Prehnite Gemstone & Information | Gemopedia by JTV | Gemopedia™
Prehnite is the first gemstone named for a person. It was named in honor of Colonel Hendrik Von Prehn, the Dutch mineralogist credited with its discovery in the 1700's in South Africa. Also, prehnite was the first mineral to be named and described from South Africa, long before the country became an important source for precious gems, including diamond. Many specimens of this gem have an interesting luminous quality, with a vitreous to mother-of-pearl luster. With color ranging from pale green to a pale yellowish green and a hardness of 6 - 6.5, Prehnite is considered to be fairly sturdy and long wearing when set in jewelry.
Light Green To Yellowish Green, Gray, Rarely White
Prehnite classificationCommonNamePrehniteSpeciesPrehniteVarietyColorsLight Green To Yellowish Green, Gray, Rarely WhiteAlternateNamesGemstoneGroupsKeySeparationsRI, birefringence, and spectrum. Might have to use birefringence blink method.ClassificationComments
Prehnite chemistry & crystallographyChemicalNamecalcium aluminum silicate hydroxideChemicalFormulaCa2Al2Si3O10(OH)2SynthesisCrystalSystemOrthorhombicChemistryClassificationSilicateNatureNaturalCrystallinityCrystalline to AggregateChemistryComments
Prehnite optical propertiesTransparencyTranslucentDispersionOpticalCommentsRefractiveIndex1.616-1.649Birefringence0.02-0.033OpticCharacterBiaxialOpticSignPositivePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: Inert
Prehnite characteristic physical propertiesHardness6-6.5CharacteristicCommentsStreakWhiteSpecificGravity2.8-2.95 Typical:2.9ToughnessVariesInclusionsPrehnite can contain epidote and copper inclusions.LusterVitreousStabilityGoodFractureConchoidal, UnevenCleavageGood, in one direction, Poor, in one direction