Zoisite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Zoisite

Zoisite is a mineral species in the epidote group. The most celebrated variety is its blue to violet occurrence, tanzanite, but other zoisite colors include red, pink (thulite), green and purple. Discovered in the early 19th century, zoisite was named after Baron von Zois, an Austrian scientist and mineral collector.

Colors

Blue To Violet To Bluish Purple, Brown, Golden, Yellowish Green, Light Toned Pink, Parti-Colored Pink, Colorless

  • Zoisite classification

    CommonName
    Zoisite
    Species
    Zoisite
    Variety
    Zoisite
    Colors
    Blue To Violet To Bluish Purple, Brown, Golden, Yellowish Green, Light Toned Pink, Parti-Colored Pink, Colorless
    AlternateNames
    GemstoneGroups
    Epidote
    KeySeparations
    refractive index, birefringence, appearance, optic character and pleochroism
    ClassificationComments
    Tanzanite: transparent blue to violet to bluish purple. Thulite: translucent to opaque pink, often with mottled or streaked with gray or white. Ruby in zoisite: translucent to opaque rock like ornamental material with ruby crystals in green zoisite
  • Zoisite chemistry & crystallography

    ChemicalName
    calcium aluminum silicate hydroxide
    ChemicalFormula
    Ca2Al3(SiO4)3(OH)
    Synthesis
    CrystalSystem
    Orthorhombic
    ChemistryClassification
    Silicate
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Zoisite optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: weak fire Value: 0.021
    OpticalComments
    RefractiveIndex
    1.691-1.7
    Tolerance:(+0.005/-0.005)
    Birefringence
    0.008-0.013
    OpticCharacter
    Biaxial
    OpticSign
    Positive
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    Trichroic, (in green gems) strong green, yellow, and greenish brown
  • Zoisite characteristic physical properties

    Hardness
    6-7
    CharacteristicComments
    Streak
    White
    SpecificGravity
    3.1-3.45 Typical:3.35
    Toughness
    Varies
    Inclusions
    Zoisite is a type I clarity stone. Stones rarely needles, chromite inclusions, growth and etch tubes.
    Luster
    Vitreous
    Stability
    Good
    Fracture
    Conchoidal, Uneven
    Cleavage
    Perfect, in one direction, Good, in one direction