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

Quartz (Cat's-Eye)

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case quartz gems. 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.

Colors

Brownish Yellow, Brownish Green, Green-Yellow To Gray

  • Quartz-cats-eye classification

    CommonName
    Quartz (Cat's-Eye)
    Species
    Quartz
    Variety
    Cat's-Eye Quartz
    Colors
    Brownish Yellow, Brownish Green, Green-Yellow To Gray
    AlternateNames
    GemstoneGroups
    KeySeparations
    Appearance, RI and SG. Magnification and fluorescence might be helpful. A bull's-eye optic figure is determinative for quartz; may also show Airy's spiral optic figure and Brazil-law twinning under crossed polarizing filters.
    ClassificationComments
  • Quartz-cats-eye chemistry & crystallography

    ChemicalName
    silicon dioxide (aka silica)
    ChemicalFormula
    SiO2
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline to Aggregate
    ChemistryComments
  • Quartz-cats-eye optical properties

    Transparency
    Semitransparent - Translucent
    Dispersion
    OpticalComments
    RefractiveIndex
    1.544-1.553
    Tolerance:very constant
    Birefringence
    0.009
    OpticCharacter
    Uniaxial
    OpticSign
    Positive
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    Unobservable
  • Quartz-cats-eye characteristic physical properties

    Hardness
    7
    CharacteristicComments
    Streak
    SpecificGravity
    2.64-2.69 Typical:2.66
    Toughness
    Good
    Inclusions
    Cat's-eye quartz has parallel needle-like inclusions that are typically asbestos or rutile.
    Luster
    Vitreous
    Stability
    Good
    Fracture
    Conchoidal
    Cleavage
    None