Adularia Gemstone & Information | Gemopedia by JTV | Gemopedia™
Adularia is a variety of feldspar found in hydrothermal veins in mountainous areas, from one of which it derives its name: the Adular Mountains of Switzerland. It commonly forms colorless to white, cream, pale yellow to pink, or reddish-brown, glassy, prismatic, twinned crystals. These transparent to colorless gems often display a white to blue sheen.
Colorless With White, Blue Sheen
Adularia classificationCommonNameAdulariaSpeciesOrthoclaseVarietyAdulariaColorsColorless With White, Blue SheenAlternateNamesGemstoneGroupsFeldsparKeySeparationsrefractive index, birefringence, optic character and possibly spectrum and fluorescenceClassificationCommentsThis stone comes from Adula mountains in Switzerland and this is where the phenomena adularescence gets its name.
Adularia chemistry & crystallographyChemicalNamepotassium aluminum silicateChemicalFormulaKAlSi3O8SynthesisCrystalSystemMonoclinicChemistryClassificationSilicateNatureNaturalCrystallinityCrystallineChemistryComments
Adularia optical propertiesTransparencyTransparent - TranslucentDispersionStrength: weak fire Value: 0.12OpticalCommentsRefractiveIndex1.518-1.526
Tolerance:(+0.010/-)0.010)Birefringence0.005-0.008OpticCharacterBiaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: Inert to weak orangy red
LWUV: Inert to weak blue or pinkCCFReactionPleochroismUnobservable
Adularia characteristic physical propertiesHardness6CharacteristicCommentsStreakWhiteSpecificGravity2.55-2.61 Typical:2.58ToughnessInclusionsAdularia will display white or blue adularescence. Stones might have centipede like inclusions and material with aventuresence or asterism might contain reflective inclusions such as fine needles or elongated hematite platelets.LusterVitreousStabilityFractureUneven, SplinteryCleavagePerfect, in two directions