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Spessartine



Spessartine

Spessartite (the yellow mineral)
General
CategoryMineral
Chemical formulaMn3Al2(SiO4)3
Identification
Coloryellowish orange to reddish orange [1]
Crystal systemcubic [1]
Cleavagenone
Fractureconchoidal [1]
Mohs Scale hardness7 - 7.5 [1]
Lustervitreous
Polish lustervitreous to subadamantine [1]
Refractive index1.810 (+.004, -.020)
Optical PropertiesSingle refractive, often anomalous double refractive [1]
Birefringencenone
Dispersion.027 [1]
Pleochroismnone
Ultraviolet fluorescenceinert [1]
Absorption spectrabands at 410, 420, 430nm (or merging to form cutoff below 430nm; also bands at 460, 480, 520nm. Possible weak bands at 504, or 573nm [1]
Specific gravity4.15 (+.05, -.03)[1]

Spessartine previously named spessartite, is a nesosilicate, manganese aluminium garnet, Mn3Al2(SiO4)3.[1] The names is a derivative of Spessart in Bavaria. It occurs most often in granite pegmatite and allied rock types and in certain low grade metamorphic phyllites. The major sources for gem quality spessartine are Sri Lanka and Brazil. Other sources include Australia, Burma, India, Israel, Madagascar and the US.[1] Spessartine of a orange-yellow is found in Madagascar (see Mandarin garnet). Violet-red spessartites are found in rhyolites in Colorado and Maine.

Additional recommended knowledge



References

  1. ^ a b c d e f g h i j k l Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN:0-87311-019-6
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Spessartine". A list of authors is available in Wikipedia.
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