For those born on the seventeenth day of October, the birthstone is not a single gem but a harmonious pair: the opal and the tourmaline. This unique duality offers a spectrum of beauty, from opal's ethereal play-of-color to tourmaline's vibrant rainbow palette. Both stones are steeped in history, geological wonder, and symbolic meaning, making them subjects of deep fascination for gemologists, collectors, and jewelry enthusiasts alike. This article explores the origins, properties, and cultural significance of these two October birthstones, providing a thorough overview grounded in gemological fact and historical lore.
History and Lore
The historical narratives of opal and tourmaline are as diverse as their colors, tracing back through ancient civilizations and evolving into their modern roles as birthstones.
Opal: The Stone of Hope and Purity The name "opal" is believed to have originated from the Sanskrit word upala, meaning "precious stone," which was later adapted into Latin as opalus. In ancient Rome, opal was revered as a symbol of purity, hope, and truth. Its dramatic play-of-color, which mimics the fiery hues of volcanoes, the vastness of galaxies, and the burst of fireworks, has inspired writers and mystics for centuries. The Bedouins of the desert held a belief that opal contained lightning and was formed from the sky during thunderstorms. Ancient Greeks attributed to opal the power of prophecy and protection from disease. For centuries, Europeans maintained that opal embodied the virtues and powers of all colored stones, making it a gem of unparalleled significance.
Tourmaline: The Stone of Mixed Colors Tourmaline's history is marked by mistaken identity and a gradual ascent to recognition. Its name derives from the Sinhalese word turmali or toramalli, meaning "mixed colored stones," a direct reference to its incredible color diversity. This very quality led to its frequent confusion with other gems. For instance, one of the "rubies" in the Russian crown jewels, the "Caesar’s Ruby" pendant, was later identified as red tourmaline (rubellite). Similarly, Spanish conquistadors in 16th-century Brazil discovered green tourmaline crystals and mistook them for emeralds. Ancient mystics believed tourmaline could inspire artistic expression, a notion supported by its vast color palette, which includes pink rubellites, emerald-green chrome tourmalines, and neon blue-to-violet Paraíba tourmalines.
The Path to Birthstone Status Opal holds the distinction of being the traditional October birthstone. Its inclusion in the modern birthstone list was solidified in 1912 by the American National Association of Jewelers, which standardized birthstones for commercial and cultural purposes. Tourmaline was added as a modern alternative, providing a more durable option and expanding the color choices for October-born individuals. Today, both stones are officially recognized, allowing for personal preference in selection. Furthermore, opal is traditionally associated with the 14th wedding anniversary.
Geological Formation and Sources
Understanding how these gems are formed and where they are mined provides insight into their rarity and value.
Opal Formation and Mining Locations Opal is a hydrated amorphous silica, meaning it lacks a crystalline structure. It forms in areas where silica-rich water seeps into cracks and voids in the earth's crust. As the water evaporates, it leaves behind layers of silica spheres, which diffract light to create the prized play-of-color. This formation process is fragile, making opal susceptible to cracking if exposed to rapid temperature changes or dehydration.
The primary sources of opal are geographically concentrated. Australia is the most productive and renowned source, responsible for the majority of the world's high-quality opal, including the famous black opal from Lightning Ridge. Other important sources include Ethiopia, Mexico, and Brazil, each producing opals with distinct characteristics. Ethiopian opals, for example, are known for their vibrant play-of-color, while Mexican fire opals are celebrated for their warm, reddish-orange hues.
Tourmaline Formation and Mining Locations Tourmaline is a complex borosilicate mineral that crystallizes in igneous and metamorphic rocks. Its chemical composition allows for a wide range of trace elements, resulting in its extraordinary color variety. Unlike opal, tourmaline is a crystalline gemstone, which contributes to its greater durability.
Tourmaline is mined in several locations across the globe. Brazil is a leading producer, particularly famous for its Paraíba tourmaline, which displays an intense neon blue-green color due to the presence of copper. Other significant sources include Afghanistan, Sri Lanka, and Africa. The United States, specifically Maine and California, also has a history of tourmaline mining, producing notable specimens.
Gemological Properties
The physical and chemical properties of opal and tourmaline dictate their use in jewelry, their durability, and their care requirements.
Opal * Hardness: Opal ranks between 5 and 6.5 on the Mohs scale of hardness. This makes it relatively soft and susceptible to scratching and abrasion. Jewelry set with harder gems like diamonds, rubies, sapphires, and emeralds can scratch opal if stored together. * Composition: Opal is a hydrated silica (SiO₂·nH₂O), typically containing 3 to 21 percent water. Its internal structure consists of microscopic spheres of silica. The size and arrangement of these spheres determine the quality and play-of-color. * Key Feature - Play-of-Color: This is the defining characteristic of precious opal. It is caused by the diffraction of light through the silica spheres, creating a spectral display of colors that shift as the viewing angle changes. No two opals are exactly alike, making each stone a unique treasure. * Durability Concerns: Opal is sensitive to heat and sudden temperature changes, which can cause cracking or loss of play-of-color. It is also prone to crazing (a network of fine cracks) if it dries out, necessitating storage in a humid environment.
