Those born in October are uniquely blessed with not one, but two captivating birthstones: opal and tourmaline. Both gemstones boast a rich history, stunning visual appeal, and symbolic significance, making them cherished choices for jewelry and collectors alike. While opal holds the distinction as the traditional October birthstone, pink tourmaline has emerged as the modern counterpart, offering a wider spectrum of color options. This article will delve into the fascinating world of these two October birthstones, exploring their history, geological origins, gemological properties, and cultural meanings.
History and Lore
The story of opal stretches back to antiquity. Its name is believed to originate from the Sanskrit word “upala,” meaning “precious stone,” adopted by the Romans as “opalus.” Ancient civilizations attributed various powers to opal. Ancient Greeks believed the stone bestowed the gift of prophecy and protection from disease, while Bedouins considered it to be solidified lightning fallen from the sky during thunderstorms. Europeans long regarded opal as a symbol of purity, hope, and truth, believing it embodied the virtues of all colored stones.
Tourmaline’s history, while also ancient, gained prominence later. In the late 1800s, the Chinese Empress Dowager Tzu-Hsi developed a fervent passion for pink tourmaline, acquiring nearly the entire output from California mines. She was even buried with pink tourmaline, and her remaining collection was crafted into intricate carvings. The formalized assignment of birthstones began in 1870 with Tiffany & Co., initially designating opal as October’s sole birthstone. The National Association of Jewellers later added tourmaline as an alternative in 1912, recognizing its growing popularity and diverse appeal.
The practice of assigning multiple birthstones to certain months arose from a combination of factors, including adapting to evolving traditions, matching supply with demand, and acknowledging the depletion of some natural crystal resources. October is among a select group of months – including March, August, November, June, and December – that benefit from having more than one designated gemstone.
Geological Formation and Sources
Opal is unique among gemstones for its formation. It is not a crystalline mineral like tourmaline but rather a hydrated amorphous form of silica. This means it lacks a regular atomic structure and contains a significant amount of water within its composition. Opals form in cracks and voids within rocks, where silica-rich solutions seep in and gradually deposit layers of microscopic silica spheres. The arrangement of these spheres determines the “play-of-color” – the shifting rainbow hues that make opal so captivating.
The most significant sources of opal are found in Australia, which produces the vast majority of the world’s supply. Other notable sources include Ethiopia, Mexico, and the United States. Different regions yield opals with distinct characteristics; for example, Australian opals are known for their black opal variety, while Ethiopian opals often exhibit a lighter body tone.
Tourmaline, in contrast, is a crystalline borosilicate mineral. It forms in igneous and metamorphic rocks, often in pegmatites – coarse-grained igneous rocks. The diverse chemical composition of tourmaline leads to a wide range of colors and varieties. Pink tourmaline, specifically, forms in granite pegmatites and is often associated with quartz and feldspar.
Tourmaline is found in numerous locations worldwide, including Brazil, Sri Lanka, Nigeria, and the United States (particularly California, where the Empress Dowager Tzu-Hsi sourced her prized pink tourmalines).
Gemological Properties
Opal’s properties differ significantly from those of tourmaline. Opal typically 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. Its specific gravity ranges from 1.98 to 2.50. The defining characteristic of opal is its play-of-color, caused by the diffraction of light through the microscopic silica spheres. Different types of opal are categorized based on their body tone and the presence or absence of play-of-color, including white opal, crystal opal, fire opal, rough opal, and black opal.
Tourmaline, on the other hand, exhibits a hardness of 7 to 7.5 on the Mohs scale, making it more durable for everyday wear. Its specific gravity ranges from 3.02 to 3.34. Tourmaline is a complex borosilicate with a chemical formula that varies depending on its composition. Pink tourmaline, a variety of elbaite, displays a striking pink hue due to the presence of manganese. Tourmaline crystals often exhibit a prismatic shape with long hexagonal structures. Some tourmaline crystals even display multiple colors, known as watermelon tourmaline, a highly sought-after variety.
Here's a comparative table summarizing key gemological properties:
| Property | Opal | Pink Tourmaline |
|---|---|---|
| Hardness (Mohs) | 5.5 - 6.5 | 7 - 7.5 |
| Specific Gravity | 1.98 - 2.50 | 3.02 - 3.34 |
| Chemical Composition | Hydrated Silica | Borosilicate |
| Crystal System | Amorphous | Trigonal |
| Defining Feature | Play-of-Color | Pink Hue |
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. Ancient cultures believed it could bestow prophetic abilities and protect against disease. Modern interpretations often link opal to creativity, inspiration, and emotional healing.
Tourmaline, particularly pink tourmaline, is often associated with love, compassion, and emotional balance. It is believed to promote self-love, reduce stress, and encourage emotional healing. Some modern sources suggest that opal can help individuals remember past lives and improve eyesight, though these claims are not widely accepted in formal gemology. The association of opal with royalty and protection, as evidenced by its use in royal talismans and crowns, further reinforces its symbolic significance.
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. Opal should be cleaned with a soft cloth and mild soapy water. Avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to heat or sunlight, as these can cause cracking or fading.
Tourmaline, being more durable, is easier to care for. It can be cleaned with warm soapy water and a soft brush. Ultrasonic cleaners are generally safe for tourmaline, but it is always best to exercise caution. Avoid exposing tourmaline to sudden temperature changes, as this can cause fractures.
Conclusion
Opal and tourmaline, the captivating birthstones of October, offer a diverse range of beauty, history, and symbolism. Opal, with its mesmerizing play-of-color, embodies hope, purity, and creativity, while pink tourmaline, with its gentle pink hues, represents love, compassion, and emotional balance. Whether chosen for their aesthetic appeal, historical significance, or perceived metaphysical properties, these gemstones continue to enchant and inspire those born under the autumn sky.