October is unique among the calendar months, boasting not one, but two recognized birthstones: opal and tourmaline. Both gems offer a stunning array of colors and possess rich histories, making them cherished choices for those born in the tenth month. While opal holds the distinction as the traditional October birthstone, tourmaline has risen to prominence as the modern alternative, offering a broader spectrum of hues and captivating beauty. This article will delve into the history, geological origins, gemological properties, symbolism, and care of both opal and tourmaline, exploring what makes each gem a treasured symbol of October.
A History of Significance
The story of opal stretches back to ancient times. Its name is believed to have originated in India, derived from the Sanskrit word upala, meaning “precious stone.” This term evolved into opalus in ancient Rome. Throughout history, opal has inspired diverse beliefs. Ancient Greeks associated the stone with prophecy and protection from disease, while Bedouins believed opals contained lightning and descended from the sky during thunderstorms. Europeans once considered opal a symbol of purity, hope, and truth, believing it embodied the virtues of all colored stones.
Tourmaline’s history, while also ancient, gained significant momentum later. In the late 1800s, the Empress Dowager Tzu-Hsi of China developed a fervent passion for pink tourmaline, acquiring nearly the entire production from California mines. Her devotion continued even in death, as she was buried with a pillow of the gemstone, and the remainder of her collection was crafted into intricate carvings. The association of tourmaline with royalty and artistry cemented its place as a desirable gem.
The designation of two birthstones for October is a relatively recent development. Until 1912, opal stood alone as the birthstone for the month. However, the National Association of Jewelers revised the official birthstone list, allowing for alternate gems for months whose traditional stones were either rare or lacked widespread recognition. Tourmaline, with its diverse palette, was a natural choice to share the spotlight with opal.
Geological Formation and Sources
Opal is not a true crystal but a mineraloid – a substance with a crystalline structure but lacking a defined crystal lattice. It is formed by the gradual natural heating of silica gel found in cracks and voids within rocks. The resulting structure exhibits a unique “play-of-color,” a phenomenon caused by the diffraction of light within the gem’s microscopic structure. While once considered rare, the discovery of rich opal mines in Australia significantly increased its availability.
Tourmaline, in contrast, is a crystalline borosilicate mineral. It forms in distinctive prism-like crystals with long hexagonal structures. Most tourmalines found in jewelry are composed primarily of the mineral elbaite. The diverse colors of tourmaline arise from trace elements within its chemical composition. Tourmaline occurs in a wide range of geological environments, and can be found in many locations around the world.
Notably, certain varieties of tourmaline are particularly prized. Paraíba tourmaline, a copper-bearing gem found in Brazil, exhibits intense shades of violet-blue and blue-green, making it exceptionally valuable. “Watermelon” tourmaline, displaying both pink and green hues within a single crystal, is also highly sought after.
Gemological Properties
Both opal and tourmaline exhibit distinct gemological properties. Opal is typically valued for its play-of-color, with the intensity and range of colors influencing its value. It has a hardness of 5.5 to 6.5 on the Mohs scale, making it relatively softer and more susceptible to scratches than many other gemstones.
Tourmaline, on the other hand, generally ranges from 7 to 7.5 on the Mohs scale, offering greater durability. Pink tourmaline, the modern October birthstone, showcases a striking pink hue with variations throughout the color spectrum. Tourmaline’s chemical formula is complex, varying depending on its composition, but it generally includes boron, silicon, aluminum, and other elements. The presence of these elements contributes to the wide range of colors observed in tourmaline.
Here's a comparative table summarizing key properties:
| Property | Opal | Pink Tourmaline |
|---|---|---|
| Chemical Composition | Hydrated Silica (SiO₂·nH₂O) | Complex Borosilicate |
| Hardness (Mohs) | 5.5 - 6.5 | 7 - 7.5 |
| Crystal System | Amorphous | Trigonal |
| Play-of-Color | Present | Absent |
| Transparency | Translucent to Opaque | Transparent to Opaque |
Symbolism and Metaphysical Beliefs
Throughout history, both opal and tourmaline have been imbued with symbolic meanings. Opal has long been associated with hope, purity, and truth. It was believed to bestow the gift of prophecy and offer protection from disease. Modern interpretations often link opal to creativity, inspiration, and emotional healing.
Tourmaline is believed to increase understanding and empathy, while warding off negative energy and emotion. Some tourmaline varieties are even piezoelectric – meaning they become electrically charged when pressure is applied – and have been used in practical applications like pressure gauges. The association of tourmaline with the Empress Dowager Tzu-Hsi also lends it an air of regal elegance and power.
Care and Cleaning
Due to its relatively lower hardness, opal requires careful handling and cleaning. It is susceptible to scratches and should be protected from impacts. Cleaning opal involves gentle washing with mild soap and warm water, avoiding harsh chemicals or ultrasonic cleaners.
Tourmaline, being more durable, can withstand more rigorous cleaning. It can be cleaned with warm soapy water, a soft brush, and rinsed thoroughly. Ultrasonic cleaners are generally safe for tourmaline, but caution should be exercised with stones that have been treated or contain fractures.
Conclusion
Opal and tourmaline, the birthstones of October, represent a captivating duality. Opal, with its ethereal play-of-color and ancient lore, embodies hope and inspiration. Tourmaline, with its diverse hues and enduring durability, symbolizes understanding and protection. Whether one chooses the traditional opal or the modern tourmaline, both gems offer a beautiful and meaningful connection to the tenth month, celebrating transformation and the vibrant colors of autumn.