Spessartite

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Revision as of 04:41, 11 March 2010 by Tim (talk | contribs) (Localities)
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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
Nigerian Spessartite garnet
Photo courtesy of Lembeck Gems

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).

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.

Inclusion images

Inclusions in a manderine garnet
Photo courtesy of John Huff, gemcollections.com
Double refractive crystal inclusion in a Loliondo, Tanzania spessartite.
© Tim Spauwen, FGA
Crystal inclusions amidst the typical "sugary inclusions" in a Loliondo, Tanzania spessartite.
© Tim Spauwen, FGA




Localities

  • Sri Lanka (Ceylon)
  • Burma
  • Brazil
  • Madagascar
  • Mozambique
  • Nigeria
  • Namibia
  • Tanzania
  • USA
  • China
  • Pakistan
  • Afghanistan
  • Myanmar
  • India
  • Italy
  • Norway
  • France
  • Germany
  • Sweden
  • Scotland
  • Russia
Faceted Mozambique Spessartite garnet
Photo courtesy of The Gem Trader