Black Onyx Gemstone & Information | Gemopedia by JTV | Gemopedia™

Black Onyx

Onyx is a chalcedony quartz with a fine texture and parallel bands of alternate colors. This gem's name comes from the Greek word onyx which means fingernail or claw. Legend says that one day while the goddess Venus was sleeping, Cupid cut her fingernails and left the clippings scattered on the ground. Because no part of a heavenly body can die, the gods turned them into a gem, which later became known as onyx.

Colors

Black

  • Black-onyx classification

    CommonName
    Black Onyx
    Species
    Quartz
    Variety
    Chalcedony
    Colors
    Black
    AlternateNames
    Black Chalcedony
    GemstoneGroups
    KeySeparations
    RI, SG, appearance and fracture
    ClassificationComments
    Gray chalcodony that has been boiled in a sugar solution then exposed to sulphuric acid to produce black color.
  • Black-onyx chemistry & crystallography

    ChemicalName
    silicon dioxide (aka silica)
    ChemicalFormula
    SiO2
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Aggregate
    ChemistryComments
  • Black-onyx optical properties

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