gemstone
Opal
Hydrated amorphous silica (SiO2·nH2O)
AI-generated identification · may be incorrectMohs hardness of 5.5 to 6.5, creamy white to yellow color with subtle play-of-color, sub-vitreous luster, and amorphous crystal structure.
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Physical properties
Mohs hardness of 5.5 to 6.5, creamy white to yellow color with subtle play-of-color, sub-vitreous luster, and amorphous crystal structure.
Formation & geological history
Formed from a solution of silica and water, typically deposited in fissures within sedimentary or volcanic rock over millions of years.
Uses & applications
Widely utilized in fine jewelry, rings, pendants, and prized by collectors worldwide.
Geological facts
Opals contain up to 20% water trapped within their microscopic silica spheres, which diffract light to produce their signature colors.
Field identification & locations
Easily identified by its smooth cabochon polish, waxy-to-vitreous luster, and lightweight feel. Commonly found in arid regions like Australia and the western United States.
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