For those born on December 21st, the birthstone is tanzanite, a gemstone of extraordinary rarity and captivating color. Discovered only in the 20th century, tanzanite is one of the few gemstones to emerge in the modern era, and it is found in a single location on Earth. This singular source has made it one of the rarest gemstones in the world. Its discovery coincided with the rise of the modern jewelry industry, and tanzanite quickly became a favorite among designers and collectors. As the birthstone for those born on December 21, it symbolizes transformation, spiritual growth, and creativity—traits that align perfectly with the Capricorn zodiac sign, which begins on this date. Tanzanite's deep blue-violet color and unique properties make it a valuable addition to any jewelry collection, and its rarity only adds to its allure.
This article explores the history, geological properties, symbolism, and care of tanzanite, drawing from expert sources and historical context. We will examine how this modern gemstone became a December birthstone, its unique geological formation, its gemological characteristics, and its cultural significance. By understanding these aspects, gemstone enthusiasts, jewelry buyers, and students of gemology can appreciate why tanzanite holds a special place in the world of colored stones.
History and Lore
Tanzanite's history is remarkably brief compared to ancient gemstones, yet it has rapidly woven itself into the fabric of modern gemology and jewelry. The gemstone was first discovered in 1967 in Tanzania, as noted in the sources. This discovery was significant because it occurred in the modern era, making tanzanite one of the few gemstones to emerge in contemporary times. The gemstone is found only in one location on Earth, making it the rarest of all birthstones. Its singular source has contributed to its mystique and value.
The journey of tanzanite from discovery to birthstone status is a story of both geological fortune and cultural adoption. In 1912, the National Association of Jewelers standardized the unofficial American birthstones, combining customs with gemstones that would be practical for jewelry companies to sell. This list evolved over time. In 1952, the Jewelry Industry Council of America updated the list, adding zircon to December’s list. Tanzanite was added to the official birthstone list in 2002. This addition reflects how birthstone lists can evolve with new gemstone discoveries and commercial offerings. The inclusion of tanzanite provided a new, vibrant option for December, a month that already had turquoise and zircon as traditional birthstones. Some believe that December has multiple birthstones to add more affordable options, though tanzanite, being the most valuable and expensive of the December stones, is a premium choice.
Tanzanite has also been embraced by zodiac traditions. For those born on December 21, it is the birthstone associated with Capricorn. December 21 marks the end of the winter solstice and the beginning of a new zodiac sign, Capricorn. Capricorn is a zodiac sign known for its ambition, determination, and practicality. Tanzanite, with its deep and introspective color, is believed to support the Capricorn's drive for success and personal growth. The gemstone is associated with transformation and spiritual development, which aligns with the Capricorn's desire to evolve and achieve their goals.
While tanzanite itself is a modern discovery, its color evokes a sense of majesty and mystery historically associated with deep blue and violet gemstones. In ancient times, such stones were often linked to royalty and divine power. Sapphires and amethysts, for example, have been revered for centuries. Tanzanite, with its rich violet-blue hue, taps into this historical reverence for blue gemstones, though its specific lore is rooted in contemporary metaphysical beliefs rather than ancient tradition. Today, tanzanite is often used in high-end jewelry and is considered a symbol of luxury and sophistication.
Geological Formation and Sources
Tanzanite is a variety of the mineral zoisite, which is part of the epidote group of minerals. Its geological formation is unique and directly tied to its extreme rarity. The gemstone is found only in the Merelani Hills of northern Tanzania, a small area of less than 20 square kilometers. This specific region is the only known source of tanzanite in the world, making it geologically exclusive.
The formation of tanzanite is linked to a specific set of geological conditions. Zoisite typically forms in metamorphic rocks, but the tanzanite variety is associated with a unique geological event. The heat and pressure from the formation of Mount Kilimanjaro and the nearby Mount Kenya are believed to have altered the original zoisite crystals, transforming them into the blue-violet tanzanite. This process involved the presence of vanadium and chromium, which are trace elements that give tanzanite its distinctive color. The combination of these elements under specific thermal conditions created the gemstone's characteristic hue, which can range from ultramarine blue to violet.
Mining for tanzanite is conducted in the Merelani Hills, where the gemstone is extracted from small-scale mines. The mining operations are often artisanal, with miners working in challenging conditions to unearth the rough crystals. The rarity of tanzanite is not only due to its single source but also because the gemstone is found in limited quantities within that area. The gemstone's scarcity is a key factor in its high market value. Of all the December birthstones, tanzanite is the most valuable and expensive, primarily because it is only mined in a specific region of Tanzania.
