Star Quartz Gemstone & Information | Gemopedia by JTV | Gemopedia™

Star Quartz

Star quartz exhibits the optical phenomenon called asterism, a star-like pattern created on the surface of a gemstone when light encounters parallel fibrous, or needle-like, inclusions within its crystal structure. Light that strikes the inclusions within the gem reflects off of the inclusions, creating a narrow band of light. When two or more intersecting bands appear, a star pattern is formed. Depending on the crystal, the star may have four, six, or even twelve rays.

Colors

Rose, Gray, Brown

  • Star-quartz classification

    CommonName
    Star Quartz
    Species
    Quartz
    Variety
    Star Quartz
    Colors
    Rose, Gray, Brown
    AlternateNames
    Star Rose Quartz
    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
  • Star-quartz chemistry & crystallography

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

    Transparency
    Semitransparent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.544-1.553
    Tolerance:very constant
    Birefringence
    0.009
    OpticCharacter
    Uniaxial
    OpticSign
    Positive
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert to weak purple
    LWUV: Inert to weak purple
    CCFReaction
    Pleochroism
    Unobservable
  • Star-quartz characteristic physical properties

    Hardness
    7
    CharacteristicComments
    Streak
    White
    SpecificGravity
    2.64-2.69 Typical:2.66
    Toughness
    Poor
    Inclusions
    Star quartz will display a six rayed star due to traces of rutile needles. Stones might show color zoning and twinning planes. Stones might contain liquid, 2-phase, 3-phase inclusions, mineral crystals and negative crystals.
    Luster
    Vitreous
    Stability
    Poor
    Fracture
    Conchoidal
    Cleavage
    None