October is a month of transition, symbolizing the harvest and the beginning of winter in many ancient cultures. It is also a month of two extraordinary birthstones: opal and tourmaline. These gemstones, each with their own rich histories, diverse color palettes, and unique properties, offer a perfect representation of the month’s themes—change, transformation, and the bounty of nature.
While opal has long been associated with October, tourmaline—specifically pink tourmaline—was added to the birthstone list in the 20th century. Together, they form a pair of stones that are as versatile as they are beautiful. This article explores the origins, properties, symbolism, and significance of both opal and tourmaline as the official October birthstones.
History and Lore
Opal: A Gem of Ancient Reverence
Opal has been treasured for thousands of years across various cultures, often regarded as a stone of transformation, hope, and inspiration. Its name is believed to derive from the Sanskrit word upala, meaning "precious stone," which was later Latinized as opalus. Opal has been found in ancient civilizations, including those of India, Egypt, and Rome, and was considered a powerful and mystical gem.
Ancient Greeks believed opal granted the gift of prophecy and protection from disease. The Romans associated it with purity and truth. During the 19th century, opal gained renewed popularity in Europe, particularly after the discovery of rich deposits in Australia, which is now the largest producer of opal in the world.
Opal was officially recognized as the October birthstone in the early 20th century by the American National Retail Jewelers’ Association. In 1912, pink tourmaline was added to the list, marking a shift in the birthstone tradition that would continue to evolve in the following decades.
Tourmaline: A Modern Addition with Ancient Roots
Tourmaline, particularly pink tourmaline, became the second official birthstone for October in 1912. Unlike opal, which had a long-standing historical association with the month, tourmaline was a relatively new entrant to the birthstone tradition.
Tourmaline is a complex silicate mineral that forms in a wide range of colors, including pink, red, green, blue, and even black. Its name comes from the Sinhalese word turmali, meaning "mixed colors," a reference to the wide variety of hues it can display. Pink tourmaline, in particular, has been especially popular in jewelry due to its soft, romantic tones.
An interesting historical anecdote involves Chinese Empress Dowager Tzu-Hsi, who was said to have an enormous passion for pink tourmaline. She once purchased nearly the entire production of a California mine and was even buried on a pink tourmaline pillow, according to legend. This story highlights the deep cultural significance and allure of the stone, particularly in East Asia.
Tourmaline was added to the October birthstone list as a more durable and accessible alternative to opal, which is relatively soft and can be sensitive to heat and light. This decision was also influenced by the growing popularity of tourmaline in jewelry design during the early 20th century.
Geological Formation and Sources
Opal: A Unique Form of Silica
Opal is a hydrated amorphous form of silica (SiO₂·nH₂O), and it is one of the few gemstones that does not have a crystalline structure. Instead, it forms in a network of microscopic silica spheres that trap water and light, creating the characteristic "play-of-color" effect. This optical phenomenon is what makes opal so visually striking and unique.
Opal is formed in the cavities of sedimentary rocks or in volcanic rock. It is commonly found in areas with high silica content and a history of volcanic activity. The most famous opal deposits are in Australia, where the country produces over 90% of the world’s opal. Other notable sources include Ethiopia, Brazil, and Mexico.
The colors of opal are determined by the size and arrangement of the silica spheres. Larger spheres tend to produce red and orange hues, while smaller ones produce blue and green. The presence of impurities can also affect the color, leading to variations such as black opal, which has a dark body color that enhances the play-of-color.
Tourmaline: A Versatile Silicate Mineral
Tourmaline is a complex borosilicate mineral that comes in a wide range of colors due to the presence of different trace elements. The most common type of tourmaline used in jewelry is elbaite, a sodium-lithium aluminum silicate. Pink tourmaline, the October birthstone, gets its color from the presence of manganese.
Tourmaline forms in pegmatite deposits, which are igneous rocks that cool slowly and allow for the formation of large crystals. The United States, particularly California and Maine, has some of the finest tourmaline deposits in the world. Other notable sources include Brazil, Nigeria, and Afghanistan.
Tourmaline is known for its piezoelectric properties—it generates an electric charge when subjected to mechanical stress. This unique characteristic has led to its use in various scientific and technological applications beyond jewelry, such as in sensors and electronic devices.
Gemological Properties
Opal: A Delicate and Enchanting Gem
Opal is one of the most unique gemstones due to its amorphous structure and the way it refracts light. Its properties include:
- Hardness: Opal has a hardness of 5.5 to 6.5 on the Mohs scale, making it relatively soft and prone to scratching.
