October boasts not one, but two recognized birthstones: the captivating opal and the vibrant tourmaline. Both gemstones offer a stunning array of colors and a rich history, making them cherished choices for those born in the tenth month. While opal traditionally held the position as the sole October birthstone, tourmaline gained prominence in 1912, offering a wider spectrum of options for jewelry lovers and collectors. This article will delve into the history, geological origins, gemological properties, symbolism, and care of these two remarkable gemstones.
History and Lore
The story of opal dates back to ancient times. Its name is believed to originate from the Sanskrit word upala, meaning “precious stone,” which was adopted into the Roman opalus. Ancient civilizations attributed various powers to opal. Bedouins believed the stone held lightning and fell from the sky during thunderstorms, while ancient Greeks associated it with prophecy and protection from disease. Europeans considered opal a symbol of purity, hope, and truth, even believing it embodied the virtues of all colored stones.
Tourmaline’s history is equally fascinating. In the late 1800s, the Empress Dowager Tzu-Hsi of China developed a strong fondness for pink tourmaline, acquiring nearly the entire production from California mines. She continued to cherish the gemstone even in death, being buried with a pink tourmaline pillow, and the remainder of her collection was crafted into exquisite carvings.
The shift to recognizing both opal and tourmaline as October birthstones occurred in 1912 when the National Association of Jewelers revised the official birthstone list. This revision aimed to provide alternatives for months with rare or misunderstood classic birthstones. Tourmaline, with its diverse palette, naturally rose to co-headliner status alongside opal.
Geological Formation and Sources
Opal is unique in its formation. It is not a crystalline gemstone like many others, 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. Opal forms in cracks and voids in rocks, where silica-rich solutions seep in and deposit the silica over long periods.
The sources of opal are varied. While ancient opals originated in India, today significant deposits are found in Australia, which accounts for the majority of the world’s supply. Other sources include Ethiopia, Mexico, and the United States. Different locations yield different types of opal, such as white opal, fire opal, boulder opal, and crystal opal, each with its distinct characteristics.
Tourmaline, on the other hand, is a crystalline borosilicate mineral. It forms in pegmatites, which are coarse-grained igneous rocks, and in metamorphic rocks. The diverse colors of tourmaline are due to the presence of various elements within its crystal structure, most notably iron, manganese, and titanium.
Tourmaline is found in numerous locations worldwide. Significant sources include Brazil, Sri Lanka, Nigeria, Mozambique, and the United States (specifically California and Maine). The variety of colors found in tourmaline crystals is remarkable, with some even exhibiting multiple colors in a single crystal, known as watermelon tourmaline.
Gemological Properties
Opal’s defining characteristic is its “play-of-color,” a phenomenon caused by the diffraction of light within its internal structure. This creates the shifting rainbow hues that make opal so captivating. Opal’s hardness ranges from 5.5 to 6.5 on the Mohs scale, making it relatively soft and susceptible to scratches.
Tourmaline, composed primarily of elbaite, forms distinctive prism-like crystals with long hexagonal structures. Its hardness ranges from 7 to 7.5 on the Mohs scale, making it more durable than opal. Tourmaline’s color variations are extensive, ranging from pink and red to green, blue, and even colorless. Pink tourmaline, the modern October birthstone, is particularly prized for its delicate hues.
Here's a comparative table of key gemological properties:
| Property | Opal | Tourmaline |
|---|---|---|
| Chemical Formula | SiO₂·nH₂O | Complex Borosilicate |
| Hardness (Mohs) | 5.5 - 6.5 | 7 - 7.5 |
| Crystal System | Amorphous | Trigonal |
| Luster | Vitreous | Vitreous |
| Play-of-Color | Present | Absent |
| Common Colors | Varied, iridescent | Varied, including pink, green, blue |
Symbolism and Metaphysical Beliefs
Throughout history, both opal and tourmaline have been imbued with symbolic meaning. Opal has been associated with hope, purity, and truth, and was once believed to bestow the gift of prophecy. It is also the traditional stone given to celebrate the 14th wedding anniversary.
Tourmaline, particularly pink tourmaline, is often linked to emotional healing, love, and compassion. It is believed to promote creativity and balance emotions. The Empress Dowager Tzu-Hsi’s devotion to pink tourmaline underscores its association with power and prestige.
Modern interpretations suggest that wearing either October birthstone can offer emotional and health benefits. Opal is believed to enhance creativity, while tourmaline is thought to promote healing and balance.
Care and Cleaning
Due to its relatively low hardness, opal requires careful handling and cleaning. It should be stored separately from harder gemstones to avoid scratches. Cleaning opal involves using a soft cloth and lukewarm soapy water. Avoid harsh chemicals or ultrasonic cleaners, as these can damage the stone.
Tourmaline is more durable than opal and can withstand more rigorous cleaning. It can be cleaned with warm soapy water and a soft brush. However, it is still advisable to avoid harsh chemicals and ultrasonic cleaners. Like tourmaline, it should be stored in a padded box or soft cloth bag to prevent scratching.
Conclusion
Opal and tourmaline represent a beautiful and diverse pairing for the month of October. From the ancient lore surrounding opal’s shifting colors to the imperial history of pink tourmaline, these gemstones offer a rich tapestry of history, symbolism, and geological wonder. Whether one prefers the iridescent play-of-color of opal or the saturated hues of tourmaline, both stones provide a meaningful and stunning connection to the tenth month of the year. Their unique properties and enduring appeal ensure their continued popularity among gemstone enthusiasts and jewelry lovers alike.