gemstone
Fire Opal
SiO2·nH2O (Hydrated Silicon Dioxide)
AI-generated identification · may be incorrectHardness is 5.5 to 6.5 on the Mohs scale. Colors range from yellow and orange to fiery red, often with a vitreous to sub-resinous luster.
Identified More gemstone →
Explore Fire Opal in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness is 5.5 to 6.5 on the Mohs scale. Colors range from yellow and orange to fiery red, often with a vitreous to sub-resinous luster.
Formation & geological history
Formed from silica-rich groundwater filling crevices in volcanic rock, typically during the Tertiary period.
Uses & applications
Used primarily in high-end jewelry, carvings, and as a prized collector's gemstone.
Geological facts
Unlike precious opal, fire opal is prized for its vivid background body color rather than its play-of-color, though specimens can exhibit both.
Field identification & locations
Identified by its warm translucent body color and lack of cleavage; commonly sourced from Mexico, Ethiopia, and Australia.
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
Topaz
Al2SiO4(F,OH)2
mineral
Amber
Succinite (Organic Gemstone)
mineral
Diamond and Gold Jewelry
Carbon (Diamond) / Au (Gold)
gemstone
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary