Quahog Pearls Gemstone & Information | Gemopedia by JTV | Gemopedia™
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.
White, Beige, Brown, Black, Purple, Lavender
Quahog-pearls classificationCommonNameQuahog PearlsSpeciesNAVarietyColorsWhite, Beige, Brown, Black, Purple, LavenderAlternateNamesCohog And QuohogGemstoneGroupsKeySeparationsAppearance, 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.ClassificationCommentsQuahog 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 & crystallographyChemicalNameCalcium carbonate, conchiolin and waterChemicalFormulaCaCO3 with H2O and other organic materialsSynthesisCrystalSystemNAChemistryClassificationOrganicNatureNaturalCrystallinityAggregateChemistryComments
Quahog-pearls optical propertiesTransparencyTranslucent - OpaqueDispersionOpticalCommentsRefractiveIndex1.53-1.685Birefringence0.155OpticCharacterNAOpticSignNAPolariscopeReactionAggregate (AGG)FluorescenceSWUV:
Quahog-pearls characteristic physical propertiesHardness2.5-4.5CharacteristicCommentsStreakSpecificGravity2.61-2.85ToughnessGoodInclusionsQuahog pearls are non-nacreous with fibrous structure. They have a color banding that sometimes creates an "eye" effect.LusterDullStabilityPoorFractureUnevenCleavageNone