16.8.5: Spessartite
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Spessartite Garnet | |
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Chemical composition | Mn3Al2(SiO4)3anganese 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 16.8.5.1: 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 16.8.5.2: 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
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