Sard Gemstone & Information | Gemopedia by JTV | Gemopedia™

Sard

Sard is a translucent chalcedony that is light to dark reddish-brown. It is formed from the deposition of silica at low temperatures from silica-rich waters percolating through cracks and fissures in other rocks. Sard is darker and browner in tone than carnelian.

Colors

Dark Brownish Red To Orangy Brown To Brown

  • Sard classification

    CommonName
    Sard
    Species
    Quartz
    Variety
    Chalcedony
    Colors
    Dark Brownish Red To Orangy Brown To Brown
    AlternateNames
    GemstoneGroups
    KeySeparations
    RI, SG, appearance and fracture
    ClassificationComments
    sard is darker and less saturated in color than carnelian.
  • Sard chemistry & crystallography

    ChemicalName
    silicon dioxide (aka silica)
    ChemicalFormula
    SiO2
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Polycrystalline
    ChemistryComments
  • Sard optical properties

    Transparency
    Semitransparent - Semitranslucent
    Dispersion
    Strength: none
    OpticalComments
    RefractiveIndex
    1.535-1.539
    Birefringence
    0.004-0.004
    OpticCharacter
    Uniaxial
    OpticSign
    Positive
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    None
  • Sard characteristic physical properties

    Hardness
    6.5-7
    CharacteristicComments
    Streak
    White
    SpecificGravity
    2.55-2.7 Typical:2.6
    Toughness
    Excellent
    Inclusions
    Luster
    Vitreous
    Stability
    Good
    Fracture
    Conchoidal, Granular
    Cleavage
    None