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

Fire Agate

Fire Agate is one of those gems whose beauty and appeal is hard to describe with mere words. A phenomenal gem, it is an opaque variety of chalcedony that exhibits a colorful iridescence. The iridescence is caused by layers of silica and iron oxides, which interfere with the passage of light. Diffraction causes the colorful metallic hues that make this gemstone a favorite of collectors. Its brown body color is also a result of the iron oxide content. Gem quality fire agate is by far rarer than diamonds, emeralds or rubies and is as colorful as any precious Australian opal, although it is typically sold at a fraction of the cost.

Colors

Dark Reddish Brown

  • Fire-agate classification

    CommonName
    Fire Agate
    Species
    Quartz
    Variety
    Chalcedony
    Colors
    Dark Reddish Brown
    AlternateNames
    GemstoneGroups
    KeySeparations
    RI, SG, appearance and structure
    ClassificationComments
    The iridescent effect is caused by light bouncing off the limonite and goethite inclusions.
  • Fire-agate chemistry & crystallography

    ChemicalName
    silicon dioxide (aka silica)
    ChemicalFormula
    SiO2
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Polycrystalline
    ChemistryComments
  • Fire-agate optical properties

    Transparency
    Semitranslucent - Opaque
    Dispersion
    Strength: none
    OpticalComments
    RefractiveIndex
    1.535-1.539
    Birefringence
    0.004-0.004
    OpticCharacter
    Uniaxial
    OpticSign
    Positive
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    None
  • Fire-agate characteristic physical properties

    Hardness
    6.5-7
    CharacteristicComments
    Streak
    SpecificGravity
    2.55-2.7 Typical:2.6
    Toughness
    Excellent
    Inclusions
    Fire agates iridescent colors and botryoidal growth structure make it distinctive.
    Luster
    Vitreous
    Stability
    Good
    Fracture
    Conchoidal
    Cleavage
    None