Kornerupine Gemstone & Information | Gemopedia by JTV | Gemopedia™

Kornerupine

With colors ranging from brown to beautiful emerald green to shades of yellow, kornerupine is strongly pleochroic. It often contains tiny rutile and graphite inclusions that lend to chatoyancy and asterism. Because of its extreme rarity, kornerupine is almost strictly a collectors stone.

Colors

Yellowish To Brownish Green, Blue-Green, Yellow, Brown, Colorless

  • Kornerupine classification

    CommonName
    Kornerupine
    Species
    Kornerupine
    Variety
    Colors
    Yellowish To Brownish Green, Blue-Green, Yellow, Brown, Colorless
    AlternateNames
        Prismatine
    GemstoneGroups
    KeySeparations
    RI, birefringence, optic character, pleochroism and possible spectrum and fluorescence
    ClassificationComments
    Kornerupine sometimes shows a pseudo-uniaxial figure. Star and cat's-eye stones are rare.
  • Kornerupine chemistry & crystallography

    ChemicalName
    magnesium aluminum borosilicate
    ChemicalFormula
    Mg3Al6(Si,Al,B)5O21(OH)
    Synthesis
    CrystalSystem
    Orthorhombic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Kornerupine optical properties

    Transparency
    Transparent - Translucent
    Dispersion
    Strength: moderate fire Value: 0.019
    OpticalComments
    RefractiveIndex
    1.667-1.68
    Tolerance:(+0.003/-0.003)
    Birefringence
    0.012-0.017
    OpticCharacter
    Biaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert to strong yellow
    LWUV: Inert to strong yellow
    CCFReaction
    Pleochroism
    Trichroic, strong green, yellow, and red-brown
  • Kornerupine characteristic physical properties

    Hardness
    6-7
    CharacteristicComments
    Streak
    White
    SpecificGravity
    3.27-3.35 Typical:3.3
    Toughness
    Varies
    Inclusions
    Kornerupine can contain natural inclusions, zircons and needles. Cat's-eye stones will have parallel rutile or graphite fibers.
    Luster
    Vitreous
    Stability
    Fracture
    Conchoidal
    Cleavage
    Good, in one direction