Sphalerite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Sphalerite

With greater dispersion than diamond, sphalerite is an intriguing, yet challenging, gem. Known primarily to collectors due to its lack of hardness, sphalerite can try the patience of even the most highly skilled lapidaries who dare to fashion it into a finished gem. Not only is it extremely soft, it also has perfect cleavage, in six directions, making it extremely difficult to cut and polish! Add in the fact that it's a brittle gem, and you have an idea of the challenge that awaits its potential cutter. When that talented lapidary is, however, able to complete his task with a fashioned gem, the results are more than worth the lapidary's efforts!

Colors

Green, Yellow, Orange, Red, Brown, Gray To Black

  • Sphalerite classification

    CommonName
    Sphalerite
    Species
    Sphalerite
    Variety
    Colors
    Green, Yellow, Orange, Red, Brown, Gray To Black
    AlternateNames
    Cleiophane, Marmatite, Zinc Blende
    GemstoneGroups
    KeySeparations
    SR nature, magnification, cleavage, spectrum, very strong dispersion, SG and possible fluorescence.
    ClassificationComments
    Cleiophane can range from nearly colorless and pale yellow to light green. Marmatite is the black variety usually found in Marmato, Italy. Ruby Blende is the red variety of sphalerite. Stones are rarely chatoyant.
  • Sphalerite chemistry & crystallography

    ChemicalName
    zinc iron sulfide
    ChemicalFormula
    (Zn,Fe)S
    Synthesis
    CrystalSystem
    Cubic
    ChemistryClassification
    Sulfide
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Sphalerite optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: extreme fire Value: 0.156
    OpticalComments
    RefractiveIndex
    Over the Limit 2.369-2.5
    Birefringence
    OpticCharacter
    NA
    OpticSign
    NA
    PolariscopeReaction
    Singly Refractive (SR)
    Fluorescence
    SWUV: Inert to strong orange-red
    LWUV: Inert to strong orange-red
    CCFReaction
    Pleochroism
    None
  • Sphalerite characteristic physical properties

    Hardness
    3.5-4
    CharacteristicComments
    Streak
    Yellowish To Light Brown
    SpecificGravity
    3.9-4.1 Typical:4.05
    Toughness
    Poor
    Inclusions
    Sphalerite is frequently color zoned and has very strong dispersion.
    Luster
    Adamantine
    Stability
    Fracture
    Conchoidal, Uneven
    Cleavage
    Perfect, in six directions