Achroite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Achroite

Achroite refers to the colorless variety of tourmaline. An elbaite tourmaline variety, these gems are very rare and especially prized by collectors.

Colors

Colorless

  • Achroite classification

    CommonName
    Achroite
    Species
    Tourmaline
    Variety
    Achroite
    Colors
    Colorless
    AlternateNames
    GemstoneGroups
    Tourmaline
    KeySeparations
    refractive index and high birefringence; then optic figure and specific gravity
    ClassificationComments
  • Achroite chemistry & crystallography

    ChemicalName
    complex boro-silicate of Al, Mg and Fe
    ChemicalFormula
    Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
    Synthesis
    CrystalSystem
    Trigonal
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Achroite optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: weak fire Value: 0.017
    OpticalComments
    RefractiveIndex
    1.624-1.644
    Tolerance:(+0.011/-0.009)
    Birefringence
    0.018-0.02
    OpticCharacter
    Uniaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    None
  • Achroite characteristic physical properties

    Hardness
    7-7.5
    CharacteristicComments
    Streak
    White
    SpecificGravity
    3-3.26 Typical:3.06
    Toughness
    Fair
    Inclusions
    Achroite has liquid and gas inclusions that are long and thin, reflective gas-filled fractures and color zoning.
    Luster
    Vitreous
    Stability
    Very Good
    Fracture
    Conchoidal, Uneven
    Cleavage
    Poor