December is uniquely blessed with not one, but three captivating birthstones, all showcasing shades of blue: tanzanite, zircon, and turquoise. These gemstones, while varying significantly in origin, history, and gemological properties, share a common association with peace and calmness, making them meaningful symbols for those born in the final month of the year. This article will delve into the individual characteristics of each of these December birthstones, exploring their history, geological sources, properties, and cultural significance, as understood from available sources.
A Historical Perspective
The use of blue gemstones dates back millennia, with lapis lazuli and sapphire being among the earliest appreciated. However, the December birthstones represent a broader timeline of discovery and appreciation. Turquoise, with its distinctive hue, boasts a long and storied past, being found in the tombs of pharaohs and utilized by ancient civilizations. Its name itself originates from the French term “turquois,” reflecting its journey to Europe through Turkish trade routes.
Zircon, while capable of displaying a range of colors, has a long history as a diamond simulant, with colorless varieties being particularly valued for their brilliance. Tanzanite, however, is a relatively recent addition to the world of gemstones. It was not until 1962 that blue stones emerging from Tanzania were identified as the mineral zoisite, and it wasn’t until 1967 that the primary source in the Merelani Hills was located. Named in honor of its country of origin, tanzanite quickly gained popularity thanks to a successful marketing campaign by Tiffany & Co. in 1968.
Geological Formation and Sources
Each of these gemstones originates from distinct geological environments. Turquoise is typically found in arid regions, forming in the near-surface zones of copper deposits. Its characteristic greenish-blue color, often veined with yellow or brown, is a result of copper impurities.
Zircon, a zirconium silicate, is found in a variety of igneous and metamorphic rocks. It is a widespread mineral, but gem-quality material is less common. The sources for blue zircon used in jewelry are not specifically detailed in the provided materials.
Tanzanite, a variety of the mineral zoisite, is remarkably unique in its origin. The Merelani Hills of northern Tanzania are currently the only commercially viable source of this gemstone worldwide. The mining operations in this region involve digging over 100 meters into the earth, amidst a landscape of grass-covered hills and rocky soil, overlooked by the snow-capped Mount Kilimanjaro.
Gemological Properties
The three December birthstones differ significantly in their gemological properties. Turquoise is generally opaque, with a hardness ranging from 5 to 6 on the Mohs scale. This relative softness requires careful handling to avoid scratches and damage.
Zircon possesses a hardness of 6.5 to 7.5 on the Mohs scale, making it more durable than turquoise. It exhibits a strong double refraction, a property that can be observed by gemologists. Blue zircon often undergoes heat treatment to enhance its color, with variations like London Blue (deep grayish-blue) and Swiss Blue (light neon blue) resulting from these treatments. Some blue topaz is created through irradiation.
Tanzanite, with a hardness of 6 to 7 on the Mohs scale, is also relatively soft and requires careful handling. It is known for its trichroism, meaning it displays three different colors – blue, violet, and burgundy – depending on the viewing angle. The most valuable tanzanite exhibits a pure, rich blue color.
Here's a table summarizing the key properties:
| Gemstone | Chemical Composition | Hardness (Mohs) | Color | Transparency |
|---|---|---|---|---|
| Turquoise | Hydrated Copper Aluminum Phosphate | 5-6 | Greenish-blue | Opaque |
| Zircon | Zirconium Silicate (ZrSiO₄) | 6.5-7.5 | Blue (various shades) | Transparent to Translucent |
| Tanzanite | Calcium Aluminum Silicate (Ca₂Al₃(SiO₄)₃(OH)) | 6-7 | Blue, Violet, Burgundy | Transparent |
Symbolism and Metaphysical Beliefs
Throughout history, gemstones have been imbued with symbolic meanings and metaphysical properties. While the provided sources do not extensively detail these beliefs for all three stones, some insights are available.
Sapphire, often associated with December alongside zircon and turquoise, is historically tied to prosperity and wisdom. Turquoise has been associated with peace and calmness. Garnet, the January birthstone, is linked to faith, fidelity, and friendship, and was historically worn for protection. While not a December birthstone, its historical context illustrates the tradition of attributing protective and symbolic qualities to gemstones.
The sources mention that tanzanite is associated with the 24th wedding anniversary, suggesting a connection to enduring love and commitment.
Care and Cleaning
Proper care is essential to maintain the beauty of these gemstones. Due to its relative softness, turquoise is susceptible to scratches and should be protected from impacts. Cleaning turquoise involves using only mild soap and warm water, avoiding harsh chemicals or ultrasonic cleaners.
Zircon and tanzanite, while harder than turquoise, still require careful handling. They can be cleaned with warm, soapy water and a soft brush. Avoid ultrasonic cleaners, as they may damage the stones. It is also advisable to remove jewelry containing these gemstones before engaging in strenuous activities.
Additional Blue Gemstones
Beyond the December birthstones, several other gemstones exhibit beautiful blue hues. Aquamarine, the birthstone for March, is a light blue beryl. Sapphire, the September birthstone, is classically a vibrant, deep blue. Other blue gemstones include apatite, aventurine, indicolite and paraiba tourmaline, and blue diamonds. These stones offer a wide range of options for those seeking the allure of blue gemstones.
Conclusion
December’s birthstones – tanzanite, zircon, and turquoise – represent a diverse and captivating collection of blue gemstones. From the ancient origins of turquoise to the recent discovery of tanzanite, each stone carries a unique history and geological story. Their varying properties and symbolic associations make them meaningful choices for those born in December, offering a spectrum of beauty and significance. These gemstones, while relatively inexpensive compared to some precious stones, rival them in beauty and offer a connection to both the earth’s history and the enduring power of symbolism.