Impregnated Turquoise Gemstone & Information | Gemopedia by JTV | Gemopedia™
As it occurs naturally, turquoise is a soft mineral that is easily scratched. Its porous nature can allow the absorption of oils and fluids that can discolor it over time. To improve its durability and appearance, much of the turquoise on the market today is stabilized. One popular method of stabilization is impregnation, which fills the porous areas with a colorless agent, usually plastic.
Slightly Yellowish Green If Wax Impregnated, Greenish Blue If Impregnated With Plastic
Impregnated-turquoise classificationCommonNameImpregnated TurquoiseSpeciesTurquoiseVarietyColorsSlightly Yellowish Green If Wax Impregnated, Greenish Blue If Impregnated With PlasticAlternateNamesImpregnated TuruqoisGemstoneGroupsKeySeparationsRI, magnification, SG, spectrum and acrid smell and sweating effect if hot point test is usedClassificationCommentsIf stones are heavily treated the RI can be as low as 1.56. If SG is below 2.60 and has fine color it is a fine indication that some impregnation has occurred. Some heavily treated material can have SG's as low as 1.80 to 2.00.
Impregnated-turquoise chemistry & crystallographyChemicalNamehydrated copper aluminum phosphateChemicalFormulaCuAl6(PO4)4(OH)8-5H2OSynthesisCrystalSystemTriclinicChemistryClassificationPhosphateNatureNaturalCrystallinityAggregateChemistryComments
Impregnated-turquoise optical propertiesTransparencySemitranslucent - OpaqueDispersionStrength: noneOpticalCommentsRefractiveIndex1.6-1.61Birefringence0.04OpticCharacterBiaxialOpticSignPositivePolariscopeReactionAggregate (AGG)FluorescenceSWUV: Inert
LWUV: Inert to weak greenish yellowCCFReactionPleochroismNone
Impregnated-turquoise characteristic physical propertiesHardness5-6CharacteristicCommentsStreakSpecificGravity2.5-2.6ToughnessVariesInclusionsImpregnated turquoise often has brown, gray or black matrix that is recessed below polished surface. Stones will have a higher luster than natural turquoise. Stones may contain pyrite or calcite inclusions. Stones can have a speckled appearance similar to the "cream-of-wheat" effect if wax impregnated.LusterVitreousStabilityFractureConchoidal, GranularCleavageNone