Tourmaline * Hardness: Tourmaline is significantly harder than opal, rating between 7 and 7.5 on the Mohs scale. This durability makes it an excellent choice for everyday jewelry, resistant to scratches and wear. * Composition: As a borosilicate, tourmaline's chemical formula is complex, often written as (Na, Ca)(Li, Mg, Al)(Al, Fe, Mn)₆(BO₃)₃(Si₆O₁₈)(OH)₄. Its color is influenced by various trace elements, such as iron, manganese, chromium, and copper. * Color Diversity: Tourmaline is celebrated for occurring in more colors and color combinations than any other gemstone. It can be found in virtually every hue, and some crystals exhibit multiple colors in a single stone, known as "parti-colored" or "watermelon" tourmaline (green on the outside, pink on the inside). * Crystal Structure: Tourmaline crystals are typically long and prismatic, often with a rounded triangular cross-section. This structure can sometimes cause dichroism, where the stone shows different colors when viewed from different directions.
The following table summarizes key gemological properties for comparison:
| Property | Opal | Tourmaline |
|---|---|---|
| Hardness (Mohs) | 5 - 6.5 | 7 - 7.5 |
| Chemical Class | Hydrated Silica | Borosilicate |
| Key Characteristic | Play-of-Color | Color Diversity |
| Crystal System | Amorphous | Trigonal |
| Durability | Fair (Soft, Sensitive) | Good (Durable) |
Symbolism and Metaphysical Beliefs
Beyond their physical beauty, both opal and tourmaline carry deep symbolic meanings that have evolved over time.
Opal's Symbolism Opal has long been associated with hope, purity, and truth. Its shifting colors have led to beliefs in its ability to enhance creativity and inspiration. In metaphysical circles, opal is often considered a stone of emotional healing, believed to help release past traumas and amplify positive emotions. Its connection to the element of water symbolizes fluidity, intuition, and emotional balance. For those born on October 17, opal is said to bring a sense of hope and joy, encouraging a positive outlook on life.
Tourmaline's Symbolism Due to its wide color range, tourmaline's symbolism is multifaceted. Generally, it is regarded as a stone of protection, believed to ward off negative energies and psychic attacks. Different colors carry specific meanings: * Pink Tourmaline (Rubellite): Associated with love, compassion, and emotional healing. * Green Tourmaline: Linked to vitality, growth, and connection to nature. * Blue Tourmaline (Indicolite): Said to promote calmness, communication, and spiritual awareness. * Black Tourmaline (Schorl): The most protective variety, used for grounding and shielding against electromagnetic fields (EMFs).
Ancient mystics believed tourmaline could inspire artistic expression, a notion that aligns with its rainbow palette. For October-born individuals, tourmaline is thought to provide balance and protection, complementing opal's more ethereal qualities.
Care and Cleaning
Proper maintenance is essential to preserve the beauty and longevity of both gemstones, though their care requirements differ significantly due to their physical properties.
Caring for Opal Opal's fragility demands gentle handling and specific storage conditions. * Cleaning: Use only a soft, lint-free cloth and lukewarm, soapy water. Ultrasonic cleaners and harsh chemicals must be avoided, as they can damage the stone. Rinse thoroughly and dry with a soft cloth to prevent water spots. * Storage: Opal should be stored separately from other jewelry to prevent scratches. A soft pouch or a lined jewelry box is ideal. It is crucial to keep opal in a humid environment to prevent it from drying out and developing cracks. Avoid prolonged exposure to direct sunlight and extreme temperatures, which can cause the stone to lose its play-of-color or fracture. * Wear Precautions: Due to its softness, opal jewelry is best suited for occasional wear rather than daily use. It should be removed before activities that could subject it to impact or abrasion.
Caring for Tourmaline Tourmaline's greater hardness makes it more resilient and easier to care for. * Cleaning: Tourmaline can be safely cleaned with warm, soapy water and a soft brush. It is also resistant to heat and chemicals, making ultrasonic cleaners generally safe for use. However, it is always advisable to check for any fractures or inclusions first, as these could be exacerbated by cleaning methods. * Storage: While tourmaline is durable, it should still be stored separately from harder gems like diamonds to avoid potential scratching. A standard jewelry box compartment or pouch is sufficient. * Sunlight and Heat: Tourmaline is not sensitive to sunlight or moderate temperature changes, making it a practical choice for various environments.
Conclusion
The birthstones for October 17—opal and tourmaline—represent a fascinating duality in the world of gemology. Opal, with its ancient heritage and captivating play-of-color, embodies hope, purity, and the fluid beauty of light. Tourmaline, with its modern appeal and unparalleled color diversity, symbolizes protection, artistic inspiration, and the earth's vibrant palette. Together, they offer October-born individuals a choice between delicate wonder and durable brilliance. Whether selected for their historical significance, geological origins, or symbolic meanings, both opal and tourmaline continue to captivate and inspire, securing their place as cherished gems in both tradition and contemporary jewelry.