Elbaite (Tourmaline) Gemstone & Information | Gemopedia by JTV | Gemopedia™
The tourmaline family consists of at least 14 distinct minerals, but the variety elbaite accounts for nearly all gem-quality tourmaline. It was named as a result of the colored and colorless tourmalines found on the picturesque island of Elba off the western coast of Italy--history buffs know this island as the place where Napoleon Bonaparte was exiled in 1814. Although best known in shades of green and red, elbaite can also be blue, purple, yellow, or colorless. Notable varieties of elbaite include rubellite, green tourmaline, indicolite, watermelon tourmaline, Paraiba tourmaline and colorless.
Green, Blue, Red, Orange, Yellow, Colorless
Elbaite-tourmaline classificationCommonNameElbaite (Tourmaline)SpeciesElbaiteVarietyColorsGreen, Blue, Red, Orange, Yellow, ColorlessAlternateNamesGemstoneGroupsKeySeparationsappearance, refractive index and high birefringence; then optic figure, pleochroism and specific gravityClassificationCommentsDark material might have birefringence as high as 0.040Paraba Tourmaline is a Cuprian Elbaite.Rubellite is the red to pink variety.
Elbaite-tourmaline chemistry & crystallographyChemicalNamecomplex boro-silicate of Al, Mg and FeChemicalFormulaNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)SynthesisCrystalSystemTrigonalChemistryClassificationSilicateNatureNaturalCrystallinityCrystallineChemistryComments
Elbaite-tourmaline optical propertiesTransparencyTransparent - TranslucentDispersionStrength: moderate fire Value: 0.017OpticalCommentsRefractiveIndex1.614-1.666Birefringence0.014-0.032OpticCharacterUniaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: Inert
LWUV: InertCCFReactionPleochroismDichroic, moderate to strong, varying shades of body color
Elbaite-tourmaline characteristic physical propertiesHardness7-7.5CharacteristicCommentsStreakWhiteSpecificGravity2.9-3.1ToughnessGoodInclusionsGreen elbaite tourmaline stones are type I clarity stones. Blue, purple, orange, yellow and bi-color or parti-colored elbaite tourmalines are type II clarity stones. Stones might contain liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.LusterVitreousStabilityVery GoodFractureConchoidal, UnevenCleavagePoor, in two directions