Moonstone-Orthoclase Gemstone & Information | Gemopedia by JTV | Gemopedia™

Moonstone is a variety of feldspar that displays an amazing optical phenomenon called, adularescence. Internally repeating feldspar layers scatter the light that enters the stone creating a mystical white glow reminiscent of moonbeams. This glow comes to life, rolling across the gems surface, when it is moved. Traditionally, adularescent orthoclase gems have been called moonstone, however, other varieties of feldspar also exhibit this magical effect, including labradorite.
Colors
Colorless To White, Orange, Yellow, Brown
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Moonstone-orthoclase classification
CommonNameMoonstone-OrthoclaseSpeciesOrthoclaseVarietyMoonstoneColorsColorless To White, Orange, Yellow, BrownAlternateNamesStar MoonstoneGemstoneGroupsFeldsparKeySeparationsRI, biaxial interference figure in polariscope and magnification. Fluorescence and SG might also be useful.ClassificationCommentsMoonstone can also be labradorite feldspar. -
Moonstone-orthoclase chemistry & crystallography
ChemicalNamepotassium aluminum silicateChemicalFormulaKAlSi3O8SynthesisCrystalSystemMonoclinicChemistryClassificationSilicateNatureNaturalCrystallinityPolycrystallineChemistryComments -
Moonstone-orthoclase optical properties
TransparencySemitransparent - OpaqueDispersionOpticalCommentsRefractiveIndex1.518-1.526
Tolerance:(+0.010/-0.010)Birefringence0.005-0.008OpticCharacterBiaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: inert to weak pink to red or orange
LWUV: inert to weak yellowish white, blue, pink or redCCFReactionPleochroismUnobservable -
Moonstone-orthoclase characteristic physical properties
Hardness6CharacteristicCommentsStreakWhiteSpecificGravity2.55-2.61 Range:+/-0.03 Typical:2.58ToughnessPoorInclusionsMoonstone will have blue or white 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.LusterVitreousStabilityGoodFractureUneven, SplinteryCleavagePerfect, in two directions