Introduction
The month of December is uniquely represented in the world of gemology by three distinct stones: turquoise, zircon, and tanzanite. Each carries a legacy of historical tradition, geological rarity, and cultural symbolism. While turquoise has served as the traditional birthstone for centuries, zircon and tanzanite have been added to the modern list, offering a spectrum of color and lore. This article explores the origins, properties, and significance of these three gemstones, drawing upon historical records and gemological data to provide a comprehensive guide for enthusiasts and collectors. We will examine their geological formation, historical journeys, and the attributes that make them enduring symbols of the winter month.
History and Lore: The Evolution of December's Gems
The concept of birthstones has evolved significantly over millennia, transitioning from the breastplate of Aaron in ancient scripture to the standardized lists used in modern jewelry.
Turquoise: The Ancient Traditional Stone
Turquoise stands as the most historically entrenched of December’s birthstones. According to the provided materials, turquoise is December’s traditional birthstone and is considered a symbol of good fortune and success. Its use dates back to ancient civilizations, where it was prized not only for its vibrant color but also for its perceived protective qualities.
The tradition of birthstones is deeply rooted in historical religious texts. While the provided sources do not detail the specific biblical origins of turquoise in the breastplate of Aaron, they confirm its longstanding status as the traditional stone for December. Over time, this association moved from religious artifacts to personal adornment, where it became a talisman for travelers and a symbol of wealth and protection.
Zircon: The Historical Misunderstanding
Zircon is one of the oldest minerals on Earth, yet its history in jewelry is often confused due to its visual similarity to diamond. In the provided sources, zircon is listed alongside turquoise and tanzanite as a birthstone for December. It comes in a variety of colors but is most popular in its blue form for jewelry.
Historically, zircon has been used for centuries, though often mistaken for higher-value gemstones. Its durability and brilliance have made it a staple in various cultures. While the sources do not provide a specific date for zircon’s inclusion in birthstone lists, its presence alongside turquoise suggests a long-standing acceptance in the gemological community as a stone of significance for the month of December.
Tanzanite: The Modern Discovery
In contrast to the ancient lineage of turquoise and zircon, tanzanite is a relatively recent addition to the gem world. The sources explicitly state that tanzanite was discovered in Tanzania in 1967. It is noted as being rarer than diamonds, a claim that highlights its geological scarcity and high value.
Tanzanite’s inclusion as a December birthstone represents the modernization of birthstone lists. Unlike the traditional stones, its history is not measured in millennia but in decades. Its rapid rise to prominence is a testament to its unique color and the marketing efforts that established it as a significant gemstone for the 20th and 21st centuries. The sources confirm its status as the third birthstone for December, completing the trio of gems that represent the month today.
Geological Formation and Sources
Understanding where these gemstones come from provides insight into their rarity and value. Each stone forms under distinct geological conditions and is sourced from specific regions of the world.
Turquoise: An Hydrous Phosphate
Turquoise is an opaque mineral that forms in arid regions where acidic water percolates through rocks containing aluminum and copper. This process creates veins and nodules that are mined and cut for use in jewelry. While the provided sources do not detail specific mining locations for turquoise, they confirm its status as a traditional gemstone. Historically, turquoise has been mined in regions such as the Sinai Peninsula, Iran, and the southwestern United States. Its formation is a slow process, often occurring in the oxidized zones of copper deposits.
Zircon: A Zirconium Silicate
Zircon is a mineral composed of zirconium silicate (ZrSiO₄). It is a common component of igneous and metamorphic rocks. The sources mention that zircon comes in a variety of colors, with blue being the most popular for jewelry. The blue color in zircon is typically achieved through heat treatment of brownish zircon crystals. Natural blue zircon is rare.
Zircon is mined in various locations globally, including Cambodia, Sri Lanka, Thailand, and Australia. The provided sources do not specify mining locations, but they emphasize the gem’s versatility in color. The geological formation of zircon involves high temperatures and pressures, often found in placer deposits where water has eroded the host rock over time.
Tanzanite: A Unique Geological Occurrence
Tanzanite’s geological story is particularly fascinating. The sources state that it was discovered in Tanzania in 1967. Specifically, tanzanite is found in only one small area of the Merelani Hills near Mount Kilimanjaro in Tanzania. This limited geographic source contributes significantly to its rarity.
Tanzanite is a variety of the mineral zoisite. It forms through the metamorphism of rocks containing zoisite, quartz, and calcite, often influenced by the intense heat from the nearby volcanic activity of Mount Kilimanjaro. The specific geological conditions required for tanzanite’s formation are exceptionally rare, which is why it is found in such a concentrated area. The sources confirm its discovery date and its origin in Tanzania, underscoring its status as a localized and rare gemstone.
Gemological Properties
The physical and chemical properties of a gemstone determine its durability, appearance, and value. Below is a summary of the key properties for turquoise, zircon, and tanzanite based on the provided sources and general gemological knowledge (where the sources are silent, we rely on the explicit data provided).
| Gemstone | Chemical Composition | Hardness (Mohs Scale) | Refractive Index | Typical Colors | Special Properties |
|---|---|---|---|---|---|
| Turquoise | Hydrous phosphate of aluminum and copper | 5-6 | ~1.61 | Sky blue to greenish-blue | Opaque; often contains matrix (host rock) |
| Zircon | Zirconium silicate (ZrSiO₄) | 6.5-7.5 | 1.92-2.01 | Colorless, blue, yellow, brown, red | High refractive index; can be heat-treated for color |
| Tanzanite | Calcium aluminum hydroxyl sorosilicate (Zoisite group) | 6.5-7 | 1.69-1.70 | Blue, violet, purple | Pleochroic (shows different colors from different angles) |
Turquoise Properties
Turquoise is relatively soft compared to other gemstones, with a hardness of 5 to 6 on the Mohs scale. This makes it susceptible to scratching and requires careful handling. Its chemical composition is a hydrous phosphate of aluminum and copper, which gives it its characteristic blue-to-green color. The presence of iron can shift the color toward green, while higher copper content results in a brighter blue. Turquoise is opaque, meaning light does not pass through it, and it often features a "matrix" – a web-like pattern of the host rock embedded within the stone.
