October boasts not one, but two captivating birthstones: the opal and the tourmaline. Both gemstones are celebrated for their remarkable color displays and rich histories, offering a diverse range of options for those born in the tenth month. The opal, known for its iridescent “play-of-color,” and the tourmaline, showcasing a spectrum of hues within a single crystal, each hold unique significance and appeal. This article delves into the history, geological origins, gemological properties, symbolism, and care of these enchanting October birthstones.
History and Lore
The opal’s story begins in India, where it was originally called “upala,” a “precious stone” in Sanskrit. This name evolved into “opalus” in ancient Rome, and the gem quickly captured the hearts of those who beheld its shifting colors. Ancient Greeks believed opals bestowed the gift of prophecy and protection from disease, while Europeans considered them symbols of purity, hope, and truth. For centuries, opal was thought to embody the virtues of all colored stones. The dramatic play-of-color inspired comparisons to fireworks, galaxies, and volcanoes, and Bedouins believed opals held lightning and fell from the sky during thunderstorms. It is also the traditional stone given to celebrate the 14th wedding anniversary.
Tourmaline’s history is equally fascinating. The name “tourmaline” originates from the Greek word “toramalli,” meaning “stone with mixed colors,” a fitting description for its ability to display multiple tones within a single crystal. Historically, tourmaline was often mistaken for other gemstones, notably rubies. A particularly vivid red tourmaline was known as “Caesar’s Ruby,” before being correctly identified as tourmaline in the 1800s. This gemstone has long been associated with protection, love, and courage, with different colors believed to possess specific meanings – black for protection, pink for love, and green for courage. It is also the preferred choice for celebrating an eighth wedding anniversary and the birthdays of October 12th, 13th, and 14th.
Geological Formation and Sources
Opals are unique in their formation, not being crystalline like many other gemstones. They are formed from silica-rich water that seeps into cracks and voids in the earth, depositing microscopic spheres of silica. The size and arrangement of these spheres determine the type of play-of-color exhibited. Australia is the world’s primary source of opals, accounting for over 95% of global production. Lightning Ridge is particularly renowned for its black opals, characterized by a dark background that accentuates the vibrant colors. Other Australian locations, such as Coober Pedy and White Cliffs, yield white opals, while Queensland is known for boulder opal, which contains ironstone. Mexico, specifically the state of Querétaro, is also a significant source, producing prized fire opals, often translucent with yellow to red base colors.
Tourmaline forms in igneous and metamorphic rocks, often in pegmatites, which are coarse-grained igneous rocks. Brazil, particularly the Minas Gerais region, is a major source of tourmaline, known for its stunning variety of colors. The discovery of vibrant green, blue, and violet tourmalines in Brazil’s Paraíba State in the late 1980s, colored by copper, created a sensation in the gem world. These “Paraíba” tourmalines have also been found in Mozambique and Nigeria and are highly sought after for their intense hues and rarity. The United States also has a history of tourmaline mining, with Mount Mica in Maine and the Himalaya Mine in California being notable locations. These mines have produced high-quality tourmalines for many years, even supplying stones to Empress Dowager Cixi of China.
Gemological Properties
Opal is distinguished by its play-of-color, a phenomenon caused by the diffraction of light as it passes through the microscopic silica spheres. This creates flashes of rainbow hues that shift and change with the viewing angle. Unlike many gemstones, opal does not have a defined crystal structure and is relatively soft, with a Mohs hardness of 5.5 to 6.5. This makes it more susceptible to scratches and requires careful handling.
Tourmaline, on the other hand, is a crystalline borosilicate mineral with a Mohs hardness of 7 to 7.5, making it suitable for everyday wear in jewelry. It exhibits a wide range of colors, including pink (rubellite), red, green, blue, and violet. Some tourmalines display a unique characteristic called pleochroism, meaning they exhibit different colors when viewed from different angles. The specific gravity of tourmaline varies depending on its composition, but generally falls between 3.02 and 3.34.
Here's a table summarizing the key gemological properties:
| Property | Opal | Tourmaline |
|---|---|---|
| Chemical Formula | SiO₂·nH₂O | (Na,Ca)(Al,Li,Mg)₃(Al,Fe,Mn)₆(BO₃)₃(Si₆O₁₈)(OH)₄ |
| Hardness (Mohs) | 5.5 - 6.5 | 7 - 7.5 |
| Crystal System | Amorphous | Trigonal |
| Specific Gravity | 1.98 - 2.15 | 3.02 - 3.34 |
| Play-of-Color | Present | Absent |
| Pleochroism | Absent | Present (in some) |
Symbolism and Metaphysical Beliefs
Opal is often associated with creativity, hope, and purity. It is believed to inspire confidence and encourage individuals to express their true selves. Some believe it protects against harmful energy and eases worries, representing personal growth and transformation.
Tourmaline carries a diverse range of symbolic meanings depending on its color. Black tourmaline is associated with protection, pink tourmaline with love and compassion, and green tourmaline with courage and healing. Overall, tourmaline is seen as a stone of strength and resilience, symbolizing eternal love and connection.
Care and Cleaning
Due to its relative softness, opal requires careful handling and cleaning. It is susceptible to scratches and should be protected from impacts. Cleaning opal jewelry involves using a soft cloth and lukewarm soapy water. Avoid harsh chemicals, ultrasonic cleaners, and steam cleaners, as these can damage the stone.
Tourmaline, being harder and 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’s best to avoid prolonged exposure.
Conclusion
Opal and tourmaline, the birthstones of October, offer a captivating blend of beauty, history, and symbolism. The opal’s mesmerizing play-of-color and association with creativity make it a unique and inspiring gemstone, while the tourmaline’s diverse range of colors and connection to strength and love offer a versatile and meaningful choice. Both gemstones represent the vibrant spirit of October, providing wearers with a touch of magic and a connection to the earth’s natural wonders.