Kyanite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Kyanite

Kyanite is named for the Greek word for blue, kyanos. And what a blue! Fine Nepali kyanite can resemble the finest sapphire. Kyanite was a gem far better known to mineral collectors until more recent finds in the Kali Gandaki river region of west central Nepal, the first source to produce a significant amount of facet grade kyanite. Prior to the Nepal discoveries, Brazil was a major source of mineral specimen material, but kyanite also occurs in a variety of locations around the world. More recent kyanite discoveries have yielded additional colors, including orange and green.

Colors

Light To Dark Blue To Green; Zoned With Blue, Green, Colorless Bands

  • Kyanite classification

    CommonName
    Kyanite
    Species
    Kyanite
    Variety
    Colors
    Light To Dark Blue To Green; Zoned With Blue, Green, Colorless Bands
    AlternateNames
    Cyanite Or Disthene
    GemstoneGroups
    KeySeparations
    refractive index, birefringence, optic character (kyanite is biaxial positive, it has been misstated as biaxial negative) and appearance.
    ClassificationComments
    Fibrous structure rarely produces Cat's-eye stones.
  • Kyanite chemistry & crystallography

    ChemicalName
    aluminum silicate
    ChemicalFormula
    Al2SiO5
    Synthesis
    CrystalSystem
    Triclinic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Kyanite optical properties

    Transparency
    Transparent - Translucent
    Dispersion
    Strength: moderate fire Value: 0.02
    OpticalComments
    RefractiveIndex
    1.716-1.731
    Tolerance:(+0.004/-0.004)
    Birefringence
    0.012-0.017
    OpticCharacter
    Biaxial
    OpticSign
    Positive
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Weak red
    LWUV: Weak red
    CCFReaction
    Pleochroism
    Trichroic, moderate to strong colorless, dark blue, and violet-blue
  • Kyanite characteristic physical properties

    Hardness
    5.5-7
    CharacteristicComments
    Streak
    White
    SpecificGravity
    3.56-3.69 Range:0.01/-0.12 Typical:3.68
    Toughness
    Poor
    Inclusions
    Kyanite displays color zoning often in bands and may appear fibrous. Stones may contain natural inclusions.
    Luster
    Vitreous
    Stability
    Fracture
    Uneven
    Cleavage
    Perfect, in one direction, Good, in two directions