Mineral Factbook

Fire opal

Varietyof Opal

Fire opal is orange to red opal. As a variety of Opal, it shares that species' composition (SiO2·nH2O), crystal structure, and hardness; the distinction is the appearance defined above.

Photos

Fire opal specimen photo
James St. John · CC BY 2.0 · Commons
Fire opal specimen photo
James St. John · CC BY 2.0 · Commons
Fire opal specimen photo
James St. John · CC BY 2.0 · Commons
Fire opal specimen photo
James St. John · CC BY 2.0 · Commons

About Opal

Full reference data — crystallography, X-ray diffraction, and cited physical properties — is on the Opal species page.

FormulaSiO2·nH2O
Streakwhite