Moonstone-Orthoclase Gemstone & Information | Gemopedia by JTV | Gemopedia™

Moonstone-Orthoclase

Moonstone is a variety of feldspar that displays an amazing optical phenomenon called, adularescence. Internally repeating feldspar layers scatter the light that enters the stone creating a mystical white glow reminiscent of moonbeams. This glow comes to life, rolling across the gems surface, when it is moved. Traditionally, adularescent orthoclase gems have been called moonstone, however, other varieties of feldspar also exhibit this magical effect, including labradorite.

Colors

Colorless To White, Orange, Yellow, Brown

  • Moonstone-orthoclase classification

    CommonName
    Moonstone-Orthoclase
    Species
    Orthoclase
    Variety
    Moonstone
    Colors
    Colorless To White, Orange, Yellow, Brown
    AlternateNames
    Star Moonstone
    GemstoneGroups
    Feldspar
    KeySeparations
    RI, biaxial interference figure in polariscope and magnification. Fluorescence and SG might also be useful.
    ClassificationComments
    Moonstone can also be labradorite feldspar.
  • Moonstone-orthoclase chemistry & crystallography

    ChemicalName
    potassium aluminum silicate
    ChemicalFormula
    KAlSi3O8
    Synthesis
    CrystalSystem
    Monoclinic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Polycrystalline
    ChemistryComments
  • Moonstone-orthoclase optical properties

    Transparency
    Semitransparent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.518-1.526
    Tolerance:(+0.010/-0.010)
    Birefringence
    0.005-0.008
    OpticCharacter
    Biaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: inert to weak pink to red or orange
    LWUV: inert to weak yellowish white, blue, pink or red
    CCFReaction
    Pleochroism
    Unobservable
  • Moonstone-orthoclase characteristic physical properties

    Hardness
    6
    CharacteristicComments
    Streak
    White
    SpecificGravity
    2.55-2.61 Range:+/-0.03 Typical:2.58
    Toughness
    Poor
    Inclusions
    Moonstone will have blue or white adularescence. Stones might have centipede like inclusions and material with aventuresence or asterism might contain reflective inclusions such as fine needles or elongated hematite platelets.
    Luster
    Vitreous
    Stability
    Good
    Fracture
    Uneven, Splintery
    Cleavage
    Perfect, in two directions