Spessartine


Spessartine
Spessartine

Spessartine from China
General
Category Nesosilicate
Chemical formula Mn(II)3Al2(SiO4)3
Strunz classification 09.AD.25
Identification
Molar mass 495.03 g
Color yellow through red
Crystal habit massive to crystalline
Crystal system Isometric - Hexoctahedral
Fracture sub Conchoidal
Tenacity brittle
Mohs scale hardness 6.5 - 7.5
Luster vitreous
Streak white
Diaphaneity transparent to translucent
Specific gravity 4.15 (+.05, -.03)[1]
Optical properties Isotropic, often anomalous double refractive
Refractive index 1.810 (+.004, -.020)
Birefringence none
Dispersion weak
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]
References [2][3][4]

Spessartine previously named spessartite, is a nesosilicate, manganese aluminium garnet species, Mn(II)3Al2(SiO4)3.[2][3][1][4]

The name is a derivative of Spessart in Bavaria, Germany, the type locality of the mineral.[2][3] It occurs most often in granite pegmatite[2][3][4] and allied rock types and in certain low grade metamorphic phyllites. Sources include Australia, Myanmar, India, Afghanistan, Israel, Madagascar, Tanzania and the US.[1] Spessartine of an orange-yellow has been called Mandarin garnet and is found in Madagascar. . Violet-red spessartines are found in rhyolites in Colorado and Maine.

Spessartine forms a solid solution series with the garnet species almandine.[3][4] Well formed crystals from this series, varying in color from very dark-red to bright yellow-orange were found in Latinka, Rhodope Mountains, Kardzhali Province, Bulgaria [5] .

References

Spessartine crystal on muscovite matrix from Tanzania