Fire Opal Gemstone & Information | Gemopedia by JTV | Gemopedia™

Fire Opal

Unique and mysterious, fire opals are appropriately named for their fiery cherries, sunburst yellows and deep tangerines. Unlike many other opals, fire opal may not display play of color, and specimens that do are highly valuable. Mexico is one of today's primary fire opal sources, where this fiery gem has been treasured since the time of the Aztecs, who called it "gem of the bird of paradise" in their native language.

Colors

Yellow, Red, Orangy Red, Orange, Brown

  • Fire-opal classification

    CommonName
    Fire Opal
    Species
    Opal
    Variety
    Fire Opal
    Colors
    Yellow, Red, Orangy Red, Orange, Brown
    AlternateNames
    Precious Opal, Mexican Fire Opal, Brazilian Fire Opal, Cherry Opal, Gold Opal, Sun Opal
    GemstoneGroups
    KeySeparations
    Appearance, RI and fluorescence
    ClassificationComments
    Fire opals RI is typically between 1.420 to 1.430, but some have been found to be as low as 1.370. Some stones might show play-of-color.
  • Fire-opal chemistry & crystallography

    ChemicalName
    hydrated silicon dioxide
    ChemicalFormula
    SiO2.nH2O
    Synthesis
    CrystalSystem
    NA
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Amorphous
    ChemistryComments
  • Fire-opal optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.45
    Tolerance:(+0.020/-0.080)
    Birefringence
    OpticCharacter
    NA
    OpticSign
    PolariscopeReaction
    Singly Refractive (SR) With ADR
    Fluorescence
    SWUV: Inert to moderate greenish brown
    LWUV: Inert to moderate greenish brown
    CCFReaction
    Pleochroism
    None
  • Fire-opal characteristic physical properties

    Hardness
    5-6.5
    CharacteristicComments
    Streak
    White
    SpecificGravity
    1.97-2.23 Typical:2.15
    Toughness
    Varies
    Inclusions
    Fire opal might have a cloudy appearance, show color zoning and have mineral or fluid inclusions.
    Luster
    Vitreous
    Stability
    Poor
    Fracture
    Conchoidal, Uneven
    Cleavage
    None