Williamsite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Williamsite

Williamsite is a semi-transparent to translucent variety of antigorite, a mineral in the serpentine group. Williamsite was named in honor of 19th century American mineral collector L.W. Williams, who first discovered it. With a range of green hues, its color has a marked resemblance to two more expensive gems, jade and chrysoprase, and is used as a simulant of both. Williamsite exhibits an oily luster when polished and often contains minor inclusions of chromite and magnetite.

Colors

Oil Green, Intense Green

  • Williamsite classification

    CommonName
    Williamsite
    Species
    Williamsite
    Variety
    Colors
    Oil Green, Intense Green
    AlternateNames
    GemstoneGroups
    Serpentine
    KeySeparations
    RI, magnification, spectrum, appearance and surface condition.
    ClassificationComments
  • Williamsite chemistry & crystallography

    ChemicalName
    hydrous magnesium iron phyllosilicate
    ChemicalFormula
    (Mg,Fe)3Si2O5(OH)4
    Synthesis
    CrystalSystem
    Monoclinic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Microcrystalline
    ChemistryComments
  • Williamsite optical properties

    Transparency
    Semitransparent - Translucent
    Dispersion
    OpticalComments
    RefractiveIndex
    1.53-1.575
    Birefringence
    OpticCharacter
    Biaxial
    OpticSign
    Negative
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: Inert
    LWUV: Weak whitish-green
    CCFReaction
    Pleochroism
    Unobservable
  • Williamsite characteristic physical properties

    Hardness
    4
    CharacteristicComments
    Streak
    White
    SpecificGravity
    2.51-2.63
    Toughness
    Poor
    Inclusions
    Williamsite is often included with black octahedral chromite or magnetite inclusions. Stones often shows scratches and poor polish due to low mohs hardness. .
    Luster
    Waxy
    Stability
    Fracture
    Conchoidal, Splintery
    Cleavage
    Perfect, in one direction