The geological properties of tanzanite, including its pleochroism, refractive index, and specific gravity, contribute to its visual appeal and make it a fascinating subject of study. Pleochroism is the property of a gemstone to show different colors when viewed from different directions. Tanzanite exhibits strong pleochroism, appearing blue, violet, and reddish-violet from different angles. This characteristic is a key identifier for the gemstone and adds to its visual complexity and beauty. The refractive index of tanzanite ranges from 1.691 to 1.700, and its specific gravity is between 3.35 and 3.38. These gemological properties are typical for zoisite and help gemologists distinguish tanzanite from other blue gemstones like sapphire or topaz.
Gemological Properties
Tanzanite is a member of the zoisite mineral family, specifically a blue-violet variety of zoisite. Its gemological properties are distinctive and crucial for identification and appreciation. The most notable characteristic of tanzanite is its strong pleochroism, a feature that causes the gemstone to display different colors—typically blue, violet, and reddish-violet—depending on the crystallographic direction from which it is viewed. This trichroic property is a hallmark of tanzanite and is a key factor in its visual allure. When cut and faceted, skilled gem cutters orient the stone to present the most desirable color, usually a rich blue-violet, to the viewer.
The color of tanzanite is its defining feature. It ranges from a pure, deep ultramarine blue to a vibrant violet, with many stones showing a combination of both hues. The color is caused by trace amounts of vanadium within the crystal structure, and the hue can be further influenced by heat treatment. Most tanzanite on the market has been heat-treated to enhance and stabilize its blue-violet color, a process that is widely accepted in the trade and does not detract from the stone's value. Untreated tanzanite is rare and typically exhibits a lighter, more brownish hue.
In terms of hardness, tanzanite registers between 6.5 and 7 on the Mohs scale. This places it in the "fair to good" category for durability, meaning it is suitable for jewelry but requires careful handling. It is softer than many popular gemstones like sapphire (Mohs 9) or topaz (Mohs 8), which makes it more susceptible to scratches and abrasions. Consequently, tanzanite is best set in protective jewelry settings, such as bezels or halo designs, especially for rings that are worn daily. For comparison, blue topaz, another December birthstone, has a Mohs hardness of 8, making it more durable for everyday wear.
Tanzanite has a refractive index ranging from 1.691 to 1.700 and a specific gravity between 3.35 and 3.38. These optical properties are within the typical range for zoisite and help gemologists differentiate it from similar-looking stones. The gemstone is also singly refractive, a common trait among many colored gemstones. Clarity is another important factor; tanzanite often contains inclusions, which are natural internal characteristics. Clean, eye-clean tanzanite is prized and commands higher prices. The gemstone is typically cut into standard faceted shapes like oval, pear, and round brilliant to maximize its color and brilliance.
The following table summarizes key gemological properties of tanzanite based on the provided sources and standard gemological knowledge:
| Property | Description |
|---|---|
| Mineral Family | Zoisite (Epidote group) |
| Chemical Formula | Ca2Al3(SiO4)3(OH) |
| Hardness (Mohs) | 6.5 - 7 |
| Refractive Index | 1.691 - 1.700 |
| Specific Gravity | 3.35 - 3.38 |
| Crystal System | Orthorhombic |
| Pleochroism | Strong (Blue, Violet, Reddish-Violet) |
| Typical Treatments | Heat treatment to enhance color |
| Primary Source | Merelani Hills, Tanzania |
Symbolism and Metaphysical Beliefs
Tanzanite's symbolism is deeply intertwined with its color, rarity, and modern discovery. As a birthstone for December 21, it is primarily associated with the Capricorn zodiac sign. Capricorns are known for their ambition, determination, and practicality. The deep, introspective color of tanzanite is believed to support the Capricorn's drive for success and personal growth. The gemstone is linked to transformation and spiritual development, aligning with the Capricorn's desire to evolve and achieve their goals. For those born on December 21, tanzanite is more than just a birthstone—it is a symbol of personal growth, creativity, and inner strength.
