Quahog Pearls Gemstone & Information | Gemopedia by JTV | Gemopedia™

Quahog Pearls

Among America's rarest and most stunning pearls, quahog pearls were first valued by Native Americans along the coast of New England. This non-nacreous calcareous concretion forms in colors from white to brown, to purple and lilac in round, button and teardrop shapes. Such pearls are typically collected by fishermen as a result of harvesting the meat of the shellfish.

Colors

White, Beige, Brown, Black, Purple, Lavender

  • Quahog-pearls classification

    CommonName
    Quahog Pearls
    Species
    NA
    Variety
    Colors
    White, Beige, Brown, Black, Purple, Lavender
    AlternateNames
    Cohog And Quohog
    GemstoneGroups
    KeySeparations
    Appearance, RI, birefringence blink and magnification. A "tooth test" is commonly used in which a pearl is rubbed against a tooth; if gritty, this is an indication that the surface is nacre, versus plastic and glass imitations that feel smooth.
    ClassificationComments
    Quahog pearls were used as trade goods by Native Americans. They are produced by the bivalve clam Venus mercenaria or Mercenaria mercenaria. Most prized specimens are the lavender and purple shades.
  • Quahog-pearls chemistry & crystallography

    ChemicalName
    Calcium carbonate, conchiolin and water
    ChemicalFormula
    CaCO3 with H2O and other organic materials
    Synthesis
    CrystalSystem
    NA
    ChemistryClassification
    Organic
    Nature
    Natural
    Crystallinity
    Aggregate
    ChemistryComments
  • Quahog-pearls optical properties

    Transparency
    Translucent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.53-1.685
    Birefringence
    0.155
    OpticCharacter
    NA
    OpticSign
    NA
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV:
    LWUV:
    CCFReaction
    Pleochroism
    None
  • Quahog-pearls characteristic physical properties

    Hardness
    2.5-4.5
    CharacteristicComments
    Streak
    SpecificGravity
    2.61-2.85
    Toughness
    Good
    Inclusions
    Quahog pearls are non-nacreous with fibrous structure. They have a color banding that sometimes creates an "eye" effect.
    Luster
    Dull
    Stability
    Poor
    Fracture
    Uneven
    Cleavage
    None