Blue opal, a captivating variety of the opal family, is renowned for its serene blue to blue-green hues that evoke the calm of the sea and sky. As a member of the opal group, it shares the mineraloid’s unique amorphous structure and high water content, contributing to its distinctive appearance and care requirements. While opal has long been recognized as the primary birthstone for October, blue opal offers a specific, soothing alternative within that category, celebrated for its tranquil color and metaphysical associations. This article explores the history, geological formation, gemological properties, and cultural significance of blue opal, drawing exclusively from authoritative sources to provide a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The history of opal is ancient and steeped in myth. According to Greek mythology, opals were considered the tears shed by Zeus after his victory over the Titans. This legend underscores the stone’s deep cultural roots, which predate even the Egyptian pyramids. Archaeologist Louis Leakey discovered man-made opal artifacts dating back more than 6,000 years, indicating that opal has been valued and crafted into jewelry for millennia.
The term “opal” itself is derived from the Roman word Opalus and the Greek word Opallios, which may have roots in the Sanskrit word Upala, meaning “precious stone.” While opals of various colors have been sourced globally—including from Australia, Mexico, Ethiopia, Honduras, and parts of Africa and Asia—blue opal has a more specific and celebrated origin. It is primarily associated with the Peruvian Andes Mountains, where it is not only a prominent gemstone but also the national stone of Peru.
In the context of modern birthstones, opal has a distinguished history. It was the sole birthstone for the month of October for many years until tourmaline was added as an alternative in 1952. This long-standing association solidifies opal’s place in the birthstone tradition. Blue opal, as a variety of opal, inherits this connection. Furthermore, beyond its monthly birthstone status, blue opal is also recognized as a mystical birthstone for the month of April and as a zodiac stone for the water signs of Cancer, Scorpio, and Pisces. Its color is seen as a reflection of the water element, and it is believed to imbue these sensitive signs with confidence and assurance.
Geological Formation and Sources
Blue opal, like all opals, is not a true mineral but an amorphous mineraloid. This means it lacks an ordered atomic structure, unlike crystalline minerals such as quartz. Its formation is a geological process known as “opalization.” This occurs when water rich in dissolved silica—often released from the decomposition of other minerals—seeps into cracks and cavities within rocks. As the water evaporates or drains away, it leaves behind silica deposits. Over vast periods, these deposits harden to form opal.
The distinctive blue coloration of blue opal is attributed to the microscopic structure of the silica spheres. The size and proximity of these spheres determine the color we perceive due to light diffraction. Blue opal forms when these silica spheres are particularly small. In some cases, such as with Peruvian blue opal, secondary mineral inclusions contribute to the color. Specifically, copper inclusions are responsible for the blue-green hues characteristic of this variety.
Blue opal is sourced from several key locations worldwide: * Peru: The primary and most famous source of blue opal, particularly from the Andes Mountains. Peruvian blue opal is often opaque and displays a distinctive teal color. It is a staple of the country and is sometimes referred to as a “teal-colored variety of common opal.” * Brazil: A neighboring country to Peru, Brazil is also known for producing blue opal, including the increasingly rare Paraiba opal, a bluish-green variety that resembles sea glass. * United States: Opal mines in Nevada, Idaho, and Oregon produce blue opal. A recent discovery in Oregon, the Owyhee opals, displays soothing light or dark shades of pastel blue. * Other Locations: Blue opal is also found in Slovakia and Indonesia.
The rarity of blue opal can vary. While the blue hue itself is a fairly common opal color, specific traits of blue opal, such as its unique geological context and the presence of play-of-color in some specimens, can make certain types more sought-after.
Gemological Properties
Understanding the physical and chemical properties of blue opal is essential for its appreciation, use in jewelry, and care.
Classification and Composition: Blue opal is a variety of opal, which is a hydrated form of silica (SiO₂·nH₂O). Its chemical composition consists of microcrystalline silica spheres that layer to refract light. Unlike crystalline minerals, it is amorphous, and its high water content (typically 3-21%) makes it relatively fragile.
Color: The color spectrum of blue opal ranges from light to dark shades of blue and blue-green. The Peruvian variety is often described as a light, translucent to opaque blue, reminiscent of the Caribbean Sea. The blue color is natural, resulting from the structural properties of the silica spheres and, in some cases, mineral inclusions like copper.
Hardness and Durability: On the Mohs hardness scale, blue opal ranks between 5 and 6. This relatively low hardness, combined with its high water content and amorphous structure, makes it susceptible to scratching and impact. It lacks cleavage, but its toughness is fair to poor. This is a critical consideration for jewelry, as it is more delicate than many other gemstones.
