Ammonite Shell Gemstone & Information | Gemopedia by JTV | Gemopedia™

Ammonite Shell

Ammonites were marine animals that existed during the Jurassic and Cretaceous periods, and are related to modern-day octopi, squid and cuttlefish. The same event that wiped out dinosaurs was the end of this species, as well. On rare occasions, the ammonite fossilized shells became mineralized, exhibiting a striking iridescent play of color. Ammonite is typically found as fossil specimens or as iridescent gems cut from the fossils under the trade name Ammolite.

Colors

Gray To Brown Sometimes With Iridescent Colors

  • Ammonite-shell classification

    CommonName
    Ammonite Shell
    Species
    NA
    Variety
    Colors
    Gray To Brown Sometimes With Iridescent Colors
    AlternateNames
    Ammolite, Ammonite, Korite, Aapaok And Calcentine
    GemstoneGroups
    KeySeparations
    Appearance, RI
    ClassificationComments
    Fossilized shell of nautilus like creature.
  • Ammonite-shell chemistry & crystallography

    ChemicalName
    Primarily aragonite or calcite; may also contain pyrite, silica and other materials
    ChemicalFormula
    fossilized ammonite shell
    Synthesis
    CrystalSystem
    NA
    ChemistryClassification
    Organic
    Nature
    Natural
    Crystallinity
    ChemistryComments
  • Ammonite-shell optical properties

    Transparency
    Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.52-1.68
    Tolerance:varies
    Birefringence
    0.155
    OpticCharacter
    NA
    OpticSign
    NA
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    None
  • Ammonite-shell characteristic physical properties

    Hardness
    4
    CharacteristicComments
    Streak
    SpecificGravity
    2.75-2.8 Typical:2.7
    Toughness
    Varies
    Inclusions
    Well preserved specimens show nautilus or spiral like appearance. Rare specimens display iridescence with mosaic patterns. Due the nature of the material it is often stabilized with polymers.
    Luster
    Vitreous
    Stability
    Poor
    Fracture
    Granular, Uneven
    Cleavage
    None