Tanzanite is a captivating gemstone recognized as a December birthstone, alongside turquoise and zircon. Discovered relatively recently in 1967, this striking blue and violet gem has quickly risen to prominence in the world of colored stones, celebrated for its rarity, unique pleochroism, and vibrant hues. This article will explore the history, geological origins, gemological properties, and significance of tanzanite, offering a comprehensive overview of this remarkable gemstone.
History and Lore
While gemstones have been associated with specific months for centuries, tanzanite is a comparatively recent addition to the birthstone calendar. It was officially added in 2002, becoming the first gemstone to achieve such status since 1912. Prior to its recognition as a birthstone, tanzanite’s story began with its discovery in the Merelani Hills of northern Tanzania. Prospectors identified the mineral as zoisite in 1962, but it wasn’t until 1967 that the primary source of this unique gem was located.
The gemstone was named tanzanite in honor of its country of origin, Tanzania. Recognizing its potential, Tiffany & Co. became its main distributor and launched a major advertising campaign in 1968, introducing tanzanite to an international audience. The campaign highlighted its vivid colors, high clarity, and potential for large cut stones, quickly establishing tanzanite as a sought-after gem. Today, it is not only a December birthstone but also the traditional gem for the 24th wedding anniversary.
The tradition of associating gemstones with specific months is rooted in ancient beliefs that each gem possesses unique powers offering protection, fortune, serenity, and happiness to those born under its influence. Choosing a gem corresponding to one’s birth month is a long-standing tradition that continues to resonate in the modern world.
Geological Formation and Sources
Tanzanite’s geological story is as unique as its color. The gem is a variety of the mineral zoisite, and its formation requires a specific set of geological conditions. It is found exclusively in the Merelani Hills of northern Tanzania, a remarkably limited geographical source. This singular origin contributes significantly to its rarity, making it rarer than diamonds.
The mines in the Merelani Hills are located at the base of Mount Kilimanjaro. These operations, ranging from small-scale excavations to large mechanized operations, extend over 100 meters (more than 300 feet) into the earth. Thousands of workers are involved in recovering tanzanite from this unique geological setting. The surrounding landscape is characterized by grass-covered hillsides, scrub brush, and rocky soil.
Gemological Properties
Tanzanite is renowned for its striking color, which ranges from a pure rich blue to violet, with blue being the most valuable hue. This captivating color is often described as “velvety” due to its depth and saturation. A key characteristic of tanzanite is its pleochroism – the ability to display different colors when viewed from different angles. This means a single tanzanite gem can exhibit blue, purple, or burgundy shades depending on the lighting and viewing direction.
Gemologically, tanzanite typically ranges from 6 to 7 on the Mohs scale of hardness. This makes it relatively durable but susceptible to scratching and abrasion. It is resistant to the effects of normal heat, light, and common chemicals, but can crack if exposed to very high temperatures or sudden temperature changes. It is also vulnerable to attack by hydrochloric and hydrofluoric acids.
Most tanzanite begins as brownish zoisite, requiring heat treatment to reveal the desirable blue to violet hues. This heat treatment is a permanent process, and does not introduce any additional durability concerns. The gem’s trichroism—appearing blue, purple, or burgundy depending on the viewing angle—is a defining characteristic.
Here's a summary of key gemological properties:
| Property | Description |
|---|---|
| Mineral | Zoisite |
| Color | Blue, violet, burgundy (pleochroic) |
| Hardness (Mohs) | 6-7 |
| Origin | Merelani Hills, Tanzania |
| Treatment | Typically heat-treated to enhance color |
| Rarity | Very Rare |
Symbolism and Metaphysical Beliefs
While tanzanite’s history is relatively short compared to many other birthstones, it has quickly acquired symbolic meaning. The deep blue and violet hues are often associated with wisdom, dignity, truth, and spiritual growth. As a December birthstone, it is believed to offer its wearer a plethora of properties, including protection, fortune, serenity, and happiness.
The tradition of associating birthstones with specific properties dates back to ancient times, with each gem believed to possess unique powers. The selection of a gem corresponding to one’s birth month is seen as a way to harness these energies and benefit from the stone’s inherent qualities.
Care and Cleaning
Due to its hardness of 6 to 7 on the Mohs scale, tanzanite requires careful handling. It is best set in earrings or pendants to minimize the risk of damage. While it can be worn in rings, a protective mounting is recommended, and daily wear should be avoided.
Cleaning tanzanite is best achieved with warm, soapy water. Ultrasonic and steam cleaners are not recommended, as they can potentially damage the gemstone. Gentle cleaning with a soft brush and mild soap will help maintain its brilliance and luster. Avoid exposing tanzanite to harsh chemicals or sudden temperature changes.
Conclusion
Tanzanite is a remarkable gemstone that has quickly established itself as a beloved December birthstone. Its unique geological origin, captivating color, and relatively recent discovery contribute to its allure and desirability. From its humble beginnings in the Merelani Hills of Tanzania to its recognition as a globally sought-after gem, tanzanite represents a fascinating intersection of geological wonder, human artistry, and cultural significance. Its rarity and beauty make it a truly special gemstone, offering wearers not only a stunning piece of jewelry but also a connection to the rich lore and symbolism of birthstones.