Astrophyllite Gemstone & Information | Gemopedia by JTV | Gemopedia™
Astrophyllite is golden-yellow to dark brown and usually forms as bladed crystals radiating from a common center. It gets its name from the Greek astron, meaning "star", and phyllon, meaning "leaf." It may also be translated as "star sheets," fitting because of the interwoven star shapes that the crystals sometimes form and because of its strange luster, which can be metallic in some crystals and pearly in others. Although there are occurrences of astrophyllite around the world, some of the finest crystals come from remote mountainous regions in arctic northern Russia.
Brown, Reddish Brown, Golden Yellow, Bronze Like
Astrophyllite classificationCommonNameAstrophylliteSpeciesAstrophylliteVarietyColorsBrown, Reddish Brown, Golden Yellow, Bronze LikeAlternateNamesGemstoneGroupsKeySeparationsRI, optic character and appearanceClassificationComments
Astrophyllite chemistry & crystallographyChemicalNamepotassium sodium iron manganese titanium silicate hydroxideChemicalFormula(K,Na)3(Fe2+,Mn)7Ti2Si8O24(O,OH)7SynthesisCrystalSystemTriclinicChemistryClassificationSilicateNatureNaturalCrystallinityCrystalline to AggregateChemistryComments
Astrophyllite optical propertiesTransparencyTranslucent - OpaqueDispersionStrength: strong fireOpticalCommentsRefractiveIndex1.678-1.758BirefringenceOpticCharacterBiaxialOpticSignPositivePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV:
LWUV:CCFReactionPleochroismTrichroic, orangy red, orangy yellow, yellow
Astrophyllite characteristic physical propertiesHardness3CharacteristicCommentsStreakGoldenSpecificGravity3.2-3.4ToughnessPoorInclusionsThe stone is composed of star or leaf like sheets some of which can have a metallic or pearly luster.LusterGreasyStabilityFractureUnevenCleavagePerfect, in one direction, Poor, in one direction