Idocrase Gemstone & Information | Gemopedia by JTV | Gemopedia™

Idocrase

Idocrase, also known as vesuvianite after its discovery at Mount Vesuvius, has crystals that are prismatic and glassy. It is usually green or chartreuse in color, but may be found in yellow to brown, yellow-green, red, black, blue or purple hues.

Colors

Yellow To Green, Yellowish Brown, Light Blue To Greenish Blue, Gray, White

  • Idocrase classification

    CommonName
    Idocrase
    Species
    Vesuvianite
    Variety
    Colors
    Yellow To Green, Yellowish Brown, Light Blue To Greenish Blue, Gray, White
    AlternateNames
    Vesuvianite, Californite, Xanthite, Cyprine
    GemstoneGroups
    KeySeparations
    RI, birefringence, optic character, spectrum, possible pleochroism
    ClassificationComments
    Jade-like variety of idocrase is often mixed with hydrogrossular garnet. Misnomers: California jade.
  • Idocrase chemistry & crystallography

    ChemicalName
    calcium magnesium aluminum silicate
    ChemicalFormula
    Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4
    Synthesis
    CrystalSystem
    Tetragonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline to Aggregate
    ChemistryComments
  • Idocrase optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: weak fire Value: 0.019
    OpticalComments
    RefractiveIndex
    1.713-1.718
    Tolerance:(+0.003/-0.013)
    Birefringence
    0.001-0.012
    OpticCharacter
    Uniaxial
    OpticSign
    Positive or Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: inert
    LWUV: inert
    CCFReaction
    Pleochroism
    Dichroic, unobservable or weak, varying shades of body color
  • Idocrase characteristic physical properties

    Hardness
    6.5
    CharacteristicComments
    Streak
    White
    SpecificGravity
    3.25-3.5 Typical:3.4
    Toughness
    Varies
    Inclusions
    Luster
    Vitreous
    Stability
    Fracture
    Conchoidal, Granular, Uneven
    Cleavage
    Poor, in three directions