Garnet var. Spessartine
Spessartine,
sometimes mistakenly referred to as spessartite, is a nesosilicate,
manganese aluminium garnet species, Mn2+3Al2(SiO4)3.
The 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, 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.
The mineral spessartite should not be confused with a type of igneous rock (a lamprophyre) called spessartite.
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