October boasts not one, but two recognized birthstones: the captivating Opal and the vibrant Tourmaline. Both gemstones are celebrated for their diverse color palettes and rich histories, offering a spectrum of choices for those born in the tenth month. This article delves into the origins, properties, symbolism, and historical significance of these remarkable gems, providing a comprehensive overview for enthusiasts and those seeking to understand the allure of October’s birthstones.
History and Lore
The story of October’s birthstones is one of evolving tradition. While formalized lists of birthstones began to emerge in the 19th century, the association of specific gems with particular months has roots in ancient cultures. Opal, the traditional October birthstone, has a particularly long and storied past. Its name originates from the Sanskrit word upala, meaning “precious stone,” and the Greek opallios, meaning “to see a change of color.” Ancient Romans valued opal, referring to it as opalus.
Legends surrounding opal are numerous and varied. Bedouins believed opal held lightning and fell from the sky during thunderstorms, while ancient Greeks associated the gem with prophecy and protection from disease. Europeans once considered opal a symbol of purity, hope, and truth, believing it embodied the virtues of all colored stones.
Tourmaline’s journey to becoming an October birthstone is more recent. The National Association of Jewellers (now Jewellers of America) designated opal as the primary October birthstone and tourmaline as the alternative in 1912. However, the gem’s history extends back centuries, notably with a fascinating connection to Chinese royalty. In the late 1800s, Empress Dowager Tzu-Hsi of China developed a profound fondness for pink tourmaline, acquiring nearly the entire production from a California mine. She was even buried with pink tourmaline, and her remaining collection was crafted into intricate carvings.
Geological Formation and Sources
Opal is unique among gemstones in its composition. It is not a crystalline mineral but rather a hydrated amorphous form of silica – essentially a hardened silica gel. Over millennia, water containing dissolved silica seeps into cracks and voids in the earth, and as the water evaporates, it leaves behind deposits of silica. This process can also occur within fossilized remains, creating “opalized fossils” or “opalized wood.”
The primary sources of opal are Australia, which produces the vast majority of the world’s supply, and Ethiopia. Other notable sources include Mexico and the United States.
Tourmaline, in contrast, is a crystalline borosilicate mineral. It forms in igneous and metamorphic rocks, often in pegmatites – coarse-grained igneous rocks. The diverse colors of tourmaline are attributed to the presence of various elements within its crystal structure.
Tourmaline is found in a variety of locations worldwide. Africa, particularly Kenya, Mozambique, Namibia, and Tanzania, is a significant source. Brazil is also a major producer, and smaller deposits exist in other regions. Pink tourmaline, specifically, gained prominence from mines in California, attracting the attention of Empress Dowager Tzu-Hsi.
Gemological Properties
Opal:
Opal’s defining characteristic is its “play-of-color” – the shifting display of iridescent hues. This phenomenon is caused by the diffraction of light as it passes through microscopic spheres of silica within the gem. The size and arrangement of these spheres determine the colors observed. Opal does not have a specific hardness rating on the Mohs scale as it is amorphous, but it generally ranges from 5.5 to 6.5.
Tourmaline:
Tourmaline exhibits a wide range of colors, including pink, red, green, blue, and even multi-colored varieties known as “watermelon tourmaline.” This diversity is due to the presence of different elements, such as iron, manganese, and lithium, within the crystal structure. Tourmaline typically has a hardness of 7 to 7.5 on the Mohs scale, making it a relatively durable gemstone.
Here's a comparative table of key properties:
| Property | Opal | Tourmaline |
|---|---|---|
| Chemical Formula | SiO₂·nH₂O | Complex Borosilicate |
| Hardness (Mohs) | 5.5 - 6.5 | 7 - 7.5 |
| Luster | Vitreous to Resinous | Vitreous |
| Transparency | Translucent to Opaque | Transparent to Opaque |
| Defining Feature | Play-of-Color | Wide Color Range |
Symbolism and Metaphysical Beliefs
Throughout history, both opal and tourmaline have been attributed with various symbolic meanings and metaphysical properties. Opal is often associated with imagination, fidelity, creativity, innocence, and hope. It is believed to inspire confidence and encourage individuals to express their true selves. Some believe it offers protection from negative energy and eases worries. The association with rainbows further enhances its symbolism of transformation and positive change.
Tourmaline, particularly pink tourmaline, is linked to love, compassion, and emotional healing. It is thought to promote emotional balance and reduce stress. Different colors of tourmaline are believed to possess unique properties; for example, green tourmaline is associated with vitality and growth.
Care and Cleaning
Due to its relative softness and hydrated nature, opal requires careful handling. It is susceptible to scratching and can be damaged by prolonged exposure to heat or dehydration. Opal should be cleaned with a soft cloth and mild soapy water. Avoid ultrasonic cleaners and harsh chemicals.
Tourmaline is more durable than opal and can withstand more rigorous cleaning. 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 captivating birthstones of October, represent a beautiful duality. Opal, with its ethereal play-of-color, embodies imagination and hope, while tourmaline, with its vibrant hues, symbolizes love and emotional healing. Both gemstones boast rich histories and unique geological origins, making them treasured possessions for those born in the tenth month and admired by gemstone enthusiasts worldwide. Their enduring appeal lies not only in their aesthetic beauty but also in the symbolism and lore that have accumulated over centuries.