October boasts not one, but two recognized birthstones: the captivating opal and the richly colored tourmaline. Both gemstones offer a stunning array of hues and possess unique histories, making them cherished choices for those born in the tenth month. This article will delve into the geological origins, historical significance, gemological properties, and symbolism of these remarkable October birthstones, drawing exclusively from available sources.
History and Lore
The story of opal stretches back millennia, originating in India where it was known as upala, a Sanskrit term meaning “precious stone.” This name evolved into opalus in ancient Rome. Throughout history, opal has inspired diverse beliefs. Ancient Greeks associated the stone with prophecy and protection from disease, while Europeans considered it a symbol of purity, hope, and truth. For centuries, opal was believed to embody the virtues of all colored stones. Bedouins held the belief that opal contained lightning and originated from the sky during thunderstorms.
Tourmaline’s history, while also ancient, gained significant momentum in the late 19th century. The Chinese Empress Dowager Tzu-Hsi developed a profound fondness for pink tourmaline, acquiring nearly the entire production from California mines. She continued to cherish the gem even in death, being buried with a pink tourmaline pillow, and the remainder of her collection was crafted into intricate carvings. The name “tourmaline” itself is derived from the Sinhalese word toramalli, meaning “mixed stone,” reflecting the gem’s remarkable capacity to occur in a wide spectrum of colors. It is also known as the “Peace Stone,” believed to remove aggressiveness, jealousy, anger, and fear, fostering a state of tranquility in the wearer.
Geological Formation and Sources
Opals are unique in their formation, differing from most other gemstones which are classified as minerals. They consist of myriad tiny silica spheres arranged in a tightly-packed lattice. These gemstones form within cavities and cracks in near-surface volcanic rocks, or within sedimentary volcanic ash rock. Percolating water dissolves silica, which then precipitates to form opal. In rare instances, opal replaces fossils – shells, bones, and wood – after their original material has dissolved.
The majority of fire opals, a vibrant variety, originate in Mexico, with significant sources emerging only in the mid-nineteenth century. These opals are characterized by red, orange, or yellow backgrounds, with transparent specimens being particularly valuable. Other opal varieties, like crystal opal, water opal, and boulder opal, also exhibit distinct formation characteristics and appearances. Crystal opals are known for their transparency and superior play-of-color, while water opals are more subtle and affordable. Boulder opals uniquely combine precious opal with portions of the host rock, enhancing durability.
Tourmaline forms in distinctive prism-like crystals with long hexagonal structures. The sources for tourmaline are diverse, with pink tourmaline notably sourced from California mines, historically favored by Empress Tzu-Hsi. The sources are not detailed beyond this in the provided materials.
Gemological Properties
Tourmaline, specifically pink tourmaline, typically registers between 7 and 7.5 on the Mohs hardness scale, making it a relatively durable gemstone, though not as hard as a pink sapphire. It consists primarily of the mineral elbaite. Tourmaline is celebrated for its diverse color range, including pink, orchid, blue, green, red, yellow, black, brown, and the striking watermelon tourmaline, which displays multiple colors within a single crystal.
Opal, in contrast, has a Mohs hardness of 5-6.5, making it more prone to fractures than many other gemstones. Its defining characteristic is its “play-of-color,” a phenomenon caused by the interference of light with its internal structure, resulting in flashes of rainbow hues. Opal can be categorized into several types based on its appearance and play-of-color:
- Precious Opal: Exhibits vibrant iridescent colors.
- Common Opal: Lacks significant play-of-color.
- Fire Opal: Features red, orange, or yellow backgrounds, sometimes without play-of-color.
- Crystal Opal: Transparent with superior play-of-color.
- Water Opal: Colorless or with light base colors, with subtle or absent play-of-color.
- Boulder Opal: Combines opal with portions of the host rock.
The value of opal is often determined by the intensity and range of its color play, similar to the evaluation of colored diamonds. The more brilliant the opal, the more valuable it is generally considered. Fire opal is unique in that play-of-color is not a primary value factor, exempting it from the traditional precious vs. potch classification.
The following table summarizes key gemological properties:
| Gemstone | Hardness (Mohs) | Chemical Composition | Key Characteristic |
|---|---|---|---|
| Tourmaline | 7 - 7.5 | Elbaite | Diverse Color Range |
| Opal | 5 - 6.5 | Hydrated Silica | Play-of-Color |
Symbolism and Metaphysical Beliefs
Tourmaline is associated with peace, compassion, self-love, and transformation. It is believed to enhance creative vision and remove negative emotions like aggressiveness, jealousy, anger, and fear. It is also the stone given to celebrate the 8th and 38th wedding anniversaries.
Opal has historically been imbued with a wide range of symbolic meanings. Ancient cultures believed it bestowed the gift of prophecy and offered protection from disease. Europeans viewed it as a symbol of purity, hope, and truth, believing it embodied the virtues of all colored stones.
Care and Cleaning
Due to its lower hardness, opal requires careful handling to avoid scratches and fractures. It is advisable to avoid harsh chemicals and ultrasonic cleaners. Cleaning can be done with a soft cloth and lukewarm soapy water.
Tourmaline, being harder, is more durable but still benefits from gentle care. Avoid harsh chemicals and ultrasonic cleaners. Cleaning can be achieved with warm soapy water and a soft brush.
Conclusion
October’s birthstones, opal and tourmaline, represent a captivating blend of history, geological wonder, and symbolic meaning. Opal, with its mesmerizing play-of-color and ancient lore, offers a connection to the earth’s volcanic past and the beliefs of civilizations long gone. Tourmaline, with its diverse hues and association with peace and creativity, provides a vibrant and versatile gem for any jewelry collection. Both stones continue to be cherished for their beauty and the unique qualities they represent, making them fitting symbols for those born in the tenth month.