Orpiment Gemstone & Information | Gemopedia by JTV | Gemopedia™

Orpiment

Orpiment is an arsenic sulfide that grows in small masses with lemon-yellow to brownish-yellow coloring. Its name comes from a Latin term meaning "gold pigment," as this mineral was once used to make yellow paint. This gem is photosensitive and should not be exposed to light for prolonged periods.

Colors

Orange-Yellow, Golden Yellow, Brownish Yellow To Lemon Yellow

  • Orpiment classification

    CommonName
    Orpiment
    Species
    Orpiment
    Variety
    Colors
    Orange-Yellow, Golden Yellow, Brownish Yellow To Lemon Yellow
    AlternateNames
    Yellow Arsenic
    GemstoneGroups
    KeySeparations
    OTL RI, SG and extreme fire.
    ClassificationComments
    This stone contains arsenic and special care needs to be used. Always wash your hands after handling.
  • Orpiment chemistry & crystallography

    ChemicalName
    arsenic sulfide
    ChemicalFormula
    As2S3
    Synthesis
    CrystalSystem
    Monoclinic
    ChemistryClassification
    Sulfide
    Nature
    Natural
    Crystallinity
    Crystalline to Aggregate
    ChemistryComments
  • Orpiment optical properties

    Transparency
    Transparent - Translucent
    Dispersion
    Strength: extreme fire
    OpticalComments
    RefractiveIndex
    Over the Limit 2.4-3.02
    Birefringence
    0.62
    OpticCharacter
    Biaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    Dichroic, strong yellow and greenish yellow
  • Orpiment characteristic physical properties

    Hardness
    1.5-2
    CharacteristicComments
    Streak
    Light Lemon Yellow
    SpecificGravity
    3.4-3.56 Typical:3.49
    Toughness
    Poor
    Inclusions
    Orpiment is usually found as a fibrous aggregate.
    Luster
    Pearly
    Stability
    Fracture
    Cleavage
    Perfect, in one direction, Good, in one direction