Beyond its zodiac connections, tanzanite is widely regarded in metaphysical circles as a stone of transformation. Its association with the throat and third eye chakras makes it a popular choice for those seeking to enhance communication, intuition, and spiritual awareness. Practitioners believe that tanzanite can facilitate a connection to higher realms of consciousness and aid in accessing past-life information. It is often described as a calming stone that can help alleviate stress and anxiety, promoting a sense of peace and tranquility.
The gemstone's vibrant violet-blue color is also linked to creativity and imagination. Many crystal healers suggest that tanzanite stimulates the mind and encourages creative thinking, making it a favored stone among artists, writers, and innovators. Its energy is said to be gentle yet powerful, helping to clear mental blockages and inspire new ideas. This association with creativity complements its connection to Capricorn, a sign that, while often seen as disciplined, also possesses a strong creative and visionary side.
In terms of emotional healing, tanzanite is believed to be a powerful ally for processing grief and loss. Its transformative energy is thought to help individuals navigate major life changes and transitions, offering comfort and support during difficult times. Some believe that wearing or meditating with tanzanite can help release old emotional patterns and embrace new beginnings, which resonates with its symbolism of transformation.
While these metaphysical beliefs are popular among crystal enthusiasts, it is important to note that they are not scientifically proven. The symbolic meanings of tanzanite, like those of many gemstones, are rooted in cultural traditions and personal belief systems. For gemstone enthusiasts and collectors, the allure of tanzanite often lies in its combination of aesthetic beauty and the rich tapestry of meanings that have been woven around it since its discovery.
Care and Cleaning
Given its gemological properties, particularly its moderate hardness and potential for cleavage, tanzanite requires careful handling and maintenance to preserve its beauty and integrity. With a Mohs hardness of 6.5 to 7, tanzanite is more susceptible to scratches than harder gemstones like sapphire or diamond. Therefore, it is advisable to store tanzanite jewelry separately from other pieces to prevent abrasive contact. Using a soft cloth pouch or a compartmentalized jewelry box is ideal for storage.
Cleaning tanzanite should be done with gentle methods to avoid damage. The safest way to clean tanzanite jewelry is with warm water, a mild dish soap, and a soft brush. After soaking the piece briefly, use a soft-bristled brush to gently remove any dirt or residue from the settings and the stone's surface. Rinse thoroughly under lukewarm running water to ensure all soap residue is removed, and then pat dry with a soft, lint-free cloth. It is important to avoid harsh chemicals, ultrasonic cleaners, and steam cleaners, as these can damage the stone or its settings. Tanzanite should also be removed before engaging in activities that could expose it to physical impact or chemicals, such as gardening, cleaning, or swimming.
Due to its relative fragility, tanzanite is best suited for jewelry that is not subjected to daily wear and tear, such as earrings, pendants, or occasional-wear rings. If worn as a ring, it should be set in a protective setting like a bezel or a halo to minimize the risk of chipping or breaking. Professional inspection of the setting is recommended periodically to ensure the stone remains secure.
The gemstone's color stability is generally good, especially for heat-treated stones. However, prolonged exposure to strong sunlight or high heat should be avoided, as extreme conditions can potentially alter the color. As with all fine jewelry, it is best to put tanzanite jewelry on after applying cosmetics, perfumes, and hairsprays to prevent chemical exposure.
By following these care guidelines, owners of tanzanite can ensure that this rare and radiant gemstone remains a stunning and cherished part of their collection for years to come.
Conclusion
Tanzanite stands as a unique and significant gemstone in the world of birthstones, particularly for those born on December 21. Its status as a modern discovery, found only in the Merelani Hills of Tanzania, underscores its rarity and exclusivity. As the birthstone for the Capricorn zodiac sign, tanzanite embodies themes of transformation, ambition, and spiritual growth, aligning with the traits of individuals born at the start of this sign. The gemstone's captivating blue-violet color, enhanced by its strong pleochroism, makes it a visually stunning choice for jewelry, though its moderate hardness requires careful handling and cleaning.
The journey of tanzanite from its discovery in 1967 to its inclusion in the official birthstone list in 2002 highlights the evolving nature of gemological traditions. It joins turquoise and zircon as a December birthstone, offering a modern alternative with deep symbolic meaning. Whether valued for its geological uniqueness, its gemological properties, or its metaphysical associations, tanzanite continues to inspire and captivate. For gemstone enthusiasts, jewelry buyers, and students of gemology, tanzanite represents a fascinating intersection of science, history, and culture—a rare gem that truly symbolizes transformation.