gemstone
Opal
Hydrated amorphous silica (SiO2·nH2O)
AI-generated identification · may be incorrectHardness of 5.5 to 6.5 on the Mohs scale, vitreous to greasy luster, and a non-crystalline amorphous structure displaying a characteristic play-of-color.
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Physical properties
Hardness of 5.5 to 6.5 on the Mohs scale, vitreous to greasy luster, and a non-crystalline amorphous structure displaying a characteristic play-of-color.
Formation & geological history
Formed from a solution of silica and water seeping into cracks and voids in sedimentary or volcanic rock over millions of years.
Uses & applications
Primarily used as a precious gemstone in fine jewelry like rings, necklaces, and earrings.
Geological facts
Opal contains up to 20% water trapped within its microscopic silica spheres, which diffract light to create its rainbow colors.
Field identification & locations
Identified by its distinctive multicolored flashes and lighter body tone, primarily mined in Australia, Ethiopia, and Mexico.
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