gemstone
Opal stud earrings
Opal, hydrated amorphous silica (SiO₂·nH₂O)
AI-generated identification · may be incorrectThe pale oval cabochons show opalescent color; opal has no crystal structure, Mohs hardness about 5.5–6.5, and a vitreous-to-waxy luster. The setting appears to be metal with small accent stones; the photo does not establish the opal type or metal.
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Physical properties
The pale oval cabochons show opalescent color; opal has no crystal structure, Mohs hardness about 5.5–6.5, and a vitreous-to-waxy luster. The setting appears to be metal with small accent stones; the photo does not establish the opal type or metal.
Formation & geological history
Opal forms when silica-rich water deposits gel in rock cavities and later dehydrates; natural opals occur in sedimentary and volcanic settings, chiefly from the Cretaceous to recent geological periods.
Uses & applications
Used in jewelry and collecting; opal is too soft for many high-wear applications.
Geological facts
Opal’s play-of-color results from light diffraction by regularly arranged microscopic silica spheres; some pale opals show only a milky sheen.
Field identification & locations
Look for shifting spectral flashes as the stone is tilted, though common opal may lack them. Major sources include Australia, Ethiopia, Mexico, and Brazil; appearance alone cannot confirm natural versus synthetic opal.
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