Hydrogrossular Garnet Gemstone & Information | Gemopedia by JTV | Gemopedia™

Hydrogrossular Garnet

Hydrogrossular garnet is typically translucent to opaque and is usually available as cabochons, but on rare occasion may be found as transparent, faceted gemstones. Generally seen as green to blue-green, pink, white, and gray, this gemstone may contain small dark gray to black inclusions and may look similar to jade if opaque. Hydrogrossular is a variety of grossular garnet where hydroxide partially replaces silica.

Colors

Green To Bluish Green, Pink, Brownish Pink, Rose Red, White, Gray

  • Hydrogrossular-garnet classification

    CommonName
    Hydrogrossular Garnet
    Species
    Hydrogrossular
    Variety
    Colors
    Green To Bluish Green, Pink, Brownish Pink, Rose Red, White, Gray
    AlternateNames
    GemstoneGroups
    Garnet
    KeySeparations
    RI, spectrum, appearance and maybe SG. If the stone is mixed with idocrase a clear identification is not possible.
    ClassificationComments
    Misnomers: African jade or Transvaal jade, garnet jade.
  • Hydrogrossular-garnet chemistry & crystallography

    ChemicalName
    calcium aluminum silicate with water or hydroxal
    ChemicalFormula
    Ca3Al2(SiO4)3-x(OH)4x with (OH) partly replacing (SiO4)
    Synthesis
    CrystalSystem
    Cubic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Aggregate
    ChemistryComments
  • Hydrogrossular-garnet optical properties

    Transparency
    Translucent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.72-1.72
    Tolerance:(+0.010/-0.050)
    Birefringence
    OpticCharacter
    NA
    OpticSign
    NA
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Green: possibly pinkish
    Pleochroism
    None
  • Hydrogrossular-garnet characteristic physical properties

    Hardness
    7
    CharacteristicComments
    Streak
    SpecificGravity
    3.15-3.55 Range:0.08/-0.32 Typical:3.47
    Toughness
    Good
    Inclusions
    Might have black magnetite inclusions that resemble pepper.
    Luster
    Vitreous
    Stability
    Good
    Fracture
    Uneven, Granular, Splintery
    Cleavage
    None