gemstone
Opal
Hydrated amorphous silica, SiO2·nH2O
AI-generated identification · may be incorrectHardness of 5.5-6.5 on the Mohs scale, vitreous to sub-resinous luster, amorphous crystal structure with no cleavage, and specific gravity around 2.10.
Identified More gemstone →
Explore Opal in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 5.5-6.5 on the Mohs scale, vitreous to sub-resinous luster, amorphous crystal structure with no cleavage, and specific gravity around 2.10.
Formation & geological history
Formed from a solution of silica and water filling cracks or voids in sedimentary or volcanic rocks, typically over millions of years.
Uses & applications
Widely used in high-end jewelry such as rings, necklaces, and earrings, as well as highly sought after by mineral collectors.
Geological facts
Opal exhibits a unique optical phenomenon called play-of-color, caused by the diffraction of light through microscopic silica spheres.
Field identification & locations
Identified by its characteristic multicolored flash and greasy-to-vitreous feel; primarily mined in Australia, Ethiopia, and Mexico.
More like this
Other gemstone specimens
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Gemstone Ring
N/A - Set piece of jewelry, likely Amethyst or Garnet with Diamond or CZ
gemstone
Amber
Succinite (Organic Gemstone)
mineral
Diamond and Gold Jewelry
Carbon (Diamond) / Au (Gold)
gemstone
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Pearl necklace
Pearl, primarily aragonite (CaCO₃) and conchiolin
gemstone