Scapolite (Cat's-Eye) Gemstone & Information | Gemopedia by JTV | Gemopedia™
The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case scapolite. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line. Gem quality scapolite is rare and highly treasured by gem collectors, particularly when exhibits chatoyancy.
Colors
White, Pink, Violet, Yellow, Reddish Brown, Brown
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Scapolite-cats-eye classification
CommonNameScapolite (Cat's-Eye)SpeciesScapoliteVarietyCat's-Eye ScapoliteColorsWhite, Pink, Violet, Yellow, Reddish Brown, BrownAlternateNamesGemstoneGroupsScapoliteKeySeparationsRI, birefringence, optic character and possible fluorescence. Use birefringence blink method on reddish brown material to separate from cat's-eye beryl.ClassificationCommentsRI in reddish brown material is usually between 1.560 to 1.585 and birefringence is around 0.025Birefringence typically 0.004 to 0.020 but it increases as the stones RI increases. -
Scapolite-cats-eye chemistry & crystallography
ChemicalNamesodium or calcium aluminum silicate carbonate chlorideChemicalFormulaNa4Al3Si9O24Cl to Ca4Al6Si6O24(CO3, SO4)SynthesisCrystalSystemTetragonalChemistryClassificationSilicateNatureNaturalCrystallinityCrystalline to AggregateChemistryComments -
Scapolite-cats-eye optical properties
TransparencySemitransparent - OpaqueDispersionOpticalCommentsRefractiveIndex1.55-1.585
Tolerance:(+0.015/-0.014)Birefringence0.004-0.037OpticCharacterUniaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV:
LWUV:CCFReactionPleochroismUnobservable -
Scapolite-cats-eye characteristic physical properties
Hardness6-6.5CharacteristicCommentsStreakWhiteSpecificGravity2.6-2.74 Typical:2.68ToughnessFairInclusionsThe eye in cat's-eye scapolite is distinct and sharp. White, pink or violet material appears fibrous because hollow tubes create the chatoyancy. The cats-eye in reddish brown and brown material is caused by black and orange-red needle like crystals, elongated platelets or dendritic inclusions.LusterVitreousStabilityFractureConchoidalCleavageGood, in two directions