The month of December is uniquely gifted with not one, but three official birthstones, each a distinct chapter in the story of gemology. Tanzanite, turquoise, and zircon—three gems united by their captivating blue hues yet separated by profound differences in origin, composition, and character. While turquoise has been cherished for millennia, tanzanite is a modern marvel, and zircon holds the title of the oldest mineral on Earth. Together, they offer December-born individuals a remarkable spectrum of choices, from the ancient and earthy to the vibrant and contemporary. This article delves into the rich history, geological formation, and gemological properties of these three December birthstones, providing a comprehensive guide for enthusiasts, collectors, and anyone drawn to the beauty of these remarkable gems.
History and Lore: From Ancient Talismans to Modern Discoveries
The historical journeys of December's birthstones span from the ancient world to the very recent past, reflecting humanity's enduring fascination with blue gemstones.
Turquoise: An Ancient Legacy Turquoise boasts the longest history as a gemstone, with evidence of its use dating back over 2000 years in the Southwestern United States. Native American cultures, including ancient artists, utilized turquoise to create beads, pendants, intricate inlay work, and small sculptures. This deep integration into culture underscores its significance as more than mere ornament; it was a material of artistic and spiritual expression. Its enduring importance is evident in the fact that turquoise remains a vital part of Southwestern culture today. The stone's name itself is derived from the French "pierre turquoise," meaning "Turkish stone," reflecting its historical trade routes from Persia (modern-day Iran) through Turkey to Europe. While its ancient origins are well-documented, the sources do not specify the exact date of its initial discovery or the earliest known use in other global civilizations.
Zircon: The Ancient Mineral Zircon is the oldest known mineral on Earth, with some specimens dating back over 4.4 billion years. This makes it a geological record keeper, withstanding the test of time and tectonic forces. While its use as a gemstone is ancient, the sources do not provide specific historical accounts of its early use in jewelry or lore. Its primary historical significance in the context of birthstones is its long-standing presence in traditional lists, often cited as the original birthstone for December.
Tanzanite: The 20th-Century Sensation In stark contrast to its companions, tanzanite is a newcomer to the gem world. It was discovered in the late 1960s in the Merelani Hills of northern Tanzania, near the base of Mount Kilimanjaro. The gem was quickly recognized for its intense, saturated blue-violet color, a phenomenon caused by the presence of vanadium in its crystal structure. Its rise to fame was meteoric; the Tiffany & Co. jewelry house introduced tanzanite to the global market in 1968, marketing it as the "stone of a generation" and positioning it as a more affordable alternative to sapphire. Due to its limited geographic origin—found only in a single, small area of Tanzania—it is often described as "a thousand times rarer than diamond." The sources note that tanzanite was added to most birthstone lists in 1952, which appears to be a significant error, as its discovery occurred much later. This highlights the importance of cross-referencing information; the correct timeline places its addition to official lists in the late 20th century.
Geological Formation and Sources
The origins of these three gems could not be more different, spanning from vast geological formations to a single, unique deposit.
Turquoise: A Hydrated Phosphate Mineral Turquoise is not a mineral in the strictest sense but a hydrated phosphate of copper and aluminum. It forms in arid regions where acidic, copper-rich groundwater percolates through rocks containing aluminum and phosphorus. Over millions of years, these minerals precipitate, creating the turquoise deposits. The sources identify the Southwestern United States as a key historical source, particularly for Native American use. However, the most significant commercial sources today are in Iran (Persia), Egypt, and China. The color of turquoise is directly tied to its copper content; more copper yields a greener blue, while higher iron content produces a greener hue. The presence of the host rock, or "matrix," which can be left in the gem, is a key characteristic.
Zircon: A Silicate Mineral Zircon is a zirconium silicate (ZrSiO₄) that crystallizes from magma. It is one of the first minerals to form as magma cools and is highly resistant to weathering and heat. Its durability allows it to survive the erosion of its host rock, often being found in alluvial deposits (riverbeds and beaches). While zircon is found in many locations worldwide, including Australia, Sri Lanka, and Cambodia, the sources do not specify primary mining locations for gem-quality blue zircon. The gem's color is typically enhanced through heat treatment, which can remove brownish tints and produce a vibrant blue.
Tanzanite: A Variety of Zoisite Tanzanite is the blue to violet variety of the mineral zoisite, which is a calcium aluminum silicate. It forms in the metamorphic rocks of the Merelani Hills, where heat and pressure from tectonic activity transformed the original minerals into zoisite containing vanadium. The deposit is incredibly localized, which contributes to its rarity and value. The sources confirm that tanzanite is mined in Tanzania, with no other commercial sources known. This geographic exclusivity is a defining feature of the gem.
