Demantoid Garnet (Cat's-Eye) Gemstone & Information | Gemopedia by JTV | Gemopedia™

Demantoid Garnet (Cat's-Eye)

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case demantoid garnet. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line. Demantoid garnets that feature a cat's eye are rare.

Colors

Light To Dark Green To Yellow-Green

  • Demantoid-garnet-cats-eye classification

    CommonName
    Demantoid Garnet (Cat's-Eye)
    Species
    Andradite
    Variety
    Cat's-Eye Demantoid Garnet
    Colors
    Light To Dark Green To Yellow-Green
    AlternateNames
    GemstoneGroups
    Garnet
    KeySeparations
    OTL RI, spectrum and SG
    ClassificationComments
  • Demantoid-garnet-cats-eye chemistry & crystallography

    ChemicalName
    calcium iron silicate
    ChemicalFormula
    Ca3Fe2(SiO4)3
    Synthesis
    CrystalSystem
    Cubic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline to Aggregate
    ChemistryComments
  • Demantoid-garnet-cats-eye optical properties

    Transparency
    Semitransparent To Opaque
    Dispersion
    Strength: strong fire Value: 0.57
    OpticalComments
    RefractiveIndex
    1.888-0
    Birefringence
    OpticCharacter
    NA
    OpticSign
    NA
    PolariscopeReaction
    Singly Refractive (SR) With ADR
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    None
  • Demantoid-garnet-cats-eye characteristic physical properties

    Hardness
    6.5-7
    CharacteristicComments
    Streak
    SpecificGravity
    3.81-3.87 Typical: 3.84
    Toughness
    Poor
    Inclusions
    Cat's-eye demantoid garnet is type II clarity stone. Chatoyancy is caused by parallel needles. Due to the stones low mohs hardness it might have scratches and abrasions. Fibrous asbestos "horsetail inclusions" in Russian material. Stress fractures in Namibian stones.
    Luster
    SubAdamantine
    Stability
    Good
    Fracture
    Conchoidal, Uneven
    Cleavage
    None