation process is unique. The zoisite crystals formed during a massive metamorphic event approximately 585 million years ago, when intense heat and pressure altered the original rock. The presence of vanadium during this process gave the crystals their distinctive blue color. Subsequent erosion and weathering brought these crystals closer to the surface, making them accessible for mining.
The mining area is extremely limited, covering only a few square kilometers. This geographic restriction is the primary reason for Tanzanite’s rarity and value. All commercial Tanzanite originates from this single source, making it more scarce than diamonds, which are mined in multiple locations worldwide. The mining operations in the Merelani Hills range from large-scale commercial enterprises to small-scale artisanal mining, each contributing to the global supply.
Gemological Properties
Tanzanite possesses a unique set of gemological characteristics that distinguish it from other blue gemstones. Its properties are a key factor in its identification and valuation.
Color: The most defining feature of Tanzanite is its color. It exhibits a range of hues from deep indigo and royal blue to vibrant violet and lavender. A key characteristic is its trichroic nature, meaning it displays three different colors when viewed from three different crystal directions: typically blue, violet, and reddish-purple. This trichroism is a direct result of its crystal structure and the pleochroic properties caused by the vanadium impurities. The color can also appear to change under different light sources; it often looks more blue in natural daylight and more violet under incandescent or fluorescent light.
Hardness and Durability: On the Mohs scale of hardness, Tanzanite ranks between 6 and 7. This makes it relatively durable but softer than many other popular gemstones like sapphire (9) or diamond (10). Consequently, while suitable for rings and other jewelry, it requires careful handling and protection from hard blows or abrasion to avoid scratches or damage. Its cleavage is also a consideration; zoisite has perfect cleavage in one direction, meaning it can be split if struck with sufficient force along that plane.
Chemical Composition: Tanzanite is a calcium aluminum hydroxyl sorosilicate, with the chemical formula Ca₂Al₃(SiO₄)₃(OH). Its blue-to-violet color is specifically attributed to trace amounts of vanadium (V) substituting for aluminum in the crystal lattice. Heat treatment is commonly used to enhance the color of naturally occurring zoisite, often transforming brownish or greenish crystals into the prized blue-violet hue.
Refractive Index and Specific Gravity: The refractive index of Tanzanite ranges from approximately 1.691 to 1.700, and its specific gravity is typically between 3.35 and 3.38. These properties are used by gemologists to distinguish it from visually similar stones like sapphire, amethyst, or iolite.
Clarity and Cut: High-quality Tanzanite is generally eye-clean, meaning inclusions are not visible to the naked eye. Common inclusions can include needle-like crystals, fingerprints, or fluid inclusions. The gem’s trichroism presents a challenge and opportunity for cutters. To display the most desirable violet-blue color, the stone must be oriented carefully during cutting, typically with the table facet perpendicular to the crystal's c-axis. This often results in a cut that sacrifices some weight to maximize color and brilliance.
Summary of Key Gemological Properties
| Property | Description |
|---|---|
| Mineral Species | Zoisite |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) |
| Color | Blue, violet, indigo, lavender; trichroic (blue, violet, reddish-purple) |
| Hardness (Mohs) | 6 - 7 |
| Refractive Index | 1.691 - 1.700 |
| Specific Gravity | 3.35 - 3.38 |
| Crystal System | Orthorhombic |
| Lustre | Vitreous |
| Transparency | Transparent to translucent |
| Primary Source | Merelani Hills, Tanzania |
Symbolism and Metaphysical Beliefs
Tanzanite is deeply imbued with symbolic meanings and metaphysical beliefs, which are a significant part of its appeal. As a modern birthstone, it has quickly accumulated a rich tapestry of associated qualities, particularly in spiritual and emotional realms.
One of the most prominent meanings attributed to Tanzanite is its connection to spiritual awareness and enlightenment. It is often described as a stone that facilitates deep meditation and opens the "third eye" chakra, promoting insight, intuition, and a heightened sense of awareness. This belief positions Tanzanite as a tool for those seeking to deepen their spiritual practice or connect with higher states of consciousness.
Tanzanite is also strongly associated with the throat chakra, which governs communication and self-expression. Metaphysical traditions suggest that wearing or carrying Tanzanite can empower individuals to articulate their thoughts with greater clarity, confidence, and truth. It is believed to help overcome shyness and facilitate honest, compassionate dialogue.
Furthermore, the gemstone is widely regarded as a stone of transformation and personal growth. Its radiant energy is said to stimulate psychic abilities and encourage resilience during life's transitions. For those born on December 28th, Tanzanite serves as a talisman for navigating change, embracing personal evolution, and finding harmony amidst chaos. These metaphysical properties, while not scientifically proven, contribute significantly to the gemstone's cultural identity and desirability.
Care and Cleaning
Given its gemological properties, particularly its moderate hardness and perfect cleavage, Tanzanite requires specific care to maintain its beauty and integrity. Proper maintenance is essential for anyone who owns or plans to purchase Tanzanite jewelry.
Cleaning: The safest method for cleaning Tanzanite is with warm, soapy water and a soft brush. Avoid using harsh chemicals, ultrasonic cleaners, and steam cleaners, as these can damage the stone or affect any treatments it may have undergone. After cleaning, rinse thoroughly to remove any soap residue and dry with a soft, lint-free cloth.
Storage: Due to its cleavage, Tanzanite should be stored separately from other jewelry to prevent scratches and hard impacts. It is advisable to keep it in a soft-lined jewelry box or a fabric pouch. When traveling, ensure it is securely packed.
Setting and Wear: Because of its hardness, Tanzanite is best suited for jewelry that is less likely to receive hard impacts, such as earrings, pendants, and brooches. If set in a ring, it should be placed in a protective setting (e.g., a bezel) and worn with caution during activities that could subject it to knocks or abrasion. Avoid wearing Tanzanite while engaging in manual labor, gardening, or sports.
Heat Sensitivity: While heat treatment is used to enhance the color of Tanzanite, the stone itself is relatively stable at moderate temperatures. However, extreme and rapid temperature changes should be avoided, as they could potentially cause thermal shock and damage the crystal structure.
Conclusion
Tanzanite stands as a remarkable gemstone for those born on December 28th, embodying a unique convergence of modern discovery, geological rarity, and profound symbolism. Its journey from a serendipitous find in the foothills of Mount Kilimanjaro to a globally celebrated birthstone highlights its captivating appeal. The gem’s stunning trichroic color, ranging from deep blues to vibrant violets, makes it a visually distinctive choice, while its relatively recent history adds a layer of contemporary allure.
Beyond its physical beauty, Tanzanite carries significant metaphysical weight, associated with spiritual awareness, clear communication, and personal transformation. These beliefs, though not empirically validated, form a core part of its cultural narrative and enhance its value for wearers seeking more than just aesthetic pleasure.
From a practical standpoint, understanding Tanzanite’s gemological properties—its hardness, cleavage, and care requirements—is crucial for its preservation. As a gemstone that originates from a single, limited source, it also holds intrinsic value due to its rarity. For the December 28th individual, Tanzanite is not merely a birthstone; it is a symbol of rarity, depth, and spiritual potential, making it a cherished gem for both jewelry and personal significance.