Tanzanite is a relatively recent addition to the world of celebrated gemstones, yet it has quickly become a highly prized December birthstone, alongside blue zircon, blue topaz, and turquoise. Discovered in the late 1960s in Tanzania, this gem is renowned for its striking pleochroism – displaying different colors depending on the viewing angle – and its limited geographical origin. This article will delve into the history, geological formation, gemological properties, symbolism, and care of tanzanite, offering a comprehensive overview of this captivating gemstone.
History and Lore
While turquoise, blue zircon, and blue topaz have long-standing traditions as December birthstones, tanzanite’s story is comparatively modern. The gemstone was first discovered in 1967 near the base of Mount Kilimanjaro in the Merelani Hills of northern Tanzania by a Maasai tribesman named Jumanne Ngoma. Initially mistaken for sapphires, the crystals were later identified as a unique variety of zoisite by the Gemological Institute of America (GIA) in 1962, with the primary source located in 1967.
Recognizing its potential, Tiffany & Co. became the primary distributor of tanzanite and launched a major advertising campaign in 1968. However, the initial name, “blue zoisite,” presented a marketing challenge. The similarity to “blue suicide” was deemed problematic, prompting Tiffany & Co. to rename the gem “tanzanite” in honor of its country of origin. This strategic rebranding proved successful, and tanzanite quickly gained popularity, becoming not only a December birthstone but also the recognized gem for the 24th wedding anniversary.
Geological Formation and Sources
Tanzanite’s formation is intrinsically linked to the geological activity of the Merelani Hills in Tanzania. The gemstone is formed within a complex geological zone characterized by metamorphic rocks and intense heat and pressure. It is found exclusively in this small area, approximately eight square kilometers, making it one of the rarest gemstones on Earth.
Mining operations in the Merelani Hills range from artisanal digging to large-scale mechanized operations, with thousands of workers involved in extracting tanzanite from mines that extend over 100 meters deep. The landscape surrounding the mines is characterized by grass-covered hillsides, scrub brush, and rocky soil, overlooked by the snow-covered slopes of Mount Kilimanjaro. The unique geological conditions required for tanzanite formation explain its limited availability and contribute to its value.
Gemological Properties
Tanzanite is a calcium aluminum silicate with a chemical formula of Ca₂Al₃(SiO₄)₃(OH). It typically exhibits a hardness of 6 to 7 on the Mohs scale, making it relatively durable but susceptible to scratching and abrasion. This hardness level makes it particularly well-suited for use in earrings and pendants, where it is less likely to be damaged. While tanzanite can be used in rings and bracelets, extra care is recommended to protect its surface.
The most desirable tanzanite gemstones display a rich, deep blue color. However, tanzanite is known for its trichroism, meaning it exhibits different colors – blue, violet, and burgundy – when viewed from different angles. This phenomenon contributes to the gem’s captivating appearance. Most tanzanite begins as brownish zoisite, which undergoes heat treatment to reveal the vibrant blue to violet hues that characterize the gem. This heat treatment is a permanent process, and does not introduce any additional durability concerns.
Tanzanite is also valued for its high clarity and potential for large cut stones. The gem’s “velvety” appearance is attributed to its deep and saturated color. It can be attacked by hydrochloric and hydrofluoric acids.
| Property | Value |
|---|---|
| Hardness (Mohs) | 6-7 |
| Chemical Formula | Ca₂Al₃(SiO₄)₃(OH) |
| Color | Blue, Violet, Burgundy |
| Trichroism | Present |
| Treatment | Heat Treatment |
Symbolism and Metaphysical Beliefs
While tanzanite’s history is relatively short compared to other birthstones, it has quickly acquired symbolic meaning. The gem is often associated with transformation, intuition, and spiritual awareness. Its vibrant blue hues are believed to promote communication, clarity of thought, and emotional healing. Some believe that tanzanite can help to connect with higher realms of consciousness and facilitate spiritual growth.
As a December birthstone, tanzanite is thought to bestow wisdom, dignity, and good fortune upon those born in the twelfth month. Its rarity and beauty also make it a symbol of luxury, sophistication, and individuality.
Care and Cleaning
Due to its hardness of 6-7 on the Mohs scale, tanzanite requires careful handling and cleaning. 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.
Warm, soapy water is the best method for cleaning tanzanite. Ultrasonic and steam cleaners are not recommended, as they can damage the gemstone. It is also advisable to avoid harsh chemicals and abrasive materials when cleaning tanzanite jewelry. For optimal preservation, tanzanite is best set in earrings or pendants, minimizing the risk of scratches and impacts. While it can be worn in rings and bracelets, protective mountings and careful handling are essential.
Conclusion
Tanzanite, a captivating and relatively recent addition to the birthstone family, has quickly established itself as a gemstone of exceptional beauty and rarity. Its unique geological origin, striking pleochroism, and vibrant colors have made it a favorite among gemstone enthusiasts and jewelry lovers alike. As a December birthstone, tanzanite offers a meaningful and elegant choice for those seeking a gem that embodies transformation, intuition, and spiritual awareness. Its limited availability and increasing popularity ensure that tanzanite will continue to be treasured for generations to come.