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

Scapolite (Cat's-Eye)

The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case scapolite. 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. Gem quality scapolite is rare and highly treasured by gem collectors, particularly when exhibits chatoyancy.

Colors

White, Pink, Violet, Yellow, Reddish Brown, Brown

  • Scapolite-cats-eye classification

    CommonName
    Scapolite (Cat's-Eye)
    Species
    Scapolite
    Variety
    Cat's-Eye Scapolite
    Colors
    White, Pink, Violet, Yellow, Reddish Brown, Brown
    AlternateNames
    GemstoneGroups
    Scapolite
    KeySeparations
    RI, birefringence, optic character and possible fluorescence. Use birefringence blink method on reddish brown material to separate from cat's-eye beryl.
    ClassificationComments
    RI in reddish brown material is usually between 1.560 to 1.585 and birefringence is around 0.025Birefringence typically 0.004 to 0.020 but it increases as the stones RI increases.
  • Scapolite-cats-eye chemistry & crystallography

    ChemicalName
    sodium or calcium aluminum silicate carbonate chloride
    ChemicalFormula
    Na4Al3Si9O24Cl to Ca4Al6Si6O24(CO3, SO4)
    Synthesis
    CrystalSystem
    Tetragonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline to Aggregate
    ChemistryComments
  • Scapolite-cats-eye optical properties

    Transparency
    Semitransparent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.55-1.585
    Tolerance:(+0.015/-0.014)
    Birefringence
    0.004-0.037
    OpticCharacter
    Uniaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV:
    LWUV:
    CCFReaction
    Pleochroism
    Unobservable
  • Scapolite-cats-eye characteristic physical properties

    Hardness
    6-6.5
    CharacteristicComments
    Streak
    White
    SpecificGravity
    2.6-2.74 Typical:2.68
    Toughness
    Fair
    Inclusions
    The eye in cat's-eye scapolite is distinct and sharp. White, pink or violet material appears fibrous because hollow tubes create the chatoyancy. The cats-eye in reddish brown and brown material is caused by black and orange-red needle like crystals, elongated platelets or dendritic inclusions.
    Luster
    Vitreous
    Stability
    Fracture
    Conchoidal
    Cleavage
    Good, in two directions