Transparency and Luster: Blue opal can range from translucent to opaque. It typically exhibits a vitreous (glass-like) to waxy luster.
Play-of-Color: A defining characteristic of precious opal is “play-of-color,” the phenomenon where flashes of spectral color appear as the stone is moved. Blue opal exists in both common and precious varieties. Common opal does not show play-of-color, while precious blue opal does. Peru produces both types, with some specimens containing small zones of color play. The term “blue fire opal” is sometimes used for specimens that display this iridescent effect.
Cut and Carat: Blue opal is often cut into cabochons to best display its color and any play-of-color. Larger sizes are available, especially from Peruvian sources, but the stone’s delicacy influences its use in jewelry.
Summary of Key Gemological Properties
| Property | Description |
|---|---|
| Species | Opal (Mineraloid) |
| Chemical Formula | SiO₂·nH₂O (Hydrated Silica) |
| Crystal System | Amorphous |
| Hardness (Mohs) | 5 - 6 |
| Luster | Vitreous to Waxy |
| Transparency | Translucent to Opaque |
| Color | Blue, Blue-Green |
| Primary Sources | Peru, Brazil, USA (Oregon, Nevada, Idaho), Slovakia, Indonesia |
| Special Characteristics | Can be common (no play-of-color) or precious (with play-of-color); high water content. |
Symbolism and Metaphysical Beliefs
Blue opal is highly regarded in crystal healing and metaphysical circles for its soothing properties and its connection to communication and emotional balance.
General Meaning: The stone is widely associated with communication, confidence, calmness, and creativity. Its tranquil blue color is believed to resonate with the throat and third-eye chakras. For those experiencing anxiety, hopelessness, or difficulty in expressing themselves, blue opal is thought to help open these energy centers and facilitate clear communication.
Physical Healing Properties: Some modern sources attribute physical healing benefits to blue opal, though these claims are not supported by formal gemological science. Beliefs include: * Boosting immunity. * Aiding with respiratory problems. * Assisting with menstrual and childbirth pain for some women. * Promoting hair growth and combating hair loss when used in elixirs. * Being used in elixirs to address cataracts and other eye issues.
Metaphysical and Emotional Healing: Blue opal is considered a powerful emotional healing stone. It is believed to: * Enhance communication skills and encourage self-expression. * Help overcome feelings of anxiety and stagnation in intuition. * Promote spiritual balance and overall well-being. * Serve as a tool for meditation, particularly when held to focus intention on specific chakras.
Zodiac and Astrological Connections: As a zodiac stone, blue opal is connected to the water signs: Cancer, Scorpio, and Pisces. Its color reflects the water element, and it is believed to imbue these signs with the confidence and assurance needed to navigate their sensitive nature.
Care and Cleaning
Given its physical properties, blue opal requires careful handling and maintenance to preserve its beauty.
- Avoid Harsh Conditions: Due to its relatively low hardness (5-6 on Mohs) and high water content, blue opal is prone to scratching and cracking. It should be protected from sharp blows and abrasive materials. Sudden temperature changes can also cause thermal shock, leading to cracking.
- Cleaning Method: The safest way to clean blue opal is with warm, soapy water and a soft brush. Avoid ultrasonic cleaners, steam cleaners, and harsh chemicals, as these can damage the stone or cause it to craze (develop a network of fine cracks).
- Storage: Store blue opal jewelry separately from harder gemstones and metals to prevent scratches. A soft cloth pouch or a lined jewelry box is ideal.
- Moisture Consideration: While opal contains water, prolonged exposure to very dry environments can sometimes cause a loss of water and lead to crazing. Conversely, excessive moisture is not a concern for the stone itself but can affect the metal settings. For jewelry, it is best to remove it before swimming, bathing, or engaging in strenuous activities.
Conclusion
Blue opal is a gemstone of serene beauty and rich cultural history. As a variety of opal, it carries the legacy of being one of the oldest known gemstones, while its specific blue to blue-green coloration offers a unique aesthetic. Primarily sourced from the Peruvian Andes, where it holds national significance, blue opal also appears in other parts of the world, including Brazil and the United States. Its amorphous mineraloid structure, characterized by microscopic silica spheres and a significant water content, defines its gemological identity and dictates its careful handling requirements. While it ranks as a relatively soft gemstone, its captivating color and association with communication, calmness, and emotional healing make it a cherished stone for jewelers, collectors, and those interested in the metaphysical world. As a modern alternative birthstone for October and a mystical stone for April, blue opal continues to be a relevant and admired gemstone in the contemporary landscape.