Gemological Properties
Understanding the physical and chemical properties of these gems is essential for both appreciation and care. The table below summarizes key characteristics based on the provided sources.
| Gemstone | Chemical Composition | Crystal System | Hardness (Mohs) | Key Properties |
|---|---|---|---|---|
| Turquoise | Hydrated phosphate of copper & aluminum | Triclinic | 5 - 6 | Opaque, often cut as cabochons; color from blue to blue-green; can have a matrix. |
| Zircon | Zirconium silicate (ZrSiO₄) | Tetragonal | 7 - 7.5 | High luster, excellent fire (dispersion); prone to breakage due to cleavage; often heat-treated. |
| Tanzanite | Calcium aluminum silicate (Ca₂Al₃(SiO₄)₃(OH)) | Orthorhombic | 6 - 7 | Pleochroic (shows different colors from different angles); has perfect cleavage, making it fragile. |
Color and Clarity * Turquoise is prized for its opaque, sky-blue to greenish-blue color. Bright, even blue is the most valued. It is often cut into cabochons, especially freeform shapes to maximize the use of the rough material. * Zircon is known for its high luster and exceptional fire, which rivals that of diamond. Blue zircon, typically produced by heating brown zircon, is a popular December birthstone. It is often transparent and can be faceted for brilliance. * Tanzanite exhibits a unique trichroism, displaying blue, violet, and reddish tones from different crystal directions. The most sought-after color is a vivid violet-blue. It is typically faceted for jewelry and is often transparent to translucent.
Durability and Care The sources provide crucial information on the durability of these gems, which is vital for jewelry care: * Turquoise has a relatively low hardness (5-6 on the Mohs scale) and is porous, making it susceptible to scratches and damage from chemicals, cosmetics, and sunlight. It requires gentle cleaning with a soft, dry cloth. * Zircon, while hard (7-7.5), is brittle and has perfect cleavage in two directions, meaning it can break if struck with sufficient force. It should be protected from sharp impacts. * Tanzanite has a hardness of 6-7 but possesses perfect cleavage, making it particularly fragile. It is not recommended for rings or bracelets that are subject to daily wear and tear. It is best suited for pendants or earrings. Cleaning should be done with mild soap, warm water, and a soft brush; ultrasonic and steam cleaners are not advised.
Symbolism and Metaphysical Beliefs
While the sources focus primarily on gemological facts, some touch upon the symbolic meanings associated with these stones, often reflecting modern interpretations.
- Turquoise is historically associated with protection, healing, and good fortune. In many cultures, it is considered a sacred stone that brings peace and balance. Its connection to the sky and water elements reinforces its symbolism of tranquility.
- Zircon is believed to promote wisdom, honor, and purity. It is sometimes associated with spiritual growth and the calming of negative energies. Its brilliant fire is thought to inspire clarity of thought.
- Tanzanite is a relatively new stone in the realm of metaphysics, often linked to transformation, intuition, and spiritual awakening. Its discovery near the majestic Mount Kilimanjaro lends it an aura of majesty and connection to higher realms.
It is important to note that these metaphysical associations are part of cultural and modern beliefs and are not supported by scientific evidence from the gemological sources provided.
Care and Cleaning: Preserving the Beauty
Proper care is essential to maintain the beauty and integrity of each December birthstone, given their distinct properties.
Turquoise Care: Due to its porosity and low hardness, turquoise requires the most careful handling. * Avoid: Exposure to chemicals (including perfumes, lotions, and cleaning agents), prolonged direct sunlight (which can cause fading), and extreme temperatures. * Cleaning: Wipe with a soft, dry cloth. For deeper cleaning, use a soft brush with mild soap and lukewarm water, then dry immediately and thoroughly. Never use ultrasonic or steam cleaners.
Zircon Care: While hard, its brittleness and cleavage make it vulnerable. * Avoid: Sharp blows and rough handling. Store separately to prevent scratching other gems or being scratched. * Cleaning: Use warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe but should be used with caution; steam cleaning is not recommended due to the risk of thermal shock.
Tanzanite Care: Its perfect cleavage is the primary concern. * Avoid: Impact, pressure, and rapid temperature changes. It is not suitable for daily-wear rings or bracelets. * Cleaning: Use only warm, soapy water and a soft brush. Never use ultrasonic or steam cleaners, as the vibrations and heat can cause the stone to crack along its cleavage planes.
Conclusion
Tanzanite, turquoise, and zircon present a fascinating triad of December birthstones, each with a unique identity. Turquoise carries the weight of ancient history and cultural significance, prized for its opaque, calming blue. Zircon, the ancient mineral, offers brilliant fire and a connection to the earliest days of our planet. Tanzanite, the vibrant newcomer, captivates with its modern elegance and exclusive origin. Their differences in hardness, cleavage, and care requirements underscore the importance of understanding each gem's unique nature. For those born in December, the choice is not merely aesthetic but a selection of a gem that resonates with personal history, style, and appreciation for the remarkable diversity of the mineral kingdom.