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Geosciences LibreTexts

16.08.05: Spessartite

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    4136
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    Spessartite Garnet
    Chemical composition Mn3Al2(SiO4)3

    Manganese aluminum silicate

    Crystal system Cubic
    Habit Dodecahedra
    Cleavage None
    Hardness 7
    Optic nature Isotropic
    Refractive index 1.795-1.815
    Birefringence None
    Specific gravity 4.12-4.20
    Lustre Vitreous

    Figure \(\PageIndex{1}\): Spessartite with Smoky Quartz
    Photo courtesy of Barbra Voltaire

     

    Spessartite image gallery

    Spessartite is also named spessartine, both names are used interchangeably.

    Diagnostics

    Color

    Orange, red, reddish-orange to yellowish-brown.

    Spectroscope

    Spessartite shows a typical spectrum due to manganese (idiochromatic) and some iron (from almandine).

    Figure \(\PageIndex{2}\): Spectra of a spessartite from the Loliondo deposit in tanzania which was discovered in 2007. The graphs represent the transmission spectrum taken with the aid of a spectrometer, the spectrum below is what you will see through a spectroscope

    Inclusions

    • Feathers of liquid droplets ("shredded inclusions"), negative crystals, crystal inclusions, "suger"; multiple tiny grains (Tanzanian stones) , small colorless fibers of tirodite which cause a sleepy look (Namibian stones)

    Specific gravity

    4.12 - 4.20

    Spessartite sinks in all common heavy liquids.

    Chelsea Colour Filter

    Spessartite will show red under the CCF.

    Varieties

    Mandarine/Kashmirine/Hollandine

    Three names for the same intense orange variety of spessartite.

    Malaia

    Main entry: pyrope

    Malaia garnet (or malaya garnet) is the red-orange variety of pyrope-spessartite.

    Localities

    • Sri Lanka (Ceylon)
    • Burma
    • Brazil
    • Madagascar
    • Mozambique
    • Nigeria
    • Namibia
    • Tanzania
    • USA
    • China
    • Pakistan
    • Afghanistan
    • Myanmar
    • India
    • Italy
    • Norway
    • France
    • Germany
    • Sweden
    • Scotland
    • Russia