Zircon Properties
Zircon is a much harder and more durable gemstone, with a hardness ranging from 6.5 to 7.5 on the Mohs scale. This makes it suitable for all types of jewelry, including rings that are worn daily. Its chemical composition is zirconium silicate. Zircon has a high refractive index (1.92-2.01), giving it excellent brilliance and fire, often compared to that of diamond. The sources note that zircon comes in a variety of colors, but the blue variety is most popular for December birthstone jewelry. It is important to distinguish zircon from the synthetic cubic zirconia (CZ), which is a diamond simulant and not a natural gemstone.
Tanzanite Properties
Tanzanite, with a hardness of 6.5 to 7 on the Mohs scale, is durable enough for jewelry but requires some care to avoid scratches. Its chemical composition is that of a calcium aluminum hydroxyl sorosilicate, placing it in the zoisite mineral group. One of tanzanite’s most captivating features is its strong pleochroism – the ability to show different colors when viewed from different crystal directions. Typically, it appears blue when viewed from one angle and violet or purple from another. This property requires skilled cutting to maximize the stone’s color in the final gem. The sources highlight its rarity, noting it is found only in Tanzania, and its discovery in 1967.
Symbolism and Metaphysical Beliefs
Throughout history, gemstones have been attributed with symbolic meanings and metaphysical powers. These beliefs add a layer of cultural significance to the stones.
Turquoise: The Stone of Protection
Turquoise has long been regarded as a stone of protection, good fortune, and success. The sources explicitly state that it is "considered a symbol of good fortune and success." This belief is ancient, spanning cultures from the ancient Egyptians and Persians to Native American tribes. It was often worn by warriors and travelers as a talisman against harm and to ensure safe passage. In many cultures, turquoise is also associated with wisdom, tranquility, and healing. Its color, reminiscent of the sky and water, connects it to elemental forces and spiritual protection.
Zircon: The Stone of Wisdom and Purity
While the provided sources do not detail the metaphysical beliefs associated with zircon, historical lore often links it to wisdom, purity, and prosperity. Colorless zircon was historically mistaken for diamond and was believed to promote clarity of thought and spiritual growth. Blue zircon, popular for December, is often associated with peace and tranquility. Its brilliance and fire have led to associations with light and truth.
Tanzanite: The Stone of Transformation
Given its recent discovery, tanzanite’s metaphysical lore is modern but rapidly evolving. It is often described as a stone of transformation, spiritual awakening, and intuition. Its striking violet-blue color is associated with the higher chakras and spiritual connection. As a gemstone born from the intense heat of the earth near Mount Kilimanjaro, it is sometimes seen as a symbol of rebirth and new beginnings. Its rarity is also linked to the idea of uniqueness and personal discovery.
Care and Cleaning
Proper maintenance is essential to preserve the beauty and longevity of gemstone jewelry. The care requirements vary significantly based on the stone’s hardness and chemical stability.
Caring for Turquoise
Due to its relatively low hardness (5-6) and porous nature, turquoise requires careful handling. It is susceptible to scratches, chemicals, and extreme temperatures. To clean turquoise jewelry, use only warm water, a soft cloth, and mild soap. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, as these can damage the stone or its stabilizing treatments (often used to enhance durability). Store turquoise separately from other jewelry to prevent scratching.
Caring for Zircon
Zircon is a durable gemstone, but it can be brittle due to its crystal structure. It is important to avoid sharp blows that could cause chipping. Cleaning zircon is straightforward: use warm soapy water, a soft brush, and rinse thoroughly. While generally stable, some colored zircon may fade if exposed to prolonged strong heat or sunlight, so it is advisable to store it away from direct light when not in use. Ultrasonic cleaners are generally safe for untreated zircon, but caution is advised for stones that have been fracture-filled or treated.
Caring for Tanzanite
Tanzanite, with a hardness of 6.5 to 7, is relatively durable but can be prone to scratching if not handled with care. It is also sensitive to heat and sudden temperature changes, which can cause fracturing. Cleaning tanzanite should be done with warm soapy water and a soft brush. Avoid ultrasonic cleaners and steam cleaning, as the vibrations and heat can damage the stone. Due to its pleochroism, the cut of tanzanite is crucial, and improper cleaning can affect the setting or the stone’s appearance. It is best to remove tanzanite jewelry during physical activities to prevent impact damage.
Conclusion
December’s birthstones—turquoise, zircon, and tanzanite—offer a diverse and rich palette for gemstone enthusiasts. From the ancient, protective turquoise to the brilliant and historic zircon, and the rare, modern tanzanite, each stone carries a unique story. Turquoise remains the traditional symbol of good fortune and success, while zircon adds brilliance and durability, and tanzanite contributes a rare, vivid hue born from a singular geological event. Understanding their origins, properties, and care requirements allows collectors and wearers to appreciate not only their beauty but also their geological and cultural significance. Together, they encapsulate the essence of December—a month of transition, celebration, and enduring natural wonder.