Chlorastrolite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Chlorastrolite

Also known as "green starstone" or "Michigan greenstone," chlorastrolite is a green to bluish green stone only found in the upper peninsula of Michigan, USA. This gem exhibits varying degrees of chatoyancy and has a distinctive "turtleback" mosaic pattern throughout.

Colors

green to bluish green

  • Chlorastrolite classification

    CommonName
    Chlorastrolite
    Species
    Chlorastrolite
    Variety
    Colors
    green to bluish green
    AlternateNames
    Green Star Stone, Turtleback Stone, Isle Royale Greenstone, Lake Superior Greenstone
    GemstoneGroups
    KeySeparations
    Appearance: radial fibrous structure
    ClassificationComments
    State gemstone of Michigan.
  • Chlorastrolite chemistry & crystallography

    ChemicalName
    hydrated calcium magnesium silicate hydroxide
    ChemicalFormula
    Ca2MgAl2(SiO4)(Si2O7)(OH)2-H2O
    Synthesis
    CrystalSystem
    Monoclinic
    ChemistryClassification
    Nature
    Natural
    Crystallinity
    Aggregate
    ChemistryComments
  • Chlorastrolite optical properties

    Transparency
    Semitranslucent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.65-1.66
    Tolerance:(+0.040/-0.040)
    Birefringence
    OpticCharacter
    OpticSign
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    Unobservable
  • Chlorastrolite characteristic physical properties

    Hardness
    5-6
    CharacteristicComments
    Streak
    Green
    SpecificGravity
    3.1-3.5 Typical:3.2
    Toughness
    Fair
    Inclusions
    Chlorastrolite has a fibrous structure with light and dark green mosaic like patterns
    Luster
    Vitreous
    Stability
    Fracture
    Splintery, Granular
    Cleavage
    None