My watch list

Spessartine

Spessartine
Spessartite (the yellow mineral)
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.