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Chinese writing opals is a rare variety of precious opal exhibiting natural patterns that resemble Chinese calligraphic characters or script-like formations within its internal structure. These distinctive opals, found primarily in Australia’s Lightning Ridge region, display black, dark blue, or gray base colors with vivid play-of-color effects that form character-like patterns against the dark background.
The unique markings in Chinese writing opals occur due to the systematic arrangement of silica spheres within the opal’s microstructure, creating diffraction patterns that produce both the play-of-color and the script-like formations. These opals rank among the most valuable varieties of precious opal, particularly when the character-like patterns appear distinctly formed and exhibit strong color contrast. The phenomenon results from the natural orientation of the opal’s internal structure during its formation process within ironstone deposits, typically occurring at depths between 6 to 18 meters beneath the Earth’s surface.
Chinese Writing Opals is typically a natural gemstone.
Common names for Chinese Writing Opals include Script Stone, Cuneiform Jasper, and Chinese Script Stone.
Chinese writing opals, like other opals, generally have a hardness of about 5.5 to 6.5 on the Mohs scale. This makes them relatively softer compared to many other gemstones, which means they require careful handling to avoid scratches.
The refractive index for opals, including Chinese writing opals, typically ranges from approximately 1.37 to 1.52. This RI contributes to the unique play of color for which opals are renowned.
Opals are well-known for their distinctive luster, which can be described as subvitreous to waxy. Chinese writing opals, in particular, exhibit a unique luster due to their intricate patterns and color play.
Opals, including Chinese writing opals, do not have any natural cleavage planes. This characteristic means that they do not split along any defined path when subjected to stress.
Opals usually exhibit a conchoidal or uneven fracture, making them somewhat brittle and sensitive to impact.
The specific gravity of opals ranges typically between 1.98 and 2.25. This property helps in identifying genuine opals from synthetic or imitative counterparts.
Opals are isotropic gems and do not exhibit double refraction. This is due to their amorphous character, lacking a crystalline structure.
Opals are famed for their dispersion or “”fire,”” which is particularly pronounced in high-quality stones. This play of color is due to the diffraction of light passing through microscopic silica spheres within the gem.
Opals are amorphous, meaning they do not have a crystal system. They are formed from silica gel that hardens over time without forming a crystalline structure.
Chinese writing opals are characterized by a base color, typically white or cream, with markings that resemble Chinese calligraphy in black or a dark color.
The transparency of opals can vary greatly, from completely opaque to translucent. Chinese writing opals tend to be on the translucent side, allowing for more visible play of color and pattern.
Opals, including Chinese writing opals, do not exhibit pleochroism due to their isotropic nature.
Some opals may show fluorescence under UV light, depending on the type and origin. The fluorescence, if present in Chinese writing opals, can vary.
Opals are generally categorized as having fair to poor toughness, which makes them susceptible to cracking and chipping.
Opals are brittle gems. This tenacity means they can be damaged if handled roughly or exposed to sharp blows.
Being isotropic, Chinese writing opals have an optic sign of uniaxial, which typically is not applicable as they do not double refract.
The absorption spectrum of opals can sometimes show a broad hump around 1400-1600 nm and a smaller hump at 1200 nm, largely depending on the water content.
Opals are primarily composed of silica (SiO2) and water, with the water content ranging from 3% to 21% by weight.
Chatoyancy is rare in opals. However, some opals can exhibit this effect if they have parallel inclusions or fibrous structures.
Like chatoyancy, asterism is uncommon in opals but can appear if structural conditions allow.
Iridescence is notably one of the defining characteristics of opals, including Chinese writing opals, due to the interference and diffraction of light.
Opals are generally non-magnetic, making this property not applicable for identification or characterization of Chinese writing opals.
Opals have very low to almost non-existent electrical conductivity due to their amorphous nature and composition primarily of silica.
Normal opals, including Chinese writing opals, are not radioactive. However, some minerals used as gemstones could have trace radioactive elements, depending on their geological environment.
