Jet Gemstone & Information | Gemopedia by JTV | Gemopedia™
Jet is generally classified as a lignite coal and has a high carbon content and a layered structure. It is typically black to dark brown and can sometimes contain tiny inclusions of pyrite. Jet has been carved for ornamental purposes since prehistoric times.
Very Dark Brown To Black
Jet classificationCommonNameJetSpeciesJetVarietyColorsVery Dark Brown To BlackAlternateNamesWhitby JetGemstoneGroupsKeySeparationsRI and SG(low heft), hot point coal like smell. Stones have very low heft and will sometimes have a spot RI of 1.680.ClassificationCommentsMisnomer: black amber. Warm to touch. Becomes electrically charged when rubbed with wool. Jet will break rather than than curl when shaved.
Jet chemistry & crystallographyChemicalNamehydrated hydro carbonChemicalFormulaC,H,O-2H2OSynthesisCrystalSystemNAChemistryClassificationOrganicNatureNaturalCrystallinityNon-CrystallineChemistryComments
Jet optical propertiesTransparencySemitranslucent - OpaqueDispersionStrength: noneOpticalCommentsRefractiveIndex1.66
Tolerance:(+0.020/-0.020)BirefringenceOpticCharacterNAOpticSignPolariscopeReactionSingly Refractive (SR)FluorescenceSWUV: inert
Jet characteristic physical propertiesHardness2.5-4CharacteristicCommentsStreakBlack-BrownSpecificGravity1.19-1.34 Typical:1.32ToughnessPoorInclusionsIn some Jet specimens the original wood structure can be seen.LusterVitreousStabilityFractureConchoidalCleavageNone