Multi-Colored Tourmaline Gemstone & Information | Gemopedia by JTV | Gemopedia™
Multi-colored tourmaline is a variety of tourmaline containing two or more colors displayed in one crystal. Green and pink is the most prevalent combination, but others are possible. Multi-colored tourmaline may be referred to as "bi-colored tourmaline" or "tri-colored tourmaline," etc.
Variations Of Two, More Colors Usually Green, Blue, Red
Multi-colored-tourmaline classificationCommonNameMulti-Colored TourmalineSpeciesElbaiteVarietyColorsVariations Of Two, More Colors Usually Green, Blue, RedAlternateNamesParti-Colored Tourmaline, Bi-Color Tourmaline, Tri-Color TourmalineGemstoneGroupsTourmalineKeySeparationsappearance, refractive index and high birefringence; then optic figure, pleochroism and specific gravityClassificationCommentsNot all multi-colored tourmaline is elbaite tourmaline Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH).Dark material might have a birefringence as high as 0.040.Pyroelectric: development of opposite charges at the ends of a tourmaline crystal due to change in temperature. Piezoelectric: development of opposite charges at the ends of a tourmaline crystal when placed under stress.
Multi-colored-tourmaline chemistry & crystallographyChemicalNamecomplex boro-silicate of Al, Mg and FeChemicalFormulaNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)SynthesisCrystalSystemTrigonalChemistryClassificationSilicateNatureNaturalCrystallinityCrystallineChemistryComments
Multi-colored-tourmaline optical propertiesTransparencyTransparent - TranslucentDispersionStrength: moderate fire Value: 0.017OpticalCommentsRefractiveIndex1.624-1.644
Tolerance:-1.22222222222222Birefringence0.018-0.02OpticCharacterUniaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: Variable
LWUV: VariableCCFReactionPleochroismDichroic, moderate to strong, varying shades of body color
Multi-colored-tourmaline characteristic physical propertiesHardness7-7.5CharacteristicCommentsStreakWhiteSpecificGravity3-3.26 Typical:3.06ToughnessGoodInclusionsMulti-colored tourmaline is Type II clarity stone. Stones will have two or more color zones. Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.LusterVitreousStabilityVery GoodFractureConchoidal, Subconchoidal, Irregular, UnevenCleavagePoor, in two directions