Spessartine crystals on larger quartz crystals from China
|Crystal class||Hexoctahedral (m3m) |
H-M symbol: (4/m 3 2/m)
|Unit cell||a = 11.63 Å; Z = 8|
|Color||Yellow through red|
|Crystal habit||Massive to crystalline|
|Mohs scale hardness||6.5 - 7.5|
|Diaphaneity||Transparent to translucent|
|Specific gravity||4.19 calculated, 4.12 - 4.32 measured|
|Optical properties||Isotropic, often anomalous double refractive|
|Absorption spectra||Bands at 410, 420, 430 nm (or merging to form cutoff below 430 nm; also bands at 460, 480, 520 nm. Possible weak bands at 504 or 573 nm|
Spessartine, sometimes mistakenly referred to as spessartite, is a nesosilicate, manganese aluminium garnet species, Mn2+3Al2(SiO4)3. The mineral spessartine should not be confused with a type of igneous rock (a lamprophyre) called spessartite.
Spessartine's name is a derivative of Spessart in Bavaria, Germany, the type locality of the mineral. It occurs most often in granite pegmatite and allied rock types and in certain low-grade metamorphic phyllites. Sources include Australia, Myanmar, India, Afghanistan, Israel, Madagascar, Namibia, Nigeria, Mozambique, Tanzania and the United States. 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. In Madagascar, spessartines are exploited either in their bedrock or in alluvium. The orange garnets result from sodium-rich pegmatites. Spessartines are found in bedrock in the highlands in the Sahatany valley. Those in alluvium are generally found in southern Madagascar or in the Maevatanana region.
Spessartine forms a solid solution series with the garnet species almandine. 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. Spessartine, like the other garnets, always occurs as a blend with other species. Gems with high spessartine content tend toward a light orange hue, while almandine prevalence induces red or brownish hues.
Spessartine crystal from Pakistan
Spessartine on smoky quartz: Wushan Spessartine Mine, Tongbei, Fujian Province, China
Media related to Spessartine at Wikimedia Commons