gemstone
White Opal
Hydrated amorphous silica (SiO2·nH2O)
AI-generated identification · may be incorrectMohs hardness of 5.5 to 6.5, white to light grey body color with characteristic play-of-color, subvitreous to resinous luster, and amorphous crystal structure.
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Physical properties
Mohs hardness of 5.5 to 6.5, white to light grey body color with characteristic play-of-color, subvitreous to resinous luster, and amorphous crystal structure.
Formation & geological history
Formed at low temperatures from silica-rich groundwater depositing in voids of sedimentary rocks like sandstone.
Uses & applications
Extensively cut and polished for use in high-end jewelry, pendants, and collector specimens.
Geological facts
Opals contain up to 20% water trapped within their microscopic silica spheres, which diffract light to produce their famous rainbow flashes.
Field identification & locations
Readily identified by its milky body tone and spectral play-of-color, primarily sourced from mines in Australia.
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