Spessartine
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| Spessartine | |
|---|---|
 Spessartite (the yellow mineral)
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| General | |
| Category | Mineral |
| Chemical formula | Mn3Al2(SiO4)3 |
| Identification | |
| Color | yellowish orange to reddish orange [1] |
| Crystal system | cubic [1] |
| Cleavage | none |
| Fracture | conchoidal [1] |
| Mohs Scale hardness | 7 - 7.5 [1] |
| Luster | vitreous |
| Polish luster | vitreous to subadamantine [1] |
| Refractive index | 1.810 (+.004, -.020) |
| Optical Properties | Single refractive, often anomalous double refractive [1] |
| Birefringence | none |
| Dispersion | .027 [1] |
| Pleochroism | none |
| Ultraviolet fluorescence | inert [1] |
| Absorption spectra | bands 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 gravity | 4.15 (+.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.
[edit] External links
[edit] References
- ^ 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
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