mineral
Opal
Hydrated amorphous silica (SiO2·nH2O)
AI-generated identification · may be incorrectHardness of 5.5 to 6.5 on the Mohs scale, variable body colors with distinctive play-of-color, vitreous to resinous luster, amorphous crystal structure (no cleavage), and specific gravity around 2.1.
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Physical properties
Hardness of 5.5 to 6.5 on the Mohs scale, variable body colors with distinctive play-of-color, vitreous to resinous luster, amorphous crystal structure (no cleavage), and specific gravity around 2.1.
Formation & geological history
Formed from silica-rich solutions seeping into cracks and voids in sedimentary or volcanic rock over millions of years.
Uses & applications
Extensively used in high-end jewelry, carvings, and prized by mineral collectors worldwide.
Geological facts
Opals can contain up to 20% water and diffract light through microscopic silica spheres to create their signature rainbow flash.
Field identification & locations
Identified easily by its characteristic play-of-color and lack of cleavage, commonly sourced from Australia, Ethiopia, and Mexico.
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Epidote
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Granite
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