Iris Quartz Gemstone & Information | Gemopedia by JTV | Gemopedia™
This unique variety of quartz displays phenomenal iridescence. Its beautiful rainbow of color is caused by reflection and refraction of light within the tiny parallel crystal layers within its structure. Fittingly, it is also called "aurora quartz," "iridescent quartz" or "rainbow quartz."
Colorless, Slightly Purple, Yellow Displaying Internal Spectral Colors
Iris-quartz classificationCommonNameIris QuartzSpeciesQuartzVarietyIris QuartzColorsColorless, Slightly Purple, Yellow Displaying Internal Spectral ColorsAlternateNamesRainbow QuartzGemstoneGroupsKeySeparationsRefractive index, appearance, birefringence, optic character and optic figure. A bull's-eye optic figure is determinative for quartz; may also show Airy's spiral optic figure and Brazil-law twinning under crossed polarizing filters.ClassificationCommentsThis interference phenomenon in iris quartz is due to reflection and refraction on extremely thin parallel brazil-law twinning lamellae. The rainbow quartz name used for other types of quartz, including those showing internal interference colors caused by fractures ("crack rainbows"), and interference colors caused by superficial thin films of limonite or other minerals.
Iris-quartz chemistry & crystallographyChemicalNamesilicon dioxide (aka silica)ChemicalFormulaSiO2SynthesisCrystalSystemTrigonalChemistryClassificationSilicateNatureNaturalCrystallinityCrystallineChemistryComments
Iris-quartz optical propertiesTransparencyTransparent - TranslucentDispersionStrength: weak fire Value: 0.013OpticalCommentsRefractiveIndex1.544-1.553
Tolerance:very constantBirefringence0.009OpticCharacterUniaxialOpticSignPositivePolariscopeReactionSingly Refractive (SR) With ADRFluorescenceSWUV: Inert
Iris-quartz characteristic physical propertiesHardness7CharacteristicCommentsStreakWhiteSpecificGravity2.64-2.69 Typical:2.66ToughnessGoodInclusionsIris quartz may contain liquid, two-phase and three-phase inclusions, negative crystals, minerals, needles, rutile and iron particles.LusterVitreousStabilityGoodFractureConchoidalCleavageNone