Adularia Gemstone & Information | Gemopedia by JTV | Gemopedia™

Adularia

Adularia is a variety of feldspar found in hydrothermal veins in mountainous areas, from one of which it derives its name: the Adular Mountains of Switzerland. It commonly forms colorless to white, cream, pale yellow to pink, or reddish-brown, glassy, prismatic, twinned crystals. These transparent to colorless gems often display a white to blue sheen.

Colors

Colorless With White, Blue Sheen

  • Adularia classification

    CommonName
    Adularia
    Species
    Orthoclase
    Variety
    Adularia
    Colors
    Colorless With White, Blue Sheen
    AlternateNames
    GemstoneGroups
    Feldspar
    KeySeparations
    refractive index, birefringence, optic character and possibly spectrum and fluorescence
    ClassificationComments
    This stone comes from Adula mountains in Switzerland and this is where the phenomena adularescence gets its name.
  • Adularia chemistry & crystallography

    ChemicalName
    potassium aluminum silicate
    ChemicalFormula
    KAlSi3O8
    Synthesis
    CrystalSystem
    Monoclinic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Adularia optical properties

    Transparency
    Transparent - Translucent
    Dispersion
    Strength: weak fire Value: 0.12
    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 orangy red
    LWUV: Inert to weak blue or pink
    CCFReaction
    Pleochroism
    Unobservable
  • Adularia characteristic physical properties

    Hardness
    6
    CharacteristicComments
    Streak
    White
    SpecificGravity
    2.55-2.61 Typical:2.58
    Toughness
    Inclusions
    Adularia will display white or blue 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
    Fracture
    Uneven, Splintery
    Cleavage
    Perfect, in two directions