October boasts not one, but two recognized birthstones: the captivating opal and the versatile tourmaline. Both gems offer a stunning array of colors and have rich histories steeped in lore and symbolism. While opal holds the distinction as the traditional October birthstone, tourmaline has gained prominence as the modern choice, offering a diverse palette to suit any preference. This article will delve into the history, geological origins, gemological properties, and cultural significance of both these remarkable gemstones.
History and Lore
The story of opal stretches back to ancient times, with its origins believed to lie in India, where it was known as upala, meaning “precious stone” in Sanskrit. From India, opals made their way westward to ancient Rome, becoming known as opalus. Ancient Greeks associated the stone with the gift of prophecy and protection from disease, while Europeans long considered it a symbol of purity, hope, and truth. Centuries ago, opal was even believed to embody the virtues of all colored stones.
Tourmaline’s history, while also ancient, has a slightly different trajectory. Egyptian myths recount tourmalines rising from the Earth’s core, gathering colors from the rainbow along the way. In the late 1800s, the Empress Dowager Tzu-Hsi of China developed a fervent passion for pink tourmaline, acquiring nearly all the production from California mines. She was so enamored with the gem that she was laid to rest with a pillow crafted from it, and the remainder of her collection was transformed into intricate carvings. Officially added to the list of October birthstones in 1912, tourmaline quickly gained recognition for its diverse color range and protective qualities.
Geological Formation and Sources
Opal is unique in its formation, not being a crystalline mineral like many gemstones. Instead, it is a hydrated amorphous form of silica, meaning it lacks a defined crystal structure and contains water within its composition. The “play-of-color” – the shifting rainbow hues that make opal so prized – is caused by the diffraction of light as it passes through microscopic spheres of silica within the stone.
The most significant source of opal today is Australia, particularly the Lightning Ridge region of New South Wales, renowned for its rare black opals. However, opal is also found in Ethiopia, Mexico, and Brazil.
Tourmaline, in contrast, is a crystalline borosilicate mineral. It forms in a variety of geological environments, often within granite pegmatites and metamorphic rocks. The diverse colors of tourmaline are attributed to the presence of different trace elements within its chemical structure.
Tourmaline is found globally, with notable deposits in Brazil, where the rare Paraíba tourmaline – known for its intense violet-blue and blue-green hues – originates. Other sources include Africa, Afghanistan, Pakistan, and the United States. Watermelon tourmaline, displaying both pink and green hues, is also a sought-after variety.
Gemological Properties
Opal:
Opal’s properties differ significantly from typical gemstones. It has a hardness of 5.5 to 6.5 on the Mohs scale, making it relatively softer and more susceptible to scratches than gems like sapphire or ruby. Its specific gravity ranges from 1.98 to 2.15. The defining characteristic of opal is its play-of-color, which is graded based on its brilliance and the range of colors displayed.
Tourmaline:
Tourmaline exhibits a wider range of properties depending on its composition. It generally has a hardness of 7 to 7.5 on the Mohs scale, making it more durable than opal. Its specific gravity varies from 3.02 to 3.22. Tourmaline is also piezoelectric, meaning it generates an electrical charge when subjected to pressure – a property that has been utilized in industrial applications, such as pressure gauges for submarines.
The following table summarizes key gemological properties:
| Property | Opal | Tourmaline |
|---|---|---|
| Hardness (Mohs) | 5.5 - 6.5 | 7 - 7.5 |
| Specific Gravity | 1.98 - 2.15 | 3.02 - 3.22 |
| Crystal System | Amorphous | Trigonal |
| Composition | Hydrated Silica | Borosilicate |
| Play-of-Color | Present | Absent |
| Piezoelectric | Absent | Present |
Symbolism and Metaphysical Beliefs
Throughout history, both opal and tourmaline have been imbued with symbolic meaning. Opal has been associated with hope, purity, truth, and creativity. Its shifting colors have been likened to galaxies, volcanoes, and fireworks, inspiring awe and wonder. Bedouins believed opal held lightning, while ancient Greeks thought it bestowed prophetic abilities. Modern interpretations link opal to imagination, emotional expression, and transformation.
Tourmaline’s symbolism is equally rich. Ancient legends suggest tourmalines journeyed from the Earth’s core, collecting the colors of the rainbow. It has long been considered a protective stone, shielding wearers from negative energies. Pink tourmaline is often associated with love and compassion, while green tourmaline symbolizes strength and vitality. Tourmaline is also believed to increase understanding and empathy.
Care and Cleaning
Due to its relative softness, opal requires careful handling. It is susceptible to scratches and can be damaged by harsh chemicals or sudden temperature changes. Opal should be cleaned with a soft cloth and mild soapy water. Avoid ultrasonic cleaners and harsh abrasives.
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 caution should be exercised with stones that have been fracture-filled.
Conclusion
Opal and tourmaline, the birthstones of October, represent a captivating blend of history, beauty, and symbolism. Opal, the traditional choice, enchants with its ethereal play-of-color and associations with hope and creativity. Tourmaline, the modern birthstone, offers a dazzling spectrum of hues and embodies protection, balance, and emotional healing. Whether one prefers the fiery brilliance of opal or the versatile charm of tourmaline, these gemstones are sure to bring joy and meaning to those born in the tenth month.