Cassiterite Gemstone & Information | Gemopedia by JTV | Gemopedia™

Cassiterite

There are very few tin minerals and cassiterite is the best known. Gemstones fashioned from cassiterite are quite striking. This is due in good part to its high dispersion, which is nearly double that of diamond. It is especially prized by gemologists and mineralogists for its unusual twinned crystal formations. Durable and dense, it has been used as the chief ore of tin from early history throughout the ages, and remains so even today. Many of the economical Cassiterite deposits exist in placer stream deposits where this very heavy mineral collects as rounded water worn pebbles. The name Cassiterite is derived from the Greek "kassiteros", meaning tin.

Colors

Dark Brown, Black, Yellowish Brown, Yellow, Colorless Banded With Brown

  • Cassiterite classification

    CommonName
    Cassiterite
    Species
    Cassiterite
    Variety
    Colors
    Dark Brown, Black, Yellowish Brown, Yellow, Colorless Banded With Brown
    AlternateNames
    Tin Stone, Tin Ore, Wood Tin, Toad's Eye Tin
    GemstoneGroups
    Rutile
    KeySeparations
    Doubling, SG, optic character
    ClassificationComments
    Rare
  • Cassiterite chemistry & crystallography

    ChemicalName
    ChemicalFormula
    SnO2
    Synthesis
    CrystalSystem
    Tetragonal
    ChemistryClassification
    Oxide
    Nature
    Natural
    Crystallinity
    Crystalline
    ChemistryComments
  • Cassiterite optical properties

    Transparency
    Transparent - Opaque
    Dispersion
    Strength: strong fire Value: 0.071
    OpticalComments
    RefractiveIndex
    Over The Limit 1.997-2.098
    Tolerance:(+0.009/-0.006)
    Birefringence
    0.096-0.098
    OpticCharacter
    Uniaxial
    OpticSign
    Positive
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: Inert
    LWUV: Inert
    CCFReaction
    Pleochroism
    Trichroic, weak to moderate greenish yellow, brown, reddish brown
  • Cassiterite characteristic physical properties

    Hardness
    6-7
    CharacteristicComments
    Streak
    White To Light Yellow
    SpecificGravity
    7.03-6.87 Typical:6.95
    Toughness
    Varies
    Inclusions
    Cassiterite is typically color zoned and has strong doubling and fire.
    Luster
    SubAdamantine
    Stability
    Fracture
    Conchoidal, Uneven
    Cleavage
    Good, in one direction