- Refractive Index: Opal has a refractive index between 1.34 and 1.64, depending on the water content.
- Specific Gravity: Opal has a specific gravity of 1.9 to 2.3, which is relatively low for a gemstone.
- Luster: Opal has a vitreous to waxy luster.
- Color: Opal is known for its "play-of-color," which includes flashes of red, blue, green, yellow, and other colors depending on the angle of light.
Opal is also hygroscopic, meaning it can absorb and lose water depending on the humidity. This makes it sensitive to sudden temperature changes and high heat, which can cause it to crack or become dry and brittle.
Tourmaline: A Durable and Colorful Gem
Tourmaline is a more durable gemstone compared to opal, making it a better choice for everyday wear. Its properties include:
- Hardness: Tourmaline has a hardness of 7 to 7.5 on the Mohs scale, making it more resistant to scratches than opal.
- Refractive Index: Tourmaline has a refractive index between 1.62 and 1.64.
- Specific Gravity: Tourmaline has a specific gravity of 3.0 to 3.3, which is relatively high.
- Luster: Tourmaline has a vitreous luster.
- Color: Tourmaline can occur in nearly every color, including pink, red, green, blue, black, and even multicolored (known as watermelon tourmaline).
- Crystal Structure: Tourmaline forms in hexagonal prisms with a distinctive trigonal shape.
Tourmaline is also known for its pleochroism, a property that allows it to display different colors when viewed from different angles. This makes it a fascinating gemstone for collectors and jewelry designers.
Symbolism and Metaphysical Beliefs
Opal: The Stone of Imagination and Transformation
Opal has long been associated with creativity, inspiration, and transformation. In ancient times, it was believed to bring good luck and protect against illness. The Greeks associated it with prophecy and healing, while the Romans saw it as a symbol of purity and truth.
In more modern metaphysical beliefs, opal is considered a stone of the heart and a powerful amplifier of emotions. It is said to enhance imagination, intuition, and spiritual awareness. Opal is also believed to promote emotional balance and help individuals navigate times of change.
Due to its association with light and color, opal is often linked with the chakras, particularly the heart and throat chakras. It is thought to aid in communication, both verbal and non-verbal, and to help individuals express their emotions more clearly.
Tourmaline: The Stone of Protection and Healing
Tourmaline, especially pink tourmaline, is often associated with love, compassion, and emotional healing. It is considered a heart-centered stone that promotes feelings of warmth, comfort, and security. Pink tourmaline is particularly popular in jewelry as a symbol of friendship, affection, and nurturing love.
In ancient Egypt, tourmaline was believed to have traveled down a rainbow from the sun to the earth, bringing with it a variety of colors and energies. This belief has persisted in modern metaphysical practices, where tourmaline is seen as a bridge between the earthly and the divine.
Tourmaline is also known for its protective properties. It is believed to shield the wearer from negative energies and to promote a sense of grounding and stability. Black tourmaline, in particular, is often used in protection and cleansing rituals.
Care and Cleaning
Opal: Gentle Handling is Essential
Due to its relatively soft and hygroscopic nature, opal requires special care to maintain its beauty and integrity. It should be kept away from heat, direct sunlight, and sudden temperature changes. Opal should also be stored separately from other gemstones to prevent scratching.
To clean opal, use a soft cloth and lukewarm water. Avoid using harsh chemicals or ultrasonic cleaners, as these can damage the stone. Opal should be dried gently with a soft cloth and stored in a cool, dry place when not in use.
Tourmaline: A Durable and Easy-to-Care-for Gem
Tourmaline is much more durable than opal and can be cleaned and maintained with greater ease. It can be cleaned with mild soap and lukewarm water, using a soft brush or cloth. Ultrasonic and steam cleaners can also be used, though it is advisable to consult a professional jeweler before doing so.
Tourmaline can be stored with other gemstones, as it is less likely to scratch or be scratched. However, it is still a good practice to store valuable gemstones separately to avoid any potential damage.
Conclusion
October’s birthstones—opal and tourmaline—represent the beauty, diversity, and depth of the natural world. Opal, with its enchanting play-of-color and ancient symbolism, is a stone of transformation and inspiration. Tourmaline, particularly pink tourmaline, is a vibrant and versatile gemstone that embodies love, protection, and emotional healing.
Together, these two gemstones form a powerful and meaningful pair, each with its own unique qualities and significance. Whether worn as jewelry, used in spiritual practices, or simply admired for their beauty, opal and tourmaline continue to captivate and inspire those born in October and beyond.