October boasts the unique distinction of having two recognized birthstones: tourmaline and opal. Both gemstones offer a dazzling spectrum of colors and rich histories, making them cherished choices for those born in the tenth month of the year. While opal has a longer-established association with October, tourmaline has gained prominence as a modern alternative, celebrated for its exceptional variety and captivating beauty. This article will delve into the history, geological origins, gemological properties, symbolism, and care of these remarkable gemstones.
History and Lore
Opal has a long and storied past, with references dating back to ancient times. The gemstone is described as embodying “fire, lightning all the colors of the rainbow and the soft shine of far seas,” suggesting its captivating play of color has been appreciated for centuries. Simplistic opal studs, like those crafted by Le Vian, exemplify the timeless appeal of this birthstone.
Tourmaline’s history, while not as extensively documented as opal’s, is equally fascinating. The name itself originates from the Sinhalese word toramalli, meaning “stone with mixed colors,” a testament to its remarkable polychromism. Ancient mystics believed tourmaline could inspire artistic expression, recognizing its diverse color palette as a source of creative energy. An Egyptian legend attributes tourmaline’s variety to its journey from the Earth’s core, passing over a rainbow and absorbing all its hues. The last empress of the Chi’ing Dynasty in China was a passionate collector of tourmaline, particularly vivid pink and magenta shades, and was even laid to rest on a tourmaline pillow, highlighting its historical significance and value.
Geological Formation and Sources
Tourmaline is not a single mineral but a group of closely related boron silicate minerals. Its formation occurs in a variety of geological environments, often within granite and pegmatite formations. The presence of different elements during crystallization accounts for the wide range of colors observed in tourmaline. Paraíba tourmaline, a particularly prized variety, owes its intense violet-blue and blue-green hues to the presence of copper and is primarily sourced from Brazil. Other notable tourmaline colors include rubellite (red to pink), chrome tourmaline (emerald green), and watermelon tourmaline (pink and green).
Opal, in contrast, is a hydrated amorphous form of silica. It forms in cracks and voids in rocks, where silica-rich solutions deposit layers of microscopic spheres. The play of color, a defining characteristic of opal, is caused by the diffraction of light as it passes through these spheres. Opal is found in various locations worldwide, but Australia is the primary source of fine opal. Opal can also be found as “doublets” or “triplets,” which are constructed layers of opal slices glued to a base material and covered with a clear quartz dome. These constructions are often used with thinner opal slices to create a more visually appealing gem.
Gemological Properties
Tourmaline exhibits a wide range of properties depending on its specific composition. It generally ranges from 7 to 7.5 on the Mohs scale of hardness, making it relatively durable for jewelry use. Some tourmaline varieties are even piezoelectric, meaning they generate an electrical charge when pressure is applied – a property utilized in pressure gauges for submarines.
Here's a table summarizing key properties of both birthstones:
| Property | Tourmaline | Opal |
|---|---|---|
| Chemical Formula | Complex Boron Silicate | Hydrated Silica (SiO₂·nH₂O) |
| Hardness (Mohs) | 7 - 7.5 | 5 - 6.5 |
| Color | Varied, all colors | Varied, play-of-color |
| Crystal System | Trigonal | Amorphous |
| Specific Gravity | 3.06 - 3.98 | 1.98 - 2.20 |
Opal, with a hardness of 5 to 6.5 on the Mohs scale, is softer than tourmaline and requires more careful handling. It can be susceptible to scratching from harder gemstones like diamonds, rubies, sapphires, and emeralds. Prolonged exposure to water can also weaken the adhesive in opal doublets and triplets, and both natural and constructed opal can fracture if exposed to sudden temperature changes or high heat. Opal may also be treated by impregnation with oil, wax, or plastic to enhance its appearance.
Symbolism and Metaphysical Beliefs
Both tourmaline and opal are imbued with symbolic meaning. Opal is associated with creativity, inspiration, and hope. Its captivating play of color is believed to stimulate imagination and enhance artistic expression.
Tourmaline is believed to promote understanding, empathy, and emotional healing. It is also thought to ward off negative energy and emotion. The diverse colors of tourmaline are linked to different metaphysical properties; for example, pink tourmaline is associated with love and compassion, while green tourmaline is believed to foster growth and abundance.
Care and Cleaning
Proper care is essential to maintain the beauty of both tourmaline and opal jewelry. Tourmaline is relatively durable and can be cleaned with warm, soapy water and a soft brush. However, opal requires more delicate handling. The safest method for cleaning opal is with warm, soapy water, avoiding harsh chemicals or abrasive cleaners. Due to its porosity and potential for damage, ultrasonic cleaners and steam cleaners should not be used on opal. It is also advisable to store opal jewelry separately from harder gemstones to prevent scratching.
For both gemstones, it is recommended to remove jewelry before showering, swimming, or engaging in strenuous activities. Avoid contact with perfumes, lotions, and other chemicals that could damage the gemstones or their settings. Regular cleaning with a soft, dry cloth will help maintain their luster.
Conclusion
Tourmaline and opal, the captivating birthstones of October, represent a beautiful duality of color, history, and symbolism. Opal, with its ancient lore and mesmerizing play of color, embodies creativity and inspiration. Tourmaline, with its remarkable variety and metaphysical properties, promotes emotional healing and understanding. Whether one prefers the fiery flashes of opal or the rich tones of tourmaline, these gemstones offer a touch of elegance and individuality to any jewelry collection, making them cherished symbols of October’s vibrant beauty.